From: "Stauffer, Don (MN65)" Subject: Two questions on seismographs Date: 02 Jan 1997 15:16:07 -0600 Just subscribed to the list, so if these questions are frequent (did browse some of the FAQ, but didn't find them) please bear with me. I am intending to build a Lehman sensor. Why the double pipe upright? I am planning to use a single pipe. I've got to believe resonance of a couple of feet of galvanized water pipe is way above frequency range of interest, or am I missing something. Second, I am thinking of an EO readout. This is something like the Hall effect device in that it reads amplitude directly. Here is my idea. I will have a blade with a notch cut out of a blade of copper. ___________________________/-----------I______________ Well, that isn't the best drawing of a notch, but for ascii, gee whiz. Anyway, a photo interrupter will straddle the notch with the angled edge centered in the beam at rest. If the copper blade moves one way, it uncovers more of the beam and the phototransistor collector current will increase. Movement in the other direction will cover more of beam, decreasing photocurrent. The response will not be real linear, but can be mapped, and in these days of Excel spreadsheets, I can easily linearize the results. The angle of the notch on the operating edge will be optimized for max amplitude. If I make it a straight 90 degrees, the max amplitude will be about 0.3 mm. If I need more, the more I cant the edge the larger the full scale amplitude. Now, the question is, what max amplitude should I design the system for? I have elected to try the photo-interrupter rather than the Hall effect device because I have 25 years of EO experience, and only a couple of magnetic sensor experience, so I feel more comfortable with the EO method. Don Stauffer in Minneapolis _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: John Lucas Subject: Re: Two questions on seismographs Date: Thu, 02 Jan 1997 20:48:43 -0500 Stauffer, Don (MN65) wrote: > > Second, I am thinking of an EO readout. This is something like the Hall > effect device in that it reads amplitude directly. Here is my idea. I will > have a blade with a notch cut out of a blade of copper. > > Don't know if this will be sensitive enough to the very small dislacement but you could double the sensitivity by reflecting the beam off a mirror on the arm. Come to think about it what about bouncing a low power laser beam between 2 roughly parallel mirrors. One fixed, the other on the beam? Beam==> -------------------------- / \ /\ /\ / \ / \ / \ / \ / \ / \ / \/ \/ \ Fixed==> / ------------------- \ / \ Laser Photocell _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Jim Hannon Subject: Re: Two questions on seismographs Date: Thu, 02 Jan 97 21:06:52 -0500 Don, A discussion of EO sensor just occured on the list. Check the PSN web site for the archives http://psn.quake.net/ My instrument is made of 1.5 inch square steel tubing welded. It has only one upright column. The resonances are way up there but when you are dealing with microinch movements things get a little rubbery hence the overkill on stiffness. The EO sensor is what I am working on also. You will need all the sensitivity you can get out of the thing. So a straight notch would be best. I also reccomend using a differential sensor. Two phototransistors or whatever one being covered while the other is being uncovered. Both half covered when centered. Feed this into a differential OP amp. You get 6 dB more sensitivity with only about 3 dB more noise with this arrangment. Karl Cunningham on the list has a EO machine running and is having trouble with noise from the sensor. We are dealing with microvolts for output here. Someone else suggested using a CDS cell for the detector. Having worked with EO sensors do you have any suggestions for low noise? PIN diodes? Both Karl's and my instruments use magnetic feedback to keep things centered. Because you are reading displacment rather than acceleration or velocity long term drift will peg out things if you don't have some way of correcting for the drift. Good luck! Jim Hannon _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Karl Cunningham Subject: Re: Two questions on seismographs Date: Thu, 02 Jan 1997 23:45:54 -0800 Greetings, Don I didn't understand all of the details of your detector, but IMHO the most important thing to concentrate on is signal-to-noise ratio. So long as you're in the right ballpark, sensitivity-wise, you can play games getting the sensitivity to what you need with optical techniques. For instance, with an analog output range of 20 volts, a noise level of 5mV will give you 4000:1 signal-to-noise ratio. This is 12 bits, which is ok but nothing to write home about. Remember, the earthquake magnitude scale is logarithmic with respect to amplitude, and if you want to cover much magnitude range, things go from big to small *very* quickly. I too believe that a differential approach is the only thing that will give you a chance of overcoming temperature effects of these detectors. I am currently struggling to do better than 12 bits (without a lot of success, I might add). I've played with photo transistors, CdS cells, high-power LED's, various photo masks/slits, and am about to order a laser diode. (I'd welcome any other ideas). My current breadboard has a full-scale (20-volt) output for about a 0.004" movement or so. I'd like to get to a signal-to-noise ratio of 16 bits, with a noise floor of 10 nanometers or less. Right now I'm at about 40-50 nanometers. I like John Lucas' idea of bouncing the laser off off parallel mirrors. I've also thought about having a lens on the moving arm with the laser beam going through the lens. WRT the Lehman mechanical system, keep in mind the order of your low-pass filter and the natural frequency of the mechanical system. Even if your vibration is 50db down in the passband of interest, there can be a lot of vibration at higher frequencies that could get amplified if your mechanical system has a high Q. Several years ago, I had a high-frequency (5Hz to 30Hz) seismic detector running at work just for fun (it was originally made to detect people walking), and during the day it would record a lot of noise. I finally tracked it down to a forklift working across the street in a warehouse about 200 feet away. I don't think it would have contributed much in the range of 0.1Hz to 1Hz, though. Keep us informed on your progress (or even lack of it). Karl Cunningham La Mesa, CA. karlc@......... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Larry P. Thomas WA0GWA" Subject: Interesting IC for EO sensors Date: Fri, 03 Jan 1997 08:51:56 -0600 I say this on another SIG dealing with PIC microprocessors and thought it might be of interest to those working on EO type sensors Documentation inf form of pdf files is at http://www-s.ti.com/sc/psheets/soes012/soes012.pdf >The other interesting chip is the TSL23x series of light to frequency >converters. I do not have an appropriate data book so the question is >what is the difference between the TSL230 and TSL235? What TI book contains this information? The 235 is a fixed output version of the 230. The 230 is pin programmable for output frequency scaling and light sensitivity. The 235 is 3 lead 230 device with the sensitivity and output scaling preset by TI. Vcc, Gnd, and Fout about 10Hz to 500kHz 50% duty square wave. All of TI optic sensors are described in the TI Intelligent Optic Sensor databook. I don't have the Book # with me but I cat get it at work if you need it. TI's web site also contains the information. ----------------------------------------------------------------------- Larry P. Thomas wa0gwa voice : 1 913 888-0282 Krell Technologies fax : 1 913 782-9359 8960 Bond pager : 1 816 989-HELP Overland Park, KS 66214-1764 e-mail : lpthomas@................ www : http://www.krell.com ----------------------------------------------------------------------- _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Karl Cunningham Subject: Re: Interesting IC for EO sensors Date: Fri, 03 Jan 1997 08:51:01 -0800 Larry -- Thanks for the tip. I've got a few samples of these devices (both IR and visible) and have played with them a little, but haven't tried to make a detector out of them. The noise seems to be quite good on the bench, but I haven't been able to come up with a good idea for a frequency counter to operate in the range of these devices (0-500kHz) that will have the dynamic range, signal-to-noise ratio, and bandwidth (I'd like to get at least 20Hz update rate). Actually I've got one idea, but it's not very practical. Count frequency and accurately measure the time it takes to count that frequency. Divide the number of counts by the time period and you have frequncy. That sounds like a large project all by itself. Any ideas on this? Karl Cunningham La Mesa, CA. karlc@......... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Jim Hannon Subject: Re: Two questions on seismographs Date: Fri, 03 Jan 97 19:20:04 -0500 Don, The major source of drift is mechanical. I can leave my instrument balanced and overnight it will drift a 1/4 inch or so. This all somewhat depends on the period you set the instrument up for, anything longer than 15 seconds and things get real touchy. With a differential EO sensor almost all of the drift associated with the sensor is canceled out. The other problem with the digital HPF is that having the headroom for the drift in the A/D converter range limits the dynamic range the overall system can have. Jim Hannon -------- REPLY, Original message follows -------- CdS cells would not make a very low noise detector, in my opinion. I want to use the photo interrupter because the path is very short. Thus, the phototransistor is working at a high SNR. For drift I plan to use a digital high pass filter with about a minute or so time constant. This will not compensate for physical drift of the edge, but will zero out shifts due to shift in operating point of photo- transistor. Do I need to worry about zeroing out mechanical drift in the unit? One of the reasons I have elected to go with the transistor rather than the photodarlington is to reduce such semiconductor drift. -------- REPLY, End of original message -------- _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: ct@....... (Charlie & Terri Thompson -- Buda MicroRanch ) Subject: Photodiodes and noise Date: Fri, 03 Jan 1997 22:14:01 -0600 I wanted to comment on electronic noise analysis using photodiodes. Several years ago I designed a 20-bit A/D converter chip for direct connection to a precision photodiode. The application was medical CAT scanners and the CAT scan imaging guys love dynamic range and LOW noise. In my opinion, Hammamatsu makes some of the best precision photo diodes on the planet. They are well specified for noise. Try to get a Hammamatsu photodiode catalog and you will learn at lot about theoretical noise limits in photo diodes. This approach is the lowest noise way to detect modest levels of light (detectable by the human eye). The key items to consider for theoretical best case noise analysis are: 1) Shot noise RMS current - this is fundamental to silicon photodiodes and goes as SQRT(2*Q*I*BW) where Q is the charge on an electron I is the photodiode current and BW is the bandwidth in Hz. The higher the operating current the better the signal-to-shotnoise ratio. Why?... the photo current goes directly as light level but shot noise only increases as the square root. 2) Input amplifier thermal noise current - JFET inputs help keep thermal noise current to a minimum. MOSFET input devices would be better but their 1/f noise is BAD NEWS! A chopped MOSFET input circuit can avoid the lousy 1/f noise problem. 3) Transimpedance resistor thermal noise current - photodiodes exhibit minimum drift when they operate into a virtual ground. (i.e. no voltage across them). This implies they normally would be connected to an op-amp summing node with the op-amp operating in the "trans- impedance" mode (also called a current-to-voltage converter). The resistor from the output back to the inverting input sets the current to voltage conversion scale factor (called the transimpedance). This resistor (all by itself) produces an input-referred RMS thermal noise current equal to: SQRT(4*kTR*BW) where k is Boltzman's constant, T is about 300K at room temp and BW is bandwidth in Hz. The goal is to "RMS sum" the noises in items 1-3 above. On item #1 you determine the shot noise current when you set the amount of light shining on your photo diode for the resting state of your seismometer. On item #2 find an op-amp with LOW thermal noise current...make sure it's specified in the .01Hz to 5 Hz range and make sure input-referred 1/f thermal noise voltage doesn't swamp your noise current contribution. On item #3 you set the thermal noise current by choice of the current-to-voltage conversion scale factor. Sum up items 1-3 as the square root of the sum of the squares. If you are wondering about 1/f noise VOLTAGE...you can input-refer it as a current by dividing the 1/f noise spectral density by the transimpedance resistor. This will give you a 1/f noise current spectral density "at a given frequency" ..i.e. like 1Hz. You can then get the total input referred noise current due to 1/f noise voltage by doing a simple integral over the bandwidth of interest. The TLC2202 has a very low input referred 1/f noise spectral density (for a MOSFET op amp at least!). It's about 60 nV/rt-Hz at 1 Hz. This is plenty low for most applications if your photo current is in the microamp range. So there you have it...you can now predict the electronic noise and compare it to your change in current for a 1 micron RMS pendulum displacement and figure out your signal-to-noise ratio. I have designed photo diode systems that come within about 1 dB of predicted using the above analysis. All-in-all the coil and magnet ain't bad! -Charlie Thompson _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Jim Hannon Subject: Re: Photodiodes and noise Date: Sat, 04 Jan 97 08:23:20 -0500 Thanks Charlie for the photodiode information. Low noise is also important in fiber optic systems where you are trying to cram as much signal bandwidth into as long a cable as possible. A number of years ago I did read up on this in the HP photodiode catalog when looking into the design of a fiber system. Now all we have to do is figure out if the LED contributes any to the noise or should we use an incandesent lamp? Jim Hannon _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Jim Hannon Subject: EO Sensors Date: Sat, 04 Jan 97 19:20:09 -0500 Another idea that might help with the sensor noise problem. That is to use a chopper stabilized amp. but do the chopping right in the sensor by turning the LEDs on and off alternatingly. A lot of noise could be stripped off with a bandpass filter before the demodulator. Jim Hannon _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Don Gentry Subject: Re: Interesting IC for EO sensors Date: Sun, 5 Jan 1997 06:44:05 -0800 (PST) Most off the shelf frequency counters have a function to measure period directly. This is the recipical of frequency. Don't know if it would be usefull at low frequncies or not. This function is normally used when looking at high rate signals and output ranges would be in micro-seconds or milli-seconds. If your output is nearly a square wave it may be able to do what you want. This would give a nice rise time to use to start the period count. I'm out of ideas at this time. Jose' On Fri, 3 Jan 1997, Karl Cunningham wrote: > Larry -- > > Thanks for the tip. I've got a few samples of these devices (both IR and > visible) and have played with them a little, but haven't tried to make a > detector out of them. > > The noise seems to be quite good on the bench, but I haven't been able to > come up with a good idea for a frequency counter to operate in the range of > these devices (0-500kHz) that will have the dynamic range, signal-to-noise > ratio, and bandwidth (I'd like to get at least 20Hz update rate). > > Actually I've got one idea, but it's not very practical. Count frequency > and accurately measure the time it takes to count that frequency. Divide > the number of counts by the time period and you have frequncy. That sounds > like a large project all by itself. > > Any ideas on this? > > > > Karl Cunningham > La Mesa, CA. > karlc@......... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Karl Cunningham Subject: Re: Photodiodes and noise Date: Sun, 05 Jan 1997 10:54:11 -0800 Hi Jim -- At 08:23 AM 1/4/97 -0500, you wrote: >Now all we have to do is figure out if the LED contributes any to >the noise or should we use an incandesent lamp? When I had two LED's and two phototransistors in a differential configuration, I tried spraying most of the parts (one at a time) with freeze spray. The most change was when I sprayed either of the LED's. That's when I decided that I should be using one LED and two phototransistors (differentially connected). Karl Cunningham La Mesa, CA. karlc@......... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "George A. Harris" Subject: Re: Novel feedback seismometer Date: Sun, 5 Jan 1997 14:03:36 -0800 (PST) For some time I have been investigating seismometer mechanisms. I am just finishing one which is similar to those being discussed recently. Following is a brief description of the construction. If there is enough interest, I could make up a packet of info. to be provided at some nominal fee. The unit makes use of a novel suspended mass which I have successfully used previously. The complete force balance two axis sensor is contained in a cylinder 1 1/2 inches in diam. and 5 inches high. Starting from the base, the construction is as follows: A base supports a short length of brass or other small tubing. It also supports a 5 inch length of 1 1/2 inch plexiglas tube surrounding the small tubing to enclose the assembly. Crimped into the top of the small tube is a length of fine wire. I use .011 in. hardened beryllium copper, but music wire of similar diameter will work. One inch up the wire, another two inch length of small tubing is crimped. To the top of this is attached a ceramic magnet 1/2 inch in diam/ and 1/4 inch thick with a flat upper surface. A one inch disk of thin bright aaluminum with a flat black target pattern on its upper surface is cemented to this flat magnet surface. When the wire length and weight at the top are properly sized, the assembly is barely stable, and will have a natural frequency near 1 Hz when accelerated or tipped in any direction. It is very tilt sensitive, and must be partially supported until vertical (the plexiglas tube does this). The plexiglas tube supports a plastic cylinder one inch high above the target. This cylinder is wound with two coils at right angles from its top to bottom. My coils have 600 turns of #38 wire each. When these coils are placed within 1/8 inch of the magnet, they will support the magnet when it is tipped about 12 degrees with 60 Ma flowing. Thus the range of the unit is approximately + or - .2G. Two sensors are mounted in holes in the plastic coil cylinder. They are a electro-optic unit manufactured by Omron, their EE-SY124. The LED source and transistor are side-by-side in a 4 lead dip which is approximately 1/8 inch square. When used with a black edge on shiny surface 1 mm away it produces a very linear signal for 1/4 mm motion. The output is near 3 volts into a 100K resistance in an emitter follower configuration when looking at the shiny surface with 4 MA drive to the LED. The sensors are stocked by Digi-Key (800-344-4539 their part OR520-ND) for less than $2 each. The present amplifier consists of a type LMC660 quad op-amp followed by type lm386 low voltage audio power amplifiers. Each axis uses two of the op-amps followed by two of the 386's in a push-pull circuit to drive each coil. A simple RC lead network provides damping. With proper gain settings, the output of the first amplifier has a 0-5 V. output corresponding to + and - .2G. George Harris harris@........ _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Mark Wilson mark@.............." Subject: Laser and fiber optics Date: Sun, 5 Jan 1997 14:30:40 -0800 (PST) I have some plans for a fiberoptic pickup unit using a fiberoptic thread coiled around 4 posts. The output is the attenuation of the light through the cable. Has anyone else tried this? I have airblown fiber cable ready to try but was wondering if it worth the effort. ********************************************************************* --- mark@.............. --- http://www.markwilson.com --- wilsonm@............ --- wilsonm@.............. --- mark.wilson@....... --- General Networking Dude and Routing Rugrat ********************************************************************* _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Robert L Barns <75612.2635@..............> Subject: Ground motion amplitude Date: 06 Jan 97 10:22:26 EST Hi gang, On Jan 2, Don Stauffer asked about what amplitude of ground motion should be considered when designing a seismometer. I found a highly enlightening bunch of info on this in 'Quantitative Seismology' vol.1, by Keiiti Aki and Paul Richards, Freeman & Co. 1980, p 493--. Barnes & Noble (a deviant spelling) report that these books are no longer in print. My comments in [ ]. I can't improve on Aki and Richards wonderfully clear exposition so I'll just quote them. "Sec 10.2.1 Surface waves with periods around 20 secs. "The most prominent signals recorded by a standard long-period seismograph, especially classical mechanical ones, for a distant shallow earthquake are surface waves with a period around 20 sec. Body waves show smaller amplitude because of stronger geometrical spreading than surface waves. The surface waves with periods less than about 10 or 15 sec suffer from scattering due to shallow heterogeneities. The attenuation of surface waves is minimal at about 20 sec, because those with periods longer than 25 sec begin to lose energy into the asthenosphere. Besides, the magnification of standard seismographs decreases with periods of more than 20 sec. It was quite natural, therefore, that a magnitude scale Ms was introduced by Gutenberg and Richter (1936) based on the surface wave amplitude at a period of 20 sec. (See Appendix 2, p. 533.) "Fig. 10.8 shows the amplitude of surface waves from a shallow earhquake with magnitude Ms = 3 as a function of epicentral distance. The curve is obtained from the table given by Richter. [Fig 10.8 shows a curve of the log of amplitude in microns vs epicentral distance in degrees. It is almost linear. ] The most sensitive long-period seismometer can detect a distant earthquake with Ms ~3, which will show an amplitude of 100 millimicrons (1e-5 cm) at dist = 20 deg and 10 millimicrons at dist = 80 deg. On the other hand, the largest earthquake (Ms = 8.5) will show an amplitude of several cm at dist = 20 deg and several mm at 80 deg. This large signal dynamic range (1e-6 to 1 cm) imposes heavy demands on seismic instrumentation and recording media (See Box 11.1). "As described in Sec. 10.1, there are three basic sensors that can be used in seismology: the inertial sensor, which is sensitive to acceleration; the strainmeter, which measures the strain in the Earth beneath it; and the gyro, which has the potential for measuring rotation. It is instructive to give the value of acceleration alpha, strain epsilon, and rotation theta associated with the 20-sec surface waves from a small earthquake, say Ms ~3. For plane Rayleigh waves with period 20 sec, phase velocity 3.5 km/sec, and displacement amplitude 0.1 micron, we have alpha ~ (2*pi/20)^2 * 1e-5 cm/sec^2 ~ 1e-6 gal = 1e-9 g [ ~ is 'approx. equal' ] epsilon ~ (2*pi)/(3.5*1e-5*20)*1e-5 ~ 1e-11 theta ~ epsilon = 1e-11 ~ 2*1e-6 arc-sec "Large explosions, such as an underground nuclear test, can also generate 20-sec surface waves with amplitude approx. proportional to the yield. A 1-megaton shot in hard rock roughly corresponds to Ms ~ 5 3/4 and thus the most sensitive long-period seismometer will detect a distant shot of several kilotons (corresponding to Ms ~ 3). "Sec 10.2.2. P-waves for dist 5 deg to 110 deg. "The signal level of P-waves from a distant earthquake may be found from Gutenberg's calibration curve (see Richter, 1958, p 688) for determining the body-wave magnitude mb. Fig. 10.9 shows the value of A/T as a function of epicentral distance, where A is the amplitude in microns and T is the period in sec for a shallow earthquake with mb = 4. This curve can be used to find mb for any shallow earthquake, as mb = log(A/T){obs} - log(A/T){mb=4} + 4 where (A/T){obs} is the observed value of A/T at a certain epicentral distance (which must be known) and (A/T{mb=4} is the value obtained from Fig. 10.9 for the distance. [The curve in 10.9 is wiggly especially below 30 degrees.] For P-waves recorded by standard seismographs, T is usually around 1 sec, and the amplitude is about 10 millimicrons at dist = 20 deg and 1 millimicron at dist = 90 deg for mb = 4. These signals may be detected by the most sensitive short-period seismometers. The greatest earthquake (mb ~ 8) will show A/T of 1mm/sec at dist = 20 deg. For such large earthquakes, T may be about 10 sec, and the amplitude on the order of 1 cm. Again, we see a requirement for large dynamic range from 1e-7 to 1 cm. [Even a 16-bit A/D converter has a dynamic range of only 65,000. Vol. 2, p 573 describes seismology as used in oil exploration. They use seismographs which have electronic binary gain controls on their amplifiers, i.e., when the signal rises above a certain level, the gain is reduced by a factor of 2 until another level is seen when the gain is again reduced by a factor of 2, etc. When the signal level falls, the gain in increased. They get a dynamic range as large as 170db! The electronics to do this are simple. You Californians and New Zealanders might benefit from this scheme] "The 1 millimicron displacement at T =1 sec corresponds to an acceleration of 4*1e-10 g. and to rotations and strains of around 1e-12." The next section (10.2.3) discusses amplitude as a function of frequency but I'm getting tired of typing so get your local library to do an inter-library loan for you. Sec. 10.2.5 is "Ambient seismic noise." This is of special interest to me since I see far more of that than quakes--New Jersey being a seismic desert. Curves are given which show rapid changes in spectral noise density with frequency and a factor of 100 between 'quiet' and 'noisy' locations. There is a fairly sharp minimun around 0.03 Hz and a sharp max. around 0.13 Hz. Wind and esp. ocean waves are the main causes of the noise. The first part of Chapter 10 is an excellant discussion of the mechanics of seismometers and, of course, detailed mathematical analysis of these things. An interesting statement here: "Since the sensitivity of a pendulum to acceleration at low frequency is proportional to the square of its free period,...". Well, I'm still digesting all this and trying to relate the quantitative aspects to what my calibrator and Lehman give. Bob Barns Berkeley Heights, NJ _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Jim Cristiano Subject: Re: Laser and fiber optics Date: Mon, 06 Jan 1997 08:25:23 -0700 Mark Wilson mark@.............. wrote: > > I have some plans for a fiberoptic pickup unit using a fiberoptic thread > coiled around 4 posts. The output is the attenuation of the light through > the cable. Has anyone else tried this? > I have airblown fiber cable ready to try but was wondering if it worth the > effort. Mark, I've seen reference to this fiber optic seismo device a while back in a mag called Science Probe!. I think Forrest Mims' son used it in a science project. I also have plans that came from a science project book on how to make one. I think it would be hard to get usefull information from this device because of the differing resonant frequencies of the separate fiber optic loops. The frequencies would also be very high. Maybe if you had ONE fiber being bent by the business end of a horizontal boom? Jim Cristiano cristiano@........... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Blatchley, Brett" Subject: Re: Laser Seismology... Date: Mon, 6 Jan 1997 13:00:27 -0500 > I have some plans for a fiberoptic pickup unit using a fiberoptic thread > coiled around 4 posts. The output is the attenuation of the light through > the cable. Has anyone else tried this? > I have airblown fiber cable ready to try but was wondering if it worth the > effort. There is a chapter entitled "Experiments in Laser Seismology" in a book called "The Laser Cookbook: 88 Practical Projects" by Gordon McComb, ISBN 0-8306-9390-4, TAB Books, $19.95. It walks you though building a laser/fiberoptic seismometer. This is a great book to have on hand, but the author does not go much into how he calibrated this unit. As I understand it, the magnitude of acceleration is proportional to the audio frequency of the change in interference fringes (at the output of the fiber as "read" by a photo diode/transistor). I'm not concerned with the sensitivity of this design as much as its apparent omni-directional view. I.e. I think you can get useful data from it. >>think it would be hard to get useful information from this device because >>of the differing resonant frequencies of the separate fiber optic loops. The >>frequencies would also be very high. If you want more accurate data, I think a ring-laser is the thing to build. Here you are actually counting phase changes (interference fringes) which are measurably stable because the laser light remains coherent throughout its trip (unlike the fiber optic unit above). I.e. every light to dark transition at the output is one wavelength, and since you know the laser's wavelength, the rest is arithmetic. Here is a good URL to get you started on ring-lasers: www.phys.canterbury.ac.nz/research/ring_laser/ring_laser.html This is my first contribution, I'm enjoying your thoughts :-) ------------------------------------------------------------------------ -- Brett Blatchley, Senior Computer Engineer INMAR Enterprises, Inc. 910-631-2825 voice 910-631-7703 fax ------------------------------------------------------------------------ -- _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Stauffer, Don (MN65)" Subject: Baseplate material? Date: 06 Jan 1997 12:59:34 -0600 In working on the design for my seismograph, I am looking for suggestions on the baseplate. One mechanical guru here at work is trying to convince me to use steel plate. My problem with that is getting steel plate locally without a hundred buck minimum. I was thinking of particle board with sheet metal glued top and bottom to make a sandwich, but he talked me out of that. I am making a two-axis sensor with each arm just shy of 2 feet in length, so I need a stable baseplate about 24 x 24 inches. Or, an L-shaped plate 24 inches on a leg. Any suggestions on a material that is readily available to the hobbyist? Don _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Karl Cunningham Subject: Re: Baseplate material? Date: Mon, 06 Jan 1997 11:22:06 -0800 Hi Don -- Look in the yellow pages under Metals. In cities of moderate size, there are usually surplus dealers that are willing to cut pieces for you (for a small fee) and have small (<$10) or no minimums. Some places have cutoff bins full of all shapes and sizes and you save the cutting charge. Another option is to look for surplus electronic equipment and find something with a chassis similar to what you want. I've used aluminum ($1.50/lb surplus) for most of my projects. It has a worse temperature coefficient of expansion that steel, but it doesn't rust and is easy to drill and tap. :) Just some thoughts. Karl Cunningham La Mesa, CA. karlc@......... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: ct@....... (Charlie Thompson) Subject: Re: Baseplate material? Date: Mon, 06 Jan 1997 14:22:57 -0600 Don't use ANYTHING that will be affected by humidity. I tried a wood base plate and the unit became a hygrometer as well as a seismometer. Steel or other humidity insensitive material would be the best material for the baseplate and upright. Tiny changes on the 'shape' due to humidity will cause you to have to readjust your sensor with each passing weather front. My steel baseplate stays adjusted nicely. Steel gets my vote. -Charlie Thompson .BUE > In working on the design for my seismograph, I am looking for suggestions >on the baseplate. One mechanical guru here at work is trying to convince >me to use steel plate. My problem with that is getting steel plate locally > without a hundred buck minimum. I was thinking of particle board with >sheet metal glued top and bottom to make a sandwich, but he talked me out of >that. > >I am making a two-axis sensor with each arm just shy of 2 feet in length, so >I need a stable baseplate about 24 x 24 inches. Or, an L-shaped plate 24 >inches on a leg. > >Any suggestions on a material that is readily available to the hobbyist? > >Don > > > >_____________________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email listserver@............. with the body of the >message: leave PSN-L > > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: George Bush Subject: Re: Baseplate material? Date: Mon, 6 Jan 1997 12:29:24 -0800 (PST) Don- At 12:59 PM 1/6/97 -0600, you wrote: > In working on the design for my seismograph, I am looking for suggestions >on the baseplate. One mechanical guru here at work is trying to convince >me to use steel plate. My problem with that is getting steel plate locally > without a hundred buck minimum. I was thinking of particle board with >sheet metal glued top and bottom to make a sandwich, but he talked me out of >that. > >I am making a two-axis sensor with each arm just shy of 2 feet in length, so >I need a stable baseplate about 24 x 24 inches. Or, an L-shaped plate 24 >inches on a leg. > >Any suggestions on a material that is readily available to the hobbyist? > I am planning on casting a simple slab from concrete for the base of my 3-axis (Amatuer Scientist) seismometer. You may want to go this route also. It is inexpensive, uses readily-available materials, is easy to cast, can be made any shape and can be made as massive as you want. George _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: bob@................. (Bob Hammond (USGS-AVO Geophysicist)) Subject: Re: Baseplate material? Date: Mon, 6 Jan 1997 11:30:49 -0900 I would suggest you look at thick PVC plastic. I used to be able to buy PVC plate as thick as 2 inches. Maybe putting two 2-inch PVC plates together would avoid the humidity problems and be less expensive than steel. The PVC was very stiff but easy to work with ordinary tools. Bob Hammond _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Al Allworth Subject: Re: Baseplate material? Date: Mon, 6 Jan 1997 22:35:12 -0800 At 12:59 PM 1/6/97 -0600, you wrote: > In working on the design for my seismograph, I am looking for suggestions >on the baseplate. I would like to suggest two pieces of railroad rail mounted on three bolts each mounted in concrete, in the form of an "L". The three bolts (2 at one end separated as far as possible and one at the other will let you adjust each sensor separately for mechanical balance. Rail is often available from the railroads as surplus, sometimes lying around their yards. Some people like to use it for fireplace andirons or truck bumpers. I have seen short lengths lying around in lots of places I have been. btw 3/8 threaded rod would be fine for the bolts. ____________________________________________________________________________ Al Allworth. Pasadena,CA aallworth@........ _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: ct@....... (Charlie & Terri Thompson -- Buda MicroRanch ) Subject: USGS missed two events! Date: Mon, 06 Jan 1997 22:08:08 -0600 The first event missed by USGS was on 1/4/97 at 3:36 UTC. I just ignored the fact that they didn't report the approx. M5.3 event located 1300 miles from Buda, TX (probably near Chiapas Mexico). Then USGS missed a second event approx M5.1 on 1/4/97 at 18:44 UTC also about 1300 miles from Buda, TX. (probably Chiapas again). I know I'm closer to Mexico than the USGS sensors but normally they have detected and reported events of this size in the past...what gives? Was USGS "down" part of the day on 1/4/97?? I have detected 3 additional events with the same epicenter in Mexico and they correlated nicely with past USGS reports. All of the events were approximately 1300 miles from Buda, TX near Chiapas, Mexico. Any clues appreciated. -Charlie Thompson .BUE _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Dott. Roberto E. Pozzo" Subject: seismic equipments used in Italy Date: Wed, 08 Jan 1997 03:59:54 +0100 Hello to all the list ! I'm on psn-list from three months (+or-). Until now, I was a 'good listener' of your very interesting (& useful) exchange of ideas and experiences on amateur seismology. Here in Italy, although here seismicity is one of the highest in Europe, amateurs are not many ( and more or less unconsidered by officials) . A dozen of us, in last four years , have developed a three period seismographic station , based on a kit published years ago by a magazine of electronics and more and more times improved and changed in circuitry by us. Essentially it is, a long-period horizontal seismograph with electromagnetic coils (with oil damping in the simplest version) linked on a op-amp circuit that drives analog signals (+or- 5v) to a first AD converter . The same thing makes our vertical sensor ( t= 1 sec.) Another equipment allows triggered or continuos printing on a high speed thermal printer at a max speed of 120 cm/hour ( 48 inches /hour )and ,finally, drives signals to a datalogger based on an AD-card and dedicated software that shows on pc screen three traces at a time and allows storage on hard disk or floppy disk ( unfortunately, using an average rate of 30 samples per second , we have a file of about 2 Mbytes in 24 hours, and so our life goes on changing diskettes !!) . Recently ( thanks, Larry Cochrane and Ted Blank ) we have reached the winquake-compatibility on our recordings , so final result is good. We preconize to use EMON or SDR on our equpments as soon as possible ( sending one of our pc-cards to U.S.A. for compatibility tests is not simple like drinking a cup of water !!). Our precison clock (connected on serial port of pc and synchronizing pc clock) is based on DCF-77 standard emission from Mainflingen (Germany) and works so and so ( LW reception is affected by a lot of disturbances, more part of them 10 minutes before a quake ! The radiocontrolled clock stops, jammed by some propagation noise, the recording shows strange times (like 34:21 am :-) ) and earthquake comes a while after !!! Mr. Murphy lives in Italy.Don't you know ? If someone of you is interested , we can mail some schematic plan and other infos about our complete system. We also collect ,naturally, complete reports on seismicity in Mediterranean area. Final remark: I live in Piedmont region,near Turin , on January weather is snowy and moderately cold. Another cold front is passing and my long period shows one-inch waves..... regards Roberto _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: cougercat@........... Subject: Re:seismic equipments used in Italy Date: Tue, 7 Jan 97 21:04:18 PDT Greetings Roberto; In regaards on details on your seismometer, I'd like a copy of the details. Currently, I'm working out the bugs (lots of them...;} on a XYZ detector using the Analog Devices ADXL05 series of tri-axial accelerometers. Thanks; Jeff Chang 2235 22nd Ave East Seattle, Washington 98112 U.S.A. FAX # [206] 325 0307 P> If someone of you is interested , we can mail some schematic plan and P> other infos about our complete system. We also collect ,naturally, P> complete reports on seismicity in Mediterranean area. ******************************************* * mail from Jeff - cougercat@........... * ******************************************* _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Dott. Roberto E. Pozzo" Subject: Re: seismic equipments used in Italy Date: Thu, 09 Jan 1997 01:45:04 +0100 Jeff, yes, I'll send to you some material dealing with our seismic system. Please, be patient....I'm preparing it . A few days again and I hope it will be ready to send .Many compliments for your good sperimentation on tri-axial accelerometers. Let me know how your work goes on. Here in Italy we can obtain some accelerometer (u.s.a.f. surplus) for a cheap price.Some time ago, I was tempted to purchase one or two of that devices . What do you think about aeronautical accelerometers ? You live in Seattle and Boeing Co. is not too far ! :-) Roberto _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: cougercat@........... Subject: Re: seismic equipments used in Italy Date: Wed, 8 Jan 97 20:43:45 PDT P> Organization: osservatorio meteosismico del monferrato Hi Roberto; Thanks for your reply. Yes Boeing's is here but I have not been able to pick up any decent accelerometers from them. The accelerometer that I am experimenting around was made for the airbag industry. They have a span of +- 4 g's, Sensitivity is 500 mV/g, Bandwidth is DC - 100 hz or anything between, Supply voltage/current 5/24 ma. Almost ideal for portable use. The August 8, 1991 issue of Electronic Design carried an good artical on them. These were sampled for another project that didn't get off the ground from Analog Devices. The bochure says the European phone # is +89 57005 0 .....Perhaps you can get ahold of them and see if they will send you a sample or 2. I'll keep you posted. --Jeff ******************************************* * mail from Jeff - cougercat@........... * ******************************************* _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: ACole65464@....... Subject: Nova TV Program: EQ Prediction and Preparedness Date: Thu, 9 Jan 1997 02:28:29 -0500 (EST) Last night here in the Seattle area the local PBS station aired an old NOVA program regarding earthquakes, and compared the quakes of Kobe Japan and Los Angeles. But what I wanted to point out, to some in our group, was the type of seismometer that they showed in an underground vault in California, contained in a glass jar. It was a Streckeisen STS-1 vertical seismometer. I only recognized it after recently coming across a description of it in an old "Bulletin of the Seismological Society of America", Dec 1982. The TV program's narrator described the seismometer only as a Swiss made instrument. The BSSA's paper described the instrument well but seeing a video of it was good because it showed an actual installation. The instrument, one for each axis, is only 180mm x 180mm x 120mm. The two horizontals have the usual styrofoam covers etc but vertical is mounted within a glass bell jar that is evacuated down to 10 mbar (that reduced the internal thermal problems). The silver container seen within the glass jar is an aluminum and "Permalloy" cover over the instrument to form both an RFI and magnetic shield. The designers used an LVDT for the displacement transducer (so when we get tied of trying to get our photo-optical type devices to work lets experiment with an LVDT). Their instruments are capable of resolving ground noise from .1 to 3000 seconds and displacement to 10xE-10 meters peak-to-peak, WOW! Also on this same program they showed the small accelerometer used to activate automobile air bags, another device that we have heard people talk about on this network, that many of us have not seen. I hope you have, or had, a chance to see this NOVA program. Regards, Allan Coleman _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Robert Mathieson Subject: Re: Nova TV Program: EQ Prediction and Preparedness Date: Thu, 9 Jan 1997 08:22:33 -0600 (CST) At 02:28 AM 1/9/97 -0500, you wrote: > Last night here in the Seattle area the local PBS station aired an old >NOVA program regarding earthquakes, and compared the quakes of Kobe .... > > The designers used an LVDT for the displacement transducer >(so when we get tied of trying to get our photo-optical type devices to work >lets experiment with an LVDT). gram. > > Regards, > Allan Coleman > What is an LVDT? Thanks. Robert Mathieson Culver-Stockton College Canton, MO 63435 (217)233-6000 rmathieson@.......... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Larry P. Thomas WA0GWA" Subject: LVDT Date: Thu, 09 Jan 1997 08:58:39 -0600 >What is an LVDT? Linear Variable Differential Transformer. Basically it is a cylinders with typically three coils on it. The outside two feed a diode detector (or better yet a synchronous detector) with one producing a positive voltage and the other producing a negative voltage. These signals are summed (i.e. differential) to produce the output. The center coil is feed with the excitation voltage. A magnetic material suitable for the frequency of the excitation voltage is allowed to slide within the cylinder this differentially will increase the coupling to one outside coil while reducing it in the other outside coil. This is a very basic explanation of its operation. I'm sure there are things that can be don to improve it's performace for very small displacements as would be found in seismic applications. ----------------------------------------------------------------------- Larry P. Thomas wa0gwa voice : 1 913 888-0282 Krell Technologies fax : 1 913 782-9359 8960 Bond pager : 1 816 989-HELP Overland Park, KS 66214-1764 e-mail : lpthomas@................ www : http://www.krell.com ----------------------------------------------------------------------- _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Jim Hannon Subject: Re: LVDT Date: Thu, 09 Jan 97 19:59:21 -0500 I started on a LVDT design a while back. Did some reading on them. Found out that the commercial ones are very expensive usually made for aerospace applications so I built the transformer and mounted it on my seismograph. I used a ferrite bead for the core and a delrin bobbin to wind the coils on. It has some 3/4 inch conduit for an outer shield. Linear has a IC that does all the support electronics for the transformer. I have two samples. Then I got switched over to thinking about the Opto sensor. I had got as far as feeding a sine wave into the coil and watching the output on a scope as the seismograph arm swung. One thing about the LVDT is that it should be very linear especially for small displacements. Once I get my workshop back together I suppose I will end up trying both sensors. Jim Hannon _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Al Allworth Subject: Request for input Date: Thu, 9 Jan 1997 22:17:26 -0800 I have recently retired (12 days ago) and have been considering interesting projects to become involved in. I am looking at the possibility of designing a seismometer kit. What do you think? I am an electronics design engineer (analog and digital) and a machinist. I have purchased equipment for a machine shop, 2 lathes, a milling machine, and a surface grinder and will be moving from Pasadena to southern Oregon in the spring. After moving and setting up the shop, and of course getting my own seismo equipment up and running, I would hope to get something started. This gives some time for planning projects so I thought I would ask for opinions on this list. I don't know of a better place. ____________________________________________________________________________ Al Allworth. Pasadena,CA aallworth@........ _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Robert Avakian Subject: Re: Request for input Date: Fri, 10 Jan 1997 02:20:26 -0800 Al Allworth wrote: > > I have recently retired (12 days ago) and have been considering interesting > projects to become involved in. I am looking at the possibility of designing > a seismometer kit. What do you think? > > I am an electronics design engineer (analog and digital) and a machinist. I > have purchased equipment for a machine shop, 2 lathes, a milling machine, > and a surface grinder and will be moving from Pasadena to southern Oregon in > the spring. After moving and setting up the shop, and of course getting my > own seismo equipment up and running, I would hope to get something started. > > This gives some time for planning projects so I thought I would ask for > opinions on this list. I don't know of a better place. > ____________________________________________________________________________ > > Al Allworth. Pasadena,CA aallworth@........ > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L As a teacher, it sounds great IF you can get the cost down to say $200-300 per kit. That would mean a full station would cost a school LT $1000 if you made both horizontal and verticla machines. That price should turn almost any earth science teacher's head. You'll need good documenation and support literature, though. Not many of us have geophysics, EE or similar degrees. Bob Avakian Midland TX _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Stauffer, Don (MN65)" Subject: LVDTs Date: 10 Jan 1997 07:48:16 -0600 One thing to watch with LVDTs is temperature coefficient of core materials. The most likely result would be scale factor error with temperature, but if the magnetic circuit is not symmetrical, it could cause a small offset. The scale factor change with temperature can be characterized and corrected for. Some expensive ones do this. Don in Minneapolis _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Robert L Barns <75612.2635@..............> Subject: Seismometer kit Date: 10 Jan 97 10:27:27 EST Al Allworth, Your idea of offering a seismometer kit sounds good to me but I have no idea how big the market is. I think that a long period (say 10-20 sec) device would have wider appeal since short period accelerometers are avail. for less than $50. Larry Cochrane, who has lots of experience with both a Lehman and a Shackelford-Gunderson, has been saying that he gets better results with the S-G. Its smaller size has great appeal. It would probably have smaller raw material cost. The S-G is well described in The Amateur Scientist column of the Scientific American mag. in Sept. 1975, pp 182-187. Also, since you live close to Larry, he could be a handy source of advice. I would be interested in buying one to work alongside my Lehman. Bob Barns _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: ct@....... (Charlie Thompson) Subject: Re: Request for input Date: Fri, 10 Jan 1997 10:49:32 -0600 Al, Congrats on your retirement! I think a seismometer mechanical kit would complement Larry Cochrane's most excellent electronics boards. Especially if you could price the mechanism right at the "nuisance level" for most of us. In other words a kit priced such that if you factor in a busy schedule (like mine) your deal couldn't be beat. Also I think the Princeton Earth Physics Project could use a sensor kit (other comments regarding PEPP welcomed). -Charlie Thompson Seismic station .BUE Buda, Texas >I have recently retired (12 days ago) and have been considering interesting >projects to become involved in. I am looking at the possibility of designing >a seismometer kit. What do you think? > >I am an electronics design engineer (analog and digital) and a machinist. I >have purchased equipment for a machine shop, 2 lathes, a milling machine, >and a surface grinder and will be moving from Pasadena to southern Oregon in >the spring. After moving and setting up the shop, and of course getting my >own seismo equipment up and running, I would hope to get something started. > >This gives some time for planning projects so I thought I would ask for >opinions on this list. I don't know of a better place. >____________________________________________________________________________ > > Al Allworth. Pasadena,CA aallworth@........ > > >_____________________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email listserver@............. with the body of the >message: leave PSN-L > > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Jeff Batten Subject: Seismic recording system for under 500$ Date: Fri, 10 Jan 1997 09:27:15 -0800 Note: If you already have a seismometer, or are thinking of constructing your own. Buy a interface card from Larry. If you want a complete system consider. The AS1 seismic recording system for under 500$. It includes a 2.5 second vertical seismometer. 12 bit interface and amp box (New and improved) Logging and Plotting software for windows and dos. (PSN Format). The system is now totally plug and play, you can have it up and running in less than a hour. Records quakes up to 10000km away. If you are a teacher and have a old XT sitting around, why not put it to good use recording quakes. Setup. Find a nice site for the seismometer. Connect the interface cable to the seismometer. Plug the interface cable into a serial port. Run the software. No offset knobs or gain settings to worry about. Check out www.primenet.com/~seismo If you are a home machinist I also have free plans for a Lehman. I also have Lehman coils if you do not want to wind your own. Jeff _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Dennis Leatart Subject: Re: Request for input Date: Fri, 10 Jan 1997 13:58:42 -0800 Hi! I am an earth science teacher and would encourage you to investigate all the possibilities. I would recommend you contact Jeff Batten in this list group for some of his experiences-- he has learned a lot by designing his own software and interface for seismometers. I am currently successfully running a station with his design. -- _____ __ | \.-----.-----.-----.|__|.-----. | -- | -__| | || ||__ --| |_____/|_____|__|__|__|__||__||_____| _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Robert W. Teller" Subject: RE: Request for input Date: Sat, 11 Jan 1997 10:06:54 -0700 Hello Al, Your idea about building an economical seismometer is GREAT! Perhaps we = can get together on this, I have just finished the initial design and = have operational a 1-8 channel 12 bit AD that uses a PC serial port for = data capture. This would allow any PC with a serial port to use the = hardware. I have also written a program that displays selected channels = much like only using Windows 3.1 or 95. It also saves captured events in = the standard PSN format so veiwing/analyasis programs like WinQuake can = be used. Let me know what you think. Bob Teller Montana Research Labs P.O. Box 977 Townsend, MT 59644 (406)266-4483 ---------- From: Jeff Batten Subject: Build your own Force Balance Seismometer Date: Sat, 11 Jan 1997 09:19:32 -0800 If you are trying to build your own force balance seismometer you should check out A miniature wide band horizontal-component feedback seismometer. Journal of Physics E: Scientific Instruments 1977 Ovulate 10 It has a pretty good description of a FBS. I think that a lot of readers of this group have the skills to construct the seismometer. The article has a good drawing and photos. If you have a milling machine and lathe, give it a try. Another good reference. The design of miniature wide band seismometers M. J. Usher and C Guralp Geophysical Journal of the Royal Astronomical Society 1978 (55), 605-613 M J usher I W Buckner R F Burch If you like seeing a lot of unique designs for seismometers check out old Bull. Seismol. Soc. Am. The BSSA has a few hundred articles on seismometer design back to 1906. You will probably have to visit a university library to find the above references. Jeff Batten - Research Engineer Caltech Seismo Lab 818-395-6965 Fax-818-564-0715 _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Lucas Haag Subject: Help!! Date: Sat, 11 Jan 97 14:41:02 CST I'm 13 years old and would like to get into sismology. I live right next to many oil fields (see http://www.swnebr.net/~lhaag/nogcc.html I designed this page). We have lots of small (2.0) tremmors or microquakes or something like that. I am trying to build a very inexpensive and simple seismograph. I ve looked at plans and stuff and on your site and its much to complicated for me. I'm OK with electronics but I'm no rocket scientist! If anybody can help please do.. Thanks Lucas Haag ************************************************* Lucas Haag, Assistant Field Agent Nebraska Oil & Gas Conservation Commission HCR 66 Box 25A Bartley, Nebraska 69020-9717 lhaag@.............. http://csb.swnebr.net/~lhaag "Through da keyboard, into the chips, over the copper, through the fiber, back through the copper into the chips, to the screen... NOTHING BUT NET!" ************************************************* _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Steve Hammond Subject: Re: Ignore the glitch in my data Date: Sat, 11 Jan 1997 14:49:44 -0800 (PST) Michoacan, Mexico 6.8Ml -- Please, will somebody in San Jose area that recorded this tell me if they also recorded a smaller event at 20:33:37 about 145KM from South San Jose? The arrival of the P wave in the Michoacan event is much too large and I think is a smaller local event that happened within seconds of the other. Regards, Steve Hammond PS: as I have six files, I have ZIPPED them and put them on the PSN BBS in San Jose. Anybody know how to send zip files to Larry's WEB site? On Sat, 11 Jan 1997, Charlie & Terri Thompson -- Buda MicroRanch wrote: > A BIG quake just occurred about 900 miles from me...about Mag 7.0.. > probably in Mexico. Peak signal was at 10,000 counts...the largest > I have ever detected. I didn't believe it and took the lid off > the sensor....hence the glitch in my uploaded data...please disregard > the 32,000 count gliches after the S-wave. > > Charlie Thompson > Seismic Station BUE > Buda, Texas > > ct@....... > > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L > _____________________________________________________________________ From: ct@....... (Charlie & Terri Thompson -- Buda MicroRanch ) Subject: Mexico Quake - now showing! Date: Sat, 11 Jan 1997 18:07:00 -0600 I added a link to my web page that allows anyone with a web browser to view today's Mexico Mag 6.8 quake..as recorded with Larry's SDR and plotted with Larry's Winquake program. http://www.onr.com/user/ct/ct.html Here's how I turned a Winquake image into a JPEG image: Basically I viewed the quake using Larry's Winquake program. Depressed the ALT-PRINT SCRN keys to capture the Winquake image to the Clipboard. I then pasted the results using Edit -> Paste into PC Paint program that comes with Windows 3.1. Then saved the file as a ".bmp" file. Finally, I used a nifty program called L-View to convert from .bmp to JPEG and added the JPEG to my web page. This technique is a good way to get any Window's program output to a JPEG file. -Charlie Thompson Buda, Texas USA _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Steve Hammond Subject: Re: Mexico Quake - now showing! Date: Sat, 11 Jan 1997 17:24:21 -0800 (PST) Charlie, I looked at the J-PEG you put on your WEB site in TX and can clearly see that you also recorded the same very large arrival waves that I recorded here in San Jose. Maybe John Lahr or one of the other folks from the USGS can jump in here, but it looks to me like there were two events; one smaller at 20:30 followed by a the second event at 20:31 time frame. Anybody care to comment... When I first looked at the data I thought that there had been one local event in California and one distant event in Mexico but, now I think I was wrong. It appears that the initial P wave had lost all it's energy by the time it reached us and we triggered on the S waves of the smaller first event. BTW, my San Jose files are on Larry's WEB site now under the FSX extension. One is three data sets spliced together and the other two are the raw data from the first two event records I captured. Regards, Steve Hammond PSN BBS San Jose. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Darrell Collins Subject: Re: Help!! Date: Sat, 11 Jan 1997 18:51:46 -0700 (MST) At 02:41 PM 1/11/97 CST, you wrote: >I am trying to build a very inexpensive and simple seismograph. I ve >looked at plans and stuff and on your site and its much to complicated for >me. I'm OK with electronics but I'm no rocket scientist! If you have a Home Depot or other home center in your town, you can get everything needed to build a very workable seismometer. The electronics, which you should be able to handle, are not difficult, although you will need to spend some cash. You posted to the net, so you must have a computer of some kind. That is the expensive part. Software (PC kind) is available from the PSN sites. All you need is some PVC (plastic) pipe, glue, a coil, and a magnet. If you are interested return my E-Mail and I'll help you. Darrell _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Steve Hammond Subject: Re: Help!! --- GIF and instructions Date: Sun, 12 Jan 1997 14:51:14 -0800 (PST) Lucas, I emailed you the VERTICAL.GIF drawing which is the same file as VERTICAL.ZIP found on all the PSN BBSs. It is a simple to build but works great seismograph developed by Terry Frost in Pasadena, Calif. This gets kind of long so if you don't want to know how to build it stop reading here-- All you need is some aluminum plate 8" x 14" and 24 inches of 3 inch aluminum channel for the boom and post. (The boom is 12" long as is the post.) The spring is a common screen door screen that you can buy in any hardware store. The coil can be made from a 2 1/2" plastic spool, such as the one Radio Shack uses on their #22 wire which has a center hole of 1" and is 3/4" thick, and #32 - #34 magnet wire (Allied Electronics 1-800-433-5700 stock number 214-3586 (#32 - $22.64) or better 214-3588 (#34 - $23.87). The magnet-- is a cow magnet bought from a farm feed and grain store for about $2.50 each. Last, a bit of hardware such as an aluminum L bracket, BRASS nuts washers and screws. You don't want anything that is steel because the magnet mounts on the free moving boom and could be drawn to it which would interfear with the seismograph operation. Building the device-- you need a hacksaw, file, and hand drill. You may have to make the L bracket from a larger length of aluminum L stock. Cut it as wide as the inside of the channel (2 3/4") so it will bolt to the base plate inside the channel at the rear of the device. Take the 24" x 3" channel and cut it into two halfs 12" long. Use the brass screws and drill and attach one of the sections, becoming the post, to the base plate. Mount the post so that the bottom part of the U channel is facing the center of the base plate. See the GIF. ------------------- I base plate I I- I U II------------- I boom channel II------------- I post I- I I I ------------------- I I \ door spring post I \ I---------M- boom M= magnet L I O C L= "L" bracket, O= oil damping, C=coil ------------------ base plate The other half becomes the boom with one end resting on the post and the other suspended by the spring. Use the file and cut a V in the post filing a grove about a 1/16" deep across the 3" inside flat face, 2" up from the base plate. File a 45 degree knife edge on what will be the left end of the boom (you will need to use the hacksaw and trim a bit of the two U parts of the channel leaving just the boom's 3" face) so it will have the minimal contact with the post when set in the V cut. It is important to file the V at a 90 degree angle to the post sides so that the boom is level when suspended and hinges freely without interference from the boom's channel sides that you trimmed off. File the boom's knife edge so it is as sharp as possible. I built one with an edge that had just two dimples --V------------V-- that came into contact with the V cut in two spots and it worked well for me. But I suggest that you start with the simple knife edge until you get the unit working, then make improvements. The magnet is held in place with a force fit. Drill a hole near the right end of the boom and then split the channel cuting down the center of the 3" channel from the right edge to the center of the magnet hole. This will allow the channel to expand a bit when you force the magnet into the slightly smaller magnet hole. The cow magnet I used was 1/2", so I drilled a 15/32" hole. Drill a small hole at the center top of the post and about a 1/2" to the left of the magnet hole (EG 1 1/2" or 10 1/2" from the ends of the 12" boom) so that the spring will be free and clear of the magnet top poking up through the boom. Use some #22 solid brass wire (if you buy the Radio Shack solid wire for its plastic spool you will have plenty after you pull it off the spool) and attach a length of the door spring to the post and boom so that the spring supports the boom at a level position with the cow magnet mounted in its hole. I later added some small screws with holes drilled in them and a small aluminum turnbuckle to adjust the spring tension (boom position) making this step much simpler than trying different length wires. A thought about the spring is appropriate at this point. Select a spring that is soft and has a slow recovery. You don't want snap-- You want soft gentle spring action because it will affect the period of the boom. I was able to cut a maximum length spring off of the longer door spring and mount it between the post and boom giving me a device with a 2.5 second period. (This is the amount of time it takes for the boom to swing up, down past center, and up again to the starting position. A device with a period of 2.5 seconds will be excellent for the oil field area you described and will be able to sense small and large regional events. Damping-- is this important-- yes, because it keeps the boom from oscillating after being set into motion. Damping is accomplished by the use of oil in this design. Other designs may use magnets. Take a long 1" brass screw, an aluminum tuna fish can, and some 30 weight motor oil and make the damping unit. Make sure the can is not steel by testing it with the cow magnet. Place the can under the boom with brass screw bolted through the boom. The end of the screw should be centered in 4 directions inside the can. You want to keep the boom as light as possible so I cut a 1" square out of the tuna lid and punched a hole in the center of it. I then bolted it with brass nuts to the bottom of the screw, centered inside the tuna can, thus becoming an oil baffle after the motor oil was added to the can; creating an oil damping system. Don't cut yourself, it's edges are sharp-- and will leave a nasty gash. You can re-mount the damper up or down the boom which will increase or decrease the amount of damping if needed. Coil-- drill a hole in one side of the Radio Shack spool near the center. Make sure there are no sharp edges, by sanding the plastic, which will catch as you wind the magnet wire. Start out buy putting 2 or 3 inches of wire through the hole and then tape it down to protect it. Caution, if this wire breaks off where you can not connect to it you will have to start over... I go to the trouble of gluing this wire in the hole and up the side a bit with clear silicon glue so I can repair it if needed. Wind the #34 magnet wire into the plastic form (spool) by hand. This takes about an hour and you don't want to break the wire. Good luck-- Fill the with the magnet wire. The part numbers from Allied I gave you is for magnet wire that can be soldered without removing the insulation. This will make solding the connecting wire simpler. I also like to have a solid wire mount so I use super glue and glue a plastic tie onto the side of the near the wire exit hole. I then loop #22 wire to it and solder the magnet wire to the larger wire. I also always add a tie down to the base plate of the seismograph and loop the #22 wire to it. This in turn stops me from accidentally ripping the wires out of the coil... when installing the seismograph. Tape the coil to the base plate so the cow magnet can is centered in the middle of the 1" spool hole. Adjust the height of the cow magnet after the boom spring is adjusted so that the cow magnet is about 1/4" above the base plate. You may want to lift the coil up with small wooden blocks so that it is 1" above the base plate. This will assure maximum induction. So at this point, you have a vertical seismograph with a 1 - 3 second period that will be great for recoding local events. I recorded a 4.5 at 400km near Bishop with this unit as well as several 1.0 events in my area. The PSN BBS in San Jose is at 37 14 43.33N - 121 48 54.52W within a few kilometers of the split of the Hayward and Calaveras and 16km from Loma Preata and the San Andreas. A simple amp circuit can be found on any of the PSN BBSs in the file PENDULUM.ZIP which contains the plans for the Lehmann sismograph. Larry C. also builds a great interface board that will interface this to a PC and there are several other circuits talked about here on the PSN forum. I'll be happy to discuss this and answer questions. Regards and best of luck, Steve Who am I? I'm SYSOP at the PSN BBS San Jose 408-226-0675, SHAMMOND@........... SHAMMON1@.............. SHAMMOND@........... and Steve Hammond at WWW.CHIPANALYST.COM. It just depends on the hour and day of the week. On Sat, 11 Jan 1997, Lucas Haag wrote: > Thanks for the reply. All of that I can handle. We have about all that stuff > laying around here (I live on a farm) I would appriceate some plans. > > At 06:51 PM 1/11/97 -0700, you wrote: > >At 02:41 PM 1/11/97 CST, you wrote: > >>I am trying to build a very inexpensive and simple seismograph. I ve > >>looked at plans and stuff and on your site and its much to complicated for > >>me. I'm OK with electronics but I'm no rocket scientist! > > > >If you have a Home Depot or other home center in your town, you can > >get everything needed to build a very workable seismometer. The > >electronics, which you should be able to handle, are not difficult, > >although you will need to spend some cash. You posted to the net, > >so you must have a computer of some kind. That is the expensive part. > >Software (PC kind) is available from the PSN sites. All you need is some > >PVC (plastic) pipe, glue, a coil, and a magnet. If you are interested > >return my E-Mail and I'll help you. > > > >Darrell > > > > > > > >_____________________________________________________________________ > > > >Public Seismic Network Mailing List (PSN-L) > > > >To leave this list email listserver@............. with the body of the > >message: leave PSN-L > > > > > ************************************************* > Lucas Haag, Assistant Field Agent From: "Dott. Roberto E. Pozzo" Subject: Re: seismic equipments used in Italy Date: Mon, 13 Jan 1997 01:33:39 +0100 cougercat@........... wrote: > > P> Organization: osservatorio meteosismico del monferrato > > Hi Roberto; > > Thanks for your reply. Yes Boeing's is here but I have not been able to > pick up any decent accelerometers from them. The accelerometer that I am > experimenting around was made for the airbag industry. They have a span of > +- 4 g's, Sensitivity is 500 mV/g, Bandwidth is DC - 100 hz or anything > between, Supply voltage/current 5/24 ma. Almost ideal for portable use. > > The August 8, 1991 issue of Electronic Design carried an good artical on > them. These were sampled for another project that didn't get off the > ground from Analog Devices. The bochure says the European phone # is > +89 57005 0 > ....Perhaps you can get ahold of them and see if they will send you a > sample or 2. > > I'll keep you posted. > > --Jeff > > ******************************************* > * mail from Jeff - cougercat@........... * > ******************************************* > > > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L Hi Jeff, many thanks for info about accelerometers. Please read my reply to Edward Cranswick about this matter. By now, the only data I can obtain on those types of accelerometers are the ones that I posted to Edward. Isn't a sensibility of +- 20 G too high for a seismo use ? What do you think about ? greetings roberto _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Dott. Roberto E. Pozzo" Subject: Re: seismic equipments used in Italy Date: Mon, 13 Jan 1997 01:28:36 +0100 Edward Cranswick wrote: > > Roberto- > Interesting what you are doing. > What are the specs on the USAF accelerometer below? > -Edward > > > tri-axial accelerometers. Let me know how your work goes on. Here in > > Italy we can obtain some accelerometer (u.s.a.f. surplus) for a cheap > > price.Some time ago, I was tempted to purchase one or two of that > > devices . What do you think about aeronautical accelerometers ? You live > > -- > Edward Cranswick Tel: 303-273-8609 > US Geological Survey, MS 966 Fax: 303-273-8600 > 1711 Illinois St cranswick@........ > Golden, CO 80401 USA E.M. Forster said, "Only connect". > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L Many thanks, Edward for your nice reply. I alway read what you write her in PSN-L because it's very interesting and well documented. Ok, here follows the only techical data that I can obtain (by now) from a catalogue issued by an italian electronics surplus company about those accelerometers: - made by ETHER Co. , Type LA2 - 2 sensors 2300 ohm (positive and negative) - sensibility ( three diferent available types) +- 20 G ,+- 30 G , +- 50 G dimension: 45x60x25 mm - new in original case The cost is about 25,000 Lire here in Italy ( about 17 U.S. dollars) I don't know much more about those devices , but I think that perhaps the sensibility is too low for seismological use ( isn't true ? ) What do you think , Edward ? many thanks again roberto Dr. Roberto Ezio Pozzo Osservatorio Meteosismico Del Monferrato Via Crova,3 14049 Nizza Monferrato (AT) ITALY tel. (039) 0141 793026 - 0337 240912 ---------------------------------------- - _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Karl Cunningham Subject: Re: LEDs in Accelerometer, wavelength question Date: Sun, 12 Jan 1997 22:01:03 -0800 Greetings -- To fill everyone in about my experiments with LED temperature coefficients ... I really didn't do much other than to spray parts with freeze spray. This was in a circuit with one LED for each of the two phototransistors. The phototransistors were in a differential configuration and right next to each other, so I figured that any temperature change in one should be matched in the other fairly closely. Those changes would be canceled electronically. The same was true for the LEDs. |----- interrupter connected to beam | LED --> || -- -- || <-- phototransistor LED --> || --|-- || <-- phototransistor | Top View After seeing some amount of low-frequency noise, I wondered how much might be due to differential temperature changes in the LEDs or the phototransistors. So I sprayed each in turn with freeze spray and noted the amount of output change. I don't have the exact numbers, but I think the change was equivalent to about 1E-5 meter of movement of the beam, when I sprayed each of the LEDs. The phototransistors showed a change too, but about 10:1 less. The phototransistors were operated saturation, with the output being derived from the difference in saturation voltage between the two. At that point, I decided to try only one LED rather than two. I mounted the one farther away from the detectors (about 1"), so it would shine clearly on both. The overall noise didn't go down because the light level reaching the phototransistors (and hence the current) went down a lot, due to moving the LED farther away (one of those 1/d^2 things, you know). After that I switched to a much brighter LED (see below), but there still wasn't any drastic improvement in noise -- perhaps 2:1 or so. Since I still had about 10:1 more noise than I wanted, I didn't pay too much attention to the details of the difference between two LEDs and one. I just figured that one has got to be at least as good as two (and ought to be better). The LEDs I was using at the time were part of a General Electric H23A1 (IR wavelength) matched emitter-detector pair, and were only specified as a coupled pair. I changed to a "super-brite" red LED (unknown manufacturer, from local surplus store). This LED is VERY bright. At 80mA it could work as a flashlight in a pinch. Even though the detector was only characterized for IR, it seems to work fine with the red LED. In fact, using the same setup geometry, the phototransistor current is about 100x what it was using the IR LED. By the way, does anyone have any idea whether using IR vs red LED vs blue LED vs a UV source for the EO detector is going to make a significant difference? I'm trying to get noise levels down to 1E-8 meter or better at the interrupter, and the wavelength of red light is 60-70 times this. It seems that what the phototransistors see is really the sum of MANY photons, and the wavelength of each one is not that significant, but I'm guessing. Comments? Karl Cunningham La Mesa, CA. karlc@......... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Peter Styles Subject: Re: seismic equipments used in Italy Date: Mon, 13 Jan 1997 21:39:34 GMT Dear Edward/Roberto We purchased a dozen of the Analog Devices ADXL05 accelerometers and a student of mine built up the tri-axial seismometer described in last years Scientific American. We weren't too impressed by its sensitivity and don't really think they are usable even they do have a good bandwidth. They do however make great digital inclinometers and we have built some to fit in a heat flow probe we will be using in Lakes in southern Chile next month. > I don't know much more about those devices , but I think that perhaps > the sensibility is too low for seismological use ( isn't true ? ) > What do you think , Edward ? > > many thanks again > roberto > > Dr Peter Styles Home: 6 Swan Lane Bunbury Tarporley Cheshire CW6 9RA 01829 260808 Work: Department of Earth Sciences University of Liverpool Brownlow Street Liverpool L69 3BX (44) 0151 794 5174 _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: watson@................ (Charles Watson) Subject: Re: USGS Missed Mag 5.0 quake Date: Mon, 13 Jan 1997 14:13:50 -0800 Charlie & Terri Thompson -- Buda MicroRanch wrote: > > I recorded a M5.4 (approx) quake at about 6:43:35 1/3/97 UTC about 1000 miles > from Buda, Texas. It appears the USGS missed this one. Did anyone > else record this event? > > Thanks, > > Charlie Thompson > Buda, Texas > ct@....... Charlie, Just a matter of record, the NEIC doesn't miss much. It is more are they are understaffed and underfinanced to perform quick analysis outside the US borders. It will probably come out on the QED and most certinly in the PED. You can sometimes get quick information from IDC: http://www.cdidc.org:65120/web-bin/recentevents You can find IDC's URL and other sources of current earthquake information at: http://www.seismo-watch.com/EQSERVICES/CurrentActivity/CurrentActivity.html --- Charles P. Watson, Consulting Geologist Advanced Geologic Exploration Seismo-Watch / Earthquake Information Services Voice: 702-852-0992 / Fax: 702-852-3226 watson@................ http://www.seismo-watch.com _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Dott. Roberto E. Pozzo" Subject: Re: Ignore the glitch in my data Date: Mon, 13 Jan 1997 01:56:27 +0100 Charlie & Terri Thompson -- Buda MicroRanch wrote: > > A BIG quake just occurred about 900 miles from me...about Mag 7.0.. > probably in Mexico. Peak signal was at 10,000 counts...the largest > I have ever detected. I didn't believe it and took the lid off > the sensor....hence the glitch in my uploaded data...please disregard > the 32,000 count gliches after the S-wave. > > Charlie Thompson > Seismic Station BUE > Buda, Texas > > ct@....... > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L Hello Charlie, for your info , the Mexico Quake made here in Italy a good recording on my home built (near Lehman type...) long T seismograph . P and S phases were confused by a weather disturbance (a cold front was passing just yesterday above us) , but Rayleigh L phases performed a fine 15 minutes recording. Unfortunately, Winquake elaboration was not available , because just in this period , my data-logger is 'explosed' on my tech-deck due to mainteinance works. Mr Murphy lives in Italy , as I always say ! regards roberto Dr. Roberto Ezio Pozzo Osservatorio Meteosismico Del Monferrato Via Crova,3 14049 Nizza Monferrato (AT) ITALY tel. (039) 0141 793026 Cell. 0337 240912 ------------------------------------------ _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Mike Lozano Subject: Re: Steve Hammond & Lucas Haag Q&A Date: Sat, 30 Nov 1996 10:51:42 -0600 > Who am I? I'm SYSOP at the PSN BBS San Jose 408-226-0675, > SHAMMOND@........... SHAMMON1@.............. SHAMMOND@........... and > Steve Hammond at WWW.CHIPANALYST.COM. Lucas Haag > Hi Steve & Lucas, I've never written anything to this newsboard, but I've been listening for a few months. In reference to your 'cheap and easy' vertical seismograph for use in local events: I too was going to build a Lehman type instrument, but (at the time) I couldn't get the magnets specified from Edmund quickly enough for my impatience. So, I visited the local farm and ranch store and purchased a set of 3 one-half inch diamenter alnico cow magnets for $11. After staring at them for the better part of a day, I came up with a slightly different approach. Since the current induced in the coil is largely dependent on the velocity of the movement, the number of turns in the coil, and the strength of the magnet; why not increase the number of magnetic lines per unit length by putting similar poles together? I took some 1/2 inch PVC, stuffed two cow magnets into it, separated by a thin piece of rubber sheet (to prevent 'clanking'), and capped the two ends with PVC caps. The coil had been placed on the PVC tube before capping: _________|***|_________ | (magnet 1)|(magnet 2) | | ______________________| End cap |***| Coil To make a long story short, this 'packing' of the magnetic lines of force really seems to increase the current produced by a substantial amount. So much so, that I had to put my Fluke 87 meter on the Volts range, because the Mv scale went right off the page with very little movement. I've yet to locate the one-inch thich 12" X 30" aluminum plate I want to use as a base plate. I know it's somewhere in storage, but I've forgotten exactly where! I'm totally new to seismology. I'm a meteorologist and electronic engineer by profession. Is this avenue worth pursuing? Or, should I just be patient, and wait for the Edmund Scientific magnets to arrive? Thanks for your help and tolerance of dumb questions. Mikel Lozano, mikel@....... -0- _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Lucas Haag Subject: Re: Steve Hammond & Lucas Haag Q&A Date: Mon, 13 Jan 97 20:29:16 CST I think your're probaly on to something there. It's a good idea. Now to I need to find a amplifier circut of some type. I'm going to record data on cassetes not paper using plans in a Radio Shack book. Do you think this will work?? At 10:51 AM 11/30/96 -0600, you wrote: >> Who am I? I'm SYSOP at the PSN BBS San Jose 408-226-0675, >> SHAMMOND@........... SHAMMON1@.............. SHAMMOND@........... and >> Steve Hammond at WWW.CHIPANALYST.COM. Lucas Haag > >Hi Steve & Lucas, .... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Mike Lozano Subject: Re: Steve Hammond & Lucas Haag Q&A Date: Sat, 30 Nov 1996 12:50:57 -0600 Lucas Haag wrote: > > I think your're probaly on to something there. It's a good idea. Now to I > need to find a amplifier circut of some type. I'm going to record data on > cassetes not paper using plans in a Radio Shack book. Do you think this will > work?? Hi Lucas, Thanks for the reply! I, myself, plan to use one of Larry Cochrane's a/d boards into my computer, but I suppose, you could build your own from Radio Shack plans. As you're planning to use a cassette as a storage medium, you'll have to turn the varying voltages into a frequency. That's assuming you want an analog system. In my design, for example, the magnets are fixed, and the coil moves. I'm sure that will present some problems with wire flexure, and the like; but I plan to have the coil wires go up the stainless steel horizontal pendulum support. I found a piece of solid brass 1/4" rod in my junk box - so, tentatively, I plan to make the pendulum about 30 inches long. As I mentioned in my first message: I'm just getting started in this, and lots of the things I try may not be according to Hoyle, but at least I'll have fun doing it. By the way, Lucas, I see you're in Nebraska. I'm in the next state, East - Iowa. Matter of fact, the television station where I work as a meteorologist can be found under http:\\www.kcci.com Be sure and check out our weather page. Anyway - got to run. Oh - by the way! I just noticed that the clock and date on this computer is screwy. Please disregard the date and time on the message. This is being written on the 13th of January, 1997 at 9:57PM CST. Again, thanks for responding! As we say in my native Basque language: 'Mila eskerrik asko - lagunak', or 'Thanks a bunch, friend' Mikel Lozano -0-> > > ************************************************* > Lucas Haag, Assistant Field Agent > Nebraska Oil & Gas Conservation Commission > HCR 66 Box 25A > Bartley, Nebraska 69020-9717 > lhaag@.............. > http://csb.swnebr.net/~lhaag > > "Through da keyboard, into the chips, over the copper, > through the fiber, back through the copper into the chips, > to the screen... NOTHING BUT NET!" > ************************************************* > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Karl Cunningham Subject: Dual Cow Magnets (was Re: Steve Hammond & Lucas Haag Q&A) Date: Mon, 13 Jan 1997 21:30:02 -0800 To Mikel Lozano: One question on your arrangement -- is the coil going to move back and forth on the outside of the PVC pipe, or are the magnets going to move inside it. No matter which, I'm sure that the more voltage (or current) you get out of the coil, the better. I think the objective is to have the moving coil cut across the most magnetic lines of flux with the smallest movement. Karl Cunningham La Mesa, CA. karlc@......... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: ct@....... (Charlie & Terri Thompson -- Buda MicroRanch ) Subject: Re: USGS Missed Mag 5.0 quake Date: Mon, 13 Jan 1997 23:52:49 -0600 You are correct...it did show up on the link you suggested below. It was a Mb4.1 of the coast of Jalisco Mexico. This is the smallest quake I've detected in Mexico...I estimated it the quake as a M5.5 event. I'm still having trouble downloading a USGS report to append to the Winquake file...will try again tommorrow. thanks! -Charlie Thompson Buda, Texas >Charlie & Terri Thompson -- Buda MicroRanch wrote: >> >> I recorded a M5.4 (approx) quake at about 6:43:35 1/3/97 UTC about 1000 miles >> from Buda, Texas. It appears the USGS missed this one. Did anyone >> else record this event? >> >> Thanks, >> >> Charlie Thompson >> Buda, Texas >> ct@....... > >Charlie, > >Just a matter of record, the NEIC doesn't miss much. It is more are they >are understaffed and underfinanced to perform quick analysis outside the >US borders. > >It will probably come out on the QED and most certinly in the PED. You >can sometimes get quick information from IDC: >http://www.cdidc.org:65120/web-bin/recentevents > >You can find IDC's URL and other sources of current earthquake >information at: >http://www.seismo-watch.com/EQSERVICES/CurrentActivity/CurrentActivity.html > >--- >Charles P. Watson, Consulting Geologist >Advanced Geologic Exploration >Seismo-Watch / Earthquake Information Services >Voice: 702-852-0992 / Fax: 702-852-3226 >watson@................ >http://www.seismo-watch.com > >_____________________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email listserver@............. with the body of the >message: leave PSN-L > > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Al Allworth Subject: Re: Dual Cow Magnets Date: Mon, 13 Jan 1997 21:57:04 -0800 This looks like a win-win arrangement to me. More flux from the two magnets and the lost flux from the ends pushed around to where it can do the most good. ____________________________________________________________________________ Al Allworth. Pasadena,CA aallworth@........ _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Al Allworth Subject: Re: Request for input Date: Mon, 13 Jan 1997 22:18:57 -0800 List, Thanks for the input re: Seismo kits. I'm getting very anxious to get moved so I can begin prototyping some of my ideas. The more I think about it the more ideas come and all must be tried. I have several, both electronic and mechanical that I will discuss when I work out some details. I have some discussions I will have privately with some of you in the near future. ____________________________________________________________________________ Al Allworth. Pasadena,CA aallworth@........ _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Ron Westfall Subject: Lehman magnet mod Date: Tue, 14 Jan 1997 11:02:45 -0800 I noticed Mike Lozano's contribution about putting several cow magnets in a PVC pipe, so I thought it was time to mention the modification I made to the Lehman design. I had noticed that using a single magnet with the pickup coil was problematic because of the limited clearance both in width of the opening between poles and depth before the coil ran into the back of the magnet. I used two magnets and their keepers to form a much larger C shaped magnet: __________ ___________ __________ | N ||___________|| S | | ____N_||___________||_S____ | | | | | | | |_________| | | | | | | | | | |______ | | ______| | | S | | COIL | | N | |________S_| | | |_N________| | | | | The advantages of this approach in order of importance are: coil dimensions are no longer critical, there is greater depth of travel, and magnetic field strength is greater. With the original design the coil was already fairly narrow to fit in the gap of the magnet. Coil form side wall material had to be carefully chosen to keep the side walls thin yet achieve stiffness, so there would be enough wire in the dense part of the magnetic field. With the above approach the side walls can be thicker opening up the range of materials that can be used. The greater depth of travel is a minor advantage, because any motion that would exercise the greater travel would probably result from a local quake. Motion from a local quake would probably saturate the electronics. The only benefit is that you now don't have to worry about the coil running into bolt heads that are fastening the magnet to a support. For those of you who have not built the seismograph yet, the magnets have a hole through the back of the magnet (base of the U shape). Its natural to use a bolt to fasten the magnet to a support. In the original design this leaves either a bolt head or nut sticking into the interior of the U shape. Given the smallish dimensions of the magnets this is an intrusion that can't really be afforded. You can also glue the magnets or use some other form of attachment, but a brass bolt is darn convenient. The two paired magnets lastly offer the advantage of greater field strength. Like Mike experienced, swinging the 10,000 turn coil through an unoptimized gap (the original keepers result in slightly too large a gap) gave voltage transients anywhere from 0.1 to 0.5 volts with 0.25 volts being typical. The greater field strength may or may not be an advantage, because you will have to turn down the gain on the preamp a corresponding amount to avoid saturating the A/D electronics. I have not installed the electronics yet, so the greater field strength could turn into a disadvantage if the preamp gain can not be turned down enough. The disadvantage of using paired magnets is that now you need two magnets instead of one, so cost goes up. On the other hand, I found a local supplier of the same magnets that Edmund distributes. They cost about $25 Canadian (about $17.50 US) each. It sure beat Edmund's price which is about $48 - $50 US each. I encourage all of you to just look in the phone book under magnets. The local supplier I found is a small hole-in-the-wall engineering company that specializes in industrial magnetics. Amongst more sophisticated magnetic gadgets, they sold the horseshoe magnets used in the seismograph. For those of you in locations where there are no suppliers close by, Mike's contribution and mine should suggest that the magnet configuration is not particularly critical. Use your imagination and find some combination of permanent magnets which will provide an overall pull roughly in the range of the 25 lb. mentioned in the original design. Ron Westfall westfall@...... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Mike Lozano Subject: Re: Dual Cow Magnets , continued . . . Date: Sun, 01 Dec 1996 01:31:33 -0600 Karl Cunningham wrote: > > To Mikel Lozano: > > One question on your arrangement -- is the coil going to move back and > forth on the outside of the PVC pipe, or are the magnets going to move > inside it. > > No matter which, I'm sure that the more voltage (or current) you get out of > the coil, the better. I think the objective is to have the moving coil cut > across the most magnetic lines of flux with the smallest movement. > > Karl Cunningham > La Mesa, CA. > karlc@......... > Hi Karl! The design I have in mind at the moment keeps the magnets stationary, with the coil being attached to the boom. Because the gap between the coil and magnet housing is about 1/16", the boom should be able to move an appreciable distance. Unlike you lucky? guys in California, I'm not too worried about saturating the amplifier. A fews months ago, I had a design project which called for an abnormally large dynamic range in the input data. I solved it with a transistorized amplifier with a very non-linear output curve. Almost like a logarithmic amplifier in reverse. Of course, the idea behind putting the magnets in opposition is to maximize the flux lines over a very small area. I wish I knew how to submit .DXF drawings, but a visualization of the fields opposed to each other will reveal that the packing of lines of force dies off exponentially from the line of max opposition. Using that logic, a deflection in either direction from the center point would produce less current as the coil encountered less and less flux lines. In a nutshell, this seems (at least on paper) that deflection per unit time would be self limiting. In the case of the horseshoe magnets, on the other hand, it would seem that current would be mostly a function of velocity, since the flux lines between unlike poles would be (at least in theory) uniformly distributed. As I said earlier, here in the MidWest, unless the New Madrid fault, or the Mid-Continent Rift Zone decide to both get frisky, I'm not too worried about saturation. As a matter of fact, Raymond Anderson of the Iowa Dept. of Geololgy & Resources instrumented the Rift zone for five years, and got nothing more than a couple of microseisms. I'd be deliriously happy if I could get even so much as a squiggle from a distant earthquake. I do intend to use the Lehman design. Incidentally, the magnets encased in PVC fit very nicely into a PVC floor flange which I am going to mount at a 90 deg angle to the base, so that the magnetic tube will be parallel to the base. Please stay in touch! Mikel Lozano -0- > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Al Allworth Subject: Re: Lehman magnet mod Date: Tue, 14 Jan 1997 20:25:08 -0800 At 11:02 AM 1/14/97 -0800, you wrote: > >I noticed Mike Lozano's contribution about putting several cow magnets in >a PVC pipe, so I thought it was time to mention the modification I made to >the Lehman design. > Ron and List, I would be surprised if this approach produced much of an improvement in output. One thing to keep in mind with these coil/magnet combinations is that it is NOT how much flux you can get through the coil on axis, it's how much flux is cut by the movement of the coil. With opposite poles facing each other the flux lines will be pulled toward the opposite pole and not as many will turn outward through the coil. Any increase in output would be caused by the increase in total flux in the area of the coil. This can be demonstrated with iron filings on a piece of cardboard over the magnets. The ideal would be if you could get all of the flux to turn 90 degrees and go outward through the center area of the coil. Then any movement would cause all of the flux to cut turns on the coil. A coil twice as long as the diameter of the hole might also capture more of the flux and give more output. ____________________________________________________________________________ Al Allworth. Pasadena,CA aallworth@........ _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Karl Cunningham Subject: Re: Dual Cow Magnets , continued . . . Date: Tue, 14 Jan 1997 22:53:23 -0800 Hi all -- I have a couple of theories about magnets in coils, but since my knowledge in magnetics is sorely lacking, I thought I'd ask for more knowledgeable comment... 1. The VOLTAGE induced in a coil cutting across magnetic lines of flux is proportional to the number of lines cut by the coil per unit time (speed of the coil). (Assuming the voltage is measured by a high-impedance amplifier.) 2. The CURRENT induced into a coil (assuming it is feeding a current shunt -- low impedance) is proportional to the amount of force applied, and that the speed of the movement will be proportional to that force. This force over a distance will be doing work, dissipated as heat in the resistance of the coil. The force is there because the coil's current will be opposing the movement by generating an opposing force proportional to the current in the coil. Not a very elegant description, but am I even close to what actually goes on? Comments appreciated. Karl Cunningham La Mesa, CA. karlc@......... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Mike Lozano Subject: Re: Dual Cow Magnets , continued . . . Date: Sun, 01 Dec 1996 05:31:05 -0600 Karl Cunningham wrote: > > Hi all -- > > I have a couple of theories about magnets in coils, but since my knowledge > in magnetics is sorely lacking, I thought I'd ask for more knowledgeable > comment... > > 1. The VOLTAGE induced in a coil cutting across magnetic lines of flux is > proportional to the number of lines cut by the coil per unit time (speed of > the coil). (Assuming the voltage is measured by a high-impedance amplifier.) > > 2. The CURRENT induced into a coil (assuming it is feeding a current shunt > -- low impedance) is proportional to the amount of force applied, and that > the speed of the movement will be proportional to that force. This force > over a distance will be doing work, dissipated as heat in the resistance of > the coil. The force is there because the coil's current will be opposing > the movement by generating an opposing force proportional to the current in > the coil. > > Not a very elegant description, but am I even close to what actually goes > on? Comments appreciated. > > Karl Cunningham > La Mesa, CA. > karlc@......... > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L Hi Karl, Seems like you're right on the money! In fact, the old-fashioned D'Arsonval meter movements (which are sort of miniature seismometers when they're on their backs) used to be protected (and probably still are) by shorting the two terminals together with a piece of solder or copper wire. It makes a dandy damper for the movement when the terminals feed an extra low impedance. Of course, in the case of a D'Arsonval movement, the term would be resistance, since it's a direct current which is generated by a single movement. I suppose for the measurement of magnitude, it's best to have a low impedance input, but since I'd be tickled to even see a squiggle here in the MidWest, I'm going for the high impedance amplifier. I'm particularly interested in seeing the generated waveforms. Mikel Lozano -0- _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Doomsday David Allen Subject: Re: Does anybody know of anyone who will doe a demonstartion Date: Wed, 15 Jan 1997 15:13:23 -0700 Darrell Collins wrote: > > At 08:42 PM 1/14/97 -0700, you wrote: > >I Am senior at Dysart High School. I am Interested in siesmology > >The earth science teacher at my school asked if me if I could get some > >one to come to our school a do a demonstration with a siesmograph. > > Hello, > I am in Scottsdale, and could help. I teach at Scottsdale Community > College. Please let me know about when you would want the talk, the > subjects to be covered, and the amount of time I would have for the > presentation. I also need to know how much background your class > has had (plate tetonics, mid-ocean rifts, sub-duction/up-heaval/slip > etc). I need to get a seismometer "portable", (these things are heavy!). > Perhaps it would be good for your teacher to phone me some evening? > Darrell > Phone: 602-948-8993 > Fax: 502-998-8931 > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L Yes I would be a good Idea if you talk to the teacher about a date and stuff. I do know how much a portable siesmic unit can Weigh, when I was a junior at Dysart I audited Asu Exploration geophysics class so I got to see a lot of the equipment used. As for the earth science class These kid are Mostly freshman Maybe one or two sophmores and the teacher will have already probably taught them the basic on earthquake and plate techtonics. I also am hopefully bringing an anclimometer in to show them too. I give your phone number to the teacher so he can call you and set up a time Thank you very much, I sure the kid will Really Enjoy it Gregory David Allen _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Al Allworth Subject: Re: Dual Cow Magnets , continued . . . Date: Wed, 15 Jan 1997 23:59:41 -0800 At 10:53 PM 1/14/97 -0800, you wrote: >Hi all -- > >I have a couple of theories about magnets in coils, but since my knowledge >in magnetics is sorely lacking, I thought I'd ask for more knowledgeable >comment... > >1. The VOLTAGE induced in a coil cutting across magnetic lines of flux is >proportional to the number of lines cut by the coil per unit time (speed of >the coil). (Assuming the voltage is measured by a high-impedance amplifier.) > >2. The CURRENT induced into a coil (assuming it is feeding a current shunt >-- low impedance) is proportional to the amount of force applied, and that >the speed of the movement will be proportional to that force. This force >over a distance will be doing work, dissipated as heat in the resistance of >the coil. The force is there because the coil's current will be opposing >the movement by generating an opposing force proportional to the current in >the coil. No.1 is correct. For No.2, you are correct except you have a situation where you can never really see a true current because of the resistance of the coil. If the coil has a resistance of 2K then you always have this 2K in series with the "generator" so that any external load can only receive the current that can be passed through the 2K from the theoretical 0 Ohm generator. Some instruments are designed with a particular winding resistance and a specified load resistance which results in critical damping of the instrument. The current through the coil produces the correct opposing force for damping. Often the signal level is reduced to much less than 1/2 what it would be using another means of damping and a high impedence amplifier. ____________________________________________________________________________ Al Allworth. Pasadena,CA aallworth@........ _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Ron Westfall Subject: Re: Lehman magnet mod Date: Thu, 16 Jan 1997 10:48:34 -0800 Al Allworth wrote: > > I would be surprised if this approach produced much of an improvement in > output. One thing to keep in mind with these coil/magnet combinations is > that it is NOT how much flux you can get through the coil on axis, it's how > much flux is cut by the movement of the coil. With opposite poles facing > each other the flux lines will be pulled toward the opposite pole and not as > many will turn outward through the coil. Any increase in output would be > caused by the increase in total flux in the area of the coil. This can be > demonstrated with iron filings on a piece of cardboard over the magnets. The > ideal would be if you could get all of the flux to turn 90 degrees and go > outward through the center area of the coil. Then any movement would cause > all of the flux to cut turns on the coil. A coil twice as long as the > diameter of the hole might also capture more of the flux and give more output. > My primary goal in coupling two magnets together with their keepers into a larger C shape was to ease the tight geometry of the original design. As I mentioned in my post, any increase in magnetic field strength is probably offset by having to turn the gain down on the pre-amp. I performed an experiment last night to try and verify whether there was any field strength increase. I used a single magnet in the original configuration and two magnets with their keepers in my modified configuration to determine what voltage was induced in one of my sensor coils. Holding the magnet(s) in my hand, I moved the magnet towards and away from the coil repeatedly in the same type of motion that would be seen when the magnet(s) and coil were installed on the seismograph. Needless to say the range of motion was larger than would be experienced by the seismograph and precision of motion did not meet any scientific standards. With the single magnet I got induced voltages anywhere between 0.1 and 0.3 volts. With the two magnets I got induced voltages anywhere between 0.5 and 1.0 volts. This implies that the magnetic field strength is stronger, but the experiment was not rigorous. I can think of a couple of aspects where the experiment was not strictly an apples to apples comparison. Whether the magnetic field strength is stronger with two magnets or not, it might be possible to increase the output with a configuration of two magnets. I reviewed my university physics book last night, and the formula it gave showed that induced current was proportional to both the magnetic flux linkages AND the number of turns being cut by the magnetic field. The number of turns parameter is why we build these coils with 10,000 turns of #34 wire rather than 100 turns of #10 wire . So what does this have to do with using two magnets you ask? Well ... by using the two magnets the gap between poles can be larger, so you can modify the design of the coil to be wider thus putting more turns into the strongest part of the magnetic field. On the other hand, the magnetic field strength will also drop as the gap increases. The million dollar question is whether the field strength drops at the same rate the number of turns increases as the gap is widened. Anybody care to wind a few 10,000+ turn coils of various widths and experiment with this ? Ron Westfall westfall@...... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: ct@....... (Charlie Thompson) Subject: Fuss over magnet design for Lehman Date: Thu, 16 Jan 1997 15:02:13 -0600 I've been listening to the discussions regarding magnet designs for the Lehman. Several observations: 1. If you have low-noise gain in your preamp it can be used instead of huge magnets and coils. 2. Once you are clearly detecting the 6 second background noise you've reached the point of diminishing returns anyway. 3. I use a cheapie blue horse shoe magnet from Radio Shack and a 240VAC relay coil and easily detect the 6 sec. background noise of the earth using Larry's most excellent preamp-filter. You can view my humble design at http://www.onr.com/user/ct/ct.html 4. Big magnets and coils are only needed if you have preamps with high input-referred noise. I can see a small amount of preamp noise but it is dominated by 6 second seismic background noise. I have the gain on the preamp cranked pretty high. I routinely detect mag 5.0 quakes 1200 miles away with this setup. 5. The Lehman design is forgiving as long as you make a low-friction pivot, adjust the period to 10 seconds or better, use a good preamp with almost any coil-magnet combination, and make the baseplate out of "non-humidity absorbing" materials like steel or aluminum. If you use a wooden base you will have to re-center the pendulum frequently. Mine stays put (bugs and spiders notwithstanding!). Lastly, you MUST have a thermal air current management system like an insulated box with a heater in the top for conditions where the floor is warmer than the air. If you don't manage the air currents properly you will LOSE 10dB of signal-to-noise or more. Basically, nothing in my design resembles the original publications but the thing still works great! The best test of sensitivity is to stand about 5 feet from your sensor and shift your weight back and forth from one foot to the other. Even on a concrete slab you should be able to record your shift in weight. If you can see your own movement you are sensitive enough to start recording earthquakes! That's my 2 cents worth and I hope everyone is encouraged to finish their designs and start recording. have fun, Charlie Thompson Buda, Texas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane Subject: Re: Force Feedback Accelerometer Finally Works Date: Thu, 16 Jan 1997 16:52:27 -0700 Hi Allan and Others, Glad to here you got you new sensor working! Hope to see some digital seismograms from your system soon. At 11:27 PM 1/15/97 -0500, you wrote: >Hello All, > I have described the basic design in some past postings to this group. >Its a crude, small device with a 4" long pendulum hanging vertically. The >natural frequency is approx 2 Hz. A chopped light beam using LEDs and CdS >cells connected to a difference amplifier. Pendulum movement of +/- .005" = >+/- 4.25 volts at the output pin of the .05 Hz low pass filter that provides >the velocity signal from the acceleration signal of the difference amp's >output. In the past I may have gotten close to success but my misconceptions >held me back especially when it came to pendulum damping. I was wondering why you are using such a low low-pass filter on your system? I think one of the reason you are/where not getting the P wave is because of this filter. I did a FFT on the P wave of several teleseismic events and I see a lot of energy between .05 (20 seconds) and .5 hz (2 seconds). > If anyone has another way that I can use to calibrate the dampening >signal PLEASE let me know. So if you are operating a S-G type seismometer >that has a healthy output signal and yet is insensitive to P wave arrivals >then you may be experiencing the same dampening problems. The method I use is a coil (I use a relay coil) temporarily placed near the pendulum's magnet and then run a wire from the coil into the other room where I have SDR running. You can connect a battery (or variable power supply) temporarily across the coil wires, or, charge up a electrolytic cap and then connect the charged cap to the coil. This method seems to work fine for both my SG and Lehman sensors. Regards, Larry Cochrane Redwood City, PSN _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: ACole65464@....... Subject: Re: Force Feedback Accelerometer Finally Works Date: Thu, 16 Jan 1997 23:33:26 -0500 (EST) Larry, To answer your question as to why I used a low pass filter for the accelerometer is as follows. The acceleration output signal from the displacement transducer needs to be integrated once to obtain a velocity signal. This integration could be done digitally with software, or electronically. I choose the later as I am not storing the data on a computer/data logger etc. The simplest way to integrate the signal is thru a low pass filter with the corner frequency set a .05 Hz. The integrated signal rolls off at 6dB per octave above this corner frequency. The instrument now gives a "flat velocity response" between .05 Hz to 2 Hz (the natural period of the pendulum). Acceleration signal appears below .05 Hz and the signal rolls off at 18 dB above 2 Hz. A simple first order filter provides this integration. I could have used a state variable filter with the center frequency set to .05Hz, at the bandpass output pick off the signal with anything above .05 Hz integrated, and at the same time I can pick off the signal at this filter's low pass output that doubely intergrates the acceleration signal, rolling off at 12dB per octave to provide a displacement signal, again "flat" between .05 - 2 Hz. I found that a true electronic integrator are difficult to keep stable and for my purposes the "filter" works fine. Using a "filter" requires some additional gain to boost the signal to see action up to 5 Hz but is no big deal. Thanks Larry for suggesting your preferred method to adjust damping. I have used the feedback coil at times to determine the dampening on my larger force feedback horizontal velocity seismometer but for the small accelerometer I find the table top warping method is easy and requires no special electronic circuit. In the posting yesterday I forgot to mention that the accelerometer's damping was adjusted to a period of .05 Hz (approx) to reduce the overall sensitivity to larger surface waves. There was a mud slide down on the train tracks not far from my house today so now no trains are running and my chart recorder looks fairly quiet. Hopefully this year I will pursue to record my seismometer's output to a computer, whereby I can easily show others on this network my results. My thanks to the people on the PSN for some great discussions and their willingness to share ideas making it possible for me to complete (it will never be truely complete) this instrument. Bye for now, Allan Coleman _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Steve Hammond Subject: Re: Fuss over magnet design for Lehman Date: Fri, 17 Jan 1997 02:53:30 -0800 (PST) Guy-- I work all weekend and see I missed out on a bunch of notes. As I started the cow magnet comments, let me add a couple more points I think are important. Everybody has such good ideas... I started using cow magnets because Dorothy Darby told me about them. She even mailed me my first few as I couldn't find them here in the bay area. I like them because they have enough field strength and the flux pattern is small enough that when it is centered in the spool frame, the lines of flux cut right through the coil mass. As I said in the original note, I use 2" x 3/4" plastic spools with a 1" center hole. While I suggested to use #32 - #34 magnet wire, I suggested it because it could be easily purchased from Allied. I built some with this gage wire and take my word for it, you want to learn to wind a coil with this gage wire. I'm currently using #52 magnet wire, which is brittle and about as thick as baby hair, in the N/S and E/W (ID = FSX) Lehman here in San Jose. Once the frame is filled, it (the coil) has 17 ohm's of resistance. I then use Pete Rowe's pre-amp design which can be obtained from the Lehman zips on the BBS's and possibly on some web pages. This consists of two Op-27's. The coil connects to pins 2&3 of OP-Amp #1 and is configured for a max gain of 10 using a 10 turn pot as the feedback resister. Between output pin 6 of Op-Amp #1 and pin 2 of Op-Amp #2 there is a 1 pole 10 HZ LP filter. The lead to the coil from the Op-Amp is less than 6-inches. Op-Amp #2 is configured for a gain of 20 and also as a coax driver. This allows for a max gain of 0 to 201 out of the preamp unit and lets me place the pre-amps with the seismographs out in the side yard seismic house while the filters, leveling, and PC interface with the PC remains in the garage. Each of the Op-Amps's +/- 12V power pins are in series with 10 ohm resister and 1uF TA caps for noise reduction. The supply is a transformer (not switching) type able to deliver 12v @ 1.0 amps and is with the PC. Bell wire is used to deliver power and ground to the pre-amps. The single come in on coax with a shield ground. I use an IBM 12-bit DACA cards in the PC for data collection configured for a 5V bipolar single. The pot in the feedback loop of Op-Amp #1 sets by using a single generator and scope. Slight changes can then be made when it is installed. The gain is currently set to 10 and the system trigger levels are set higher than normal in the software because I don't have time to review a bunch of false trigger files. I also think that Parkfield might hit this year or next and I would like to get some good data out of it. Parkfield's 201km south of me. When I'm willing to look through lots and lots of false trigger files from the lightrail that passes at the end of the block or the SP train tracks 1.5km from me, I can crank the gain back up and will record distant faint teleseismic events. I have recorded 5's in the Far East when it's locally seismicly silent. The down side of running with the gain cranked up to 201 is that when there is a local 3.0, it's off scale. So as you can see, one cow magnet works just fine for me. I'm a big fan of cow magnets. They are low cost and easy to obtain if your a cow farmer. I really don't think there is a justifiable advantage to two magnets for a couple of other reasons then the field strength. I agree, you might see an increase in field strength but nothing is free in engineering and there is some side effects. One is the introduction of additional magnet flux field in a small area near the end of the boom. I use disk drive break magnets for damping magnets and they are polarized and placed on the floor at the end of the boom in a little frame to hold them. A 3/8" x 2" x 8" brass bar is mounted on a T hanger off the end of the boom and is centered between the opposing magnet faces. I mount the cow magnet in a holder which holds the magnet 90 degrees to the boom about 12" down the boom from the damping magnet. A second cow magnet could introduce a conflicting flux field. The coil is also on the floor in a holder set parallel, 2-inches to the left, of the 40" long, 3/4 x 3/4 square, solid aluminum boom and the cow magnet passes through the center hole in the coil's plastic spool. The design is simple and easy to maintain. The square aluminum boom is much easier to work with then a round boom and is rigged and does not flex when the 5 lbs lead mass is set in place. To sum this up, a good clean single to start with is a must. But you don't need to arcweld with the output of the coil and magnet. Remember, if you put the magnet on the boom, anything that is metal will draw the boom to it because of the magnet. This includes metal wire in the cement garage floor... About the base plate. Steel is a bad idea if the magnet is going to be mounted on the boom. Use aluminum because it is easy to work with and can be drilled and tapped without exotic tools. I saw a comment about wood base plates in one of the notes, and I have never used wood so I can't comment. But I can tell you that the earth will swell and cause the unit to require realignment. This happens in rain and dry weather. Overnight in a good rain storm, the unit can shift from exact center to resting on the boom stop. Make sure you allow for a three point adjustment in the base plate feet. I mount my Lehmans on three 1/2" machine lags set into the cement. I also include two long machine screw in the rear corners of the base plate that will tweak the plate slightly so I can easily adjust the centering without having to realign the entire unit when the ground swells. I just drilled and tapped two hole and then ran long hex head machine screw down through them and bottomed the screws out on two metal slugs set on the cement. A slight twist on one of the screws and the corner of the plate tweaks up slightly changing the alignment of the boom support. It works great and I can realign the boom in a second. Regards, Steve Hammond PSN BBS San Jose, California 408-226-0675 Public Seismic Network Mailing List (PSN-L) From: ct@....... (Charlie Thompson) Subject: Lehman's with steel bases and boom magnets Date: Fri, 17 Jan 1997 11:08:29 -0600 I use a boom-mounted horse shoe magnet with a steel base. The concern over magnetic attraction to the base (thus causing a boom offset) is not too bad in my design because the steel base is a FRAME not a plate. As a result, the near-field of the magnet is safely spaced away from the steel frame. In theory there is a tiny attraction but a tiny tilt of the base will easily allow re-centering. Using giant powerful magnets on the boom may cause a problem with a steel frame but I use a simple ALNICO horse shoe magnet and have not noticed a problem. Also my unit sits on a slab with imbedded re-bar. The height of the magnet above the slab is high enough not to cause any significant attraction to the re-bar. One suggestion on re-leveling.... If you place your sensor on a small slab outside you may experience more problems with ground swelling than placing your sensor in a quiet corner of the garage or basement. There is little movement in a house slab...at least one that not cracked anyway! It's also harder for water to soak under a large house slab as opposed to a 4'x4' slab in the back yard. ....hence less visits to the sensor for re-levelling. I'm making these statements based on average Texas rainfall not Portland floods. Bottom line...turn it on and start recording! The best refinements are made while collecting and observing recorded data. -Charlie Thompson Buda, Texas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Steve Hammond Subject: Re: Lehman's with steel bases and boom magnets Date: Fri, 17 Jan 1997 12:22:26 -0800 (PST) Hi Charlie-- I saw the picture of you seismograph some time back and was impressed with the frame you built. I sent that note out last night at 2AM and don't mean to imply that aluminum is the only way to go. I just had a lot of problems the steel frame I built. I built my first seismograph completely out of steel and mounted the magnet on the boom and installed it in the garage. It was small and light and had a 12" boom. I spent a lot of time trying to get ride of the effects the frame had on the placement of the magnet. The boom was also an 1" off the cement and after running for a week, the boom would alway drift to the left stop. I then worked on it one night and reinstalled it 90 degrees to where it had been and the drifting problem went away. I found the rebar with a magnet on a long string.... I then built the second FS1 long period for $12. This had a 36" round brass 3/8" boom and I clamped a toilet tank float filled with water to the end of it for a mass weight and used oil and magnets for damping. It had a double wire suspension in it giving it almost zero percent friction in the pivots. I built this frame out of plexe glass (sp?). This unit had two real bad design flaws. One was that the plexe glass flexed from time to time and forced me to realign the unit when it happened. The other problem was that the boom was too light for the length and mass weight and It would go into vertical oscillation after an event. I ended up placing abutments above the boom and ran two tension wires from end-to-end of the boom to give the boom some support. I also had the unit in the garage and found that walking near it would case a trigger. Working in the garage mean taking the unit off-line. I built a couple of more units out of a variety of parts and things but ended up using more and more aluminum because I could drill it in a drill press and tap it without any special tools. When I finally built the Lehmans, I selected a 1"x 12"x 18" plate to be the base. I wanted something that was solid and would support the unit like your steel frame. I don't have a welder. My unit does have some steel in the design because I used the 3/4 water pipe as in the original drawing for the upright support but, I changed the lower pivot to be a point set into a hole in the end of a machine screw. This allows me to adjust the boom pivot location in and out changing the lower alignment after leveling the base plate. I clamped an aluminum bar to the lower pip frame with u-bolts and drilled and tapped a hole in the center for the adjusting screw. Anyway-- that's sort of sums up how I ended up building it the way I did. There are a dozen other ways. And your right Charlie-- San Jose is not Texas. My location is atop deep clay that was once farm land. So regardless of where I place my seismograph, in the garage or out on a slab in the yard, it is going to move and require attention. That's way I made everything adjustable. Regards, Steve Hammond San Jose BBS 408-226-0675 On Fri, 17 Jan 1997, Charlie Thompson wrote: > I use a boom-mounted horse shoe magnet with a steel base. > The concern over magnetic attraction to the base (thus causing ... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Karl Cunningham Subject: Re: Force Feedback Accelerometer Finally Works Date: Fri, 17 Jan 1997 20:48:28 -0800 At 11:27 PM 1/15/97 -0500, you wrote: > Finally sorted out my home brewed horizontal force feedback accelrometer >in time to record the 6.8Ms eq in Mexico back on 1-11-97 UTC. THAT'S GREAT! CONGRATULATIONS! Hi Allan -- Glad to hear you've got it working. I've got a few questions... 1. Did you end up using one LED or two? 2. Do you have an idea how much (force) feedback you are giving the system? That is, how much LESS does your mass move (with respect to the instrument frame) due to the force feedback than it would without the feedback. 3. For calibration, have you thought about using Robert L. Barns' calibration scheme involving a meter movement (described in this list a few months ago). I found it to work well. It provides a calibrated force to the system, which converts to acceleration when you multiply by your mass, assuming the force frequency is above the natural frequency of your system. Karl Cunningham La Mesa, CA. karlc@......... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: ct@....... (Charlie & Terri Thompson -- Buda MicroRanch ) Subject: Re: Lehman's with steel bases and boom magnets Date: Fri, 17 Jan 1997 22:55:19 -0600 HI Steve, It sounds like you have more experience with Lehman's than I do for sure! I guess the advanatage of a force-balance system is that the pendulum stays in one place....maybe that's one reason the commercial units use force balance? I have my sensor under the stairwell in the garage...which is a place sort of away from my garage activities. I do get a lot of false triggers...like everytime I go up the stairs to my office where the computers reside! To be honest I don't even look at the Auto Save count. I just set the X value to 141 and number of lines to 16 and reveiw the data every morning. When you use X=141 and display 16 lines you can whip through 12 hours of data in about 2 minutes. The 141 was the suggested number for 30 minutes per displayed line of data. I can quickly sort through the kitty events, door slams, and stairwell events...since they really don't look like a genuine earthquake. Quakes happen so rarely (I pick up about 1-3 per week) that the man-made and animal-made noise has not interfered with any quake recordings yet. Tonight the 6 second wavelets are big again...apparently a wx front is approaching ...or something...I don't know what to correlate the varying amplitude to. I'm lucky I can see them...if I lived in the city they would probably be obscured by local noise. They seem to change from day-to-day. BTW I've built a "baby Lehman" which fits under an inverted 10-gallon fish tank. It's not wired up yet but the goal was to have a nice small sensor under a glass case. The fish tanks are available at PetSmart for $10. The period is about 8 seconds. IF it works I may retire the big Lehman which, with box included, is about the size of a coffee table and takes up some precious room in my garage. The baby Lehman has a very small base with 3 levelling screws for feet. The design is basically the same just smaller. I still have to nail the spider annoyance but the fishtank will have a tight seal to keep bugs OUT once and for all. Take care and post some quakes to event@............. for us to see. Regards, Charlie Thompson Buda, Texas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Tim Kearsley Subject: Where to locate a Lehman? Date: Sat, 18 Jan 1997 12:00:43 +0000 Hi all. I've been following this group with great interest for a while now. I must say there are some clever people out there, and the dialogue is extremely stimulating. I've recently built myself a fairly conventional Lehman design of seismometer. It still needs "tweaking", but I think it will work. However, my problem is where to site it? I don't have a garage or outbuilding except a greenhouse. Presumably the thermal cycling in that would make it utterly useless. I naively thought that I could simply install the seismometer outside and cover it with a frame made of timber and perspex, but of course this has not worked, presumably because all sorts of draughts are finding their way in. Does anyone have any idea how I can progress, or am I basically "stuck"? Many thanks in advance for any help. Tim Kearsley G4WFT Higham Ferrers England _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Frank McJunkins Subject: Lehman 'clone' info Date: Sat, 18 Jan 1997 09:04:42 -0800 (PST) Just for filing purposes, 'Ward's Natural Science Establishment Inc.' [P.O. Box 92991 Rochester NY 14692-9021 (800) 962-2660] offers a 'Horizontal Seismograph' with amplifier and chart recorder. The unit is apparently offered for school use and costs over $2,000 complete. I have been researching sesimographs for the school district here, and although the price tag for this unit is very steep, Ward's offers their User's Guide in a three ring binder for $25 plus shipping. The Users Guide is full of great information on the mechanics of earthquakes, and how to set up their seismograph...which would be extremely useful to anyone setting up any Lehman type unit. The info is very concise with regards to damping and adjustment and is excellent for anyone building their own unit. Their catalog number for the manual is 227-0004. I have done a lot of research and this is by far the best one-place reference manual for the home seismo builder. Frank McJunkins K7RSD fmcjunki@................. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: toddm@........... (Todd Miller) Subject: Earthquake curriculum Date: Sat, 18 Jan 1997 09:37:58 -0800 To those of you all on this list in education there is a pretty cool curriculum called Seismic Sleuths available. It includes many activities relating to seismology with an emphasis on earthquake preparedness. The best news is its free! It is supported by our tax dollars through FEMA and developed by the American Geophysical Union and single copies are available at no charge from them. FEMA Warehouse P.O. Box 2012 Jessup MD 20794-2012 1-800-480-2520 Have fun-Todd Miller _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Dennis Leatart Subject: Re: Earthquake curriculum Date: Sat, 18 Jan 1997 10:54:50 -0800 Hi Todd: Thanks for the post!!! I am an earth science teacher and really get into seismology in my 8th grade curriculum. I wonder if they have other units available??? Will definitely contact them!!! -- _____ __ | \.-----.-----.-----.|__|.-----. | -- | -__| | || ||__ --| |_____/|_____|__|__|__|__||__||_____| _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Steve Hammond Subject: Re: Where to locate a Lehman? Date: Sat, 18 Jan 1997 11:07:20 -0800 (PST) Welcome to the club Tim-- nice to hear from you. I know of two that are installed just as you describe below. Jan Froom in Gilroy, California and Old Howard's in Sebastopol, California. The story told around the campfire goes, in the early 50's, the guys' at Berkeley would call-up old Howard (who is now well into his 90s) and second source their distance and magnitude data from time to time... But anyway-- So I know of two that built a wooden house of plywood and covered it with rolled plastic trap a few mills thick. Jan described a thing called moon walking, which just came on suddenly, but he pulled his gear off-line for other reasons before it was resolved. I would give it a try at least. It will require a base. Jan set a steel pole in the ground. Howard's is on cement. Do you have spiders in England? On Sat, 18 Jan 1997, Tim Kearsley wrote: > Hi all. > > I've been following this group with great interest for a while now. > I must say there are some clever people out there, and the dialogue > is extremely stimulating. > > I've recently built myself a fairly conventional Lehman design of > seismometer. It still needs "tweaking", but I think it will work. > However, my problem is where to site it? I don't have a garage or > outbuilding except a greenhouse. Presumably the thermal cycling in > that would make it utterly useless. I naively thought that I could > simply install the seismometer outside and cover it with a frame made > of timber and perspex, but of course this has not worked, presumably > because all sorts of draughts are finding their way in. > > Does anyone have any idea how I can progress, or am I basically > "stuck"? > > Many thanks in advance for any help. > > Tim Kearsley G4WFT > Higham Ferrers > England > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: ct@....... (Charlie & Terri Thompson -- Buda MicroRanch ) Subject: Lehman drawing added to my web page Date: Sat, 18 Jan 1997 17:38:40 -0600 For those of you considering construction of a Lehman sensor I have added a drawing detail to my web page. This is my version of a Lehman so it may look a little different but it does work. The link to the drawing is below the "photo #2" link on my main page: http://www.onr.com/user/ct/ct.html have fun! -Charlie Thompson Buda, Texas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: David A Nelson Subject: Re: Lehman drawing added to my web page Date: Sun, 19 Jan 1997 12:56:48 +1200 Greetings Charlie, Great Pic, any chance in putting some measurements on the drawing, eg, length of boom, height of vert. support, also you didn't show any lumped mass on the boom..... are you using any.... if so how much??? At present I am using two short period commercial seismometers, but I need to construct two lehman's, 1 for myself and 1 for a recording installation at the local civil defence offices which will be computer logged with Larry's SDR sys. Dave At 05:38 PM 1/18/97 -0600, you wrote: >For those of you considering construction of a Lehman sensor >I have added a drawing detail to my web page. This is my >version of a Lehman so it may look a little different but it does work. >The link to the drawing is below the "photo #2" link on my main page: > > http://www.onr.com/user/ct/ct.html > >have fun! > >-Charlie Thompson > Buda, Texas > > > > > >_____________________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email listserver@............. with the body of the >message: leave PSN-L > > Dave A. Nelson 24 Jensen St., Green Is., Dunedin, South Is.. New Zealand. http://psn.quake.net/dave/home.htm ( world wide access ) http:/www.es.co.nz/~dann/home.html ( New Zealand access only ) _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: ACole65464@....... Subject: Re: Where To Locate a Lehman Date: Sat, 18 Jan 1997 22:05:25 -0500 (EST) Tim, I had made a simple wooden enclosure, 3 feet wide x 5 feet long, out doors for a home-made horizontal long period velocity type seismometer (aka Lehman) and used it for over 4 years. A spot was smoothed out on the dirt then packed down a 3" layer of gravel over it. A plywood box 3' x 5' with a open bottom and a hinged lid was placed over the gravel and then it was pegged down to hold it in position. This box was 2 1/2 feet high so there was enough space inside the box to have an inner lid, set 6" below the hinged lid. An internal ledge around the inside of the box provided the support for the lid. A simple weather proof gasket went between the lid and ledge to keep out drafts and bugs. The gravel bed that was exposed to the inside of the box was covered with a sheet of plastic. The edges of the plastic were sealed to the inside walls of the box with duct tape. A couple of concrete blocks were placed on the plastic sheet and wiggled into place to ensure good seating. These blocks supported the seismometer. The only problems were the odd weeds pushing up through the plastic and when the moisture in the ground beneath it froze then thawed, the seismometer had to be relevelled to compensate for the tilting. This box was semi portable so it could be moved to find the quietest spot in the back yard. I hope you can find something to work for you. Bye for now, Allan Coleman _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Robert L Barns <75612.2635@..............> Subject: Re: Where to locate a Lehman? Date: 19 Jan 97 11:19:37 EST Tim Kearsley, I don't think that the greenhouse is an impossible place for a Lehman. If the floor is not concrete, you could pour a concrete slab say 3" thick and set the seis on that. A box to minimize drafts (draughts) is a must. I built one from 2" thick polystyrene foam insulation which I got at a lumber yard. This stuff is extraordinary insulation. The box has no bottom--it just sits on the concrete floor. If you are careful when cutting the foam with a knife to make the edges square, the box can be glued together with carpenters white glue (Elmer's in the USA). It takes at least 24 hrs. for the glue to set because the insulation is so good that the water evaporates slowly (the heat of evaportaion of water is large). The lid just sits on the top--no tape needed if the top surface of the box is nice and flat. I think that it is essential to stagnate the air in the box but this is easy to do. Just put a heater near the center of the top of the box. I use a ceramic wire-wound resistor of 5 ohms and 20 watts rating. This is powered by a 9V AC transformer. The dissapation is thus 16 watts. This gave a temperature gradient of XXXX deg F from top to bottom. A resistor is superior to a light bulb because the light can attract bugs. Bob Barns _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Dennis Leatart Subject: Local Earthquake?????? Date: Sun, 19 Jan 1997 12:47:10 -0800 I have detected a local event??? at 20:42UT. I am at 118.1 long. and 34.1 latitude in Moorpark, CA. Did anyone else pick up this event-- I can not rule out a teleseismic event???!!!!! -- _____ __ | \.-----.-----.-----.|__|.-----. | -- | -__| | || ||__ --| |_____/|_____|__|__|__|__||__||_____| _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Robert Avakian Subject: Re: Where to locate a Lehman? Date: Sun, 19 Jan 1997 20:51:39 -0800 Tim Kearsley wrote: > > Hi all. > > I've been following this group with great interest for a while now. > I must say there are some clever people out there, and the dialogue > is extremely stimulating. > > I've recently built myself a fairly conventional Lehman design of > seismometer. It still needs "tweaking", but I think it will work. > However, my problem is where to site it? I don't have a garage or > outbuilding except a greenhouse. Presumably the thermal cycling in > that would make it utterly useless. I naively thought that I could > simply install the seismometer outside and cover it with a frame made > of timber and perspex, but of course this has not worked, presumably > because all sorts of draughts are finding their way in. > > Does anyone have any idea how I can progress, or am I basically > "stuck"? > > Many thanks in advance for any help. > > Tim Kearsley G4WFT > Higham Ferrers > England > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L I'll bet a local school (years 7-12) Earth Science teacher would be delighted help you. Many I know would easily trade you a few square feet of floor in a stockroom for the data from the machine and the ability to show their students a "real" instrument. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Charlie Plyler Subject: Missing data Date: Sun, 19 Jan 1997 23:21:27 -0500 It is my understanding that the AT&T satellite which disapeared last week has caused some data interruptions which interferes with transmissions from the USGS seismic stations. I have noticed that some international seismic data is missing, beginning around 2200 hours and lasting until around 0700 hours UTC. Could someone advise me if an alternate source, other than autodrm@....... USGS.Gov, for reporting real time data, of the time, coordinates, and strength of seismic events is available. Thanks very much, Charlie ELFRAD GROUP _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Ken Navarre Subject: Re: Where to locate a Lehman? Date: Tue, 21 Jan 1997 06:40:07 -0800 (PST) On Sat, 18 Jan 1997, Tim Kearsley asked: > I've recently built myself a fairly conventional Lehman design of > seismometer. It still needs "tweaking", but I think it will work. > However, my problem is where to site it? I don't have a garage or > outbuilding except a greenhouse. Presumably the thermal cycling in > that would make it utterly useless. I naively thought that I could > simply install the seismometer outside and cover it with a frame made > of timber and perspex, but of course this has not worked, presumably > because all sorts of draughts are finding their way in. Tim, I located a section of steel culvert pipe with 32 inch diameter. It stands about 2 1/2 feet high when placed on it's end. I leveled the soil and placed the pipe on its end. This makes for a nice enclosure. I have plastic sheeting laid under the pipe and up 3/4 of the height to help keep out critters (yep, Steve's not the only one who records spiders building webs...) I made a plywood cover with a plexiglas window for observation. The Plex window is set above the plywood by resting it on 3 nuts to allow condensation to escape. I also have placed a 60 watt lamp inside the enclosure and just let it burn... :( (Seems as if the spiders don't care much for the light...) This setup is in my back yard and I don't have much problem with drafts. I have another plastic sheet that lays over the whole thing and is secured down with a bungee. I also like Larry's suggestion on including a coil near the magnetic end of the boom so that I can push a button in my room and send a DC current to the coil to "thump" the boom occasionally and see the oscillation. saves a lot of time if I want to check for motion... Ken _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Ron Westfall Subject: Re: [Fwd: USNSN alternatives] Date: Tue, 21 Jan 1997 18:52:32 -0800 Edward Cranswick wrote: > On Feb. 13-15, I will be attending a meeting in Memphis about > connecting regional seismic networks through the country, e.g,. > Calnet, together via the Internet, and I plan to present the > PSN by cruising the PSN Websites with a laptop. When I am a > little clearer about the details, I will post a more complete > statement here and solicit you all for advice. I was going to wait to explore this issue until I got my seismographs up and running, but it seems like an appropriate time ... I understand that a lot of the operators of PSN seismographs share traces by copying each other's data files. Looking just now, I also see that Larry's web site has copies of data files from several sites. While data file copying is great, it is rather manual and subject to the whims of individual operators to offer and acquire each other's files. It seems to me that the PSN could be enhanced to actually be a network. WARNING! Severe fantasy ahead! Assume for the moment that most PSN sites will be permanently connected to the Internet in the next few years. In the interim, a PSN site could be configured to connect to the Internet shortly after a significant event. Permanently connected web sites (e.g. sites such as Larry's) would act as permanently available data repositories for non-permanently connected sites. Each non-permanent site would be matched up with a permanent data repository site. Data repository sites would keep data for some standard time period before the trace data files were either deleted or archived. Software at each site would be capable of autonomously setting up a network connection with another site for the purpose of sharing traces. Non-permanent sites would connect to permanent data repository sites to upload traces of significant events. All sites would connect to one or more permanent data repository sites simultaneously to receive traces for a single event or a set of events. All permanently connected sites would be able to offer a real-time feed from their seismographs on demand for real-time viewing. We have all seen the postings by the high school people who want access to seismographs. Imagine if you will a scenario where a student fires up their web browser and cruises to a PSN site. There they find a reference which downloads a Java applet for viewing traces. The Java applet dynamically connects (probably via the first PSN site) to one or more of the permanent data repository sites. The Java applet indicates the time range of interest for historic traces or real time for current traces (which are not being saved unless the site is processing an event). The sites proceed to feed the desired traces to the Java applet which displays them time synchronized. It would be possible to see an event hit first one station and then the the others in sequence. It would be doubly interesting for the high school people if their own sites were contributing to the action. Since I don't have my own seismographs in operation yet, I am not fully acquainted with the capabilities of SDR, WinQuake, and any other applications which people are using. From previous postings I know that these applications seem to figure out distance to the epicenter, but given data for only one PSN site, it does not seem likely the applications can actually locate the epicenter. I'm guessing here. It appears that most people figure out actual epicenter by referring to USGS sites? If the above conjecture is true, then it should not be a large step to take the above scenario one step further by automatically setting up network connections between sites so the PSN can figure out epicenters itself. The first site to detect an event would broadcast the info in a network message. When the second and subsequent sites detect the event, network connections would be set up autonomously and epicenter identification would kick in. Anybody who happened to be near their seismograph or browsing from the web at the time would see the event notification, would see the event itself ripple across the various sites, and could watch in real-time as epicenter identification occurred. The same process could also be used to play back a historical event. Beyond this people can go really wild by combining traces from multiple sites to perform studies that interest them. As the number of PSN sites increase, the value of the data and the ability to perform serious work should increase as well. Amateur astronomers have been collecting information and performing studies of scientific value for years. There is no reason why the amateur seismologists could not contribute similarly. The amateur astronomers can generally contribute to studies that take advantage of their large numbers, their ability to dedicate lots of unpaid time, and their unrestricted access to telescopes. Probably all the amateur seismologists need is some ideas about what would be worthwhile to work on (hint, hint you professionals!). End of fantasy! We return you now to your regularly scheduled program. I somehow imagine this post might generate some discussion, even if its only to respond "What a crock!" Well? Ron Westfall westfall@...... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Barry Lotz Subject: Re: [Fwd: USNSN alternatives] Date: Tue, 21 Jan 1997 19:00:10 -0800 From: Edward Cranswick Subject: Re: [Fwd: USNSN alternatives] Date: Tue, 21 Jan 1997 20:51:53 -0700 Ron- > I understand that a lot of the operators of PSN seismographs > share traces by copying each other's data files. Looking just > now, I also see that Larry's web site has copies of data files > from several sites. While data file copying is great, it is > rather manual and subject to the whims of individual operators > to offer and acquire each other's files. It seems to me that > the PSN could be enhanced to actually be a network. > > WARNING! Severe fantasy ahead! I couldn't have said it better myself! ... even though I have been saying something like this since 1990, and others, such as the old IBM PSN mafia of Ted Blank and Steve Hammond and the group in San Jose, have actually implemented prototype versions of it after the 1989 Loma Prieta Eathquake. I really welcome the post-Web developments that Larry Cochrane and others have spearheaded, and I look forward to what happens next. I will give you some more feedback soon. -Edward -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 1711 Illinois St cranswick@........ Golden, CO 80401 USA E.M. Forster said, "Only connect". _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane Subject: My thoughts on the 4/96 SA seismograph article. Date: Tue, 21 Jan 1997 21:16:41 -0700 Hi, After receiving my first SAS (SOCIETY FOR AMATEUR SCIENTISTS) Amateur Scientist's Forum email (see http://www.thesphere.com/SAS/) I wrote the following response to two messages about the ADXL05 accelerometer article. This forum is a moderated list and goes out periodically (not sure how often) so it has not been sent out yet (if they ever use it). -------------------------------------------------------------------------- Greetings, This is my first message to this list so I apologize for being so negative, but here it goes... In the last SAS Amateur Scientist's Forum email (Vol 3 #1) I read two messages about this article, here are my thoughts on it. I think the April 1996 Scientific American article on a New Backyard Seismograph has been a big disservice to the amateur seismology community. If the article had been labeled as a strong motion sensor I wouldn't have any problems with it. I hope to get a hold of some of the IC sensor chips myself someday and make a strong motion sensor using these chips. The problem is these chips are designed to detect a car crash not the very small movements that most events make. Someone on the Public Seismic Network mailing list (see http://psn.quake.net/maillist.html) once calculated that it would take a local (under 100km) quake of magnitude 5 or larger before you would get a useful signal out of this type of sensor. If you do not live near active faulting you are not going to pick anything up. You will be spending a lot of time and money for nothing. If you do live in a place where you have large earthquakes (like myself, I live in the San Francisco Bay Area) this sensor should be your second sensor, first make a more sensitive seismometer like a Lehman or Shackleford-Gundersen. Even in areas with large events you can wait a long time between events that will be large enough to pick up. I have been recording local and teleseismic events for over 2 years with sensor in my house and monitoring USGS telemetry signals, and so far there have been only one event that I could barely feel. I would be surprised if this type of sensor would have pick up anything. One more thing about this type of sensor. Given that you will only be recording large local events I would suggest you have all of system/electronics on some sort of battery backup system or UPS. If the event is large enough you may loss AC power and loss the data before it can be stored. Now for some good news. You can pick up earthquakes at home. You just need to make a more sensitive device. Both the Lehman sensor (see July 1979 SA) or the Shackleford-Gundersen (SG) sensor (Sept 1975 SA) will record a lot more events then a sensor based on a ADXL05 accelerometer IC chip. This making the hobby of seismology a lot more enjoyable. I have found that the SG sensor design makes for a very good seismometer for recording teleseismic (distant) events. I have compared seismographs from my SG sensor to broadband commercial sensor, run by the Berkeley University near me, and am amazed at how similar they are. Not bad for a sensor that costs under $200.00 for the parts compared to a STS-1 or STS-2 Streckeisen seismometer costing a lot more (I think I read that they are around $10K). I hope to have a Web page showing the differences between the different sensor on the Redwood City PSN Home page soon. For more information on making a seismograph system please see my PSN home page at http://psn.quake.net. Regards, Larry Cochrane (cochrane@.............. Public Seismic Network Redwood City, Cal USA _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Robert L Barns <75612.2635@..............> Subject: Re: My thoughts on the 4/96 SA seismograph article. Date: 22 Jan 97 10:56:14 EST Larry, Good show on spelling out the severe shortcomings of the chip accelerometers! Bob Barns _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane Subject: Re: [Fwd: USNSN alternatives] Date: Thu, 23 Jan 1997 01:30:00 -0700 At 07:00 PM 1/21/97 -0800, Barry Lotz wrote: > I mentioned to Larry that I think Winquake would be even more powerful >if it could triangulate between our stations. Our locations are known, >our magnitude factors could be zero'd in. I did download a program (both the code and exe) called hypocenter from ftp://elepaio.soest.hawaii.edu/pub/lienert. This program takes a set of phases (P, S etc) and arrival times from several stations and computes the location of the event. The problem is it's all written in Fortran and I don't do Fortran. I was able to find the formula for calculating the magnitude based on Ms (using the surface waves) in the code and added it to WinQuake. The next version of WinQuake will also calculate the magnitude based on Md (the duration of the event rather then the max amplitude of the event) thanks too John Lahr who dug up the formula for me. Unfortunately Md only works for local events that are recorded using short period sensor. >Station clocks may vary. This is a real problem if we ever want to accurately locate events, especially if only the arrival of the P is going to be used. Even with using the P-S distance it's nice to have accurate timing so that the time of origin can be used in the equation for locating the event. I have found the using a shortwave receiver tuned to WWV (2.5, 5.0, 10.0 or 15.0 Mhz) and the top of one minute mark (a 800 millisecond 1000hz tone) broadcasted every minute to be a good method for keeping accurate time. My SDR data logging software, along with the tone decoder on my 12/16 bit A/D card, use this method and am able to keep my system time to within a few milliseconds. On a side note: A small company called Hamtronics (they now have a web page at www.hamtronics.com) has a WWV receiver kit for $59.95 and an assembled versions for a little more. I bought the kit and it seems to work pretty well. The problem is it only receives on 10.0 mhz and this band has a lot of computer noise from my 5 PC systems I can running. Regards, Larry Cochrane Redwood City, PSN _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: watson@................ (Charles Watson) Subject: Re: Punta Gorda Earthquake Date: Thu, 23 Jan 1997 14:39:44 -0800 Edward Cranswick wrote: > > > I confused myself; this is the Webpage I have problems with: > > http://www.seismo-watch.com/EQS/AB/9701/A970122-017.Men5.7.html > > -Edward > Thanks for alerting me to the situation! Ya know, Edward, I updated the web site Alert Bulletin with the OSU Moment Tensor solution and I may have miss-directed the location of the graphic. I use Adobe PageMill for constructing the web pages. It sets graphics within the web page via a nifty directory system which mirrors the same configuration as my desktop. Unfortunately, the drawback is if I move the web page to another directory, I have to manually relocate the PageMill directory path as well. When I made the OSU update, I changed the directory for .html file without changing the PageMill graphic path. Unknowingly, I sent it to the Seismo-Web Page for public review. ACK! I corrected the error and you'll find it working just fine now. http://www.seismo-watch.com/EQS/AB/9701/A970122-017.Men5.7.html I'll be changing the graphic to reflext the OSU analysis shortly. Best regards, Charlie --- Charles P. Watson, Consulting Geologist Advanced Geologic Exploration Seismo-Watch / Earthquake Information Services Voice: 702-852-0992 / Fax: 702-852-3226 watson@................ http://www.seismo-watch.com _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Punta Gorda Earthquake Date: Thu, 23 Jan 1997 16:49:15 -0800 Edward Cranswick wrote: > > Charlie- > > > I corrected the error and you'll find it working just fine now. > > http://www.seismo-watch.com/EQS/AB/9701/A970122-017.Men5.7.html > > Works perfectly now and looks very good! In Memphis, I'll have to ask > you how you did it (can only type with one digit and only about one Gig > of neurons are operating at present). > -Edward > Oh, my! I just realized the Ml was revised to 5.6 rather than the preliminary of 4.8. So...an other up date. The graphic placement seems to work ok with this one. I am still fiddling with how to do this. Ya know, after talking to several residents in the area, it sure doesn't seem like a temblor of Mw 5.8/Ml 5.6. I get a MMI of III-IV, and most of these people were about 6-10 miles from the epicenter. Humm... Seems like stuff should have been knocked off the table with a M+5 at those distance. Any ideas from the group on why this would be so? One idea that was presented to me earlier was it was a "slow" earthquake resulting in an enrichment in very-long-period energy. --- Charles P. Watson, Consulting Geologist Advanced Geologic Exploration Seismo-Watch / Earthquake Information Services Voice: 702-852-0992 / Fax: 702-852-3226 watson@................ http://www.seismo-watch.com _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane Subject: Re: Punta Gorda Earthquake Date: Thu, 23 Jan 1997 17:33:43 -0700 IMHO this was not a Ml 5.6! I'm not sure about a 5.6Mw since this was the first time I have seen Mw used for this location/size of quake. The automatic picking system from the Berkeley or local USGS, I don't remember which one, (using the finger quake@...) first came out with a Md of 4.8 then I saw a Ml of 5.0. A few hours later they changed it to 5.6 Mw. Then the next day they changed it again to 5.6 Ml. All of the seismograms from my system, I now have 10 channels going, all registered the event around 4.8 to 5.0 Ml or Md, not 5.6. If you finger quake@....................... they have the event at Mag 4.8. The finger service at quake@................. is still not reporting this event! Just my .02 cents... Larry Cochrane Redwood City, PSN At 04:49 PM 1/23/97 -0800, Charles Watson wrote: >Oh, my! I just realized the Ml was revised to 5.6 rather than the preliminary of >4.8. So...an other up date. The graphic placement seems to work ok with this >one. I am still fiddling with how to do this. > >Ya know, after talking to several residents in the area, it sure doesn't seem like >a temblor of Mw 5.8/Ml 5.6. I get a MMI of III-IV, and most of these people >were about 6-10 miles from the epicenter. Humm... Seems like stuff should >have been knocked off the table with a M+5 at those distance. > >Any ideas from the group on why this would be so? One idea that was >presented to me earlier was it was a "slow" earthquake resulting in an >enrichment in very-long-period energy. > > >--- >Charles P. Watson, Consulting Geologist >Advanced Geologic Exploration >Seismo-Watch / Earthquake Information Services >Voice: 702-852-0992 / Fax: 702-852-3226 >watson@................ >http://www.seismo-watch.com > >_____________________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email listserver@............. with the body of the >message: leave PSN-L > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: watson@................ (Charles Watson) Subject: Re: Punta Gorda Earthquake Date: Thu, 23 Jan 1997 20:06:23 -0800 This quake is surely a candidate for further research, eh? As far as the MT results, both Berkeley and Oregon State calculate energy releases for events in the western US and off the coast: Here is OSU's URL: http://quakes.oce.orst.edu/moment-tensor/#recent I haven't used the UCB MT results for years.....I am not sure they have a URL for their results. But you can e-mail Michael Pasyanos at mike@................... for results. --- Charles P. Watson, Consulting Geologist Advanced Geologic Exploration Seismo-Watch / Earthquake Information Services Voice: 702-852-0992 / Fax: 702-852-3226 watson@................ http://www.seismo-watch.com _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: David A Nelson Subject: who is recording and with what Date: Fri, 24 Jan 1997 16:05:14 +1200 hi ya all, I'm hoping that you all will indulge me in my wonderings, there are some 200 + on this PSN mailing list (substantially less with operating gear) and I am keen to find out who is actively doing recording , gear being used eg SDR a to d, analog etc, type of sensors and the location.... town/city, country If you know your lat/long. well thats a bonus it would be great to have a database and I would love to stick some pins in a world map of where we all are anyone else interested in the list (once compiled) can have it e-mailed to them well how about it Thanks Dave Dave A. Nelson 24 Jensen St., Green Is., Dunedin, South Is.. New Zealand. http://psn.quake.net/dave/home.htm ( world wide access ) http:/www.es.co.nz/~dann/home.html ( New Zealand access only ) SOD'S-LAW--- When Something Does Go Wrong, There Is Sod All You Can Do About-It When The Last Of Ten Screws Has Been Removed From A Cover, -It Will Be Discovered That The Wrong Cover Has Been Removed When The Last Of Ten Screws Has Been fitted back Into A Cover, -It Will Be Discovered That The gasket Has Been Left Out _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: David A Nelson Subject: seis. rec. info reply form Date: Fri, 24 Jan 1997 18:10:22 +1200 yep Steve good thought.... here it is please return this questionaire to: dann@........ thanks Dave Your Name....... E-mail address ..... Homepage address.... Type of seismometer/s (eg 15 Sec Lehman, 4.5Hz geophone) commercial/homebrew, put a C or H after each type listed below for each channel CH1 .... CH2 .... CH3 .... CH4 .... CH5 .... More?? (Larry can get your info from your site) ...... Type of recorder A to D card (eg SDR) ....... Analog (rotating drum) ..... Other (eg strip chart) ...... Location Lat/Long. (eg 45.8S 172.5E) ...... Town/city (in or closest to) ......... State/Province(if applic.) ........... Country ....... Any other general comments you think relavent ............ I will look at producing a gif image World map and adding it to my homepage for viewing/downloading Dave A. Nelson 24 Jensen St., Green Is., Dunedin, South Is.. New Zealand. http://psn.quake.net/dave/home.htm ( world wide access ) http:/www.es.co.nz/~dann/home.html ( New Zealand access only ) SOD'S-LAW--- When Something Does Go Wrong, There Is Sod All You Can Do About-It When The Last Of Ten Screws Has Been Removed From A Cover, -It Will Be Discovered That The Wrong Cover Has Been Removed When The Last Of Ten Screws Has Been fitted back Into A Cover, -It Will Be Discovered That The gasket Has Been Left Out _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Edward Cranswick Subject: PSN Station Database Date: Sun, 26 Jan 1997 18:42:59 -0700 Dave Nelson and the rest of the PSN- It is absolutely amazing that you all have got the station info together. Probably if someone were brave they might come up with a longer staion/instrument/channel code of 10 characters or so that would not be DOS-file (8.3 character) compatible, but would be unambiguous and globally unique. Individuals running DOS could change the names to this new format when they uploaded to Windows'95+ machines over the Web. The same would be good for a longer, more precise and unique time specification for the waveform timeseries files. It is the nature of the top several hundred meters of the Earth (site) that is most important in controlling ground condition; i.e., are you on hard rock or mud? The geologic provenance of rafted terranes or so is important for plate tectonocists but has less effect on the ground motions. The closer an Earth structure is to the sensor, the more profound its effect upon the recorded signal content. The PSN is doing what we wish we could do! -Edward -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 1711 Illinois St cranswick@........ Golden, CO 80401 USA E.M. Forster said, "Only connect". _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Jim Hannon Subject: Re: Thoughts on Ron Wesfall's ideas to use the Web to integrate the PSN Date: Sun, 26 Jan 97 21:02:29 -0500 I too am quite excited by this idea. First thing though, we will have to come up with a shorter subject (thread name) . :) I am busy learning about the WEB and internet and what can be done with it. A current project I am working on at work is to put a radio receiver on the WEB real time so that you can access a WEB page tune the radio to any frequency between 5KHz and 2000 Mhz and listen to the results with RealAudio .. I suspect that it will be a longtime before I am on the net full time but my ISP is, and I have 15 mb of storage there along with a WEB page for what I pay for access. I hope that I can help design and participate in this network. Jim Hannon _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: ACole65464@....... Subject: Calibrating a Home Brewed Force-Feedback Accelerometer Date: Mon, 27 Jan 1997 02:27:19 -0500 (EST) Hello All, Just got through calibrating a force-feedback accelerometer using Bob Barns' "seismo calibrator", details he put on this network on 9-12-96. I need your (Bob, or anyone else who is familiar with what I am trying to do here) feedback to let me know if I did the calibration procedure correctly on the seismometer. Tell me where I may have gone wrong. Calibrating a horizontal accelerometer (using Bob's great design) is different than doing it to a horizontal long period velocity seismometer, aka Lehman. The calibrator's pulse for an accelerometer must be of a longer duration than for a velocity seismometer as any pulse frequency higher than the corner frequency of the actual accelerometer will not be seen by it. I had set the calibrator's pulse to 20 seconds. The accelerometer has its feedback circuit adjusted to give it a 30 second period response. So the calibrator has more than enough time to hold the pendulum in place so voltage readings etc can be taken. The calibrator was "calibrated" with pieces of copper wire as described in Bob's posting. Applying Newton's second law of motion: Force = mass x acceleration and then transposing it to the following: a = F / m then it was possible to determine the sensitivity of the force-feedback accelerometer. Given the mass of the pendulum is .07 Kg and the force as applied directly to the C.G. of the pendulum's mass by the needle of the milliamp meter it was found that the accelerometer is sensitive to accelerations less than .00004 m/s^2 and with 4 volts max available from the power rails max accel is clipped at .0057 m/s^2. Please point out any errors to this arrangement or ask for more details if necessary. From observations made so far of the seismometer's performance, its responses to cultural noises and EQs it appears to be working fine as currently connected to my ink-on-paper recorder. This is the instrument that I had told this group about lately regarding the damping of the pendulum. The pendulum is 4" long and chops the light beams of two LEDs shining on CdS cells. Eventually I will document how I made this instrument if there is enough interest in it. It may quickly replace my trusty Lehman (somewhat modified) that has been in service for the last 11 years. Building the Bob Barn calibrator was a fun and interesting project. I should have made it sooner, thanks Bob. Regards, Allan Coleman _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: lahr@................. (Dr. John Lahr (USGS-GI Seismologist)) Subject: Re: My thoughts on the 4/96 SA seismograph article. Date: Mon, 27 Jan 1997 13:26:53 -0900 John Evans has done a lot of testing of the potential use of the new accelerometer chips for seismology. I asked him to comment on some of his findings to date. He mentions the SMA-1 for comparison, which is the film-recording strong- motion instrument that was the standard for strong motion seismology prior to the introduction of digital instrumentation. JCLahr ----- Begin Included Message ----- From evans@.................... Wed Jan 22 11:02 AKS 1997 To: lahr@................. Subject: Re: My thoughts on the 4/96 SA seismograph article. John L., A quick response ... The ADXL-05 is better than an SMA-1 but by today's standards not very good. It has many mg noise (PTP) over the seismic band. It is a fair (but robust and temperature compensated and cheap) strong-motion sensor. It most certainly was vastly overhyped by the Amateur Scientist article. Still, it's possible to do useful and interesting things with it. The ones we're looking at most seriously now are the EG&G ICSensors (Milpitas) offerings, which are somewhat more expensive (say $50 versus $15 in very large quantities) and need conditioning. Their ICS-3031 can do about 0.25 mg PTP noise from 0-35 Hz with an OP270 amp and LT1019 voltage reference for its Wheatstone bridge. It's pretty tough but highly temperature sensitive (but a thermistor and the maker's calibration takes that out fine). However, IDS's next-better sensor (the ICS-3028) reaches to urban noise levels (10-100 ug PTP). It runs about $100 per channel with conditioning in 500 quantities. We may work with PEPP to make it available to high schools as a strong-motion and general physics sensor, so the amateurs should keep in touch over the next year. More difficult to use and more expensive but a much more capable sensor. The next tier up is in the $300 range and not relevant to cheap seismology. Also pointless since we can get to the background noise level for $100! --John E. ----- End Included Message ----- _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Roger Sorensen Subject: Re: My thoughts on the 4/96 SA seismograph article. Date: Mon, 27 Jan 1997 17:49:39 -0800 Dr. John Lahr (USGS-GI Seismologist) wrote: > > John Evans has done a lot of testing of the potential use of > the new accelerometer chips for seismology. I asked him to > comment on some of his findings to date. He mentions the > SMA-1 for comparison, which is the film-recording strong- > motion instrument that was the standard for strong motion > seismology prior to the introduction of digital instrumentation. > > JCLahr > > ----- Begin Included Message ----- > > >From evans@.................... Wed Jan 22 11:02 AKS 1997 > To: lahr@................. > Subject: Re: My thoughts on the 4/96 SA seismograph article. > > John L., > > A quick response ... > > The ADXL-05 is better than an SMA-1 but by today's standards not very > good. It has many mg noise (PTP) over the seismic band. It is a fair > (but robust and temperature compensated and cheap) strong-motion > sensor. It most certainly was vastly overhyped by the Amateur > Scientist article. Still, it's possible to do useful and interesting > things with it.more interesting stuff followed... Hello all! I'm in the final stages of getting an ADXL05 based sensor up and running and I am concerned about some of the comments I've seen here on PSN-L. I decided to built the '05 sensor rather that the more popular Leahman because of my location. I am 20 or so miles north/northwest of Los Angeles (in the city) and within 1000 feet of 10 lanes of freeway and a main railroad route. I felt a teleseismic sensor just wasn't suitable for my location, so I went with the '05. This is my question. Is the less than desirable noise characteristics of the '05 way above what one would expect of the geologic background noise (given my location)? Are there any tricks for reducing the noise level of the device (other than the usual electronic noise reduction techniques)? I would like to hear more about the experiences of others with the device. Since it appears that there are only a couple of us PSN'ers using the ADXL05, an e-mail discussion might be better. I'd be happy to forward any information to those that are interested. Thanks for the help! Roger Sorensen - roger.sorensen@................ Chatsworth CA _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: latest map Date: Tue, 28 Jan 1997 22:31:37 +1200 hi all, just finished updating the latest map at this URL http://psn.quake.net/dave/map.htm It contains the dots and data for all 30 (so far logged operators) Dave Dave A. Nelson 24 Jensen St., Green Is., Dunedin, South Is.. New Zealand. http://psn.quake.net/dave/home.htm ( world wide access ) http:/www.es.co.nz/~dann/home.html ( New Zealand access only ) SOD'S-LAW--- When Something Does Go Wrong, There Is Sod All You Can Do About-It When The Last Of Ten Screws Has Been Removed From A Cover, -It Will Be Discovered That The Wrong Cover Has Been Removed When The Last Of Ten Screws Has Been fitted back Into A Cover, -It Will Be Discovered That The gasket Has Been Left Out _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: lahr@................. (Dr. John Lahr (USGS-GI Seismologist)) Subject: Re: Map of Amateur Seismologists Date: Tue, 28 Jan 1997 14:17:21 -0900 The interactive station map is almost too good to believe. FAST work! One suggestion. To keep the name "Public Seismic Network" prominent and to avoid comfusion with other amateur groups, I would suggest changing the name from Amateur Seismologists to Public Seismic Network Stations and the html to Public Seismic Net Station Map. Cheers, JCLahr _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Edward Cranswick <cranswick@..................> Subject: Recording Velocity or Acceleration Date: Tue, 28 Jan 1997 17:49:25 -0700 Larry- Last week you posted the following message: Subject: My thoughts on the 4/96 SA seismograph article. Date: Tue, 21 Jan 1997 21:16:41 -0700 From: Larry Cochrane <cochrane@..............> and yesterday John Lahr responded by forwarding a message by John Evans of the USGS regarding the characteristics of low-cost accelerometers that he has tested. This are some of my thoughts on the subject. I completely agree with you that if one only monitors acceleration in the urban environment, you have to wait until hell freezes over or a local magnitude 6 earthquake happens before you would get any high signal-to-noise accelerograms with nice wiggles worth looking at. Most of the time, you would be seeing only your washing machine or the neighbor's car driving in and out of the driveway. So it's not only a question of sensitivity, but also a question of signal-to-noise. Signal-to-noise is strongly controlled by the frequency band observed, and acceleration and velocity, respectively, effectively sample different parts of frequency band. Acceleration amplifies high frequencies relative to low frequencies, and the velocity amplifies low frequencies relative to high frequencies. Mathematically, the expression for acceleration amplitude in terms of velocity as a function of frequency is A(f) = V(f) * 2 * pi * f where A(f) is the acceleration amplitude (cm/s**2), V is the velocity amplitude (cm/s), and f is frequency (Hz). The Lehman seismometers work because there are alot of teleseismic events greater than magnitude 5-6 around the world that produce relatively large ground velocities in the low-frequency band, 0.1 - 1.0 Hz, these frequencies efficiently propagate teleseismic distances (they suffer little anelastic attenuation going through the asthenosphere), and there is not alot of cultural noise from the neighbors in this frequency band. However, the Lehmans will go off-scale when there is an event large/close enough to cause local damage and be felt. Therefore, the Lehmans will miss the most important events, the earthquakes that have the largest impact on the community. Strong motion seismologists, which we have all become at the USGS (in principle, if not in fact), are concerned about those large, relatively infrequent local earthquakes. We need the on-scale recordings of strong ground motions that only accelerometers can provide so that we can find out why buildings fall down during earthquakes. The seismic engineering rule of thumb is that the natural period of a building is equal to 0.1 seconds times the number of its floors and the fundamental resonant frequency of the building is the reciprocal of that period, e.g., 1 floor = 0.1 s = 10 Hz, 2 floors = 0.2s = 5 Hz, etc. Buildings, like other harmonic oscillators, respond most to and are thus most susceptible to damage from strong ground shaking in the frequency bands near their resonant frequencies. Most buildings are less than 10 floors and therefore most sensitive to ground motions in the frequency band 1 - 10 Hz. However, with respect to living downtown and trying to record weak ground motions produced by earthquakes, this frequency band is dominated by cultural noise. So the problem is: to record ground motions useful to study for the reduction of earthquake hazards, we have to use accelerometers and be paid to be patient; but to keep members of the Public Seismic Network (PSN) interested in operating seismographs at home, they have to record from long period velocity sensors. One solution is to record both velocity and acceleration simultaneously and keep only the record that is on-scale. We do this with the USGS GEOS 6-channel portable autonomous digital seismograph (PADS); we record 3 channels of acceleration from an FBA-23 (force balance accelerometer) and 3 channels of velocity from an L-22 (2 Hz geophone). This requires twice the recording band-width. Alternatively, using low-noise accelerometers, one could digitize and record acceleration but then generate a velocity timeseries by digitally integrating the acceleration timeseries. The velocity trace would be used most often because the act of integrating effectively low-passes the original signal and filters out much cultural noise. When a large/close earthquake happened that produced strong ground motions, the acceleration would still be on-scale. However, this scheme requires an accelerometer with a range of at least 10**-6 at the low end to about 2.0 g at the high end. This corresponds to a dynamic range of about 130 dB or 21-22 bits of resolution. That is alot of umph to get out of a low-cost accelerometer at present, so perhaps the acceleration/velocity hybrid is the way to go in the meantime. I am also going to post my suggestion to the USGS Strategic 5-year Program Plan: USING THE EARTH AND THE WEB TO CONNECT THE USGS ERHP TO THE US PUBLIC -Edward -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 1711 Illinois St cranswick@........ Golden, CO 80401 USA E.M. Forster said, "Only connect". _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Edward Cranswick <cranswick@..................> Subject: USING THE EARTH AND THE WEB TO CONNECT THE USGS ERHP TO THE US PUBLIC Date: Tue, 28 Jan 1997 18:03:15 -0700 USING THE EARTH AND THE WEB TO CONNECT THE USGS ERHP TO THE US PUBLIC EHRP (Earthquake Hazard Reduction Program) The consensus of the discussion on Research was that shallow site response is the most important topic to be investigated. Shallow site response can magnify strong ground motions by as much as an order of magnitude, and, more than any other mechanism, shallow site response controls the variation of strong ground motions over short distances, on the scale of 100 m or approximately one city block. We are trying to understand shallow site response because we are trying to understand why buildings and other structures are damaged by earthquakes. It is the task of seismologists to predict the strong ground motions produced by earthquakes, and the task of seismic engineers to predict the response of structures to these strong ground motions. In either case, it is necessary to have strong ground motion information. Seismologists need the information to test the output of their predictions, and seismic engineers need this information as the input into their predictions. If we are going to be able to understand why a house on one side of the street collapsed but the house on the other side of the street did not, we are going to have to record strong ground motion data with the same spatial density. In seismogenic regions, we need to put strong ground motion recorders in every structure whose response to earthquakes we wish to predict. This can be accomplished by using solid-state accelerometers as sensors, using the World Wide Web for telemetry, and including the public whose buildings are to be instrumented in a ground motion acquisition program coordinated by the USGS. The main roles of the USGS would be establishing and maintaining data standards, hardware specifications and software formats, and acting as a clearinghouse for the resulting data. Involvement of the public would have two consequences: 1) provide a sufficient density of ground motion information that can be used to understand earthquake hazard; 2) create a constituency of voting and taxpaying members of the community who participate in the realization of EHRP goals. Public participation in a program of ground motion monitoring could be linked to a national earthquake insurance program in a fashion similar to the role of smoke detectors in homeowners insurance: if you have an operating seismic data acquisition unit in your house, you are eligible for a discount on national earthquake insurance. Spudich, Evans, and Rogers have developed a prototype seismic data acquisition unit designed for mass distribution. Bogart, Bittenbinder, and others have developed the Earthworm as a means of using the Internet for seismic data telemetry. The Web is a means of using this hardware/software to connect the awareness of the human community to the seismogenic processes in the neighborhood. Television has taken a half century to get where it is today, but the Web has burst upon the scene in 2-3 years. Interactive (two-way) communication distinguishes the Web from the centralized hierarchy of the single television transmitter and its many passive receivers. The public who experience earthquakes have already received the significant signal about the occurrence of the earthquake =96 of that= they do not need to be informed. Instead, they need their experience to be collaborated by the authorities, i.e., us, and by other members of the community. Via the Web, each member of the public would have access to not only the near-realtime map of ground motions maintained by the USGS but also to the recorded ground motion information and the seismic intensity =96 the human consequences and responses -- of all other sites.= Thus, the community would be joined not only by the shared experience of ground motions but also by the shared perception of the impact of those ground motions on the whole community. -- = Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 1711 Illinois St cranswick@........ Golden, CO 80401 USA E.M. Forster said, "Only connect". _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Robert L Barns <75612.2635@..............> Subject: Frost heave Date: 29 Jan 97 14:04:28 EST Hi gang, My friend, Bill Scolnik (about 50 mins. from here), thought it would be good to move his seismometers from the basement to the outdoors since some of his seismograms showed the effects of traffic in the house. He cast a concrete slab about 30' from his house and built a substantial doghouse to cover them plus pipe to house the wires--a first-class job. He has 2 horizontal and 1 vertical Geo-Techs, all long period plus a short period vertical. Things were working pretty well until recently when we had a long cold snap--down to -2 deg. one night. The Geo-Techs have boom position sensors and leveling adjustment--all remote. He found the horizontals up against the stop one time and changed the level to re-center them. A short time later, the same thing happened. These lovely instruments are normally very stable. My guess is that the slab had been tilted by frost heave. You guys in California probably never heard of this, but it is a well-known event elsewhere. Frost heave occurs when water in soil freezes. When frost heave occurs, things, such as boulders, can be pushed up out of the ground. The same sort of thing can cause pot-holes in pavement. The forces produced are practically unlimited-certainly enough to tilt a concrete slab. He also thinks that he sees seismic noise due to the swaying of nearby trees when the wind blows. I guess the message here is that outdoors is not always an ideal location for seismometers. Have others seen or suspected frost heave problems? He saw another interesting effect. In FFT's of some of his seismograms, there was a sharp peak at exactly 10 HZ. This in spite of the 10Hz low pass filter in Cochrane's amplifier and filter board. His sampling rate is 50/sec. I think that the 10 Hz peak is aliasing from some 60 Hz hum getting in somehow. Has anyone else seen this? Bob Barns _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: ct@....... (Charlie Thompson) Subject: Re: Frost heave Date: Wed, 29 Jan 1997 13:36:49 -0600 Bob, I see tree sway noise on blustery windy days...but not gentle breezes... actually he may be seeing "dog-house sway" as well. As I mentioned in one of my earlier postings small slabs can be probematic depending on your weather and soil. I also have a small 10Hz component in the FFT's.....it's quite small but I believe it's 60 Hz pickup aliased back to 10 Hz when using a 50 Hz sample rate. 6th order gives 36 dB per octave but we only have 1.26 octaves from 25 Hz to 60 Hz or about 45 dB of 60 Hz rejection. So if the 60 Hz is bigger than -45 dBFS we will see some if it at 10Hz as an alias...make sense? -Charlie > He also thinks that he sees seismic noise due to the swaying of nearby trees >when the wind blows. I guess the message here is that outdoors is not always an >ideal location for seismometers. > Have others seen or suspected frost heave problems? > He saw another interesting effect. In FFT's of some of his seismograms, there >was a sharp peak at exactly 10 HZ. This in spite of the 10Hz low pass filter in >Cochrane's amplifier and filter board. His sampling rate is 50/sec. I think >that the 10 Hz peak is aliasing from some 60 Hz hum getting in somehow. Has >anyone else seen this? > Bob Barns > > >_____________________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email listserver@............. with the body of the >message: leave PSN-L > > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Steve Hammond <shammond@..........> Subject: Re: Frost heave Date: Wed, 29 Jan 1997 15:19:47 -0800 (PST) I also built a seismic dog house (more like a small horse barn... but anyway-- ) here in San Jose, and experience rain heave. The Lehman can go to the stop over night. The wind in the trees can put me off the air at times. But you mentioned a shift in frequency, and that got my attention. My system also records a shift in freq after sudden changes in conditions For 5 years I have been recording the lightrail train that runs at the end of the block, just before the first rain, and just after it. In each data set, the FFT is scattered and unfocused before the rain. After the rain it is shifted to 11Hz and extremely focused. I am of the opinion that the water is creating a tightly coupled sender/receiver relationship much like that of the classic depth-charge and submarine. There have been a few papers written on the effects of site response and water but, I can't list them off the top of my head. Two come to mind, one was from Tenn. and the other Long Island. If the change in water content effects the local site response, than one could reason that the effects of a large earthquake could be quite different given the times of the year and the amount of water or in your case, frozen water in the ground. It will be interesting to see what two years of data will show at your location. Let me suggest that you pick something that occurs year round, other than earthquakes, (like my light rail train) and maintain a monthly record of it to see if the site response freq. shifts during the seasons. Regards, Steve Hammond PSN BBS San Jose 408-226-0675 On 29 Jan 1997, Robert L Barns wrote: > > Hi gang, > My friend, Bill Scolnik (about 50 mins. from here), thought it would be good > to move his seismometers from the basement to the outdoors since some of his > seismograms showed the effects of traffic in the house. He cast a concrete slab > about 30' from his house and built a substantial doghouse to cover them plus > pipe to house the wires--a first-class job. > He has 2 horizontal and 1 vertical Geo-Techs, all long period plus a short > period vertical. Things were working pretty well until recently when we had a > long cold snap--down to -2 deg. one night. The Geo-Techs have boom position > sensors and leveling adjustment--all remote. He found the horizontals up > against the stop one time and changed the level to re-center them. A short time > later, the same thing happened. These lovely instruments are normally very > stable. > My guess is that the slab had been tilted by frost heave. You guys in > California probably never heard of this, but it is a well-known event elsewhere. > Frost heave occurs when water in soil freezes. When frost heave occurs, things, > such as boulders, can be pushed up out of the ground. The same sort of thing > can cause pot-holes in pavement. The forces produced are practically > unlimited-certainly enough to tilt a concrete slab. > He also thinks that he sees seismic noise due to the swaying of nearby trees > when the wind blows. I guess the message here is that outdoors is not always an > ideal location for seismometers. > Have others seen or suspected frost heave problems? > He saw another interesting effect. In FFT's of some of his seismograms, there > was a sharp peak at exactly 10 HZ. This in spite of the 10Hz low pass filter in > Cochrane's amplifier and filter board. His sampling rate is 50/sec. I think > that the 10 Hz peak is aliasing from some 60 Hz hum getting in somehow. Has > anyone else seen this? > Bob Barns > > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Rev. Bob Shannon" <rshannon@.......> Subject: Re: Frost heave Date: Wed, 29 Jan 1997 15:39:32 -0800 (PST) On Wed, 29 Jan 1997, Steve Hammond wrote: > I also built a seismic dog house (more like a small horse barn... but > anyway-- ) here in San Jose, and experience rain heave. hhhmmmm....well let me think..san Jose.....Bear scat......yeah...There is an old come back to total truth " Does a bear ---- in the woods?" Now if you were a animal biologist and also an owner of a nice seismic device you could tell just when your dog went doo-doo..What a concept! I know if I lived in SF I would not be worried about quakes but I would be worried about doggie doo..You may have a patent on your hands here bud! Let me be the first to sign the non-disclosure!:-> <VBG> etc.. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Karl Cunningham <karlc@.........> Subject: Re: Frost heave Date: Wed, 29 Jan 1997 17:24:38 -0800 At 02:04 PM 1/29/97 EST, you wrote: > He saw another interesting effect. In FFT's of some of his seismograms, there >was a sharp peak at exactly 10 HZ. This in spite of the 10Hz low pass filter in >Cochrane's amplifier and filter board. His sampling rate is 50/sec. I think >that the 10 Hz peak is aliasing from some 60 Hz hum getting in somehow. Has >anyone else seen this? Hi Bob -- I've had a similar problem testing position sensors for incorporation into my seismometer, only my spike in the FFT was at about 0.05 Hz. The A/D was sampling at a 30Hz rate. Apparently, the 60-Hz power line frequency and twice the sample frequency were different by about 0.05 Hz. I put in more filtering to reduce the 60Hz hum, which helped a great deal. The other thing I did was choose a sample frequency so that multiples of it did not come very close to 60Hz. 40Hz turned out to be a good number -- it itself is 20 Hz from 60Hz, and double (80Hz) is also 20Hz away -- both out of the passband of interest. Karl Cunningham La Mesa, CA. karlc@......... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Edward Cranswick <cranswick@..................> Subject: Re: Frost heave Date: Wed, 29 Jan 1997 21:02:07 -0700 Bob- > He also thinks that he sees seismic noise due to the swaying of nearby trees > when the wind blows. I guess the message here is that outdoors is not always an > ideal location for seismometers. > Have others seen or suspected frost heave problems? > He saw another interesting effect. In FFT's of some of his seismograms, there > was a sharp peak at exactly 10 HZ. This in spite of the 10Hz low pass filter in > Cochrane's amplifier and filter board. His sampling rate is 50/sec. I think > that the 10 Hz peak is aliasing from some 60 Hz hum getting in somehow. Has > anyone else seen this? There is no substitute for putting seismometers on outcrop -- exposures of bedrock -- as a solution for frost heave, wind noise, or cultural noise from house, cars, people, etc., therefore, put it outside on rock. The Nyquist, or, folding frequency for 50 sps is 25 Hz. 60 hz could be doubly folded around 25 Hz to produce 10 Hz, I think: 60 - 25 = 35 and 35 - 25 = 10. 60 Hz is the only monochromatic signal around that could produce at really sharp spike in the frequency domain. -Edward -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 1711 Illinois St cranswick@........ Golden, CO 80401 USA E.M. Forster said, "Only connect". _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Barry Lotz <gbl@.......> Subject: Re: Frost heave Date: Wed, 29 Jan 1997 22:27:18 -0800 Robert L Barns wrote: > > Hi gang, > My friend, Bill Scolnik (about 50 mins. from here), thought it would be good > to move his seismometers from the basement to the outdoors since some of his > seismograms showed the effects of traffic in the house. He cast a concrete slab > about 30' from his house and built a substantial doghouse to cover them plus > pipe to house the wires--a first-class job. > He has 2 horizontal and 1 vertical Geo-Techs, all long period plus a short > period vertical. Things were working pretty well until recently when we had a > long cold snap--down to -2 deg. one night. The Geo-Techs have boom position > sensors and leveling adjustment--all remote. He found the horizontals up > against the stop one time and changed the level to re-center them. A short time > later, the same thing happened. These lovely instruments are normally very > stable. > My guess is that the slab had been tilted by frost heave. You guys in > California probably never heard of this, but it is a well-known event elsewhere. > Frost heave occurs when water in soil freezes. When frost heave occurs, things, > such as boulders, can be pushed up out of the ground. The same sort of thing > can cause pot-holes in pavement. The forces produced are practically > unlimited-certainly enough to tilt a concrete slab. > He also thinks that he sees seismic noise due to the swaying of nearby trees > when the wind blows. I guess the message here is that outdoors is not always an > ideal location for seismometers. > Have others seen or suspected frost heave problems? > He saw another interesting effect. In FFT's of some of his seismograms, there > was a sharp peak at exactly 10 HZ. This in spite of the 10Hz low pass filter in > Cochrane's amplifier and filter board. His sampling rate is 50/sec. I think > that the 10 Hz peak is aliasing from some 60 Hz hum getting in somehow. Has > anyone else seen this? > Bob Barns > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L Very interesting! I have the same "dog house" ,pipe to the house,and problem with wind in trees. I live at about 2500' so I get some snow but no frost heave. I do have to adjust in the winter for what I believe is differential moisture conditions under the slab causing differential soil expansion. When I poured the slab I dug 3' deep post holes (cassions) in the corners to get the slab support about 4' below the surface. I guess it helps. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Barry Lotz <gbl@.......> Subject: Re: Frost heave Date: Wed, 29 Jan 1997 22:34:24 -0800 Charlie Thompson wrote: > > Bob, > > I see tree sway noise on blustery windy days...but not gentle breezes... > actually he may be seeing "dog-house sway" as well. As I mentioned > in one of my earlier postings small slabs can be probematic depending > on your weather and soil. > > I also have a small 10Hz component in the FFT's.....it's quite small but > I believe it's 60 Hz pickup aliased back to 10 Hz when using a 50 Hz > sample rate. 6th order gives 36 dB per octave but we only have 1.26 > octaves from 25 Hz to 60 Hz or about 45 dB of 60 Hz rejection. So if > the 60 Hz is bigger than -45 dBFS we will see some if it at 10Hz as > an alias...make sense? > > -Charlie > > > He also thinks that he sees seismic noise due to the swaying of nearby trees > >when the wind blows. I guess the message here is that outdoors is not > always an > >ideal location for seismometers. > > Have others seen or suspected frost heave problems? > > He saw another interesting effect. In FFT's of some of his seismograms, > there > >was a sharp peak at exactly 10 HZ. This in spite of the 10Hz low pass > filter in > >Cochrane's amplifier and filter board. His sampling rate is 50/sec. I think > >that the 10 Hz peak is aliasing from some 60 Hz hum getting in somehow. Has > >anyone else seen this? > > Bob Barns > > > > > >_____________________________________________________________________ > > > >Public Seismic Network Mailing List (PSN-L) > > > >To leave this list email listserver@............. with the body of the > >message: leave PSN-L > > > > > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L Charlie&Bob: As an addition to the earlier entry. I origally had the Leyman in a detached (20'x20') garage and didn't have a problem with trees and minor problem with moisture. I moved I because it was to close to my driveway. Lesser of two evils- maybe. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Al Allworth <aallworth@........> Subject: Re: Frost heave Date: Wed, 29 Jan 1997 23:51:55 -0800 At 03:19 PM 1/29/97 -0800, you wrote: just before the first rain, and just after it. In each data >set, the FFT is scattered and unfocused before the rain. After the rain it >is shifted to 11Hz and extremely focused. I am of the opinion that the >water is creating a tightly coupled sender/receiver relationship much like >that of the classic depth-charge and submarine. > >There have been a few papers written on the effects of site response and >water but, I can't list them off the top of my head. Two come to mind, one >was from Tenn. and the other Long Island. If the change in water content >effects the local site response, than one could reason that the effects of >a large earthquake could be quite different given the times of the year >and the amount of water or in your case, frozen water in the ground. I was just today planning a post on this phenomenon as I have been seing it here. Pasadena has been having a lot of rain for the past several weeks which ended earlier in the week. As the ground dries out I am noticing a decrease in traffic noise of all types but especially that from the 210 freeway about 1 1/2 miles away. It is easy to identify because of the time of day that it shows up. I have seen this for the last 3 winters and was waiting for the drying out to see if it happened again. I think it is more noticable here on the Pasadena gravel pile than it would be on soil that dries out more slowly. The rain stopped rather abruptly this time making the noise propagation falloff quite interesting. It took about 2 days for the major decline and is still falling. I haven't done a FFT or any kind of analysis, just watching it happen. ____________________________________________________________________________ Al Allworth. Pasadena,CA aallworth@........ _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane <cochrane@..............> Subject: Re: My thoughts on the 4/96 SA seismograph article. Date: Fri, 31 Jan 1997 18:11:43 -0700 At 05:49 PM 1/27/97 -0800, Roger Sorensen wrote: >Hello all! > >I'm in the final stages of getting an ADXL05 based sensor up and >running and I am concerned about some of the comments I've seen >here on PSN-L. > >I decided to built the '05 sensor rather that the more popular >Leahman because of my location. I am 20 or so miles north/northwest >of Los Angeles (in the city) and within 1000 feet of 10 lanes >of freeway and a main railroad route. I felt a teleseismic >sensor just wasn't suitable for my location, so I went with >the '05. I to live near a freeway, US 101, that is about the same distance away. I also have train tracks about 2/3 of a mile away. I can receive teleseismic events if they are large enough. I routinely receive M7.0 10,000km with both my Lehman and even better with my SG sensor. Local ground noise tends to be pretty high frequency compared to the low frequencies involved in teleseismic events. So it is possible to receive teleseismic events even if you live near a lot of local ground noise. The SG sensor has a poor response above 1 hz so it does a good job at filtering out the ground noise. With a Lehman you can run the signal thru a low low-pass filter say .5 seconds (or lower) that will remove a lot of the high freq noise, or, you can use WinQuake and filter the event file using the FFT / filtering feature. > >This is my question. Is the less than desirable noise >characteristics of the '05 way above what one would expect of >the geologic background noise (given my location)? > >Are there any tricks for reducing the noise level of the device >(other than the usual electronic noise reduction techniques)? I >would like to hear more about the experiences of others with >the device. Since it appears that there are only a couple of >us PSN'ers using the ADXL05, an e-mail discussion might be better. >I'd be happy to forward any information to those that are >interested. Lets keep it on-line so we can all can learn from the information. I don't have any of the chips yet. Steve Hansen is donating 2 chips too me, so I will be able to play around with them soon. What I plan to do is put them in a push-pull configuration and see if two in the same axis will help. I agree with Ed Cranswick, you should get the chips on-line to see if you can get any information from larger events. You might also go ahead and build a Lehman and / or a SG sensor so you will have a more sensitive device for teleseismic and smaller local events. > >Thanks for the help! Good luck, keep us informed on your progress. Regards, Larry Cochrane Redwood City, Cal PSN _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Barry Lotz <gbl@.......> Subject: Re: My thoughts on data acq. routines. Date: Sat, 01 Feb 1997 12:33:48 -0800 > At 05:49 PM 1/27/97 -0800, Roger Sorensen wrote: > >Hello all! > > > >Are there any tricks for reducing the noise level of the device > >(other than the usual electronic noise reduction techniques)? I > >would like to hear more about the experiences of others with > >the device. Since it appears that there are only a couple of > >us PSN'ers using the ADXL05, an e-mail discussion might be better. > >I'd be happy to forward any information to those that are > >interested. > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L Hi What I think could enhance monitoring is to incorporate more elaborate triggering methods using STA/LTA or one of the other published methods, not just the simple threshold monitoring method. This will allow a station to weed thru their site specific noise . It is a lot easier to modify numbers to fit a site than hardware. Maybe there is some available software that is more powerful that the version of EMON that I am currently using. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Roger Sorensen <Roger.Sorensen@................> Subject: Re: My thoughts on data acq. routines. Date: Sat, 01 Feb 1997 20:17:22 -0800 Barry Lotz wrote: > > > Hi > What I think could enhance monitoring is to incorporate more elaborate > triggering methods using STA/LTA or one of the other published methods, > not just the simple threshold monitoring method. This will allow a > station to weed thru their site specific noise . It is a lot easier to > modify numbers to fit a site than hardware. Pardon my ignorance, but what is STA/LTA? Thanks, Roger _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Barry Lotz <gbl@.......> Subject: Re: My thoughts on data acq. routines. Date: Sat, 01 Feb 1997 21:02:18 -0800 Roger Sorensen wrote: > > Barry Lotz wrote: > > > > > > Hi > > What I think could enhance monitoring is to incorporate more elaborate > > triggering methods using STA/LTA or one of the other published methods, > > not just the simple threshold monitoring method. This will allow a > > station to weed thru their site specific noise . It is a lot easier to > > modify numbers to fit a site than hardware. > > Pardon my ignorance, but what is STA/LTA? > > Thanks, > > Roger > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L Sorry STA(short term average)& LTA(long term average).Briefly, one method to determine when an event occurs is to compare the signal over a long time period prior to the present time with a short time period prior. If the ratio exceeds a predetermined value an event is registered. This helps to null out noise always present. There are papers in The Bulletin of the Seismologicial Society of Ammerica (BSSA). I will try to find them and let you know. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane <cochrane@..............> Subject: New mailing list for event files Date: Sun, 02 Feb 1997 01:54:14 -0700 Greetings, A while back Ron Westfall wrote an email about PSN stations being able to locate large events by using the Net to share event files. In a step to bring this a little closer to reality I would like to announce the following: I have setup another mailing list for event files. This mailing list works with the archiving of PSN format event files sent to event@............. (events@ will also work). When an event file is sent to event@ it is archived on my system and also sent to a mailing list setup on another system (DRNET.COM) called NEWEVENT. Members of the NEWEVENT list will receive a copy of the original message and attachments sent to my system. For you to receive / decode the event file you must have a email program that can handle attachments in MIME or BinHex40 formats. If you would like to be a member of the list you can sign up using the following Web page: http://psn.quake.net/maillist.html or you can send email to the list server at ListServer@......... and in the body of the message (the first line only) place: join newevent or subscribe newevent You should receive an acknowledgment email if everything works ok. To remove yourself from the list use the Web page above or send a message to ListServer@......... and in the body place: leave newevent or if you are using another email account use: leave newevent your_address_on_the_list PLEASE NOTE: This list is handled on another system. Do not use the list server (listserver@.............. on my system for adding or remove yourself from the NEWEVENT list. Remember to use listserver@.......... The drnet.com system has a faster connection on the Internet and should be able to handle the larger email messages with the attached data. Enjoy, Larry Cochrane Redwood City, Cal PSN _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Jim Hannon <jmhannon@........> Subject: Re: My thoughts on data acq. routines. Date: Mon, 03 Feb 1997 20:19:30 -0600 I just had to stick in my 2 cents worth on event triggering. The STA/LTA method sounds like an improvment over the fixed threshold if the noise tends to vary over time. Another idea is to use the differences in the spectral content of the noises vs the telesisimic signal. Take a series of short FFT's and trigger when the spectral content is representive of an event. This method is used for the squelch in HF radios where there is always noise of some sort present at the same level as the desired signal due to the receiver's AGC. It work quite well and can distinguish between speech, vaarious modem signals and noise. -- Jim Hannon _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Barry Lotz <gbl@.......> Subject: Re: My thoughts on data acq. routines. Date: Mon, 03 Feb 1997 18:50:28 -0800 Jim Hannon wrote: > > I just had to stick in my 2 cents worth on event triggering. The > STA/LTA method sounds like an improvment over the fixed threshold if the > noise tends to vary over time. Another idea is to use the differences > in the spectral content of the noises vs the telesisimic signal. Take a > series of short FFT's and trigger when the spectral content is > representive of an event. This method is used for the squelch in HF > radios where there is always noise of some sort present at the same > level as the desired signal due to the receiver's AGC. It work quite > well and can distinguish between speech, vaarious modem signals and > noise. > -- > Jim Hannon > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L Two cents: I agree. I had problems with doing FFTs in real time for window widths large enough to give one a reasonable frequency bandwidth. I have used a assembly version of the walsh transform instead and this works fast but there are some aliases. The basic reason for its speed is that it uses square waves instead of sine waves ;therefore, no multiplication is needed,just shifts right and left.There is a general description in BSSA vol. 71 aug 1981. I think a 128-256 pt FFT in a sampling rate of 32s/s would probably work but there must still be time left to do the filtering etc. I haven't as yet been able to write a assembly version of the FFT routine that works. Any sources? _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: David A Nelson <dann@........> Subject: what is....? Date: Wed, 05 Feb 1997 11:41:51 +1200 hi all, been meaning to ask for ages..... in a magnitude reading of 4.5 mblg what does the ' lg ' stand for ?? Thanks Dave Dave A. Nelson 24 Jensen St., Green Is., Dunedin, South Is.. New Zealand. http://psn.quake.net/dave/home.htm ( world wide access ) http:/www.es.co.nz/~dann/home.html ( New Zealand access only ) _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Edward Cranswick <cranswick@..................> Subject: Re: what is....? Date: Tue, 04 Feb 1997 17:32:40 -0700 David- > been meaning to ask for ages..... in a magnitude reading of 4.5 mblg > > what does the ' lg ' stand for ?? > Otto Nuttli devised the mbLg scale in the early 1970's. The Lg phase is an S-wave from a source within the crust that propagates with relatively low attenuation as a series of perfectly reflected internal reflections from the Earth's surface and the Moho (crust/mantle boundary), respectively. --------------------------------- /\ /\ /\ / * \ / \ / \ / \/ \/ \/ --------------------------------- For places like Eastern North America where: 1) sources, earthquakes, are small; 2) the spacings between stations are large; and, 3) the anelastic attenuation is small; the Lg phase is characteristically the largest "body wave" observed on seismograms. Hence, the "mb", i.e., body wave magnitude, determined from the Lg phase. -Edward -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 1711 Illinois St cranswick@........ Golden, CO 80401 USA E.M. Forster said, "Only connect". _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane <cochrane@..............> Subject: Two events in N. Cal, new sensor on-line Date: Tue, 04 Feb 1997 17:08:19 -0700 It looks like up north is rocking and rolling. We just had 2 events near Santa Rose California. The first was 3.4 MD followed by a 3.8MD about 40 minutes later. Here are the numbers from finger quake@............... 97/02/04 23:45:45 38.36N 122.65W 5.9 3.4MD B* 3 mi ENE of Rohnert Park,CA 97/02/05 00:25:41 38.36N 122.65W 6.3 3.8MD B* 3 mi ENE of Rohnert Park,CA The events are about 100km (64mi) from me. I have a new sensor that I am monitoring. I was able to barrow a Forced- Balance Accelerometer from the local USGS (thanks to Ed C. help). It's a Kinematics FBA 23 with an output of +-10 volts for a +-2 G input. I currently have one channel (N-S orientation) connected to one of my 16 bit A/D cards. It's producing *.LC5 files on my system. The output of the sensor is DC and goes directly into the A/D card with no filtering or gain change except a divide by 2 so the +-10 output matches the +- 5 volt input of the A/D card. I will be adding more channels (the sensor has 3 axis), low-pass filtering and AC coupling when I get some time. The FBA sensor did not go out of the normal background noise, about 20 counts P-P or about 1.2 mG [(4G's / 65000 counts) * 20 counts]. I think the 3.8MD just broke the background noise. That's it... Larry Cochrane Redwood City, PSN _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane <cochrane@..............> Subject: Re: Two events in N. Cal, new sensor on-line Date: Wed, 05 Feb 1997 13:23:59 -0700 Hi Edward and other who download files from my system, After an event happens I review all of the event files. If there is no useful information in a file I delete it. At the time of the two events yesterday the sensor that produce *.lc4 files was off line so I deleted the file. The new event list (http://psn.quake.net/cgi-dos/event.exe) gets updated when my data loggers produce an event file. Twice a day (midnight and noon local time) my system updates the event file list, if the event file is no longer there it is then removed from the event list. So there can be a 12 hour window where a file can show up on the new event list (or the finger quake@............. list) but may actually have been deleted. Regards, Larry Cochrane Redwood City, PSN At 11:55 PM 2/4/97 -0700, you wrote: >Larry- >I am conscientiously checking everything out but I get an error when I >try to look at 970205a.lc4 though I have no problem with .lc1-.lc5 >otherwise. >-Edward >PS. Yeah, there is no question that you can't see nothing in >acceleration, i.e., .lc5, for an event that small and so far away. >-- >Edward Cranswick Tel: 303-273-8609 >US Geological Survey, MS 966 Fax: 303-273-8600 >1711 Illinois St cranswick@........ >Golden, CO 80401 USA E.M. Forster said, "Only connect". > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: bob@................. (Bob Hammond (USGS-AVO Geophysicist)) Subject: Re: GPS clock Date: Thu, 6 Feb 1997 13:03:53 -0900 hi folks, Garmin International (Lexena, KS, 800-800-1020) makes a GPS evaluation kit for $499 (!) which includes antenna, cabling, board, and software which outputs 1 pulse per second at +/- 1 microsecond accuracy. The 1 pps is a 0-5v TTL level shift. regards, Bob. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Jim Hannon <jmhannon@........> Subject: Re: GPS clock Date: Thu, 06 Feb 1997 19:16:35 -0600 Jeff Batten wrote: > > Does anyone sell a GPS clock that interfaces to a IBM comp. P.C. at a > reasonable cost. > > Jeff > Jeff Batten - Research Engineer > Caltech Seismo Lab > 1200 E. California Bl. > Pasadena, Ca. > 91125 > 818-395-6965 > Fax-818-564-0715 > > _____________________________________________________________________ > > Jeff, Your best bet for inexpensive and ready to go is the Delorme TripMate it sells for $149.95 list and is a complete GPS unit antenna and all, looks like a large yellow PC mouse. Plugs into the PC serial port and provides position and time info via the serial port. It doesn't have the 1PPS output so you would be able to resolve time to only about 1 sec. Around here you can buy them at the local discount consumer electronice store. There is currently a lot of discussion of this unit and the Garmin GPS on the news group sci.geo.satellite-nav I will have a look at the schematics for it tomorrow and see if the 1pps signal is avaliable inside the unit. It uses a custom Rockwell engine so I have some access to info on it. -- Jim Hannon _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane <cochrane@..............> Subject: GPS time Date: Thu, 06 Feb 1997 21:21:13 -0700 Hi, About two years ago I bought a Magellan Meridian GPS receiver with the serial output option. I was hoping to use it as a time source for my SDR program. I was shock to find that the time coming out of the serial port was of my several seconds. Also the output would stop all together if it lost lock to the satellites. If you buy a GPS system make sure it has accurate time output before buying it. The problem I see with the GPS systems that produce a 1 PPS output is making sure you know what second it is. I hope that the serial output information is synchronized somehow so you can be absolutely sure you know the UTC time and match it up with one of the 1 PPS pulses. If one only uses the 1PPS output it would be very easy to be off, when compared to UTC time, by hole seconds. My SDR program (when the WWV option is used) has a similar problem because it uses the 1 ppm mark from WWV. Its up to the user to make sure the PC's time is within +- 15 seconds of UTC time to make sure it locks up to the right minute. It's a lot easier to make sure you have the right minute then the right second. Regards, Larry cochrane Redwood City, PSN _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: mindtech@......... Subject: advanced dielectric transducer Date: Mon, 10 Feb 1997 20:47:28 +1100 About ten years ago I was briefly shown a report by an associate working under government contract. The device described consisted of a cylinder of dielectric material (lead zirconate titanate). A thin film of silver was sintered to the inside and outside (but not the edges), thus forming a capacitor. One conductive tube each was then slid over its outside and into its inside (mylar between), effectively forming another tubular capacitor around it. This was driven by a high voltage sinewave of undisclosed frequency, which I suspect served to resonate or excite the LZT matrix. It was asserted that the charge/discharge time ratio of the inner cap, in response to the superimposed AC field, was variable depending on certain geophysical transients. Mention was also made of its potential use for communications based on resulting scalars within the dielectric. I obtained several LZT caps from Plessy (used in sonobouys), but have so far been unable to replicate the above effect. Has anyone heard of this approach, or have a theoretical understanding of how it might work? Peter M. Nielsen E.E. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: David <david@...............> Subject: Re: advanced dielectric transducer Date: Mon, 10 Feb 1997 12:23:01 -0800 (PST) On Mon, 10 Feb 1997 mindtech@......... wrote: > About ten years ago I was briefly shown a report by an associate working > under government contract. The device described consisted of a cylinder of > dielectric material (lead zirconate titanate). A thin film of silver was > sintered to the inside and outside (but not the edges), thus forming a > capacitor. One conductive tube each was then slid over its outside and into > its inside (mylar between), effectively forming another tubular capacitor > around it. This was driven by a high voltage sinewave of undisclosed > frequency, which I suspect served to resonate or excite the LZT matrix. It > was asserted that the charge/discharge time ratio of the inner cap, in > response to the superimposed AC field, was variable depending on certain > geophysical transients. Mention was also made of its potential use for > communications based on resulting scalars within the dielectric. > The operative effect is probably piezoelectric transduction of the LZT material. I would expect that the inner and outer mylar films served simply as coupling capacitors. Piezeoelectric materials are often piezoresistive too, which might explain the use of an excitation signal; current drawn by the cell would be dependent on AC component of strain or bending; if coupled tightly to the soil or some solid structure this might make a lower noise strain gauge than the conventional type, and DC component of the strain would be absent. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: mindtech@......... Subject: Re: advanced dielectric transducer Date: Tue, 11 Feb 1997 12:07:13 +1100 >The operative effect is probably piezoelectric transduction of the >LZT material. I would expect that the inner and outer mylar films >served simply as coupling capacitors. Piezeoelectric materials are >often piezoresistive too, which might explain the use of an excitation >signal; current drawn by the cell would be dependent on AC component >of strain or bending; if coupled tightly to the soil or some solid >structure this might make a lower noise strain gauge than the >conventional type, and DC component of the strain would be absent. > To clarify, the assemby consisted of a total of four, nested conductive cylinders, with LZT deposited between the second and third (inner). 3KVAC was applied across the first and fourth (outer). Aside from the AC, this configuration stikes me as similar to a Gunn oscillator. Perhaps an inverse principle applies. The trick was to mobilize free electrons _through_ the matrix, as "pumped" by the superimposed field. There would be a natural attraction of electrons toward the curved surfaces of the outermost tube. I believe the term "barrier layer capacitor" was used. A external return (recitifed) was then provided from which to record any deviations induced upon the dielectric by geophysical events. If anyone can help me narrow down the experimental options on this, I will attempt to replicate the effect and report back to the list. Peter M. Nielsen, E.E. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Charlie Rond <rond@................> Subject: Re: update to Dave's list of operators Date: Tue, 11 Feb 1997 23:46:41 -0600 Edward, >I am very glad you have forwarded this info. I hope that Dave will >update the map ASAP so that your station shows up when we display the >PSN websites during the Seismic Network Conference in Memphis >13-15 Feb. I will get there tomorrow, 12 Feb, to start setting things >up on the PC you have been instrumental in obtaining for that purpose. The mortification of not being "on the map" - especially during your auspicious visit to our fair city - finally got me to extricate my boots from this Mississippi River mud and send my info on to Dave. I'm sorry to make extra work for Dave, but all the folks who have helped us in the past deserve to see our light added to that great map. Charlie Rond -\/\--Public Seismic Network-Memphis rond@................ (901) 360-0302 [ free BBS ] http://gandlf.ceri.memphis.edu/~rond http://gandlf.ceri.memphis.edu/~rond/psn _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Charlie Rond <rond@................> Subject: Re: latest up date Date: Wed, 12 Feb 1997 00:10:48 -0600 In a region that loves landfills, we're sometimes embarrased to ask! My concrete slab sits on thick soil of unknown depth. Our soil is generally described as a mixture of loess and clay. The bedrock is probably deeper than 20-feet. This soil is prone to liquifaction in a quake which compounds the seismic danger in the New Madrid fault region. "Loess is a geologic term that refers to deposits of silt (sediment with particles 2-64 microns in diameter) that have been laid down by wind action (aeolian activity to geologists). Extensive, thick loess deposits generally formed in areas bordering large, continental glaciers...Frequently the resulting loess deposits are several meters thick (tens of feet). Because the source of the silt is the outwash from the glaciers, loess deposits are frequently most extensive and thickest downwind from large river valleys. Often several different loess deposits are stacked on top of each other in an area because each glaciation causes the formation of a loess deposit. The midwestern U.S. has numerous examples of multiple loesses deposited in the same place. Approximately thirty percent of North America has one or more loesses deposited over the bedrock." --Illinois State Museum Web Page Charlie Rond -\/\--Public Seismic Network-Memphis rond@................ (901) 360-0302 [ free BBS ] http://gandlf.ceri.memphis.edu/~rond http://gandlf.ceri.memphis.edu/~rond/psn _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: bzimmerman@............ Subject: Dos Networking Date: Wed, 12 Feb 1997 09:35:39 -0500 (EST) I know that I could find this information for myself but I am both lazy and busy. Can Larry (or anyone else) provide details regarding the hardware/software required to connect two DOS machines. My first goal is to get the two machines working on the same clock. I would also like to share files and am working toward "real time" access to data. If you have the URL where the software is available, I would appreciate it. As a side note, we have been playing around with running SDR in a LINUX environment without much luck (for one thing the clock runs at 1/10 the normal rate). The reason for trying this is the built in networking that LINUX offers. To get an idea of what is possible check out one of the best real-time weather stations on the WEB at: http://coop20.geos.edinboro.edu/~bullock/METEOR_LINKS.HTML For those not familiar with LINUX it is a UNIX-like operating system. I believe "LINUX" stands for "LINUX is not UNIX" or something like that. Brian S. Zimmerman Department of Geosciences Edinboro University of Pennsylvania Edinboro, PA 16444 Phone: (814) 732-2207 Email: BZimmerman@............ _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane <cochrane@..............> Subject: Re: Dos Networking (long) Date: Wed, 12 Feb 1997 16:16:18 -0700 Hi, At 09:35 AM 2/12/97 -0500, Brian S. Zimmerman wrote: > >I know that I could find this information for myself but I am both lazy >and busy. Can Larry (or anyone else) provide details regarding the >hardware/software required to connect two DOS machines. My first goal is >to get the two machines working on the same clock. I would also like to >share files and am working toward "real time" access to data. If you have >the URL where the software is available, I would appreciate it. At the bottom of this message is a copy of the text file (netwin95.txt) that is in the current release of SDR. (SDR18.ZIP). It describes how to connect two PC's using LAN cards. One system is setup to run SDR in the DOS only mode of Win95. Even though the data logging system is running only DOS, you can still us the network to map a drive across the LAN to the other system running Windows. You can then have the event files produced by SDR show up on the system that is running Windows. This should also work with EMON, but I have not tried it. Since I think you are running SDR you should be know that the only way to keep the time accurate within SDR is to do one of several things. Use the WWV time option. Since you do not have my A/D board you can build the tone detector (see tonedet.gif in the SDR release) and connected it to a shortwave receiver. Another way is to simulate the 800 ms top of the minute mark and feed this into one of the digital inputs on the PC-Labs 711s card. The other way is to use a serial port. Normally this is used to keep two SDR systems in synic. One would have the WWV option and act as a time server using one of the comm ports. The other system would be set up to use the serial port as the time reference. You can simulate the output a SDR time server using another compuer that has accurate time. The other system needs to run a program that waits or a "T" on the serial port from the SDR system and then sends back the time as an offset in milliseconds from midnight. Contact me if you want more info on this option. > >As a side note, we have been playing around with running SDR in a LINUX >environment without much luck (for one thing the clock runs at 1/10 the >normal rate). This means that SDR is dropping interrupts. This is not surprising, the same thing happens under a DOS box in Windows. The operating systems are disabling interrupts for to long so SDR is losing time. The only way around this is write a device driver that can run at a higher priority. This is not an easy task. When I wrote SDR I was hoping to port it over to Windows after I got the basic stuff working. After getting the DOS version working I then looked into getting to work under windows. I then found out that Windows 3.1 (the only version available at the time) can disabled interrupts for hundredths of milliseconds during task switching, and, the only way around this is to write a devices driver. Even a driver may not be able to keep up with the 1 millisecond interrupt rate on slower PC's. At that point I gave up with porting SDR over to Windows. >The reason for trying this is the built in networking that >LINUX offers. The networking under DOS works pretty good. Once you get it setup and working it should work just fine. SDR has one undocumented feature for creating event files using a mapped drive over a network. When this feature is enabled SDR checks a directory (every 10 seconds) on the other system (running Windows or any other system that can use NetBEUI) for a files. In this file is information about the data request like channel, start time, number of minutes to save etc. SDR parse the file, creates the event file and places it on the other system, and then deletes the request file. This is how my Request Data web page at http://psn.quake.net/request.html works. The web server runs a CGI script that produces the request file and then waits for the event file to be created. The CGI script then creates and returns a new web page with a link to the file. I will document this feature and send it out to the SDRUSER email mailing list. > To get an idea of what is possible check out one of the >best real-time weather stations on the WEB at: > >http://coop20.geos.edinboro.edu/~bullock/METEOR_LINKS.HTML > This is a really nice page! I have a Davis Weather Station that I would like to connect up to the Redwood City PSN system someday. If only I could clone myself.... Regards, Larry Cochrane Redwood City, PSN ------------------------netwin95.txt------------------------------- Network Setup for Win95 and SDR Below is the information you need to setup two computer systems, one running SDR and the other running Windows 95. This configuration will allow SDR to write PSN format event files to your main Windows system eliminating the need to transfer files using a floppy disk. For this to work you must keep both systems running 24 hours a day. This file also has information on how to setup Win95 so it can run SDR in the DOS Only Mode at bootup. Network Card: Be sure and get the type with a BNC connector. If you get a card that only has the RJ type telephone connector on it you will need to get a hub box. The card should be NE2000 compatible. Set the interrupt to IRQ 11 or 15 and the port address should be 300hex (usually the default). The card should not cost more then $50.00. The ones I buy only cost around $35.00. Connect the two cards using RG-58 50 ohm coax cable. You must terminate both ends with a 50 ohm termination resistor. You should get a T connector with the network card but you will have to buy the two 50 ohm BNC termination resistor. The next thing to do is load Windows 95 on both systems. During the setup Win95 should see your network cards. At some point I think you will be asked for a computer and workgroup name. The computer name needs to be different but the workgroup name needs to be the same for your two systems. If you are not asked (it's been a while since I load 95) for a computer name or workgroup name select the My Computer icon then the Control Panel. In the Control Panel you should see Network icon. Click on it and then the Identification Panel. There you can enter the computer and workgroup names. When setting up your two systems use the same User Name and Password for both systems. On the system that will be running WinQuake you need to enable the disk drive for sharing. Select the My Computer icon. Now click on the C: (or the drive letter you want to share) drive icon and then click on the File Menu item (use the file menu item for the My Computer dialog box). Select the Share menu item. Click on the Share As: button. Enter a Share name for the drive (I use the drive letter) and select the Full Access button. Under the Full Password enter the same password you use for loggin onto the system. Then click on OK. The next thing to do is create a directory (like c:\events) that SDR will place event files into. SDR will create sub-directories like 9612 and 9701 under this root directory you create. Now on the SDR system start Win95. Make sure you have the Workgroup name the same as the other system and that the computer name is different. Now select the Network Neighborhood icon. If everything is working you should see the name of both systems in the dialog box. If you see the name of the other system then you have your network working properly! Now select the other system by double clicking on the name of the other system. You should see the shared name for the drive on the other system. Now click on the drive name and then the File menu item. Now select the Map Network Drive. Use this dialog to select a drive letter for the mapped drive. If very thing is working you should see the directories and files on the other system. The next thing to do is shutdown Win95. In the shutdown dialog box select "Start the Computer in MS-DOS Mode? option and then Yes. When the system restarts it will be in a DOS only mode that SDR can run in. Now you will be using the net command to start the network and map to a drive to the other system in the DOS only mode. For a complete list of commands type NET at the dos prompt. The first command to do is start the network and map a drive. Type "net logon" at the dos prompt. Answer Yes to the first prompt and then enter the User and Password you are using for both systems. If very thing is working you should see "The command was completed successfully" message. Now map a drive letter to the remote disk on the other system. Use the following command to do this: net use drive_letter: \\system_name\shared_drive_name Example: net use e: \\sys1\c This will map drive letter e to the drive C on the system sys1. If the map worked you should be able to do a dir on the new drive letter and see all of the files on the other system. Note: you can not map a drive the other way. Meaning that the system that is running the pure DOS mode can only map to a drive running Windows. The Windows system can not map to a drive on the DOS only system. You can now run SDR. Under the F5 settings set the Event File Path to the mapped drive and directory on the other system. Example: E:\EVENTS SDR will now save event files on the other system where WinQuake can easily see them. One more thing you need to do. This is to force your data logging system to boot right to the pure DOS mode and map to the other system without having to shutdown Win95 first. The starting of the network and mapping of the drive will be done in the autoexec.bat file. First you need to edit a file called MSDOS.SYS. This file is located on the root directory C:\. This file is hidden and read only. You must first use the attrib command so you can see and edit the file. Do the following command: attrib -S -H -R msdos.sys After doing this command you should be able to edit the file. Change the BootGUI under Options from a 1 to a 0 and save the file. Now when you reboot the system it should come up in the DOS only mode. If you want to start Win95 type WIN at the prompt. The last thing to do is edit your autoexec.bat file and add the network startup commands to map your drive to the other system. Here is my bat file: @ECHO OFF C:\WIN95\net start C:\WIN95\NET logon system_name your_password /yes PROMPT $p$g SET COPYCMD=/y PATH C:\WIN95;C:\WIN95\COMMAND;C:\DOS;C:\BAT;C:\;C:\BIN SET TEMP=C:\TMP SET TMP=C:\TMP C:\WIN95\COMMAND\DOSKEY C:\WIN95\NET use e: \\sys1\c cd \sdr tsrpsn sdr There is my config.sys file: DEVICE=C:\WIN95\SETVER.EXE DEVICE=C:\WIN95\HIMEM.SYS DOS=HIGH _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Robert L Barns <75612.2635@..............> Subject: Strange SDR record Date: 13 Feb 97 15:52:12 EST Hi gang, I sent an SDR quake (?) file to Larry's archive. It is 970110A.RLB. As far as I can tell, this quake (?) was seen by no one else in the world. Scolnic, who runs 3 long period Geo-Techs (2 horiz. and 1 vert.) only 40 miles from here did not see it and I did not find it in any of the professional lists of quakes. Also, it looks like no other that I have seen in books or any of the other ~ 50 quakes I have recorded. The amplitude is far above the noise level I have ever seen here (signal/noise = 37). This leads me to believe that it cannot be local stuff such as traffic, etc. The recording is from my Lehman (period ~ 30 secs.) which is aimed at ~ 350 deg. My clock was 4" slow on this date. It is FFT band-pass filtered 0.025-0.08 Hz. This filtering is in addition to the 0.08 Hz active low-pass filter that is between my amp. and the A/D. The small burst at the extreme right end of the trace is foot traffic in the house. If my meter-movement calibrator is not too far off, the peak ground velocity was about 22,000 nm/sec. The peak velocity is about 50% larger than the max. of the surface waves I got from the Jujuy, Argentina (dist. 3,220 mi) quake, a 6.4 at 2:15:22 on 1/23/97. Well, I hope that someone can suggest what this might be! If someone sez "You ignoramus, that is obviously a such-and-such', I won't be offended, just enlightened. Bob Barns _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: David A Nelson <dann@........> Subject: Re: Strange SDR record Date: Fri, 14 Feb 1997 13:17:55 +1200 Gidday Bob, just downloaded your file from Larry's archive.... reminds me of what happens to my sys when the lawn mower comes within a couple of metres of the sensor, it sends the signal off the scale. On the other hand I do have ONE seismogram in my collection of 100's that showed similar traits... slow build up peak for a while and then a slow decline..... to this day I still have not labeled where the 'S' arrival is... I just cannot determine. It doesn't look like a quarry blast, I record many of those from a quarry 3 km away and they show a distinct sudden high amplit. onset with a die off over ~10-15 sec. If I interpreted correctly the event lasted ~ 110 minutes ( almost 2 hrs) The fact that the other station you mentioned didnt record anything tends to confirm that it was close to you was there something happening on a local building site heavy machinery of some sort?? large hydraulic concrete breaking hammer.... pile driver??? ask around any neighbours up to any construction ??? like you I am grasping at straws...... ( Ah.... the beginnings of an alien invasion building an underground chamber) hi hi Cheers Dave At 03:52 PM 2/13/97 EST, you wrote: >Hi gang, > I sent an SDR quake (?) file to Larry's archive. It is 970110A.RLB. > As far as I can tell, this quake (?) was seen by no one else in the world. >Scolnic, who runs 3 long period Geo-Techs (2 horiz. and 1 vert.) only 40 miles >from here did not see it and I did not find it in any of the professional lists >of quakes. Dave A. Nelson 24 Jensen St., Green Is., Dunedin, South Is.. New Zealand. http://psn.quake.net/dave/home.htm ( world wide access ) http:/www.es.co.nz/~dann/home.html ( New Zealand access only ) SOD'S-LAW--- When Something Does Go Wrong, There Is Sod All You Can Do About-It When The Last Of Ten Screws Has Been Removed From A Cover, -It Will Be Discovered That The Wrong Cover Has Been Removed When The Last Of Ten Screws Has Been fitted back Into A Cover, -It Will Be Discovered That The gasket Has Been Left Out _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Jack Sandgathe <jsandgat@.......> Subject: Got them! Date: Mon, 17 Feb 1997 20:39:13 -0800 Dear Larry, Well, the package came today, and I am really pleased - you do fine work. I am in the process of going through the files supplied. I like to move them into WordPerfect so that I can add bold and reformat to some extent. When printed they are sometimes easier to read. Thanks very much. When I opened the box, I had some questions about details, but I think they will be answered in your documentation. Will be back with more when I have a chance to look things over. Jack _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: David A Nelson <dann@........> Subject: map page addition Date: Tue, 18 Feb 1997 20:53:07 +1200 Hi all, for those of you who have not discovered it yet.... I have added a link from the PSN map page to the IRIS DMC GSN (Global Seismic Net) map page. This is also a clickable map which will display info for each station. Cheers from the " Land of the Long White Cloud " Dave Dave A. Nelson 24 Jensen St., Green Is., Dunedin, South Is.. New Zealand. http://psn.quake.net/dave/home.htm ( world wide access ) http:/www.es.co.nz/~dann/home.html ( New Zealand access only ) _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Barry Lotz <gbl@.......> Subject: Re: filtering Date: Tue, 18 Feb 1997 18:39:51 -0800 To all- I was thinking of subtracting real and inaginary parts of the two windows separately and going thru the inverse routine to get an event which is filtered for the previous few minutes of background noise.I know a little of FFTS but my high level math is limited. Any input? Barry Larry Cochrane wrote: > > Hi Barry, > > I'm not an FFT expert. I was able to get WinQuake to have the FFT option by > finding some code on the net. You might forward this to the PSN mailing > list. Maybe someone with a better background with FFTs can help. If you get > something working let me know. > > Regards, > Larry Cochrane > > At 10:00 AM 2/16/97 -0800, you wrote: > >Hi Larry > > > >I have been toying with a problem I have been having for a while. > > > >Problem: In general, many of the events I obtain have background noise > >in the same frequency band as the event, making standard filters > >limited. > > > >Thought: Even with great picking routines the recored event still > >can have a lot of noise. Presumably, the background noise would be the > >same during an event as before. When one performs an FFT the frequency > >spectrum obtained has an amplitude range before it is normalized. What > >if one choses two event windows, one before and one during an event. An > >FFT is done for both and the resulting non-normalized spectrums > >differenced. This process would filter noise frequencies at their > >particular magnitude and not 100%. The resulting spectrum would then be > >transformed back to the time domain. Since the window before the event > >may be somewhat shorter than the event window, some low frequency noise > >could get thru, but a low pass could fix that. All one would have to > >pick is the start of an event. I am working with this in my DOS program > >to see if it works. Think of it this way, one could have background > >noise spectrums for their particular station (day,night,summer,winter > >etc) that could be updateable or averaged from many smaller noise > >windows over time. If one so desires, the particular noise spectrum > >chosen could be processed with the event. > > Regards > > Barry > > > > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: David <david@...............> Subject: Re: filtering Date: Tue, 18 Feb 1997 19:43:02 -0800 (PST) Re the recent thread on filtering, or subtracting the spectrum of a time averaged FFT to get rid of noise, it won't work. My background in this in in the other seismic stuff, exploration seismic where we generate a signal and look for echoes. Also a lot of work in active acoustic noise cancellation in air. Subtracting a spectrum from a spectrum works if what you want is a spectrum out -- and might be useful if you just want to monitor noise level, for instance for triggering. But if you want to recover the time domain waveform, you can't do it that way. The only exception is if you know something about the periodicity of the noise -- for instance if it's a pump that makes a tone at 3.5 Hz, you can with enough averaging generate a local 3.5 Hz that's in phase with the pump's tone, and subtract that from the data, or synchronize your sample rate with the noise frequency so the noise drops out. But most environmental noise is random, and these techniques depend on the non-randomness of the noise. FFTs of teleseismic waveforms are principally useful, I would imagine, for determining depth of and distance to the event (I'm out of my element here) and of course if you see a spike in the FFT you have proof that there is some periodic noise that you can get rid of with a synchronous filter. -- David Josephson _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: David A Nelson <dann@........> Subject: Re: Got them! Date: Wed, 19 Feb 1997 21:39:49 +1200 Jack, sounds like we will see some event files from you in the near future good one!! Just in the middle of the construction of another A to D system myself for installation into the local Civil Defense HQ..... should be up and runnng soon Dave At 08:39 PM 2/17/97 -0800, you wrote: >Dear Larry, > > Well, the package came today, and I am really pleased - you do fine >work. I am in the process of going through the files supplied. I like to >move them into WordPerfect so that I can add bold and reformat to some >extent. When printed they are sometimes easier to read. Thanks very much. >When I opened the box, I had some questions about details, but I think they >will be answered in your documentation. > > Will be back with more when I have a chance to look things over. > > Jack > > >_____________________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email listserver@............. with the body of the >message: leave PSN-L > > Dave A. Nelson 24 Jensen St., Green Is., Dunedin, South Is.. New Zealand. http://psn.quake.net/dave/home.htm ( world wide access ) http:/www.es.co.nz/~dann/home.html ( New Zealand access only ) Public Seismic Network Mailing List (PSN-L) From: Steve Hammond <shammond@..........> Subject: Re: filtering Date: Wed, 19 Feb 1997 13:44:00 -0800 (PST) David and others, I'm looking for white papers on triggering and noise filtering that also include any type of neural network or fuzzy logic. Any sugestions where I might look on the WEB? Thanks in advance, Steve Hammond PSN BBS San Jose 408-226-0675 On Tue, 18 Feb 1997, David wrote: > Re the recent thread on filtering, or subtracting the spectrum of a time > averaged FFT to get rid of noise, it won't work. My background in this in > Subtracting a spectrum from a spectrum works if what you want is a > spectrum out -- and might be useful if you just want to monitor noise > level, for instance for triggering. But if you want to recover the time > domain waveform, you can't do it that way. The only exception is if you > know something about the periodicity of the noise -- for instance if it's snip snip > David Josephson _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: David <david@...............> Subject: Re: filtering Date: Wed, 19 Feb 1997 17:58:06 -0800 (PST) On Wed, 19 Feb 1997, Steve Hammond wrote: > David and others, I'm looking for white papers on triggering and noise > filtering that also include any type of neural network or fuzzy logic. > Any sugestions where I might look on the WEB? > Thanks in advance, Steve Hammond PSN BBS San Jose 408-226-0675 Rather than looking for some magic in neural networks or fuzzy logic, it will help you much more to understand some basic information theory. The original work of Shannon and Nyquist, and a fundamental understanding of the Fourier transform between frequency and time domains, will tell you all you need to know (and, speaking from experience having gone through this exhaustively some years ago looking for a way to clean up airborne magnetic survey data, a lot more quickly than with 'modern' interpretations). This is an area where thought experiments work as well as the real thing. The basic truth (I hope to be proven wrong some day) is that you can only remove that component of a signal which you can exactly recreate. If there is a spectral peak in the frequency domain, that translates to a continuous signal in the time domain, you can synchronize with it and generate its inverse. This applies to complex waveforms too, but if the noise spectrum follows a constant function (flat, or sloped, or curved) there simply isn't anything you can do but look for more correlations in some other domain like space (multiple sensors) or direction (multi-axis sensors). _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Jeff Batten <batten@...............> Subject: Basic or C code for FFT Date: Wed, 19 Feb 1997 18:31:22 -0800 Does anyone have a BASIC or C program that will read a data file and do a FFT. Or a good book on the theory that has code. Thanks Jeff Batten - Research Engineer Caltech Seismo Lab 1200 E. California Bl. Pasadena, Ca. 91125 818-395-6965 Fax-818-564-0715 _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Richard J. Goff" <rgoff@................> Subject: Re: Basic or C code for FFT Date: Wed, 19 Feb 1997 21:07:46 -0600 Jeff Batten wrote: > > Does anyone have a BASIC or C program that will read a data file and do a FFT. > > Or a good book on the theory that has code. > > Thanks > Jeff Batten - Research Engineer > Caltech Seismo Lab > 1200 E. California Bl. > Pasadena, Ca. > 91125 > 818-395-6965 > Fax-818-564-0715 > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L Look @ : Robert W. Ramirez,:The FFT Fundamentals and Concepts",Prentice- Hall, 1985. They have a basic program. Dick Goff _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Barry Lotz <gbl@.......> Subject: Re: filtering Date: Wed, 19 Feb 1997 20:02:34 -0800 David wrote: > > On Wed, 19 Feb 1997, Steve Hammond wrote: > > > David and others, I'm looking for white papers on triggering and noise > > filtering that also include any type of neural network or fuzzy logic. > > Any sugestions where I might look on the WEB? > > Thanks in advance, Steve Hammond PSN BBS San Jose 408-226-0675 > > Rather than looking for some magic in neural networks or fuzzy logic, it > will help you much more to understand some basic information theory. The > original work of Shannon and Nyquist, and a fundamental understanding of > the Fourier transform between frequency and time domains, will tell you > all you need to know (and, speaking from experience having gone through > this exhaustively some years ago looking for a way to clean up airborne > magnetic survey data, a lot more quickly than with 'modern' > interpretations). This is an area where thought experiments work as well > as the real thing. The basic truth (I hope to be proven wrong some day) is > that you can only remove that component of a signal which you can exactly > recreate. If there is a spectral peak in the frequency domain, that > translates to a continuous signal in the time domain, you can synchronize > with it and generate its inverse. This applies to complex waveforms too, > but if the noise spectrum follows a constant function (flat, or sloped, or > curved) there simply isn't anything you can do but look for more > correlations in some other domain like space (multiple sensors) or > direction (multi-axis sensors). > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L David- Not to belabor the point but---- I speak only for myself now, I am not looking for precision in the event record. There are too many other variables which affect my record vs that from another station. You mentioned about knowledge of the noise like a pump etc. .What if the "known" noise is composed of more than one frequency? Say I record noise for a long period of time and average different windows (night, day, summer, winter etc) to get various characteristic noise fingerprints. Could this then be considered a "known" noise as far as the degree of accuracy available for the whole seismic recording process? P.S. Hi Steve- I picked up a book from Analog Devices called "Digital Signal Processing in VLSI" by Richard J. Higgins (Prentice Hall). It has been very useful to me. It's readable and its math is not extremely complicated. Regards Barry _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Barry Lotz <gbl@.......> Subject: Re: Basic or C code for FFT Date: Wed, 19 Feb 1997 20:15:49 -0800 Richard J. Goff wrote: > > Jeff Batten wrote: > > > > Does anyone have a BASIC or C program that will read a data file and do a FFT. > > > > Or a good book on the theory that has code. > > > > Thanks > > Jeff Batten - Research Engineer > > Caltech Seismo Lab > > 1200 E. California Bl. > > Pasadena, Ca. > > 91125 > > 818-395-6965 > > Fax-818-564-0715 > > > > _____________________________________________________________________ > > > > Public Seismic Network Mailing List (PSN-L) > > > > To leave this list email listserver@............. with the body of the > > message: leave PSN-L > > Look @ : Robert W. Ramirez,:The FFT Fundamentals and Concepts",Prentice- > Hall, 1985. They have a basic program. > > Dick Goff > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN- Jeff The book I referenced in my earlier note has a FFT routine(only one page) hardly worth buying the book. I have a Quick Basic version of a Fortran routine which I can send the text. The generation of the time domain array will depend on the format of your data. I will be back. Regards Barry _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Mike Lozano <mikel@.......> Subject: Re: C code for FFT Date: Sun, 16 Feb 1997 06:12:27 -0600 Jeff Batten wrote: > > Does anyone have a BASIC or C program that will read a data file and do a FFT. > > Or a good book on the theory that has code. > > Thanks > Jeff Batten - Research Engineer > Caltech Seismo Lab > 1200 E. California Bl. > Pasadena, Ca. > 91125 > 818-395-6965 > Fax-818-564-0715 > Jeff, The book 'Numerical Recipes in C' by Wm. H. Press, Saul A. Teukolsky, Wm. Vetterling, and Brian P. Flannery. (Cambridge University Press) ISBN 0-521-43108-5 is an excellent reference on FFT's and all sorts of neat manipulations. It's available at Barnes & Noble or Borders Book Stores. It has a companion book which lists practical examples. Another possible one is 'Engineering problem solving with ANSI C" by Delores M. Etter. It's a Prentice Hall book. ISBN 0-13-061607-9 I've used these books extensively, and can say THEY'RE GREAT!!! Mikel (That's Basque for Mike) Lozano mikel@....... -0- _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Barry Lotz <gbl@.......> Subject: Re: Basic or C code for FFT Date: Wed, 19 Feb 1997 21:27:18 -0800 Jeff Batten wrote: > > Does anyone have a BASIC or C program that will read a data file and do a FFT. > > Or a good book on the theory that has code. > > Thanks > Jeff Batten - Research Engineer > Caltech Seismo Lab > 1200 E. California Bl. > Pasadena, Ca. > 91125 > 818-395-6965 > Fax-818-564-0715 > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L Hi Jeff I hope this helps a little. Barry From: Charlie Rond <rond@................> Subject: Edward Cranswyck Date: Thu, 20 Feb 1997 02:14:23 -0600 Wanted all to know that our progenitor, Edward Cranswyck, did a great job at the Seismic Network Workshop this past week at the Center for Earthquake Research and Information (CERI), University of Memphis. Edward quickly established his own Public Seismic Network - Memphis station in CERI's Seismic Resource Center, with E-mail flowing, and Friday afternoon was demonstrating PSN resources available on the Web. Onlookers enjoyed his highlighting different PSN stations around the globe on Dave Nelson's map, and Larry Cochrane's Winquake seismogram displays. It was a wonderful opportunity for Edward to highlight the accomplishments of the PSN and how well it can serve as a model for gathering and organizing scientific data. John Lahr was there, Allen Jones was demonstrating his Seismic software (you should hear it booming from a subwoofer), Arch Johnston of CERI, of course, and many other notables. Charlie Rond -\/\--Public Seismic Network-Memphis rond@................ (901) 360-0302 [ free BBS ] http://gandlf.ceri.memphis.edu/~rond http://gandlf.ceri.memphis.edu/~rond/psn _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane <cochrane@..............> Subject: Photos of comet Hale-Bopp Date: Thu, 20 Feb 1997 00:28:36 -0700 Hi, This is off topic but one of our list members, Mark Halliday, has some great photos of the comet Hale-Bopp that is now visible in the northern hemisphere. I scanned in the photos and place the jpg images on my home page at http://psn.quake.net. You can lick on the images for a better view of the image. Mark lives in the mountains near the city of Ben Lomond (near Santa Cruz California). He also has a seismograph system running (# 5 on Dave's map). Here are the details for each photo: Photo #1 -------- Comet Hale-Bopp taken 2/18/97, 4:55am PST in Ben Lomond, CA. 200mm f4.0 lens, Nikon F2 camera, 15 minute exposure on ASA 400 color print film (Kodak Gold 400). The camera was piggybacked on a small Celestron telescope which has a motorized equatorial mount. I tracked on the nucleus. Photo #2 -------- Comet Hale-Bopp taken 2/18/97, 5:20am PST in Ben Lomond, CA. 50mm f1.4 lens, Nikon F2 camera, 1 minute exposure on ASA 400 color print film (Kodak Gold 400). Enjoy, Larry Cochrane Redwood City, Cal _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: JHammes@......................... Subject: Re: Basic or C code for FFT Date: Fri, 21 Feb 1997 08:54:15 -0800 Jeff requested: >Does anyone have a BASIC or C program that will read a data file and do a >FFT. >Or a good book on the theory that has code. >Thanks >Jeff Batten Jeff, Check out the "Simple FFT" freeware Windows program. It can be accessed at http:www.shareware.com. Search for file: sfft21.zip. I have not had any time to play with this myself, but a review in "Test & Measurement World" last year indicated it is pretty good for a free program; it has a 16 Ksamples data file size limit. Jerry Hammes _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Steve Hammond <shammond@..........> Subject: Re: Basic or C code for FFT Date: Sat, 22 Feb 1997 13:09:32 -0800 (PST) First of all let me thank everybody that responded to my note a few days back. I'm working on a paper for an ISM degree at USF and as you might have guessed, I have a term paper due on Neural Networks. The teacher wants it tied to a subject we are working with in real life, and EQ triggers got mentioned, and she thought it would be interesting. So do I-- If I just had a bit more time... What I wanted was other papers for short quotation and APA reference. Thanks for all the book refs however, and I'll hit the book store and see what I can find. ---- FFT's ---- Also as you might have guessed I needed some source code for the term paper. And in looking at the PSN BBS here in San Jose I found five or six different FFT zip files. Berry L. posted most of them I think. They are made up of code samples for BASIC and C and include a couple of fun DOS programs. I zipped them into a 303K zip file and will E-mail them to you, or other, if you want them, just send me a note. Thanks again-- Regards, Steve Hammond PSN BBS San Jose 408-226-0675 On Fri, 21 Feb 1997 JHammes@......................... wrote: > > > > Jeff requested: > > > >Does anyone have a BASIC or C program that will read a data file and do a > >FFT. > > >Or a good book on the theory that has code. > > >Thanks > >Jeff Batten > > > > Jeff, > > Check out the "Simple FFT" freeware Windows program. It can be accessed at > http:www.shareware.com. Search for file: sfft21.zip. I have not had any > time to play with this myself, but a review in "Test & Measurement World" > last year indicated it is pretty good for a free program; it has a 16 > Ksamples data file size limit. > > Jerry Hammes > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: toddm@........... (Todd Miller) Subject: Connecting to a Mac II Date: Sat, 22 Feb 1997 13:50:05 -0800 Hello, Some months ago I found your group and was excited about using amateur seismography in the science classroom. Now I student teaching at the middle school level. In the intervening months I have built a Lehman sensor. I have tested it using a PASCO Mac interface and it works fine. I wrote long ago asking for advice about using Macs (which I have several of, and as well, here in Washington state 80% of the computers in schools are still Macs) instead of PC's which seems to be your standard. I lost the responses I got and besides I now have some more specific questions. First, about an inexpensive A/D for the Mac. Will the one Larry Cochrane builds work? It is the maximum on my affordibility scale (being a student teacher means, not only do you not get paid for interning, one pays tutition for the privelage) Does any one know of a less expensive option? I am virtually illiterate on the electronic/programing front though, if I have time, I am a pretty quick study. Second, on data logging software. As Winquake obviously won't work on a Mac, someone responded last time (I apologize for losing it) about some Mac software they wrote. Care to respond again? Another option I have been considering is the student version of LabView. I have been told the full version would do what I need easily but I don't know anything about the student version which is much less expensive. Any help would be appreciated. Todd Miller _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane <cochrane@..............> Subject: Re: Connecting to a Mac II Date: Sat, 22 Feb 1997 14:45:05 -0700 At 01:50 PM 2/22/97 -0800, Todd Miller wrote: > First, about an inexpensive A/D for the Mac. Will the one Larry >Cochrane builds work? No sorry, my A/D card uses the IBM PC buss (ISA). > Second, on data logging software. As Winquake obviously won't work >on a Mac, someone responded last time (I apologize for losing it) about >some Mac software they wrote. Don't the newer Macs run Windows programs? Larry Cochrane Redwood City, PSN _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: toddm@........... (Todd Miller) Subject: Re: Connecting to a Mac II Date: Sat, 22 Feb 1997 17:18:01 -0800 Virtually any Mac will run IBM software if the Mac has SoftWindows, SoftPC, and Apple DOS card, or and third party software/hardware. I think that the new Performa/PowerMacs have SoftWindows bundled with them. Bye-- Todd _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Mark Wilson mark@.............." <wilsonm@............> Subject: Station Up. Date: Sun, 23 Feb 1997 10:26:09 -0800 (PST) 33 57' N 116 57'W I got my PS-1 unit up with a geophone for the pickup. It picked up 3 small events here locally last night. The Geophone is a GS-11D, 4.5 Hz Vertical. Seems to be sensitive enough. Any comments on using the geophone?? I like the fact that it is small and I can bolt it to a solid foundation easily. I have a Lehman unit that I built a few years ago,.. wondering about the difference and if I should go back to it. I like the longer period recording, and I doubt the geophone is good for that. Awaiting any comments.... ********************************************************************* --- mark@.............. --- http://www.markwilson.com --- wilsonm@............ --- General Networking Dude and Routing Rugrat ********************************************************************* _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Edward Cranswick <cranswick@..................> Subject: Re: Basic or C code for FFT Date: Sun, 23 Feb 1997 15:09:51 -0700 Steve- Glad to hear that you have embarked in pursuit of one of the Holy Grails of seismology: the cosmic trigger algorithm. They got real hot&bothered about this for detecting Soviet nukes from NORSAR in Norway. My feeling about it from a ground motion perspective was that if you had to riddle the Sphinx to find out whether the Earth moved, it probably hadn't moved enough, i.e., there wasn't enough signal to do much with ... However, I have a burnt-out, low-Tech approach; but I have forwarded your message to one of the Armenian Seismo-Mafia who recently got his Seismology Ph.D. from Bolt at Berkeley, and he is also cognizant of the neural network method (which I am not). Good luck and regards to family. -Edward Steve Hammond wrote: > > First of all let me thank everybody that responded to my note a few days > back. I'm working on a paper for an ISM degree at USF and as you might > have guessed, I have a term paper due on Neural Networks. The teacher > wants it tied to a subject we are working with in real life, and EQ > triggers got mentioned, and she thought it would be interesting. So do I-- > If I just had a bit more time... What I wanted was other papers for short > quotation and APA reference. Thanks for all the book refs however, and > I'll hit the book store and see what I can find. > > ---- FFT's ---- Also as you might have guessed I needed some source > code for the term paper. And in looking at the PSN BBS > here in San Jose I found five or six different FFT zip files. Berry L. > posted most of them I think. They are made up of code samples for BASIC > and C and include a couple of fun DOS programs. I zipped them into a 303K > zip file and will E-mail them to you, or other, if you want them, just > send me a note. > > Thanks again-- > Regards, Steve Hammond PSN BBS San Jose 408-226-0675 -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 1711 Illinois St cranswick@........ Golden, CO 80401 USA E.M. Forster said, "Only connect". _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane <cochrane@..............> Subject: Re: Station Up. Date: Sun, 23 Feb 1997 18:35:58 -0700 Hi Mark, Welcome to the wonderful world of seismic recording <GRIN>. Glad to here you got your station up and running. At 10:26 AM 2/23/97 -0800, you wrote: > >33 57' N 116 57'W > >I got my PS-1 unit up with a geophone for the pickup. >It picked up 3 small events here locally last night. > > >The Geophone is a GS-11D, 4.5 Hz Vertical. Seems to be sensitive enough. > >Any comments on using the geophone?? I like the fact that it is small >and I can bolt it to a solid foundation easily. The geophone will work fine for local quakes. They have high enough frequencies for your sensor to pick up. It will not work very well, if at all, for teleseismic events. You may pick up the P wave from very large teleseismic events, but thats it. All of the other waves are a lot lower in frequency and will not be pick up with your geophone. > >I have a Lehman unit that I built a few years ago,.. wondering about the >difference and if I should go back to it. I like the longer period recording, >and I doubt the geophone is good for that. Depending on the period of your Lehman it should work a lot better for teleseismic events. The Lehman design also works just fine for local events. You should run both sensors, if you can. Regards, Larry Cochrane Redwood City, PSN _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Charlie Rond <rond@................> Subject: Re: Station Up. Date: Mon, 24 Feb 1997 01:14:16 -0600 Larry (and all), Got a call this PM from Steve Jones, a NASA EE from Huntsville, AL who has just gotten his drum recording system working today. I referred him to Larry's Redwood City page for info, circuitry, software, etc. Also told him about subscribing to the PSN-L list. Keep an eye out for him on this channel. Charlie Rond -\/\--Public Seismic Network-Memphis rond@................ (901) 360-0302 [ free BBS ] http://gandlf.ceri.memphis.edu/~rond http://gandlf.ceri.memphis.edu/~rond/psn _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Greg Lyzenga <lyzenga@.................> Subject: Re: Connecting to a Mac II Date: Mon, 24 Feb 1997 08:48:20 -0800 > First, about an inexpensive A/D for the Mac. Will the one Larry >Cochrane builds work? It is the maximum on my affordibility scale (being a >student teacher means, not only do you not get paid for interning, one pays >tutition for the privelage) Does any one know of a less expensive option? I >am virtually illiterate on the electronic/programing front though, if I >have time, I am a pretty quick study. > Second, on data logging software. As Winquake obviously won't work >on a Mac, someone responded last time (I apologize for losing it) about >some Mac software they wrote. Care to respond again? Another option I have >been considering is the student version of LabView. I have been told the >full version would do what I need easily but I don't know anything about >the student version which is much less expensive. > Any help would be appreciated. > Todd Miller Todd: Sorry to be so late in responding, but I wasn't checking email over the weekend... I'm the person you referred to with experience in hooking up Macs to homebrew seismometers. First the hardware issue. I came up with an approach which was very cheap, but required some tinkering. If you are familiar with Mac hardware companies, you've probably heard of a company called Farallon up in the Bay area that makes networking products. The company started off as a small group of hobbyists who spun off a do-it-yourself sound digitizer for the Mac called MacRecorder, which was first sold as a kit by the Berkeley Mac Users Group (BMUG). This was a simple 8-bit device costing around $50, to which I made very simple modifications so that it recorded input voltages, rather than microphone input. I don't really know whether MacRecorder is still sold as a commercial product any more, since most modern Macs come with built-in sound recording capability now. However, a completely equivalent alternative (at least for someone handy with a soldering iron) is a completely from-scratch set of circuit schematics for a Mac serial-port digitizer that I have copies of. Again, the cost for parts would probably be on the order of $50. A more "plug-and-play", but considerably more expensive solution would be to buy a ready-made commercial digitizer. I am aware of commercial options that do 8-bit, 12-bit, 16-bit and more on multiple channels, for prices that range from a few hundred to a couple thousand bucks. There are options that use the serial port, the SCSI port, or the NuBus expansion slot inside the Mac II. (At the college where I teach, we have an 8-channel 16-bit NuBus card from National Instruments, but it is a bit pricey for hobbyist use at $1700.) As far as the software is concerned, yes I have an application I wrote myself which does the 8-bit serial port thing with the simple sound digitizer circuit described above. I'm happy to share the program with anyone who is interested. On the other hand, if you want to go the more sophisticated commercial hardware route, you probably do want to use something like LabView. I'm fairly confident that it should be easy to make any version of Labview emulate a simple strip-chart recorder appropriate for seismometer use. As a final note, as Larry mentioned in an earlier response, if all you want to do is run Windows or PC software, emulation software like SoftWindows should work just fine on most modern Macs. However, I'm pretty sure that if you start talking about hardware-specific issues like serial ports and A/D cards and such, it's pretty much hopeless to try to mix systems. I hope my experiences give you some idea of what's possible. Let me know if I can be of more help! - Greg |Gregory A. Lyzenga <lyzenga@.................> *** (909) 621-8378 |Dept. of Physics, Harvey Mudd College *** fax (909) 621-8887 |Claremont, CA 91711-5990 http://www.physics.hmc.edu/profs/lyzenga.html _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Geotechnical Resources, Inc." <gri@............> Subject: Re: Basic or C code for FFT Date: Mon, 24 Feb 1997 09:02:12 -0800 At 01:09 PM 2/22/97 -0800, you wrote: > ---- FFT's ---- Also as you might have guessed I needed some source >code for the term paper. And in looking at the PSN BBS >here in San Jose I found five or six different FFT zip files. Berry L. >posted most of them I think. They are made up of code samples for BASIC >and C and include a couple of fun DOS programs. I zipped them into a 303K >zip file and will E-mail them to you, or other, if you want them, just >send me a note. I'd like to get a copy of your "global search" FFT file, when you find the time, or you might post it on the PSN BBS. Bill Titus gri@............ _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Steve Hammond <shammond@..........> Subject: Nature imitates art... Date: Mon, 24 Feb 1997 12:20:20 -0800 (PST) For anybody that watched Fire on the Mt. last night on TV here in the States. (It was the unfactual depiction of a volcanic eruption at Mammoth Lakes) This morning, most of us in the Bay area recorded a 4.5ML at 37.57N 118.85W SE of Mammoth Lakes. It was preceded by several 1's, 2's and 3's. In the following hour, there was 15 events <2.0. Humm.... I wonder if the Mayor of Mammoth is now tell the Sheriff not to talk about it? Regards, Steve Hammond PSN BBS San Jose 408-226-0675 _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: ACole65464@....... Subject: Home-made Shaker Table Date: Wed, 26 Feb 1997 21:38:56 -0500 (EST) Hi gang, Where have all the daily postings on the PSN gone? We need something new for us to think/talk about! Here is something constructive to do. Nothing to do with whale strandings, dew on the ground or any other attempt at predicting EQs, which are popular topics on our favorite news group! To see what the high end frequency sensitivity of a home-made accelerometer was I built a simple shaker table to put it through it paces. The accelerometer under test is small, fitting in a 6" cube, and designed to detect horizontal motion. The natural freq is 2 hz but with its output integrated to derive a velocity signal the Bode plot for the instrument shows that the velo signal is flat up 30 Hz but the instrument when installed will have a low pass filter (with a cut off at 5 Hz) between it and the recorder. So I am only looking for a freq response up to 5 Hz from the seismometer. The shaker table was a piece of 1/4" thick foam board about 12" square and with several ribs of the same material bonded on edge to the under side of the table for stiffeners. This table was suspended with a peice of string approx 4" long in each corner. The strings were inclined up and away from the table at a 45 deg angle and tied to nails hammered in a wooden frame. Since the seismometer did not weigh a lot (about 1 1/2 lbs) the driving motor on the table was light duty. An old speaker coil magnet, 1/2" dia by 3/4" long attached to an arm bonded to the center on one edge of the table. The magnet extended into a coil of 34 ga copper magnet wire with about 200 ohms resistance. The coil was connected to a sine wave generator and its output was sufficient to drive the table from 1 to 20 Hz. The table worked well and the seismometer's response was easliy observed on the oscillascope for both amplitude and frequency. Amplitude dropped off with frequency but I could see that at 10 Hz I had no problems with the instrument as designed and the performed as predicted by the Bode plot. Along with Bob Barnes' seismo calibrator I am finally starting to build an instrument with some known properties. Now, if you want to shake a 20+ lb Lehman horizontal seismometer, then you will have a really big project on your hands. Regards, Allan _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Jim Hannon <jmhannon@........> Subject: Re: Home-made Shaker Table Date: Wed, 26 Feb 1997 21:36:37 -0600 Interesting, I have one question though, how do you know the response of the table itself? At work we use shaker tables to vibration test Mil equipment. They could easily handle a 20# seismograph, vibrate it to 5 G from 100Hz to 3KHz. There probably would not be much left of the instrument after that kind of abuse. These tables have 10KW amplifiers to drive them. They use calibrated accelerometers attached to the table for feedback to control the acceleration. -- Jim Hannon _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: steve jones <stejones@..........> Subject: hello from newbie Date: Wed, 26 Feb 1997 22:15:19 -0800 hello to all - looks like I finally got connected up on the psn list - I live in Huntsville, AL and have had a suppressd interest in seismo for years - after finding references to amateurs on the www, I decided to go ahead and jump in! Thanks to Charlie Rond for encouragement. I have very litte in the way of working hardware - I did hook up a borrowed short-period vertical sensor and a home-made drum recorder (nothing digital here - yet), but all I am getting is road noise from a major city street about a 1/2 mile away, judging from the 24-hr period of the "squiggles"...I have a good connection to "the mother of all rocks" exposed in my basement, which probably explains the rather good conduction to the roadbed down at the bottom of the hill...anyway, I'm looking for advise and counsel as I stumble around in this activity... Steve Jones _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Jim Hannon <jmhannon@........> Subject: Seismic Tomography Date: Wed, 26 Feb 1997 21:48:51 -0600 This is not too related to earthquake seismology but I thought I would ask the question anyway. I used to do a lot of cave exploration before I got old and too fat. One thing that I have always thought about was building a system to try and image a cave from the surface. The basic idea was to get a few geophones, a computer to log data and a sledge hammer to pound the ground. Then spend a day pounding and moving geophones. Then spend a few months processing the data. The goal is to get an idea of the presence or not and shape of a cave in a volume no bigger than a few hundred feet on a side. Does anyone have any comments and is this sort of project a thing that an amateur could tackle? -- Jim Hannon _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: ct@....... (Charlie & Terri Thompson -- Buda MicroRanch ) Subject: Re: Seismic Tomography Date: Wed, 26 Feb 1997 22:40:09 -0600 Jim, That's pretty much what the oil exploration business is all about. Exchange the sledge hammer for a huge hydraulic truck called a vibrator truck. The truck generates massive vibrations that are continuously swept in frequency (a chirp). Data is collected and a cross-correlation function is done between the truck's chirp and the geophone recorded data. There will be a cross-correlation peak at each time delay that represents a reflection from the earth's interior. (called correlation wavelets). To improve the signal-to-noise down to 30,000 feet averaging is used along with some filtering. A sub-surface image is formed from the correlation data and you can actually see salt domes or other oil bearing formations. Companies like Input/Output make the geophones and A/D converters. Companies like Conoco Oil pioneered the big vibrator trucks called "Vibroseis". You can check out the Input/Output web page at: web.i-o.com for more info. Happy earth thumping... Charlie Thompson Buda, Texas >This is not too related to earthquake seismology but I thought I would >ask the question anyway. > >I used to do a lot of cave exploration before I got old and too fat. >One thing that I have always thought about was building a system to try >and image a cave from the surface. The basic idea was to get a few >geophones, a computer to log data and a sledge hammer to pound the >ground. Then spend a day pounding and moving geophones. Then spend a >few months processing the data. The goal is to get an idea of the >presence or not and shape of a cave in a volume no bigger than a few >hundred feet on a side. Does anyone have any comments and is this sort >of project a thing that an amateur could tackle? >-- >Jim Hannon > > >_____________________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email listserver@............. with the body of the >message: leave PSN-L > > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: David A Nelson <dann@........> Subject: Re: Seismic Tomography Date: Thu, 27 Feb 1997 18:21:26 +1200 Charlie can you please resend the webpage listing that you had partially below..... as it gives the invalid error when http://web.i_o.com is tried TNX Dave >Companies like Input/Output make the geophones and A/D converters. >Companies like Conoco Oil pioneered the big vibrator trucks called "Vibroseis". >You can check out the Input/Output web page at: > > web.i-o.com > >for more info. > >Happy earth thumping... >Charlie Thompson >Buda, Texas > > Dave A. Nelson 24 Jensen St., Green Is., Dunedin, South Is.. New Zealand. http://psn.quake.net/dave/home.htm ( world wide access ) http:/www.es.co.nz/~dann/home.html ( New Zealand access only ) SOD'S-LAW--- When Something Does Go Wrong, There Is Sod All You Can Do About-It When The Last Of Ten Screws Has Been Removed From A Cover, -It Will Be Discovered That The Wrong Cover Has Been Removed When The Last Of Ten Screws Has Been fitted back Into A Cover, -It Will Be Discovered That The gasket Has Been Left Out _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: David Josephson <david@...............> Subject: Re: Seismic Tomography Date: Wed, 26 Feb 1997 22:07:24 -0800 (PST) On Wed, 26 Feb 1997, Jim Hannon wrote: > This is not too related to earthquake seismology but I thought I would > ask the question anyway. > > I used to do a lot of cave exploration before I got old and too fat. > One thing that I have always thought about was building a system to try > and image a cave from the surface. The basic idea was to get a few > geophones, a computer to log data and a sledge hammer to pound the > ground. Then spend a day pounding and moving geophones. Then spend a > few months processing the data. The goal is to get an idea of the > presence or not and shape of a cave in a volume no bigger than a few > hundred feet on a side. Does anyone have any comments and is this sort > of project a thing that an amateur could tackle? Call Geometrics (where I worked years ago) at 408-734-4616, talk to Rob Huggins and ask him this question; get the applications notes for shallow refraction seismic and decide for yourself. They will happily sell or rent you a multi-channel seismograph so you don't have to spend a day to map a little piece of soil. > -- > Jim Hannon > > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Robert Avakian <ravakian@............> Subject: Re: Seismic Tomography Date: Thu, 27 Feb 1997 03:29:39 -0800 David Josephson wrote: > > On Wed, 26 Feb 1997, Jim Hannon wrote: > > > This is not too related to earthquake seismology but I thought I would > > ask the question anyway. > > > > I used to do a lot of cave exploration before I got old and too fat. > > One thing that I have always thought about was building a system to try > > and image a cave from the surface. The basic idea was to get a few > > geophones, a computer to log data and a sledge hammer to pound the > > ground. Then spend a day pounding and moving geophones. Then spend a > > few months processing the data. The goal is to get an idea of the > > presence or not and shape of a cave in a volume no bigger than a few > > hundred feet on a side. Does anyone have any comments and is this sort > > of project a thing that an amateur could tackle? > > Call Geometrics (where I worked years ago) at 408-734-4616, talk to > Rob Huggins and ask him this question; get the applications notes > for shallow refraction seismic and decide for yourself. They will > happily sell or rent you a multi-channel seismograph so you don't > have to spend a day to map a little piece of soil. > > > -- > > Jim Hannon > > > > > > _____________________________________________________________________ > > > > Public Seismic Network Mailing List (PSN-L) > > > > To leave this list email listserver@............. with the body of the > > message: leave PSN-L > > > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L Depending upon the depth of the caves I would suggest the following: A) GRP Ground Penetration Radar B) Look up "Fan Shooting" in a basic geophysical text such as Dobrin's "Geophysical Prospecting" if you want to do recon work. C) Use blasting caps or larger fireworks as an energy source if you can get hold of them legally. You have to slap that plate a lot to get any energy into the ground. D) Investigate a "Betsy" which is a shotgun siesmic source. If you can give me an idea of where you want to work, I may be able to put you in touch with some folks who can help. I used to be an exploration geophysicist before the oil boom busted. Bob Avakian _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: bob@................. (Bob Hammond (USGS-AVO Geophysicist)) Subject: Re: Seismic Tomography, Caves, GPR Date: Thu, 27 Feb 1997 08:49:12 -0900 To Jim Hannon: I built several seismic energy sources for cavity detection while in graduate school. All were used with a 12-channel engineering seismograph (Geometrics ES-12F). The first one was a powder-actuated nail driver used in construction. I modified it to include a trigger circuit and a steel plate to fire into. It used .22 caliber blanks and worked quite well at shallow (20 feet) depths. I also built a 12-ga shotgun seismic source which was electrically activated (solenoid on trigger). The barrel was about 4 inches long and protruded through a 1" thick steel plate. The breech was surrounded by a 4" diameter pipe with a cap on the end. The enclosure for the breech and firing mechanism was attached to the plate with dogs for easy access. We bored a 2-foot hole into the soil with a soil auger and fired a 1-oz slug into the hole. Worked great! Probably illegal as hell. Didn't ask. This is a poor man's BETSY SEISGUN. We digitized the seismic traces, stacked them together to make a seismic section, and interpreted reflections ala the oil geophysics method. There are a few articles in Geophysics on such seismic energy sources, mostly by Don Steeples. He is famous for mounting a .50 caliber machine gun (pointed straight down) on the tailgate of his pickup and using it as a seismic source for shallow reflection work. I suggest you work with GPR for caves. Limestone is a good medium for radar. My former grad school advisor and I have been working on a cheap GPR system based on a laptop PC, waveform digitizer, resistively- loaded antennas, and mono-pulse TX. I can send info if you'd like. A commercial GPR system is about $15K minimum. Rentals are expensive. GPR data analysis can be tricky. hope this helps. Bob Hammond _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Jim Hannon <jmhannon@........> Subject: Re: Seismic Tomography Date: Thu, 27 Feb 1997 21:15:10 -0600 I want to thank every one for there responses to my question. What I have gathered from the responses is that it looks feasable but a sledge might not give enough signal to be useful. Part of the idea here was to trade sweat and time for the cost of equipment. This would include doing multiple strikes with the sledge at each position and summing the waveforms to bring the signal out of the noise. Of course if it is too far down this wouldn't work. A rough engineering calculation (SWAG) tells me that a shotgun shell is about 10 times the energy of an 8 pound sledge blow. But of course it is considerably more expensive. Maybe I could figure a way to drop a 100 pound weight from about 10 feet. -- Jim Hannon _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane <cochrane@..............> Subject: Admin Note: Please read. Date: Fri, 28 Feb 1997 02:22:39 -0700 Hi, Yesterday someone (I don't won't to pick on anyone) sent a bitmap to the list. PLEASE don't send attachments to this list, especially large files. I had to delete the message from the email servers's output queue. This email message, with the B/W bitmap around 250k, produced a 400K encoded message that was going to go out to over 230 email address. This is the equivalent of transferring ~95+ megabytes of data! I only have a 28.8K (if I am lucky, 1/2 of the time I only get 26K) modem, so it would have taken forever to get the message out to everyone. If you want to show an image to everyone, please do the following. First convert it to jpg or gif format. A Windows bitmap file has no image compression and are always very large, even black and white ones. Had the image been converted to gif (gif format is the best for black and white line drawings) the attachment would only be around 20 or 30K. There are many image conversion programs out there on the Net that will convert your bitmap image to any number of other formats. If you have your own web/ftp site place you image there and tell everyone using the PSN-L list. If you don't have access to a web/ftp site you can use mine. Using FTP, transfer your image (remember to use the binary mode) to my system at ftp://psn.quake.net. The /incoming directory is open for read and write. After transferring your file then announce it too the list. One more thing, it would help if everyone who replies to a message edit the reply and remove any unneeded text like the unsubscribe message at the bottom of each message. Also, some people have a signature file longer then there messages, it would be nice if that was also edited out. I archive each message (I go through and edit out unneeded ones) and the quarterly archive files are getting very large. This quarters file (psnl97q1) is already 330k, last quarters was 390k. As an experiment I made a change to the configuration for the PSN-L list. I set a limit of 50k for incoming messages to the PSN-L address. A 50K message is about 12megs of output data with 230 addresses. Back to earthquakes. I did not receive much from the 7.3 yesterday. Only a few surface waves came out of the background noise. Regards, Larry Cochrane Redwood City, Ca PSN _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane <cochrane@..............> Subject: Re: hello from newbie Date: Fri, 28 Feb 1997 02:41:33 -0700 Welcome Steve, At 10:15 PM 2/26/97 -0800, you wrote: >hello to all - looks like I finally got connected up on the psn list - I >live in Huntsville, AL and have had a suppressd interest in seismo for >years - after finding references to amateurs on the www, I decided to go >ahead and jump in! Thanks to Charlie Rond for encouragement. I have >very litte in the way of working hardware - I did hook up a borrowed >short-period vertical sensor and a home-made drum recorder (nothing >digital here - yet), but all I am getting is road noise from a major >city street about a 1/2 mile away, judging from the 24-hr period of the >"squiggles"...I have a good connection to "the mother of all rocks" >exposed in my basement, which probably explains the rather good >conduction to the roadbed down at the bottom of the hill...anyway, I'm >looking for advise and counsel as I stumble around in this activity... > >Steve Jones You need to build a long period device like a Lehman or the Shackleford-Gundersen sensor. I have plans for both on my web page at http://psn.quake.net/equip.html. To receive distant events you need a sensor that is more sensitive to lower frequencies. Your short-period sensor will only record local events. Good luck... Regards, Larry Cochrane Redwood City, Ca PSN _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: bzimmerman@............ Subject: Re: Pakistan 7.3 Date: Fri, 28 Feb 1997 09:34:12 -0500 (EST) Got a few surface waves on our AS1 here in Edinboro. Background was high due to a storm moving off the coast so it's not a great record. Brian S. Zimmerman Department of Geosciences Edinboro University of Pennsylvania Edinboro, PA 16444 Phone: (814) 732-2207 Email: BZimmerman@............ On Thu, 27 Feb 1997, Jeff Batten wrote: > Anyone record it ? > Jeff Batten - Research Engineer > Caltech Seismo Lab > 1200 E. California Bl. > Pasadena, Ca. > 91125 > 818-395-6965 > Fax-818-564-0715 _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: steve jones <stejones@..........> Subject: Re: hello from newbie Date: Fri, 28 Feb 1997 18:33:04 -0800 Larry Cochrane wrote: > > Welcome Steve, > > At 10:15 PM 2/26/97 -0800, you wrote: > >hello to all - looks like I finally got connected up on the psn list - I > >live in Huntsville, AL and have had a suppressd interest in seismo for > >years - after finding references to amateurs on the www, I decided to go > >ahead and jump in! Thanks to Charlie Rond for encouragement. I have > >very litte in the way of working hardware - I did hook up a borrowed > >short-period vertical sensor and a home-made drum recorder (nothing > >digital here - yet), but all I am getting is road noise from a major > >city street about a 1/2 mile away, judging from the 24-hr period of the > >"squiggles"...I have a good connection to "the mother of all rocks" > >exposed in my basement, which probably explains the rather good > >conduction to the roadbed down at the bottom of the hill...anyway, I'm > >looking for advise and counsel as I stumble around in this activity... > > > >Steve Jones > > You need to build a long period device like a Lehman or the > Shackleford-Gundersen sensor. I have plans for both on my web page at > http://psn.quake.net/equip.html. To receive distant events you need a sensor > that is more sensitive to lower frequencies. Your short-period sensor will > only record local events. > > Good luck... > > Regards, > > Larry Cochrane > Redwood City, Ca PSN > > _____________________________________________________________________ Larry - in reply to your most perceptive messages ("...why would anyone want to build a drum recorder?...) and the comments above, I am using what I have had from surplus scrap in the great basement "junk box" for years, and must admit that I am still amazed to see even short-period "squiggles" come out of the pen of my paper-hogging drum...I'm sure that, in time, I'll get over that novice fascination, and get more used to looking at event records through the filter of the "Great Microsoft"...in fact, I'm already making plans to join the "21st Century" with a digital approach to matters. Larry, you can feel gratified that your products have been recommended to me on more than one occasion during the past few days. However, I will still probably keep my "drum" in operation, both for occasional recording from the sensor, and for playback from digital, just so I can watch events as they are being (or would have been) laid down in real-time. I have not decided yet on the Lehman sensor, or the SG design (I have kept up with the evolutions of both of these, and in fact, started collecting the Scientific American seismic articles many years ago...), but the Lehman looks simpler, so I'll probably go that route...thanks for the affirmation that I need to get into the 10-20 second period range to get away from the man-made noise... The PSN-l list had better stand by for stupid questions - thanks for the replies so far... 73, Steve KT4AY _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Mike Lozano <mikel@.......> Subject: Re: Final assembly help Date: Fri, 28 Feb 1997 16:25:13 -0600 Hi everyone! I'm about THAT CLOSE to having my Lehman put together. It's made of 2 pieces of 3/4" thick, 6" wide aluminum. The horizontal section is 30" long and the vertical section stands 15" high. The two pieces are reinforced at the right angle with a third piece of 3/4" X 6" X 3" aluminum, held in place with 4 ea. 1/4"X20 stainless bolts into tapped holes in the aluminum. The boom is made out of 28" of 3/8" brass rod which has a dimple in one end. This end fits into a 1/4"X20 stainless bolt with its end ground into a needle sharp point. The weight is a 5 lbs. circle (puck) of plumber's lead. The suspension is a combination of 3" of nichrome wire, one end of which terminates in a stainless turnbuckle. The other end goes to a piece of 1/4" brass rod which I've threaded on the turnbuckle end. On the other end is another 3" piece of nichrome wire which goes to a brass screweye which is threaded into the boom piece. The magnet consists of my now imfamous dual cow magnet configuration. The coil is fastened to the boom with a brass screw into a tapped hole. My question is this: Following the old adage of measuring twice and cutting once, I'm reluctant to drill the hole for the boom bolt. I'm not sure if I imagined it or not, but I recall hearing somewhere that the bolt holding the suspension line should not be directly in line with the bolt hole for the boom. Is that true? When I looked at Larry Cochrane's GIF for the Redwood City Lehman, it SEEMED that the top hole is slightly out of line with the bottom hole, yet when I look at other designs, it's hard to tell if that's the case or not. Any and all suggestions will be appreciated. After yesterday's Pakistan 7.3, I'm eager to get Des Moines on line. I've even got a great location. The management of the TV station where I work says I can put it in the station's basement, atop the 40 foot concrete pier which cuts through the glacial morraine to dolomite bedrock. Thanks, Mikel Lozano, N0BDF -0- _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: ACole65464@....... Subject: Re: Home-made Shaker Table Date: Fri, 28 Feb 1997 23:11:17 -0500 (EST) Jim, I used the seismo calibrator of Bob Barnes to determine its sensitivity to acceleration. The shaker table was only intended to display frequency response. Allan _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: dsevold@.............. (Dean Sevold) Subject: Interfacing A/D converters to Emon Date: Thu, 27 Feb 97 23:41:45 PST I've been trying to get Ted Blank's Emon running with an exploration geophone connected to the Analog Devices AD0804 8 bit a/d converter. The hardware works fine, as I can fire off a row of 8 led's = continuously.This particular chip has 8 data outputs, a parallel output. = My I/O card has 8 bit capabilities, and is capable of input on the 8 data= lines of the printer port, which I am trying to access from Emon. Now, = there is an option of using Jan Froom's Collect routine to access the printer port , and the Collect routine is included with the Emon package, but it is listed as an .obj file, as is also Emon .obj . as wel= l as Emon .exe . Does this mean that it must be compiled before it will use = the printer port, or is the Emon .opt file all that is needed to set thi= s up? The 8 bit converter is not really sufficient for this use, it was just = the first a/d chip available with documentation, and now I have acquired three more 12 bit converters, the Maxim 186 serial output, as is described by = Radio-Sky Publishing Louisville, KY -http://www.win.net/~radiosky as well as 2 more parallel output 12 bit converters. I would appreciate any comments or suggestions about this matter as I would like to get a seismic station running ,living in a sesmically activ= e zone on the Canadian west coast, and a nice granitic whaleback just a few steps from the back door. Dean Sevold dsevold@ saltspring.com _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Barry Lotz <gbl@.......> Subject: Re: Interfacing A/D converters to Emon Date: Sat, 01 Mar 1997 08:08:48 -0800 Dean Sevold wrote: > > > My I/O card has 8 bit capabilities, and is capable of input on the 8 data > lines of the printer port, which I am trying to access from Emon. Now, > there is an option of using Jan Froom's Collect routine to access the > printer port , and the Collect routine is included with the Emon > package, but it is listed as an .obj file, as is also Emon .obj . as well as > Emon .exe . Does this mean that it must be compiled before it will use > the printer port, or is the Emon .opt file all that is needed to set this up? > > Dean Sevold > Hi Dean I am running EMON( an older version). Im not sure about Jan's routine but an .exe file is compiled. With my version you select the appropriate instrument from the end of the .opt(option file) which is in ASCII(text). the .obj files are object files which are compiled but must be linked. ie if you want to combine more than one program you would link their ..obj files with a MASM or TASM linker. Since the perspective files to link may have parameters that are passed make sure the files you want to link are compatable. Regards Barry _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Darby <darby@..........> Subject: Re: Admin Note: Please read. Date: Sat, 1 Mar 1997 11:46:08 -0800 (PST) Thanks Larry for requesting that everyone edit their reply. I too archive all msgs for the Pasadena PSN and it takes forever to edit all extraneous stuff out. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: David A Nelson <dann@........> Subject: seismologist TV stars Date: Sun, 02 Mar 1997 10:49:55 +1200 to Steve Hammond and Edward Cranswick, I just recorded you guys on video tape today, Both of you were involved with an item on seismology on the BEYOND 2000 program. I noticed that it was a repeat so not sure how long ago it first screened .... prob. within the last two years. It is great to put faces to two e-mail friends. well done ! for the others info BEYOND 2000 is an Australian produced program which looks at scientific breakthroughs and general science items from around the world. Cheers Dave Dave A. Nelson 24 Jensen St., Green Is., Dunedin, South Is.. New Zealand. http://psn.quake.net/dave/home.htm ( world wide access ) http:/www.es.co.nz/~dann/home.html ( New Zealand access only ) SOD'S-LAW--- When Something Does Go Wrong, There Is Sod All You Can Do About-It When The Last Of Ten Screws Has Been Removed From A Cover, -It Will Be Discovered That The Wrong Cover Has Been Removed When The Last Of Ten Screws Has Been fitted back Into A Cover, -It Will Be Discovered That The gasket Has Been Left Out _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: steve jones <stejones@..........> Subject: Re: hello from newbie Date: Sat, 01 Mar 1997 16:50:10 -0800 Lucas Haag wrote: > > How did you make the drum recorder. I've been sort of looking for plans. > Thanks, > > Lucas Haag > > At 10:15 PM 2/26/97 -0800, you wrote: > >hello to all - looks like I finally got connected up on the psn list - I > >live in Huntsville, AL and have had a suppressd interest in seismo for > >years - after finding references to amateurs on the www, I decided to go > >ahead and jump in! Thanks to Charlie Rond for encouragement. I have > >very litte in the way of working hardware - I did hook up a borrowed > >short-period vertical sensor and a home-made drum recorder (nothing > >digital here - yet), but all I am getting is road noise from a major > >city street about a 1/2 mile away, judging from the 24-hr period of the > >"squiggles"...I have a good connection to "the mother of all rocks" > >exposed in my basement, which probably explains the rather good > >conduction to the roadbed down at the bottom of the hill...anyway, I'm > >looking for advise and counsel as I stumble around in this activity... > > > >Steve Jones > > > >_____________________________________________________________________ > > > > > ************************************************* > Lucas Haag, Assistant Field Agent > Nebraska Oil & Gas Commission > HCR 66 Box 25A > Bartley, Nebraska 69020-9717 > lhaag@.............. > http://www.swnebr.net/~lhaag > > "Through da keyboard, into the chips, over the copper, > through the fiber, back through the copper into the chips, > to the screen... NOTHING BUT NET!" > ************************************************* > > _____________________________________________________________________ hi lucas - that drum recorder i mentioned was a "recompilation" of a OLD junker recorder - the drum and drive itself were in good shape - so I added some home-brew electronics to drive the pen - i need to build a decent horizontal sensor, and then later i'll get some digital data acquisition gear and start collecting bits & bytes as well ... i want to be able to get both horizontal axes recorded in the near term, and then maybe later on add a long-period vertical sensor (but that looks like a harder nut to crack than the horizontal units - go you - or anyone - have any neat plans for a EASY TO BUILD vertical sensor???) thanks for the reply! 73, Steve KT4AY _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Steve Hammond <shammond@..........> Subject: Re: Final assembly help Date: Sat, 1 Mar 1997 15:01:39 -0800 (PST) Hi Mike-- can't wait to see how the two cow magnets work out. Keep us posted Let's see if I can offer a few answers-- On Fri, 28 Feb 1997, Mike Lozano wrote: > pieces of 3/4" thick, 6" wide aluminum. The horizontal section is 30" > long and the vertical section stands 15" high. The two pieces are > reinforced at the right angle with a third piece of 3/4" X 6" X 3" This sounds OK-- you don't want any flex at this joint.> > The boom is made out of 28" of 3/8" brass rod which has a dimple in one > end. This end fits into a 1/4"X20 stainless bolt with its end ground > into a needle sharp point. The weight is a 5 lbs. circle (puck) of > plumber's lead. I have a concern about the 3/8 brass rod and 5 lbs. of lead. I think the rod will flex and will induce vertical single into the data if there is a near focus earthquake. I used 3/8 brass rod on the original Falon Station FX1 seismograph and while it existed for two years, I can show you lots of examples of vertical tweaking when an event was large enough. Try hanging the rod in a vise and tape the lead to the other end looking for flex in the rod. If there is any at all, I would suggest you go to a larger size if you live in an area where earthquakes are felt. I played with this for some time and this is what I came up with. My FSZ units uses 3/4" x 3/4" x 36" sq. aluminum rod. The end of the boom, where the brass damping flag is mounted on an L bracket, is 37.25" from the pivit point because I scew a 1.25" stud with a point ground on it into the end of the 36" sq. rod. At the 31.25" point I have centered and bolted a 12" cross bar to form a cross shape. I made a short Y shaped bridle and connect two ends of it to the crossbar. The upper guide wire is connected to third bridle via a loop in the bridle and hook in the end of the turn buckle. This allows for easy removal of the boom when I need to work on it. The crossbar keeps the boom extremely stable and avoids unwanted twisting due any off center of balance created once the coil magnet, or damping flag is mounted to it. The lead weight is mounted at the 20.25" point. I also used 5 lbs. of lead but cast it to be 1" thick and cut a 3/4 x 3/4' hole in the center. This allowed it to be simply slipped onto the boom and butted to the crossbar. I'll just add a caution here about lead poisoning from the fumes when lead is melted. Don't breath them because they can do long lasting damage to brain cells. They also case your finger nails to turn blue. > My question is this: Following the old adage of measuring twice and > cutting once, I'm reluctant to drill the hole for the boom bolt. I'm > not sure if I imagined it or not, but I recall hearing somewhere that > the bolt holding the suspension line should not be directly in line with > the bolt hole for the boom. Is that true? NO-- IT IS NOT TRUE. This is the point that governs the centering of the boom. You want it to be AS TRUE AS YOU CAN MAKE IT so when you level the base you also maintain the center resting point of the boom. I'll add a point here. I think you have already considered it but I'll mention it anyway. You should also think about how you will bolt the unit to the ground. I use a three point triangle bolt pattern. I can then tilt the base in three directions to effect the vertical alignment of the two holes mentioned above. To improve adjustment and the ability to create a fractional alignment adjustment, I also added two 10x32 machine screw at each rear corner of the base plate that bottom out on two small aluminum blocks placed on the cement under the plate. I level the base plate using the three large anchor bolts set into the cement and then use the two machine screws to maintain the booms vertical alignment as the ground under the site changes slope. > > Any and all suggestions will be appreciated. After yesterday's Pakistan > 7.3, I'm eager to get Des Moines on line. Humm.. Remember that the earth's inner and outer core bends the path of seismic waves and horizontal seismographs will not record the P waves from India and Pakistan if you are in California, but will record the later arrivals of some S phases and LQ and LR waves. A good explanation for this can be found in any of Bruce Bolt's books on seismology under the discussion of seismic rays through the earth's core. Regards, Steve Hammond _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Steve Hammond <shammond@..........> Subject: Re: seismologist TV stars Date: Sat, 1 Mar 1997 15:09:35 -0800 (PST) Hi Dave, That--- that was the first year we started the PSN in 1990. The house in the tape is mine in San Jose. It was a lot of fun. The Beyond 2K crew spent the day. I don't think my guarge will ever be that clean again. The data they were showing was from the old FX1 seismograph. Watch it again and you will understand why I never went into acting... Regards, Steve On Sun, 2 Mar 1997, David A Nelson wrote: > to Steve Hammond and Edward Cranswick, > > I just recorded you guys on video tape today, Both of you were involved > with an item on seismology on the BEYOND 2000 program. > > for the others info BEYOND 2000 is an Australian produced program which > looks at scientific breakthroughs and general science items from around the > world. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: David A Nelson <dann@........> Subject: PSN Map update Date: Sun, 02 Mar 1997 12:55:27 +1200 Hi all, Our first amateur seism. from the "Land of the Kangaroo" is now on the map, we welcome Albert (Alby) Judge, from the city of Perth in Western Australia, to the net on other matters..... I have changed the title of my home pages to "New Zealand Public Seismic Net" as this will make it much easier to find when using web search engines I was originally listed as Daves World and Ii discovered that there were dozens of similar named pages making searches difficult. the heading on the page is still Dave's World with info on: but the quakes link name has also been changed. Cheers Dave Dave A. Nelson 24 Jensen St., Green Is., Dunedin, South Is.. New Zealand. http://psn.quake.net/dave/home.htm ( world wide access ) http:/www.es.co.nz/~dann/home.html ( New Zealand access only ) SOD'S-LAW--- When Something Does Go Wrong, There Is Sod All You Can Do About-It When The Last Of Ten Screws Has Been Removed From A Cover, -It Will Be Discovered That The Wrong Cover Has Been Removed When The Last Of Ten Screws Has Been fitted back Into A Cover, -It Will Be Discovered That The gasket Has Been Left Out _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Steve Hammond <shammond@..........> Subject: Re: Interfacing A/D converters to Emon Date: Sat, 1 Mar 1997 17:38:24 -0800 (PST) Dean, Ted is part of the group but may not be reading mail these days... Jan's routine is used to access the parallel port and input 8 data bits at a time. I think Ted has it linked into EMON, but it will only work on very specific hardware. Look at the assembler code and see if the control lines select the control lines used on your A/D card. The I/O address must also be exact. Jan's home brew interface for parallel port required the IBM printer card be modified to allow input. This required a gate pin on the 373 chip have its tiedown on pin 1 cut and yellow wired to -select. As you can see, you just can't plug in any parallel card and have this work. We have never been able to get the AT class parallel card to work for instance. You must also make sure that the correct I/O address is compiled into the assembler code; X278, 378, or 3BC depending on your card. Lets just talk about how you might start from scratch, kuz that's more likely to work. You'll need a PC assembler to creat the OBJ code and PC link programs to link them together. I'll run through the step to create a data collection EXE entitled 521EMON.EXE. First take the assembler code below and change it to drive your interface. ;******************************************************************* page 60,132 title PCOLLECT: Seismic Data Collection Routine subttl Falon Data Collection Facility ;*********************************************************************** ;* COLLECT * ;* DATA COLLECTION SUBROUTINES * ;* * ;* Name Steve Hammond ;* Location San Jose, California 95123 * ;* Date August 13, 1991 * ;* * ;* Written for Jan Froom / Steve Hammond ;* * ;* COLLECT Selects the port requested and reads * ;* two bytes of data (actually 12 bits). * ;* * ;* Usage CALL Collect(Port%,Count%,Data%(0),Flag%) * ;* * ;* Port% 0 Ground * ;* 1 Seismic #1 * ;* 2 Seismic #2 * ;* 3 Seismic #3 * ;* 4 Seismic #4 * ;* 5 Seismic #5 * ;* 6 Seismic #6 * ;* 7 Seismic #7 * ;* * ;* Count% Number of reads (make sure Data%(array)) * ;* is large enough to hold data. * ;* * ;* Data%(0) Address of array where data is to * ;* saved * ;* * ;* Flag% Completion Code: * ;* x'0000 if all OK * ;* x'FFFE CONVERT COMPLETE alway active * ;* x'FFFF No CONVERT COMPLETE in time allocated * ;* * ;* Change History: * ;* * ;* * ;* * ;*********************************************************************** page ;A ;********************* Routine Over Head ******************************************** ; ; AUTO CALIBRATION is done on return to SDAS program ; to reduce execution time overhead. First read MAY contain invalid data. ; ; STATUS BITS ; 0 = +EOC End of conversion ; 1 through 7 = unused ;******************************************************************************* BASE_ADDR equ 0304h ; Base Address SELECT_ADDR equ BASE_ADDR ; Start conversion Address CONVERT_ADDR equ BASE_ADDR + 1 ; Transfer command Address READL_ADDR equ BASE_ADDR + 4 ; Address of Low Data READH_ADDR equ BASE_ADDR + 5 ; Address of High Data STATUS_ADDR equ BASE_ADDR + 6 ; Address of Status latch CAL_ADDR equ BASE_ADDR + 7 ; Address of Auto calibration code segment para public 'code' COLLECT proc far assume cs:code public COLLECT push bp mov bp,sp mov bx,[bp+10] ; Collection Count mov cx,es:[bx] mov di,[bp+8] ; Array Address mov bx,[bp+12] ; Port address mov ax,es:[bx] mov bx,ax ; Save Port Address page ;B ;********************* Select Port and Issue Convert ******************************** push cx ; Save Loop Count mov dx,SELECT_ADDR ; Start conversion mov al,0 ; null the data (unused) out dx,al ; Send write to ADC chip Address: mov dx,STATUS_ADDR ; Wait for +EOC mov cx,256 ; Set escape counter Wait1: in al,dx ; Read convert status test al,01h ; Test "Convert Complete" Bit je Trans ; Go to Stat if NO Convert Complete loop Wait1 ; Otherwise, try again. pop ax ; dummy pop to restore stack mov ax,0FFFFh ; Indicate "CONVERT NOT COMPLETE" jmp end ; always active. Trans: mov dx,CONVERT_ADDR ; Set Convert Address mov al,0 ; Null data out dx,al ; Transfer ADC data to latches ;********************* Wait for Convert Complete and Read Data ********************** mov dx,SELECT_ADDR ; Start next conversion mov al,0 ; null the data (unused) out dx,al ; Send write to ADC chip mov dx,READH_ADDR ; Set read high address in al,dx ; get the high data mov ah,al ; Save High Order Bits mov dx,READL_ADDR ; Set Address of Low Order Bits in al,dx ; Read Low Order Bits mov es:[di],ax ; Save data add di,2 ; Bump transfer storage pointers pop cx ; Get transfer count. Drecement loop Address ; COUNT% and loop until COUNT% ; equals zero. mov ax,0 ; Indicate Transfer completed OK page ;C ;******************** RETURN TO CALLING ROUTINE ************************************* END: mov dx,CAL_ADDR ; Start calibrate address mov al,0 ; null the data (unused) out dx,al ; Start a calibration cycle ; then exit mov bx,[bp+6] ; get flag address mov es:[bx],ax ; Return END code pop bp ; Restore BP ret 8 ; Return to calling routine COLLECT endp code ends end This was Jan's original code before I modified to drive a 12-bit ADC National 1241 and an interface that I designed. Because the PC has an 8-bit bus, the data has to be gated in to acquire the two bytes. This ADC also has auto calibration, so I bumped it to make it recalibrate between A/D conversions. So now that you created the code to drive your card you then assemble it into xxx.OBJ. I assembled the code above into SDAS531.OBJ. Next step is to link the OBJ code. LINK EMON.OBJ+SDAS521.OBJ 521EMON.EXE (At least that was the JCL for the linker I used) Note: On the BBS'es in San Jose 408-226-0675, Tennessee, and Pasadena, you will find two zip files in the SDAS code section. One is the SDASLPTx.zip and the other is the SDASASM.ZIP. Before Ted created EMON, he created SDAS. I think it was on the sixth day. He rested on the seventh. If you get into this and find out EMON is giving problems with your interface, come back and try linking with the the OBJ files in the older SDASASM.ZIP. I know they all work, because I have used them for years. LINK SDAS313+DAS4+STOD+SDAS521 MYSDAS.EXE The last thing you need to do is setup the EMON.OPT file or the SDAS.OPT file for Jan's routine. Put the correct code to indicate to EMON to interface to Jan's routine, set the base address to be 0, 1, or the the printer port address X278, 378, or 3BC. It should work after that. Regards, Steve <<<Snip snip below >>> On Thu, 27 Feb 1997, Dean Sevold wrote: > I've been trying to get Ted Blank's Emon running with an exploration > geophone connected to the Analog Devices AD0804 8 bit a/d > converter. The hardware works fine, as I can fire off a row of 8 led's > lines of the printer port, which I am trying to access from Emon. Now, > there is an option of using Jan Froom's Collect routine to access the > printer port , and the Collect routine is included with the Emon > package, but it is listed as an .obj file, as is also Emon .obj . as well as > Emon .exe . Does this mean that it must be compiled before it will use > the printer port, or is the Emon .opt file all that is needed to set this up? _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Ken Navarre <kjn@..........> Subject: Re: hello from newbie Date: Sat, 1 Mar 1997 19:57:39 -0800 (PST) On Fri, 28 Feb 1997, Larry Cochrane wrote: > Why in the world would anyone want to build a drum recorder? We are going > into the 21 century... Just the paper and all of the hassles can pay for a > computer system real fast. yeah but you miss that great meditative hummmm as the drum grinds along whe you use a computer... You just gotta have a drum recorder to maintain that "Zen" quality so indicative of "real seismology". Ambiance, doncha know... :) Ken _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Lucas Haag <lhaag@..............> Subject: Re: hello from newbie Date: Sat, 1 Mar 97 22:08:26 CST I am building a sensor right now that is simple to build. I could copy off the schamatics and mail them to you or if you are in a hurry They are in a book you can get at a local Radio Shack store. Its a good idea to know how to wire wrap before you build this It is VERY HARD to solder because it involves microchips.. At 04:50 PM 3/1/97 -0800, you wrote: >Lucas Haag wrote: >> >> How did you make the drum recorder. I've been sort of looking for plans. >> Thanks, >> >> Lucas Haag >> >> At 10:15 PM 2/26/97 -0800, you wrote: >> >hello to all - looks like I finally got connected up on the psn list - I >> >live in Huntsville, AL and have had a suppressd interest in seismo for >> >years - after finding references to amateurs on the www, I decided to go >> >ahead and jump in! Thanks to Charlie Rond for encouragement. I have >> >very litte in the way of working hardware - I did hook up a borrowed >> >short-period vertical sensor and a home-made drum recorder (nothing >> >digital here - yet), but all I am getting is road noise from a major >> >city street about a 1/2 mile away, judging from the 24-hr period of the >> >"squiggles"...I have a good connection to "the mother of all rocks" >> >exposed in my basement, which probably explains the rather good >> >conduction to the roadbed down at the bottom of the hill...anyway, I'm >> >looking for advise and counsel as I stumble around in this activity... >> > >> >Steve Jones >> > >> >_____________________________________________________________________ >> > >> > >> ************************************************* >> Lucas Haag, Assistant Field Agent >> Nebraska Oil & Gas Commission >> HCR 66 Box 25A >> Bartley, Nebraska 69020-9717 >> lhaag@.............. >> http://www.swnebr.net/~lhaag >> >> "Through da keyboard, into the chips, over the copper, >> through the fiber, back through the copper into the chips, >> to the screen... NOTHING BUT NET!" >> ************************************************* >> >> _____________________________________________________________________ > >hi lucas - that drum recorder i mentioned was a "recompilation" of a OLD >junker recorder - the drum and drive itself were in good shape - so I >added some home-brew electronics to drive the pen - i need to build a >decent horizontal sensor, and then later i'll get some digital data >acquisition gear and start collecting bits & bytes as well ... i want to >be able to get both horizontal axes recorded in the near term, and then >maybe later on add a long-period vertical sensor (but that looks like a >harder nut to crack than the horizontal units - go you - or anyone - >have any neat plans for a EASY TO BUILD vertical sensor???) > >thanks for the reply! > >73, Steve KT4AY > >_____________________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email listserver@............. with the body of the >message: leave PSN-L > > ************************************************* Lucas Haag, Assistant Field Agent Nebraska Oil & Gas Commission HCR 66 Box 25A Bartley, Nebraska 69020-9717 lhaag@.............. http://www.swnebr.net/~lhaag "Through da keyboard, into the chips, over the copper, through the fiber, back through the copper into the chips, to the screen... NOTHING BUT NET!" ************************************************* _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Steve Hammond <shammond@..........> Subject: Re: Seismic Tomography Date: Sat, 1 Mar 1997 23:48:53 -0800 (PST) Jim, I have a 1976 copy of California Geology with the title of Shear Wave Velocity propagation and measurement by Jay Power, Geologist and Charles R.Real, Seismologist. On the front page it shows a picture of a pickup truck with the two front wheels on top of a 4-inch x 12-inch x 10-feet board. Then there is a guy with a "BIG" wooden sledge giving the end of the board a wack. The wave date supplied in the report shows a real nice P and S wave. They had 12 geophones on a line 225 feet long from the source and were able to show the offset of arrival at each sensor in a scale of 0.0 to 0.2 seconds for P and 0.0 to 0.3 for the S wave. (I just noticed, they also had one of the geophone set into a hole drilled into the board) Their conclusion was: The horizontal traction ( this must be geology/seismology talk for tire on board) method has greatly facilitated the measurment of shear wave velocity in subsurface rock and soil formations. The technique has been successfully used in a variety of geologic settings. You might try the horizontal tracktion method. I could probably make a GIF out of the picture and email it to you. Regards, Steve Hammond PSN BBS San Jose 408-226-0675 On Thu, 27 Feb 1997, Jim Hannon wrote: > far down this wouldn't work. A rough engineering calculation (SWAG) > tells me that a shotgun shell is about 10 times the energy of an 8 pound > sledge blow. But of course it is considerably more expensive. Maybe I > could figure a way to drop a 100 pound weight from about 10 feet. > -- > Jim Hannon _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: David Josephson <david@...............> Subject: Re: Seismic Tomography Date: Sun, 2 Mar 1997 02:32:00 -0800 (PST) Just another plug to go bother Geometrics in Sunnyvale for info on shear wave stuff, ask for Doug Crice's book on shear wave surveys (including all the data on parking a pickup on a 4x12 and whacking the board). A 100 pound weight in a 10 ft tube is also well known (they called it a Dynasource). They have a whole collection of manuals and papers they will give you if there's any chance you might buy one of their seismographs in the years to come. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Karl Cunningham <karlc@.........> Subject: Re: hello from newbie Date: Sun, 02 Mar 1997 08:53:17 -0800 At 07:57 PM 3/1/97 -0800, Ken Navarre wrote: >yeah but you miss that great meditative hummmm as the drum grinds along >whe you use a computer... > >You just gotta have a drum recorder to maintain that "Zen" quality so >indicative of "real seismology". Ambiance, doncha know... :) Not to mention the soothing click click once per minute for the time marker. It gives a person a sense of peace. Karl Cunningham La Mesa, CA. karlc@......... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Kees Verbeek <kverb@........> Subject: drum-recorder Date: Sun, 2 Mar 1997 20:09:57 +0100 (MET) Hello seismo-fanatics Without trying to set on a discussion , i had to react to the remark from Larry "Why in the world would anyone want to build a drum-recorder..... 21 century... hassles.... computer-systym....etc.etc.. Here there is another (drum-recorder) fool ,Just like Ken Nevarre told, its great to look and listening to the turning drum. Maybe i should make a copy of that sound ,together with scratching and scraping sound of the pen and send it to the members, so they can play this "music" while working on theire computer. Also the a4 computer-print is nothing to compare whit the long drum (smoked) seismogram. "ambiance, doncha know" many greetings, Kees Verbeek, Netherlands kverb@........ _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: steve jones <stejones@..........> Subject: Drum Wars Date: Sun, 02 Mar 1997 14:28:59 -0800 With apologies to the list...honest, I really didn't mean to "poke the nest" when I mentioned using a drum recorder a week ago. I AM a real 21st Century bit-junkie, and truly believe in the power of digital hardware (although I must confess that I think all of this software stuff is just a passing fad!)...Sure is neat, though, to watch that pen wander around as it tracks movement in what we suppose to be the solid earth (uh-oh - there I go again with my novice mentality!) Having said that, does anyone know of a quick/dirty way to cause a 386/486 machine to spin up a hard drive to start logging event data samples, upon a trigger from the A/D input card (SDR or otherwise)? I want to set up a data logger that will be "mostly idle" until something interesting comes along to record...maybe the pre-trigger data could be stored in RAM until the HD was up and running, and then the pre-trigger stuff and following event file could be pushed off to the HD as it came in...any suggestions? 73, Steve KT4AY _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Steve Hammond <shammond@..........> Subject: Re: drum-recorder Date: Sun, 2 Mar 1997 12:20:43 -0800 (PST) On Sun, 2 Mar 1997, Kees Verbeek wrote: <<Snip snip>> Kees, yours may be cool but mine has a history. I'm told mine was once installed at Berkeley Seismic Station before they got rid of it. Mine was original designed for film. I had to talk a friend of Old Harold's from Sebastopol into giving me "one" of the galvanometers he had in his junk box to make a pen drive for it. Old Harold, in fact, showed me how they built pens from a hypodermic needles and bits of copper plate back in the old days. I changed the drive motor to 2 RPD and let it run in the background. It doesn't have a time tick so I just mark the start time and count the ink bands. "ambiance, doncha know" Sit back and give the propeller on your cap a spin. Steve Hammond PSN BBS San Jose, California 408-226-0675 _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane <cochrane@..............> Subject: Re: Final assembly help Date: Sun, 02 Mar 1997 12:52:52 -0700 At 04:25 PM 2/28/97 -0600, Mikel Lozano wrote: >My question is this: Following the old adage of measuring twice and >cutting once, I'm reluctant to drill the hole for the boom bolt. I'm >not sure if I imagined it or not, but I recall hearing somewhere that >the bolt holding the suspension line should not be directly in line with >the bolt hole for the boom. Is that true? When I looked at Larry >Cochrane's GIF for the Redwood City Lehman, it SEEMED that the top hole >is slightly out of line with the bottom hole, yet when I look at other >designs, it's hard to tell if that's the case or not. > I think Steve H. covered this but heres some more info. The bottom and top pivot points need to be as straight as possible in the up/down direction as view from the front or back of the system. The offset, to get the boom to have a natural swing, is in the position of the top pivot point in relationship to the bottom one. If you look at your sensor from the side, the top pivot point sticks out a little more then the bottom one. As you bring the top pivot closer to the same point as the bottom one your get a longer and longer period until it goes out to infinity. This happens when you have the two pivot points straight up and down, or no offset between the two. It sound like from you sensor description that you are using a single point at the bottom instead of a knife-edge. I tried this a long time ago and hand all types of problems. Since the Lehman is a horizontal sensor you really need the knife-edge (or something like it) to stop any vertical motion of the boom. The knife-edge helps keep the boom from moving in all directions. You only want the boom to be free to move in the horizontal directions. Just my .02 cents... Regards, Larry Cochrane Redwood City, PSN >Thanks, Mikel Lozano, N0BDF _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Robert W. Teller" <mrlabs@..........> Subject: Quake Watch Update Date: Sun, 2 Mar 1997 14:00:34 -0700 Hello All, Just a note to let everyone know what the status of the A/D board/Win 3.x software is developing. The A/D board is completed and has been functioning 24 hrs/day for the past 3 weeks. It is still in the breadboard state but nothing special would be required in the construction. The A/D is 12 bit 8 channel capable. The software being developed is 16 bit. We choose 16 bit development because we feel most seismic monitoring would be done on older machines. The design goal is to make the software functional with 386 class machines running Windows 3.1 or greater. At this point the software is running on a 386 @ 40Mhz with 8Meg RAM running WFW 3.11. This system IS networked into the LAN. The only problems we have encountered is the limited runtime environment of the 386 class machines. In order to work around this limitation, we have reduced the number of channels from 8 to 4 and reduced sample rate to 50 samples/second. It produces WinQuake compatible event files. What we would like to do is ask you to provide us with a list of things you would like the software to include. Quake Watch: System Requirements: 386DX @ 33 MHz or higher. ( will work with slower machines! ) 4 Meg RAM Large HD (Data Files = 8.5 Meg/day/channel) Serial Port capable of 19200 baud. ( 16550 recommended ) VGA or better graphics monitor and video card Windows 3.1, Windows for Workgroups 3.11, Win95 or higher ( 16 bit program ) A/D Card: 12 Bit 4 Channel 50 samples/second -2.5 to 2.5 input. (Inputs are adjustable) Microprocessor controlled Compatible with Larry's Filter Board Powered by serial port Connects to serial port (works with laptops!) Software Features: View 1 to 3 channels simultaneously Individual channel color. Auto saving of events to user selected directory Auto saving of incoming data (8.5 Meg/day/channel) WinQuake compatible Event files Completely muti-tasking enabled The schematics and software will be made available FREE. There will be a small charge for the pre-programmed microprocessor needed for the A/D card. We will make available complete kits or built systems. We will trade a complete system for a circuit board layout design for the kit. E-mail us for more information. We might consider putting the software up on our homepage if there is enough interest. Thank you, Bob Teller ------------------------------------------------ Montana Research Labs P.O. Box 977 Townsend, MT 59644 U.S.A. Tel 406-266-4483 email mrlabs@.......... web http://www.commerce-center.com/mrlabs _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane <cochrane@..............> Subject: Re: hello from newbie Date: Sun, 02 Mar 1997 14:10:03 -0700 At 06:33 PM 2/28/97 -0800, steve jones wrote: > >I have not decided yet on the Lehman sensor, or the SG design (I have >kept up with the evolutions of both of these, and in fact, started >collecting the Scientific American seismic articles many years ago...), >but the Lehman looks simpler, so I'll probably go that route...thanks >for the affirmation that I need to get into the 10-20 second period >range to get away from the man-made noise... I think the SG sensor is a little bit easier to build and maintain. It has a smaller foot print so its easier to make a box that has good thermal control. It does not have the problem of the "wondering boom" that happens with the Lehman when the floor tilts a little. I have to check almost daily my Lehman to see if the boom is in the right position. I try and keep the outer edge of the coil at the outer edge of the horse-shoe magnet. If the boom changes position, do to rain changing the tilt of the concrete slab, it either moves away from the stationary coil or moves to loss eventually hitting the inside of the magnet. This moving around causes the sensitivity to change and screws up the magnitude calculation. The SG sensor, do to its short period vertical pendulum, is inherently more stable (IMHO). The tilt of the floor does show up on the SG sensor but this is only a DC offset that is blocked by the high-pass filter. Don't get me wrong, I'm not knocking the Lehman design (well, not too much). As you all know I have one and it works just fine. Its just that I think the SG sensor design as some advantages over the Lehman. I think one of the reasons that people go for the Lehman over the SG sensor is the extra electronics need to make it work. To help out I am in the process of making another PC board for the SG sensor electronics. I have finished the final design and my dear dear brother has agreed to layout one more board for me. He laid out my other boards (A/D card, Amp/Filter and telemetry demodulator boards) and has done an excellent job. I hope to have the PC board ready in 3 to 4 weeks. I will be selling other components of the sensor like a pre-wound damping coil and the transmitter/receiver plates. The receiver plates will be pre-tuned to the 4.0 Mhz oscillator I use on the pendulum. I hope to have a complete kit or event an assembled version someday. This will give me a complete product line from sensor to event viewing software. As I get closer to a SG electronics board I will be announcing the availability. I will also setup a Web page with a block diagram of the different parts/functions of the board. Regards, Larry Cochrane Redwood City, PSN _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: ct@....... (Charlie & Terri Thompson -- Buda MicroRanch ) Subject: Re: Final assembly help Date: Sun, 02 Mar 1997 16:51:25 -0600 Larry Cochrane wrote: >It sound like from you sensor description that you are using a single point >at the bottom instead of a knife-edge. I tried this a long time ago and hand >all types of problems. Since the Lehman is a horizontal sensor you really >need the knife-edge (or something like it) to stop any vertical motion of >the boom. The knife-edge helps keep the boom from moving in all directions. >You only want the boom to be free to move in the horizontal directions. Just >my .02 cents... > I use a single point at the bottom not a knife edge. Things are quiet around here and I don't seem to have too much problem with the point instead of the knife edge...the Lehman design is forgiving if you keep the air currents away and gain cranked up. The main thing is to TURN IT ON AND START RECORDING! Tweaks can follow...that's the fun of it all. Tweak tweak. -Charlie Thompson _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: George Bush <gbush@.......> Subject: Re: hello from newbie Date: Sun, 02 Mar 1997 15:48:22 -0800 At 07:57 PM 3/1/97 -0800, you wrote: > >On Fri, 28 Feb 1997, Larry Cochrane wrote: > >> Why in the world would anyone want to build a drum recorder? We are going >> into the 21 century... Just the paper and all of the hassles can pay for a >> computer system real fast. > >yeah but you miss that great meditative hummmm as the drum grinds along >whe you use a computer... > >You just gotta have a drum recorder to maintain that "Zen" quality so >indicative of "real seismology". Ambiance, doncha know... :) > I have been lurking, but had to come out of the woodwork and put in my $.002 worth. I don't think that the drum/computer is an either/or decision. I have both and use the drum to see what I have 'caught' and as a backup if the comput _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: George Bush <gbush@.......> Subject: Re: hello from newbie Date: Sun, 02 Mar 1997 15:48:23 -0800 At 07:57 PM 3/1/97 -0800, you wrote: > >On Fri, 28 Feb 1997, Larry Cochrane wrote: > >> Why in the world would anyone want to build a drum recorder? We are going >> into the 21 century... Just the paper and all of the hassles can pay for a >> computer system real fast. > >yeah but you miss that great meditative hummmm as the drum grinds along >whe you use a computer... > >You just gotta have a drum recorder to maintain that "Zen" quality so >indicative of "real seismology". Ambiance, doncha know... :) > Hey, this isn't an either/or issue. I have both a drum and an old XT running EMON and I think they compliment each other. The drum is what I first show people who want to see my seismic system (nobody wants to see a computer that is running with the monitor turned-off), and then I show them WINQUAKE on my 486 for analysis of past quakes. I mainly use the drum to see if something has happened, and should I turn on my monitor and see what EMON has caught, or not. I also like the warm-fuzzy feelings of having a drum as a safety net, so if the computer hatches, I still have something on the drum record. George Bush, Sea Ranch, CA _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Ken Navarre <kjn@..........> Subject: Re: drum-recorder Date: Sun, 2 Mar 1997 18:24:53 -0800 (PST) On Sun, 2 Mar 1997, Kees Verbeek wrote: [snip] > Here there is another (drum-recorder) fool ,Just like Ken Nevarre told, its > great to look and listening to the turning drum. > Maybe i should make a copy of that sound ,together with scratching and > scraping sound of the pen and send it to the members, so they can play this > "music" while working on theire computer. Larry and I would have to sometimes take a wander down to the seismology bldg. at USGS in Menlo Park to reset the USGS/PSN BBS. Whenever my girlfriend would accompany me she would drag one of the chairs in front of their bank of 18 - 20 drum recorders and, zonk..., she'd be "gone"! I'd nearly have to BLAST her outta there! Sometimes she'd actually sit there for hours. I'd be done with whatever I had to do and she would be just as happy to be left alone there with a book and the whirring and clicks... The whirring of the hard disk as it seeks and writes just isn't quite the same! :) We ought to be able to make one of those synthetic white sound generators produce the sound of a drum recorder for us seismo junkies... Ken _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Ken Navarre <kjn@..........> Subject: Re: Quake Watch Update Date: Sun, 2 Mar 1997 19:03:19 -0800 (PST) On Sun, 2 Mar 1997, Robert W. Teller wrote: [snip] > What we would like to do is ask you to provide us with a list of things you > would like the software to include. 1) User selectable audible alarms that announce once a trigger occurs. 2) User selects the number of lines of display and the gap between lines automatically adjusts. 3) User sets the colors for background, foreground, data trace, and text. 4) LArry's display of both local and UTC is a nice feature that I find useful. 5) One feature that I have included in the DOS software that runs the LPT ANALOG A/D convertor/plug for the parallel port is a calculation that displays the duration of time before the screen redraws. 6) Number of files saved since the program was started. 7) Ability to read the data from file and redisplay a specific time interval. So we can "replay" an event. 8) User selects the x and y scales. 9) Programmable features read from a *.ini or *.dat file so that the program can execute and enter the data logging mode without human intervention. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Ken Navarre <kjn@..........> Subject: Re: hello from newbie Date: Sun, 2 Mar 1997 19:09:34 -0800 (PST) On Sun, 2 Mar 1997, Larry Cochrane wrote: [snip] > I hope to have a complete kit or event an assembled > version someday. This will give me a complete product line from sensor to > event viewing software. Larry, I keep telling you that it's only a matter of time til "The Seismo Shoppee" opens it's doors! :) Put me down for one of the SG xmitter/rcvr kits... I'm working on the mechanical layout now... :( Ken _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Steve Hammond <shammond@..........> Subject: Re: drum-recorder Date: Sun, 2 Mar 1997 19:10:04 -0800 (PST) Hey Ken, I was thinking. Maybe us guys' with drum recorders could get a D put on top of the yellow spot on Dave's world PSN location map. All this talk about drum recorders-- I had to fix the pen in mine this afternoon. The ink tip got pluged. Regards, Steve On Sun, 2 Mar 1997, Ken Navarre wrote: > On Sun, 2 Mar 1997, Kees Verbeek wrote: > [snip] > > Here there is another (drum-recorder) fool ,Just like Ken Nevarre told, its _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Barry Lotz <gbl@.......> Subject: Re: Final assembly help Date: Sun, 02 Mar 1997 19:20:45 -0800 Charlie & Terri Thompson -- Buda MicroRanch wrote: > > I use a single point at the bottom not a knife edge. Things are quiet > around here and I don't seem to have too much problem with the point > instead of the knife edge...the Lehman design is forgiving if you > keep the air currents away and gain cranked up. The main thing is > to TURN IT ON AND START RECORDING! Tweaks can follow...that's the > fun of it all. > > Tweak tweak. > To all I agree. You need to begin and then enjoy the rest of the time tweaking. Understanding the whole process and finding ways to improve upon it is my real enjoyment. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Barry Lotz <gbl@.......> Subject: Re: drum-recorder Date: Sun, 02 Mar 1997 21:10:37 -0800 Steve Hammond wrote: > > Hey Ken, I was thinking. Maybe us guys' with drum recorders could get a D > put on top of the yellow spot on Dave's world PSN location map. All this > talk about drum recorders-- I had to fix the pen in mine this afternoon. > The ink tip got pluged. > > Regards, Steve > Hi Steve- $0.02 : That's is one of the reasons I gave up the drum several years ago. The others included getting cross-eyed trying to determine the time of an event, and not being able to do much with the event once you recorded it (filtering etc). I don't know to much about your monitoring routine Larry but I have problems with triggering routines and reviewing several recorded "events" to weed out the false triggers. How about this: You have a "drum on the screen". Have the computer display time lines horizontally across the screen (could include scrolling). When the computer gets to the end of the page it goes to the next page. (say 8-12 hrs/page).One channel per page. This would allow a quick scan of time. If you see something interesting "click and drag" with the mouse to zoom in. The time associated with the mouse position would be always displayed in a box. If you would like to save a portion of time then point to the start and end and a file will be created. No more splicing teleseismic files.If there is nothing on a particular page you could delete it and the info on the harddrive. The brain and eyes can do a better job of recognition than alot of trigger routines. Barry _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Mark Wilson mark@.............." <wilsonm@............> Subject: Re: drum-recorder Date: Sun, 2 Mar 1997 21:27:03 -0800 (PST) I want to also say, I love the drum... There is just something to say about that PS-1 sitting there in my den. When I started this, my wife didn't really care, but every morning now I either catch her with a cup of coffee looking at the drum, or found that she changed the paper for me. Computers are so... data... :) ********************************************************************* --- mark@.............. --- http://www.markwilson.com --- wilsonm@............ --- wilsonm@.............. --- mark.wilson@....... --- General Networking Dude and Routing Rugrat ********************************************************************* _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: David A Nelson <dann@........> Subject: Re: drum-recorder Date: Mon, 03 Mar 1997 22:26:39 +1200 OK guys, Now its my turn, I will NEVER dispense with my drum recorder as others have noted it is very eye-catching for visitors to the workshop.... probably ~80% know what it is for without being told and whilst I service their piece of electronic gear they sit entranced by the wiggles. and several have been lucky enough to be present when an event comes in... It gives me the permanent printout on the spot.... the rush of adrenalin when that pen really starts to swing stop-to-stop on a good event is hard to beat ( oh dear... the cat's out of the bag....I really am a seismojunkie) Yes the digital system has its advantages in the analysis process.... the analog system is far easier to keep powered during times of mains power failure. I can work out S-P and magnitude much faster with the drum record, 30 sec with a ruler With the digital sys. the event file has to be saved to 3.5" disk transferred to the windows based computer, winquake fired up.... file loaded and analysed prob. all up 3-4 minutes Dave Dave A. Nelson 24 Jensen St., Green Is., Dunedin, South Is.. New Zealand. http://psn.quake.net/dave/home.htm ( world wide access ) http:/www.es.co.nz/~dann/home.html ( New Zealand access only ) SOD'S-LAW--- When Something Does Go Wrong, There Is Sod All You Can Do About-It When The Last Of Ten Screws Has Been Removed From A Cover, -It Will Be Discovered That The Wrong Cover Has Been Removed When The Last Of Ten Screws Has Been fitted back Into A Cover, -It Will Be Discovered That The gasket Has Been Left Out _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Robert W. Teller" <mrlabs@..........> Subject: Re: Quake Watch Update Date: Mon, 3 Mar 1997 09:31:07 -0700 Hello Ken, To save space, I will use your list to indicate things already implemented. 1) User selectable audible alarms that announce once a trigger occurs. DONE - USER CAN SUPPLY OWN WAV FILE FOR ALARM 2) User selects the number of lines of display and the gap between lines automatically adjusts. DONE - DISPLAY 1 TO 3 CHANNELS 3) User sets the colors for background, foreground, data trace, and text. COLORS FOR DATA TRACE ONLY 4) Larry's display of both local and UTC is a nice feature that I find useful. 5) One feature that I have included in the DOS software that runs the LPT ANALOG A/D convertor/plug for the parallel port is a calculation that displays the duration of time before the screen redraws. SCREEN IS UPDATED @ 0.1 SECONDS WITH A MOVING CHART SORT OF LIKE A PEN RECORDER. 6) Number of files saved since the program was started. HAS A LISTBOX INDICATING LAST 100 EVENTS OR PROGRAM ACTIVITY 7) Ability to read the data from file and redisplay a specific time interval. So we can "replay" an event. DONE - OPEN A DATA FILE PROGRAM SHOWS START AND STOP TIMES YOU CHOOSE START AND STOP TIMES OF EVENT TO DISPLAY PROGRAM SHOWS YOU ONLY THAT DATA CAN SAVE DISPLAYED DATA AS EVENT FILE 8) User selects the x and y scales. THERE IS A X2 DISPLAY MODE FOR DOUBLING THE Y SCALE DISPLAY X SCALE IS FIXED AT THE 0.1 SECOND UPDATE RATE 9) Programmable features read from a *.ini or *.dat file so that the program can execute and enter the data logging mode without human intervention. DONE _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: bob@................. (Bob Hammond (USGS-AVO Geophysicist)) Subject: Drum recorders will never die! Date: Mon, 3 Mar 1997 08:51:49 -0900 Seismologists: With regard to drum recorders, I wanted to point out that most (if not all) of the world's major seismograph network operators run drum recorders in parallel to their digital recording systems. Here at the Alaska Volcano Observatory/Alaska Earthquake Information Center in Fairbanks, we run one of the latest digital trigger/recording/analysis systems based on UNIX and PC computers. We also run 25 analog drum recorders so we can see things quickly. I cannot foresee a time when we WON't run drums. They're just too handy for quickly determining seismic activity across the network. And like Timex says, they take a licking and keep on ticking! When I bring people into our lab for tours, it's the drums that hold their attention, not the computer screens. That says something, I think. regards to all, Bob Hammond APSN Fairbanks _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Joe Irvine <Joe Irvine> Subject: Drum recorders Date: Mon, 03 Mar 1997 11:45:54 I believe there is an old heavy weight seismograph with a drum recorder atop MT.Lassen in California. Joe Joe Irvine _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane <cochrane@..............> Subject: Re: drum-recorder Date: Mon, 03 Mar 1997 13:25:43 -0700 Ok, Ok, I promise to NEVER EVER bad mouth drum records again, well not to the group anyways <G>. >With the digital sys. the event file has to be saved to 3.5" disk >transferred to the windows based computer, winquake fired up.... file loaded >and analysed prob. all up 3-4 minutes > > Dave > Dave A. Nelson Well, all you need to do is network your two systems together. This way SDR can save the event files on your Windows system directly. You won't have to use floppies again. Currently you do need to keep both systems on all of the time. This does increase you electric bill a little. If you use your Windows system everyday you should leave the system on all of the time anyways. One thing I am thinking about adding to SDR is to check to see if it can save the event file over the network, if it can't it would save it locally. The user could then startup their Windows system and then have SDR transfer the event files over to the other system. If you do network your systems, remember to get LAN cards with BNC connectors on it. If you get the type with phone line (RJsometing) connectors you will also need a hub box. Regards, Larry Cochrane Redwood City, PSN _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: shansen@........ (shansen) Subject: Re: drum-recorder Date: Mon, 3 Mar 1997 17:14:43 -0500 (EST) Guess I'll add my bit to this. I really like paper output and for my solar flare records I still use a dependable Rustrak recorder with a 1"/hr. feed. At first it cost me about $60 a year for the chart paper but a chance find at a surplus warehouse got me a 14 year supply for $5. Quite a few years ago I built a "drum-equivalent" recorder from an old computer printer tractor feed - the real wide type. Not wanting to bother with a driver for the stepper motor I adapted a 1 rph clock motor. This gave the required 1"/hr. A few continuous pieces of scavanged printer paper were then put into the feed and the ends were spliced with Scotch tape to make a 48" loop, i.e. 2 days per pass. Excess was trimmed with scissors. For the pen transport mechanism I used a threaded rod of the sort described in one of the old Scientific American articles. This was driven by another clock motor. The pen driver itself was a model airplane servo: not a good high freq device but good for slow events. This was going to replace the Rustrak until I hit on the box of chart paper. I imagine tractor feeds are still readily avail and cheap from surplus dealers. Steve _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane <cochrane@..............> (by way of Kees Verbeek <kverb@........ Subject: Verbeek <kverb@........>) Date: Tue, 4 Mar 1997 00:59:37 +0100 (MET) Ok, Ok, I promise to NEVER EVER bad mouth drum records again, well not to the group anyways <G>. Thanks guys!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! keep them rolling, regards, Kees Verbeek ,Netherlands _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: David A Nelson <dann@........> Subject: another new country on map Date: Tue, 04 Mar 1997 13:22:27 +1200 Hi all, Roberto Pozzo from Italy is now on the map and I extend a welcome to him from the group. Dave Dave A. Nelson 24 Jensen St., Green Is., Dunedin, South Is.. New Zealand. http://psn.quake.net/dave/home.htm ( world wide access ) http:/www.es.co.nz/~dann/home.html ( New Zealand access only ) SOD'S-LAW--- When Something Does Go Wrong, There Is Sod All You Can Do About-It When The Last Of Ten Screws Has Been Removed From A Cover, -It Will Be Discovered That The Wrong Cover Has Been Removed When The Last Of Ten Screws Has Been fitted back Into A Cover, -It Will Be Discovered That The gasket Has Been Left Out _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: toddm@........... (Todd Miller) Subject: Re: drum-recorder Date: Mon, 3 Mar 1997 17:50:26 -0800 >Quite a few years ago I built a "drum-equivalent" recorder from an old computer >printer tractor feed - the real wide type. Not wanting to bother with a >driver for the stepper motor I adapted a 1 rph clock motor. This gave the >required 1"/hr. A few continuous pieces of scavanged printer paper were then >put into the feed and the ends were spliced with Scotch tape to make a 48" >loop, i.e. 2 days per pass. Excess was trimmed with scissors. > >For the pen transport mechanism I used a threaded rod of the sort described >in one of the old Scientific American articles. This was driven by another >clock motor. The pen driver itself was a model airplane servo: not a good >high freq device but good for slow events. > Just a thought a friend of mine suggested, using fax paper and some sort of heat source as the "pen". I didn't get any futher than thinking I would remember this as a good idea, but thought I would add it to the mix. Todd Miller _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Charles R. Patton" <patton@..........> Subject: Re: Seismic Tomography Date: Tue, 04 Mar 1997 13:10:49 -0800 (I tried to send this from home, but I got error messages from the server saying it had timed out and it will retry for the next 5 days -- so if this re-appears later, I applogize in advance.) JMHANNON@........ wrote: >Maybe I could figure a way to drop a 100 pound weight from about 10 >feet. A couple of thoughts: Use an air cannon -- Here in California in the strawberry, and avocado fields during the ripening season, they shoot off noise cannons to scare away the birds. I believe there may be two versions -- an air reservoir with a quick release solenoid and a version which uses an LP gas/air which is ignited every once in awhile. Also I have seen a 3" x 3' or 4' pipe open ended pipe filled with an acetylene/air mixture that when ignited, made a tremendous report in the air. Any of these could be easily adapted to thump against a plate to couple into the ground. Simple and portable for field operation. Another idea is to make a 10' (?) high tripod with an electric winch with a quick-release clutch at the top (or bottom with a pulley at the top, which is easier to man-handle.) When you have lifted the weight to the top, the clutch is released, dropping the weight. This method is suitable anywhere you can get your vehicular mode of transport -- in order to use the vehicle's 12V power system. Hire a low-rider with the hydraulic elevators for the day, and tune his suspension to the frequency of interest. Now you're exciting with about 1000 to 1500 pounds of weight from about 2'. And for the ultimate version, pick up one of the diesel pile drivers used for bridge construction on the freeways. I figure it's about 500# bouncing about 6' or so. Looks like they move a concrete pile a couple of inches at a time. Seriously, the most portable, with the least weight, would be an LP or acetylene cannon with electronic ignition and flame sense. This would be to make sure you had set off the last charge before attempting to start another cycle. The same as a pilot detector in a furnace to make sure you don't flood the room with explosive mixtures and then set it off. Another good point of this would be that you could time the explosion/seismic hit very accurately -- within a few milli-seconds -- this would make it possible to accurately pull your signal up out of the grass (of noise). Charles R. Patton, Editor, Geo-Monitor _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: ACole65464@....... Subject: Re: Drum-recorder Date: Tue, 4 Mar 1997 23:21:08 -0500 (EST) Hi All, Talking of home-made chart recorders I made one out of an old strip chart recorder. A motorized potentiometer (with 180 degrees of rotation per day) provides the off-set signal to move the pen across the width of the paper in a 26 hr period, there is a slip clutch on the pot so it can be manually overriden to reset it. This off-set signal goes through a summing amplifier along with the seismic signal and time pulse signal. The pot's input voltage level is a adjusted to provide the correct amount of pen off-set. The chart paper was was made into a continous loop to make an "equivalent drum" type recorder, one revolution of the loop per 1 hour at 5/8" per minute feed rate. The paper loop was suppored with some out-rigger rollers and a weight tube is placed in the free swinging end of the loop to keep tension on the drive roller. The respone of the recorder is good for teleseismic work only. Chart recorders go really cheap at used equipment surplus stores. I bought mine, a 2 channel model, for $39 US and has been running for 98% of the time for the last 7-8 years. It makes a nice sound as the motors twirl too. You dont need a helical recorder to be entraced. Regards, Allan Coleman _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Robert L Barns <75612.2635@..............> Subject: name for seismologists list Date: 06 Mar 97 20:12:25 EST Dave Nelson, After 2 weeks in the hospital, it's good to be back watching the action--septagenarians are not supposed to have appendicitis, but I like to break new ground. I downloaded the DAS list--great progress to have 37 people already! After looking over the info, I propose a better name for the list--"World List of Amateur Seismologists" ( WLAS) since it is truly international. The acronym doesn't conflict with any I know. I was unable to print the list nicely because some of the lines are > 80 characters. Also, it took 22 pages to print. I suggest eliminating most of the blank lines so that there would be less paper to handle. Also, the list would be easier to read on the screen. Please add to my entry that my quake files have a .RLB extension. It would probably be helpful to future joiners if instructions on where to submit an entry were listed at the top of the WLAS. Also, maybe Larry could be persuaded to add a link in his home page "Send data about your seis. station for addition to the World List". Maybe this could pop up a form to be filled in. Bob Barns _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Mike Lozano <mikel@.......> Subject: Re: Many thanks to all! Date: Thu, 06 Mar 1997 21:19:44 -0600 Thanks to everyone who took the time to respond to my final assembly help request! It was a great help! I can see I'll have to change my leveling bolts from 1/4"X20 to a much finer thread, so I'll have greater control over the leveling. I think it was a sign - right after I received the responses, the nichrome wire in this version of the Lehman snapped. Repaired that, and now I'm back to trying to tweak the longest period I can get out of this monster. Although my home is about 20 miles from the Mid-Continent Rift zone's southeastern boundary, it's so quiet that the Dept. of Natural Resources placed sensors up and down the zone, and recorded nothing more than microseismic activity. In fact, that's what so unusual about this rift - it's extreme stability, and great age (1.8 Billion). The only REAL active fault is the Plum River Fault which passes from Clinton on the eastern border to between Cedar Rapids and Iowa City (if my recollection is accurate). The last quake within the state's borders took place in 1947, and was recorded as a 4.3 I'm hoping that because of this quiet, I'll be able to get away with using a single point mount rather than the knife edge. Soon, I hope to have everything working and recording - the sooner, the better; and I was delighted to learn that there's another Iowa station north of Cedar Rapids. Again, thanks everyone!!!!! Mikel Lozano, N0BDF -0- > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Ron Westfall <westfall@......> Subject: Re: Many thanks to all! Date: Thu, 06 Mar 1997 20:03:12 -0800 > I think it was a sign - right after I received the responses, the > nichrome wire in this version of the Lehman snapped. Repaired that, For my Lehmans I used steel guitar strings. They are widely available at musical instrument stores. They cost only a buck or two. Replacements, if needed, are cheap and readily available. One string is enough to do one Lehman with some to spare. I got the thinnest one available. I believe it was .013 inch thick. I can confirm this if anybody wants to know. A steel guitar string has a brass eyelet at one end. You can run the rest of the string around the upper cross support tube and through the eyelet to fix the one end to the cross support. From there the string runs through/over your top support (notched bolt, furnace nozzle, whatever). I cut the guitar string in two in order to splice in a small turnbuckle part way along. The other end of the string was then attached to the boom. At the two ends of the turnbuckle and the boom there is a loop to which an end of a guitar string piece must be attached. I used the smallest (for the finest wire guage) AC electrical crimp connectors that I could find. These connectors are short lead (maybe copper?) tubes that are covered in a brightly coloured plastic. They can be readily found in the electrical section of a hardware or automotive electric store. For each attachment you: - put a connector onto the end of the guitar string piece and push it up the string away from the end - the string end is run through the turnbuckle or boom loop 3 times (no particular reason for doing it more than once) - the 3 loops of the string will tend to spread out on the turnbuckle or boom loop, but a firm pull will bring them back into line - the string end is brought parallel and next to the string entering the turnbuckle or boom loop - the crimp connector is slid down over the paired wire and crimped It took a crimp or two to get the knack of doing it, but you get good at it quickly. If the crimp is not good and tight, I suspect the guitar string will slip out. I recommend a set of long-handled pliers or proper crimping pliers that can really flatten the crimp. CAUTION: Guitar strings are extremely springy and want to slip out of your hands and spring back into roughly a straight line. Imagine what would happen if a free end whipped across your eye. 'Nuff said, wear eye protection! The guitar strings work beautifully in practice. They have such a high tensile strength that I noticed no measurable stretch after two days (yes, I measured the height of the boom end before and after) of an 8 lb boom weight hanging from them. Although I have not measured since I haven't noticed any stretch since then. They behave well as a pseudo-frictionless support point. I don't know if this is because of or in spite of the springy quality of the guitar string. Ron Westfall westfall@...... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Karl Cunningham <karlc@.........> Subject: Re: Many thanks to all! Date: Thu, 06 Mar 1997 21:33:32 -0800 At 09:19 PM 3/6/97 -0600, Mikel Lozano wrote: >I think it was a sign - right after I received the responses, the >nichrome wire in this version of the Lehman snapped. Greetings -- I used a piece of music wire from the local hobby store. I think it was $0.69 or so for a 3-foot piece of the smallest size they had -- 0.015". I went to a guitar repair shop and got a used guitar string tuning mechanism (the kind with a worm gear) for adjusting the wire for $1. I attached the tuner to the top of the mast and have the wire go over a fulcrum on its way down to the weight. I can make adjustments in height without disturbing the swinging arm. With respect to the knife edge vs. the point -- I used a point but I didn't run the wire all the way down to the weight. I only ran the wire from the top of the mast for the first inch or so. The rest of the way, I used two pieces of 1/32" brass stock, soldered together at right angles to each other (like the letter T) to cut down on resonances. I had the wire going further down, but had resonances in the wire that didn't settle out for quite some time (guess that's why they call it music wire!). After shortening the wire, the resonances are still there, but at a high enough frequency that they don't matter. Karl Cunningham La Mesa, CA. karlc@......... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Barry Lotz <gbl@.......> Subject: Re: Many thanks to all! Date: Thu, 06 Mar 1997 22:24:16 -0800 Mike Lozano wrote: > > Thanks to everyone who took the time to respond to my final assembly > help request! It was a great help! I can see I'll have to change my > leveling bolts from 1/4"X20 to a much finer thread, so I'll have greater > control over the leveling. Mike- I found some used surveying transit leveling screws that work well. You might check with a surveying store that does repair. They usually carry spare parts taken from instruments parted out. Barry _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Robert Ogburn" <bobo@.........> Subject: documentation request Date: Thu, 6 Mar 1997 23:12:08 -0800 If anyone has (or can suggest a source for) a copy of the manual for the IBM Acquisition & control adapter assy 6323710 I would like to obtain one. Thanks Bob Ogburn PSN Daly City, CA It is better to travel happily than to arrive... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane <cochrane@..............> Subject: Re: SG Date: Thu, 06 Mar 1997 23:46:15 -0700 Hi Barry (and group thought I would CC the list for more help/info on this one), At 10:38 PM 3/6/97 -0800, Barry Lotz (gbl@........ wrote: >Hi Larry > I modified my SG to include an integrator thus converting >accelleration to velocity. What I am doing with my SG sensors is making two output ports. One is the integrated output and the other straight out of the summing amp and then into a 6 pole 10 hz low-pass filter. The integrated output is great for teleseismic events, and the higher frequency port (like you had your sensor before it had the integrator) works fine for local events. The integrator cuts into the high frequency response too much for the local events. The integrator does help filter out the higher frequency local ground noise, this allowing you to increase the gain (if you live in an area of high local ground noise like I do) of the system a little. >I hoped it would lower my frequencies so as >to be compatable with my 10 hz low pass filters (my measuring >acceleration with 10hz LP cut some of the acc. signal). What I found was >the integrator has a 6db drop off above the RC frequency so it killed my >output. I seem to have to much low freq waves. You are now seeing the air currents and other low frequency information in your sensor. You need to (if you haven't done it already) fill the inside of the box that covers the sensor with foam rubber (or something similar) so almost all of the free air space is removed. This stops any air currents from building up inside the box. Make sure that the foam rubber is not touching the sensor, this also causes problems. With the integrator you will also start seeing more of the ~6 second micro-seismic background noise. >Did you see something >like this? I guess I'll have to crank the gain up. Sure did, when I first made my SG sensor I thought I could get away from filling the inside of the box (as recommended by the original SG article) with the foam rubber. I had all types of problems until I added the insulation. Regards, Larry Cochrane Redwood City, PSN _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: dsevold@.............. (Dean Sevold) Subject: A/D interface with Emon Date: Thu, 06 Mar 97 15:51:59 PST Many thanks to Steve Hammond and Barry Lotz for responding to my inquiry regarding Emon. The advice given was specific enough to be of use, and I should be on screen shortly. Probably the quickest way to get an interface is with a dedicated card, but being somewhat of a tinkerer, I couldn't resist ordering a few A/D chips. All of them come with specifications in PDF format, and most manufacturers will send out samples, which is a real godsend to us up here in "no frills" Canada, where such things are either unavailable or with a very long lead time, from local sources. Thanks again for your help. Dean Sevold _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane <cochrane@..............> Subject: Leveling screws Date: Fri, 07 Mar 1997 01:02:35 -0700 At 10:24 PM 3/6/97 -0800, Barry Lotz wrote: > I found some used surveying transit leveling screws that work well. >You might check with a surveying store that does repair. They usually >carry spare parts taken from instruments parted out. This has been a real problem for me. I have been trying to finding a high turn screw and nut for leveling my sensors. This sounds like a great source, any other ideas out there? I was able to find, at a local surplus electronics part place, a micro-adjustment "screw" (its not really a screw, it has a pin that moves in/out as you turn the adjustment, it also has a graduate scale on the side) that may have been used for something like a microscope slide positioning. It cost ~18.00, but they only had a few of them. This would work great for a SG sensor, if I could get more of them. Regards, Larry Cochrane Redwood City, PSN _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane <cochrane@..............> Subject: Photos of sensors Date: Fri, 07 Mar 1997 02:06:49 -0700 Karl Cunningham <karlc@.........> wrote: >Greetings -- >I used a piece of music wire from the local hobby store. I think it was >$0.69 or so for a 3-foot piece of the smallest size they had -- 0.015". I >went to a guitar repair shop and got a used guitar string tuning mechanism >(the kind with a worm gear) for adjusting the wire for $1. I attached the >tuner to the top of the mast and have the wire go over a fulcrum on its way >down to the weight. I can make adjustments in height without disturbing >the swinging arm. I (and I'm sure others) would like to see a picture, or drawing, of this. Since we now have a map with our stations it would be nice if we could document things like this using photos. I'm sure it would help others, who are just starting to build there sensor, in seeing things like this. I am not very good at mechanical design, so seeing how others do things sure helps. If you have a working sensor and would like to share your design with others please take some pictures of it. If you can scan them in and send then too me (not the list) that would be great. I will work with Dave N. and set up some links pointing to your pictures. If you don't have access to a scanner I have one. Just send me the pictures and I will scan them in. One other thing, I was looking through my web server log file and came across this access: nameless.house.gov [06/Mar/1997:11:02:27 -0800] "GET /wwvcorr.txt HTTP/1.0" 200 6553 This is the first access I have seen from U.S. House of Representatives. They only accessed the wwvcorr.txt page. Must of used some keywords in a search engine that came up with my page. Regards, Larry Cochrane Redwood City, PSN _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Karl Cunningham <karlc@.........> Subject: Re: Photos of sensors Date: Fri, 07 Mar 1997 07:20:22 -0800 At 02:06 AM 3/7/97 -0700, Larry wrote: >I (and I'm sure others) would like to see a picture, or drawing, of this. >Since we now have a map with our stations it would be nice if we could >document things like this using photos. I'm sure it would help others, who >are just starting to build there sensor, in seeing things like this. I am >not very good at mechanical design, so seeing how others do things sure helps. Larry (& the group) -- I'm more than happy to share anything I've got here (including pictures) with others. If you could, give me a week or two to compile things and get it to you. I'm in the final throws of getting my force-balance unit working. I've thought about posting some stuff right now, but that would take time away from completing the seismometer :( . Being this close is really exciting and I'm really focused on getting it done and working. More in a week or two, if that's ok. Thanks. Karl Cunningham La Mesa, CA. karlc@......... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Mark Wilson mark@.............." <wilsonm@............> Subject: Re: Photos of sensors Date: Fri, 7 Mar 1997 07:48:52 -0800 (PST) I read this as I was taking a break trying the same thing. I have also found some very thin stranded cable that is used in old chart recorders. Very thin, highly flexible and multistranded. It seems to work well and since it is multistranded, it does not seem to stretch. On Fri, 7 Mar 1997, Larry Cochrane wrote: > Karl Cunningham <karlc@.........> wrote: > >Greetings -- > > >I used a piece of music wire from the local hobby store. I think it was > >$0.69 or so for a 3-foot piece of the smallest size they had -- 0.015". I > >went to a guitar repair shop and got a used guitar string tuning mechanism > >(the kind with a worm gear) for adjusting the wire for $1. I attached the > >tuner to the top of the mast and have the wire go over a fulcrum on its way > >down to the weight. I can make adjustments in height without disturbing > >the swinging arm. > ********************************************************************* --- mark@.............. --- http://www.markwilson.com --- wilsonm@............ --- wilsonm@.............. ---==== DiscoverNet Network Operations ====--- ********************************************************************* _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Jeff Batten <batten@...............> Subject: Forget earthquakes - Check out the comet!!!! Date: Fri, 07 Mar 1997 08:31:58 -0800 Saw the comet this morning from the light polluted skies of Pasadena, Ca. Got up at 5:15am. Very bright nucleus, with jets. 3 degree tail. From a dark sky it must be FANTASTIC. ANOTHER COMET WEST. CHECK IT OUT!!!!!! Just look to the North-East, you cannot miss it. WOW!!!!!!! Jeff Batten - Research Engineer Caltech Seismo Lab 1200 E. California Bl. Pasadena, Ca. 91125 818-395-6965 Fax-818-564-0715 _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Roger Griggs <rdg8@.............> Subject: Re: Iowa Seismo History Date: Fri, 07 Mar 1997 11:31:48 -0800 At 09:19 PM 3/6/97 -0600, you wrote: >Although my home is about 20 miles from the Mid-Continent Rift zone's >southeastern boundary, it's so quiet that the Dept. of Natural Resources >placed sensors up and down the zone, and recorded nothing more than >microseismic activity. In fact, that's what so unusual about this rift >- it's extreme stability, and great age (1.8 Billion). The only REAL >active fault is the Plum River Fault which passes from Clinton on the >eastern border to between Cedar Rapids and Iowa City (if my recollection >is accurate). The last quake within the state's borders took place in >1947, and was recorded as a 4.3 >Mikel Lozano, N0BDF Its interesting to note that my copy of USGS paper 1527, Seismicity of the US from 1568 to 1989 shows no quakes in Iowa during that period. Their threshold is 4.5 so your 4.3 could be valid. Roger Griggs "the guy on the other side of the bay" _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: JACK HERRON <JHERRON@.........> Subject: Re: Leveling screws Date: Fri, 7 Mar 1997 12:18:00 -0800 Barry, Send me a snail-mail address and I will send you a sketch of a cheap solution. Jack At 01:02 AM 3/7/97 -0700, you wrote: >At 10:24 PM 3/6/97 -0800, Barry Lotz wrote: >> I found some used surveying transit leveling screws that work well. >>You might check with a surveying store that does repair. They usually >>carry spare parts taken from instruments parted out. > >This has been a real problem for me. I have been trying to finding a high >turn screw and nut for leveling my sensors. This sounds like a great source, >any other ideas out there? > >I was able to find, at a local surplus electronics part place, a >micro-adjustment "screw" (its not really a screw, it has a pin that moves >in/out as you turn the adjustment, it also has a graduate scale on the side) >that may have been used for something like a microscope slide positioning. >It cost ~18.00, but they only had a few of them. This would work great for a >SG sensor, if I could get more of them. > >Regards, >Larry Cochrane >Redwood City, PSN > > > > > > > >_____________________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email listserver@............. with the body of the >message: leave PSN-L > ----------------------------------------- Jack Herron - Editor Society for Amateur Scientists 8118 E. 20th St. Tucson, AZ 85710 USA jherron@......... 520 885-6933 _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Jim Hannon <jmhannon@........> Subject: Re: Iowa Seismo History Date: Fri, 07 Mar 1997 19:58:59 -0600 Roger Griggs wrote: > > Its interesting to note that my copy of USGS paper 1527, Seismicity of the > US from 1568 to 1989 shows no quakes in Iowa during that period. Their > threshold is 4.5 so your 4.3 could be valid. > > Roger Griggs > "the guy on the other side of the bay" A few years ago I felt a quake here in Iowa (Marion). I had just sat down on my sofa and it felt like someone pushed on the back of the sofa, just one pulse. It was reporten in the local news but I can't remember where the origin was or when exactly it happened. I knew right away what it was after having been on the edge of a big quake in Iran. The after shocks of that one lasted for weeks. -- Jim Hannon _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: ralvarez@........ (Raul Alvarez) Subject: Re: documentation request Date: Fri, 7 Mar 1997 19:10:08 -0700 (MST) Hi Bob, I have one of those cards and the documentation. I will be glad to copy it for you. It may take a few days, as I still have much of my "junk" packed after my move from FL to Colorado. Raul >If anyone has (or can suggest a source for) a copy of the manual for >the IBM Acquisition & control adapter assy 6323710 I would like to >obtain one. > >Thanks >Bob Ogburn PSN Daly City, CA > >It is better to travel happily than to arrive... > >_____________________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email listserver@............. with the body of the >message: leave PSN-L > > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Barry Lotz <gbl@.......> Subject: Re: Leveling screws Date: Fri, 07 Mar 1997 20:26:20 -0800 JACK HERRON wrote: > > Barry, > > Send me a snail-mail address and I will send you a sketch of a cheap > solution. > Jack > >This has been a real problem for me. I have been trying to finding a high > >turn screw and nut for leveling my sensors. This sounds like a great source, > >any other ideas out there? > > Hi Jack- I think I'm ok, it was Mike lozano who raised the question which I provided just one solution for. (mikel@......... I would like to see your solution though. Barry Lotz c/o Capitol Engineering Labs 631 Commerce Dr. Roseville, Ca. 95678 cu Barry _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Mike Lozano <mikel@.......> Subject: Re: Comet Hale-Bopp Date: Fri, 07 Mar 1997 11:51:42 -0600 Jeff Batten is right! Comet Hale-Bopp is at least as bright as Hyakatake of last autuum - if not brighter! Didn't see the western comet. Checked at 5:15AM from Des Moines, Iowa > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Jim Hannon <jmhannon@........> Subject: Re: Leveling screws Date: Sat, 08 Mar 1997 09:52:15 -0600 I have decided that the 20 tpi screws will work fine for my instrument, especially if you use a long handled wrench to turn them. But if you want to try something with finer control here is a suggestion. I will decribe the basic principle since it requires a picture to adequately describe an implementation that would work. You can get 1/4 20 tpi screws (national coarse) and 1/4 24 tpi (national fine). Now join the two screws end to end and put an appropriate nut on each screw. Now if you prevent the nuts from turning and turn the screw one turn the nut on the 20 tpi thread will move 1/20 inch and the nut on the 24 tpi thread will move 1/24 inch and the nuts themselves will move apart or together by the difference or .0083 inch. I leave it to your imagination how to make this work as and adjustment. -- Jim Hannon _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Barry Lotz <gbl@.......> Subject: Re: Leveling screws Date: Sat, 08 Mar 1997 09:37:46 -0800 Jim Hannon wrote: > > You can get 1/4 20 tpi screws (national coarse) and 1/4 24 tpi (national > fine). Now join the two screws end to end and put an appropriate nut on > each screw. Now if you prevent the nuts from turning and turn the screw > one turn the nut on the 20 tpi thread will move 1/20 inch and the nut on > the 24 tpi thread will move 1/24 inch and the nuts themselves will move > apart or together by the difference or .0083 inch. I leave it to your > imagination how to make this work as and adjustment. > I like that. Good idea. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Robert L Barns <75612.2635@..............> Subject: Lehman suspension wire Date: 08 Mar 97 19:51:41 EST Hi gang, Recent discussion of wire for use as the suspension in a Lehman type seismometer prompted me to do the following analysis which may might be of interest. I used 0.012" dia. music wire. "Music wire" is also called "piano wire" and is high carbon steel wire which is work-hardened during the drawing process. This stuff has an amazing yield strength which is about as high as any steel wire and is of the order of 300,000 psi. Steel guitar strings are very likely made of this. Lehman's article suggested either #26 Nichrome or piano wire. #26 is 0.0159" dia. This seems larger than necessary for steel wire but may be OK for Nichrome since it is not as strong. Nichrome is easier to work with since it is easier to bend around attachment points. For the 0.012" wire, the yield stress would be 34 lbs. (The breaking stress would be somewhat higher than this.) My Lehman has about 8 lbs. on the end (lead + magnet). The angle between the wire and the boom is 30 deg. The sine of 30 deg is 0.5 so the tension on the wire is about 16 lbs (8/0.5). This is about 1/2 the yield stress which seems a generous safety factor (since no one will get killed if the wire breaks). For other wire sizes: dia yield stress 0.016 60 lbs 0.012 34 0.010 24 0.008 15 0.006 8.5 I have fairly large quantities piano wire of the following sizes: 0.035, 0.026, 0.020, 0.016, 0.013, 0.012, 0.010, 0.009 and 0.006". I would be happy to supply say 15' of any of these to anyone who needs some. Alternatively, your local piano tuner or technician can supply small quantities, probably free. Bob Barns _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Steve Hammond <shammond@..........> Subject: Re: Lehman suspension wire Date: Sun, 9 Mar 1997 11:02:06 -0800 (PST) Robert-- I have a 42 degree angle on the boom. and a 5 pound mass and 1 pound of copper damping flag at the end. Using your example I get 42 sin= ..66913 6 pounds / .66913 = 8.96 pounds tension on the wire. .010 wire has 24 pound yield stress, well under the tension stress. The reason I ask is because I also use music wire, size .010, and found that it continuously brook in different spots up and down the wire. I now double it and use two wires. I'm thinking of picking up a 1/4lbs box of the .012 wire and giving it a try. Another point. With the seismograph installed outside, the wires do rust and break about once a year. Regards, Steve Hammond PSN BBS San Jose 408-226-0675 On 8 Mar 1997, Robert L Barns wrote: > I used 0.012" dia. music wire. "Music wire" is also called "piano wire" and > is high carbon steel wire which is work-hardened during the drawing process. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Barry Lotz <gbl@.......> Subject: Re: Lehman suspension wire Date: Sun, 09 Mar 1997 12:33:06 -0800 Robert L Barns wrote: > > Hi gang, > Recent discussion of wire for use as the suspension in a Lehman type > seismometer prompted me to do the following analysis which may might be of > interest. > I used 0.012" dia. music wire. "Music wire" is also called "piano wire" and > is high carbon steel wire which is work-hardened during the drawing process. ...... Hi all- Just as another idea. I made my Lehman as a brass rod truss with an upper chord of a brass rod. My upper pivot is a knife edge pointed the opposite direction as the lower one, with both edges vertically alligned. I still need a fine "torsion" wire to hold the whole thing up at the support, but it only supporting the system weight and I have limited the height of the 36" beam to about 8-9". Barry _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Kees Verbeek <kverb@........> Subject: experiment Date: Sun, 9 Mar 1997 23:13:48 +0100 (MET) Hello all, Maybe the next experiments are worth knowing. recently i did a experiment where i did replace the upper and lower pivot by two blade-springs from the pendulum of a clock, so the mass is hanging at these springs , than there's no knife-edge friction , no wear and tear and no maintenance. Later i put two n-pole magnets under the mass to "lift" the mass, to me it was a suprise that this seems to work very well, but it needs some more time to realy work this out ( maybe not just one support-magnet but a few in hollow form for adjustment(period)) But again it will take some time to do a real good experiment. i'll let you know, regards, Kees Verbeek, Netherlands _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Roger Sorensen <Roger.Sorensen@................> Subject: Re: Lehman suspension wire Date: Sun, 09 Mar 1997 16:40:46 -0800 Steve Hammond wrote: .... > > > Another point. With the seismograph installed outside, the wires do > rust and break about once a year. > Has anyone used stainless steel safety wire, the kind used to retain nuts on aircraft and race cars? It is used in many critical applications and with the low load rates being discussed, I would think it would work well (and not rust). Of course, I think alot of things (your milage may vary). Roger. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Charles R. Patton" <patton@.........> Subject: Re: Leveling screws Date: Sun, 09 Mar 1997 18:51:43 -0800 I had a thought for how you might do high resolution leveling screws. Get two barn-door (strap) hinges at least 6" or more long. Drill and countersink a screw within about 1/2" of the hinge point. Now bolt the hinge on your seismometer so that your old leveling screw pushes on the very end of that same tang. Now you have a 12 to 1 or more (depending on how close you set the countersunk point) lever advan- tage, so your coarse 20 TPI screw will look like a 120 TPI or more. leveling screw || || -----------------------------------------------Mounting plate || |||| || |||| <strap hinge attach to \/ |||| mounting plate -------------------------------||----O------ \/ | | +---hinge of strap hinge +----permanent point on strap hinge that rests on floor Charles R. Patton Editor, Geo-Monitor patton@......... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Karl Cunningham <karlc@.........> Subject: Force-Balance Progress Date: Sun, 09 Mar 1997 21:57:34 -0800 Hi All -- I'm at the point of having my force-balance seismometer running. I been using a borrowed laptop with a 12-bit A/D for data logging but haven't written a conversion to the WinQuake file format yet. But, I am getting some good-looking waveforms -- at least in the range of 0.1Hz to 5Hz. I am very happy (honored) to share any and all construction details with anyone who wants them. I plan to post some pictures and a desciption on my web page (not currently up yet). Assuming I don't find any more serious problems with the hardware, I should have time to work on a write up in the next week or so. If anyone wants specific information, please let me know. *caution -- serious bragging ahead* Description -- It uses a Lehman-type mechanical setup with a 5# lead mass and a piano-wire top pivot. The force coil is out of a digital scale from a surplus store. It was originally intended as a force-balance coil/magnet combination and has a resistance of 7ohms and a force constant of 522 grams/amp. It is very much like a speaker voice coil and magnet, with poles of the magnet outside and inside the coil. I mounted the coil on the boom and the magnet is attached to the base plate. Except for the 1/2" of piano wire near the top of the mast, there are no ferrous materials on the boom. I gave up on optoelectronic position detectors. The problem was the light source. I tried incandescent, LED, and laser diodes, and all suffered from light distribution changes over time and temperature. The pattern of the light projected from the source would change. Not by very much, but there were perhaps 0.1% changes in the intensity in different parts of the pattern -- too much for what I wanted. I went with an LVDT for position detection. I wound my own, which has a linear range of +/-2.5mm and, with some electronic gain, a sensitivity of about 0.1 mm/volt and equivalent noise of <1 nanometer RMS. It uses 5kHz excitation and a synchronous demodulator. Most of the signal to the feedback coil is from the differential of position, with a smaller linear component for feedback to maintain position of the boom. The acceleration output (same as the feedback coil input) has flat response from dc to about 4Hz, measured using a meter-movement calibrator as described by Robert Barns. The noise floor of the acceleration output is about 1E-9 m/s^2 RMS, over 0.1Hz to 4Hz. The dc response is interesting, since the base plate can be leveled by measuring across the feedback coil and adjusting the leveling screws for zero. I rolled it off at 4Hz because there are *many* mechanical resonances in the range of >20Hz which cause peaking and phase shift in the feedback and cause the system to oscillate if the bandwidth goes out further. I've spent quite a bit of time on these resonances, and plan to work on that some more, but I if I want to do much better I think I'll have to go to a different mechanical arrangement. There's just too much flexure in the boom, suspension, and baseplate. For instance, the base plate (1/2" aluminum 6"x24") resonated in tortion at about 20Hz until I went to 4 leveling screws instead of 3. That, along with stiffeners along the sides of the base plate, raised the resonance to 50Hz or so. The method I've be using is to stiffen things up to drive the resonances up in frequency (and away from the passband), or to dampen them with foam. The whole thing is enclosed in a plywood box with 2" of insulating foam on all sides. There's a 1-watt resistor as a heater in the top. I tried to get a wideband velocity output over the range of 0.01Hz to 4Hz, but had too much trouble with the noise and stability of the hi-pass filter and integrator. I cut back on the range, and at this point plan two outputs -- one from 0.1Hz to 4Hz (already working), and the other from 0.01Hz to 0.5Hz (in a week or so). The longer-period output will have higher gain up front and therefore less dynamic range but should still be ok for teleseismic recording. I've been monitoring the 0.1Hz to 4Hz output, and the 6-sec earth noise comes through very clearly (assuming the washing machine isn't on the spin cycle). The other background noise is at least 10:1 below peaks of the 6-sec waveform. Yet to be built -- A/D convertor. I am planning to incorporate a 16-bit A/D and use SDR. If anyone is in a position to order some, I'd like some earthquakes to test / calibrate the system ;-) . It's been awfully quiet in So. Calif. this weekend. Thanks for everyone's help in answering questions. That, and the continuing stream of helpful thoughts and ideas on the list has saved countless hours of fiddling myself, not to mention the things I never would have thought of. Karl Cunningham La Mesa, CA. karlc@......... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Karl Cunningham <karlc@.........> Subject: Data Request Date: Sun, 09 Mar 1997 21:58:16 -0800 Greetings -- Since I've gotten my force-balance unit working (see other post), I would like to compare my background noise to that of other people. If someone could send me private email with a Winquake data file of their background noise as an email attachment, I'd appreciate it. PLEASE DON'T SEND IT TO THE LIST. Thanks, Karl Cunningham La Mesa, CA. karlc@......... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "George A. Harris" <harris@........> Subject: Re: Leveling screws Date: Sun, 9 Mar 1997 22:10:59 -0800 (PST) > At 10:24 PM 3/6/97 -0800, Barry Lotz wrote: > > I found some used surveying transit leveling screws that work well. > >You might check with a surveying store that does repair. They usually > >carry spare parts taken from instruments parted out. > > This has been a real problem for me. I have been trying to finding a high > turn screw and nut for leveling my sensors. This sounds like a great source, > any other ideas out there? > A good way to get a very fine adjustment screw is to use two screws attached together. That is, using a piece of tubing, attach a 1/4 20 screw to one end and a 5/16 to the other. Place a pair of corresponding nuts on each end. Now when the screw is turned once, the nuts separate by an amount which is the difference between the two screws. With the screws suggested, the motion is only .005 inches approximately. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: patrick jasper <KF6HOU@................> Subject: Re: Forget earthquakes - Check out the comet!!!! Date: Sat, 01 Mar 1997 23:35:32 -0800 Jeff Batten wrote: > > Saw the comet this morning from the light polluted skies of Pasadena, Ca. > Got up at 5:15am. > > Very bright nucleus, with jets. 3 degree tail. From a dark sky it must be > FANTASTIC. > > ANOTHER COMET WEST. CHECK IT OUT!!!!!! > > Just look to the North-East, you cannot miss it. WOW!!!!!!! > > Jeff Batten - Research Engineer > Caltech Seismo Lab > 1200 E. California Bl. > Pasadena, Ca. > 91125 > 818-395-6965 > Fax-818-564-0715 > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L jeff,my name is pat,wr6s..im new to the psn e-mail list and saw ur message regarding the comet[hale -bopp] you got that right !!!its pretty gud so far[though not as good as haik...yet?] i live in pinon hills abt 5 km n/of the S.A. but when i left for work last thu at 4am i cud not believe how much h-b had brightened..you should see it from my house[no street lights or roads haha] anyway,it was so bright i saw it for about 20 minutes dawn from my work in baldwin park. i have a 8 inch mead that im gonna turn on it,,cant wait!!!oh well, thought id give you a rundown on the location here,u should see it from some dark skies..totally cool..have a gud 1,cul8tr,pat _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: patrick jasper <KF6HOU@................> Subject: Re: Comet Hale-Bopp Date: Sat, 01 Mar 1997 23:55:14 -0800 Mike Lozano wrote: > > Jeff Batten is right! Comet Hale-Bopp is at least as bright as > Hyakatake of last autuum - if not brighter! Didn't see the western > comet. Checked at 5:15AM from Des Moines, Iowa > > > Public Seismic Network Mailing List (PSN-L) > > > > To leave this list email listserver@............. with the body of the > > message: leave PSN-L > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L hi,my name is pat and saw ur e-mail on the psn...i live in the high desrt about 40 mi ne of la at 4000ft, h-b is outstanding..brighter nucleus then hi but no whre near the tail lenght..im still waiting to see how bright and long it gets..anyway,gud watching es 73.pat..wr6s _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Steve Hammond <shammond@..........> Subject: Daly City event Date: Mon, 10 Mar 1997 23:16:31 -0800 (PST) FYI-- Most of us in the Bay area recorded two 3.6 events, a 2.3 and a 2.4 on the San Andreas (37.71N 122.56W north of Devils Slide and west of San Francisco at 06:30 UTC. This is right at the point where the San Andreas goes into the Pacific and crosses west of the Golden Gate. It is also just north of the epicenter of the 1906 earthquake (37.67N 122.48W). Regards, Steve Hammond PSN BBS San Jose 408-226-0675 _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: ct@....... (Charlie & Terri Thompson -- Buda MicroRanch ) Subject: Re: Daly City event Date: Tue, 11 Mar 1997 09:01:26 -0600 I noticed they Coyoty Point USGS sensor was saturated! You can tell it's digitized to 12 bits because +-2048 was as large as the numbers went. Larry I noticed that good old .LC1 just barely saturated at +32767. Didn't get anything here....a M5.5 is required for Buda, Texas visibility. (NOT that I'm hoping for one in your populated area!) -Charlie Thompson _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane <cochrane@..............> Subject: Re: Daly City event Date: Tue, 11 Mar 1997 13:40:20 -0700 At 09:01 AM 3/11/97 -0600, you wrote: >I noticed they Coyoty Point USGS sensor was saturated! You can >tell it's digitized to 12 bits because +-2048 was as large as the >numbers went. The telemetry system only has a dynamic range of a 12 bit system. I remove the lower 4 bits because they only contain noise. > >Larry I noticed that good old .LC1 just barely saturated at +32767. > All of my other sensor have the full 16 bit data saved. Just barely felt the two events. Regards, Larry _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane <cochrane@..............> Subject: Re: Data Request Date: Tue, 11 Mar 1997 14:54:04 -0700 Glad to here you got your FB unit working. For background noise you have come to the right place. I've got lots of it<G>. You can use your Web browser (http://psn.quake.net/request.html) and request data from any of my sensors I am monitoring. Regards, Larry Cochrane Redwood City PSN At 09:58 PM 3/9/97 -0800, you wrote: >Greetings -- > >Since I've gotten my force-balance unit working (see other post), I would >like to compare my background noise to that of other people. If someone >could send me private email with a Winquake data file of their background >noise as an email attachment, I'd appreciate it. PLEASE DON'T SEND IT TO >THE LIST. > >Thanks, > > >Karl Cunningham >La Mesa, CA. >karlc@......... > > >_____________________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email listserver@............. with the body of the >message: leave PSN-L > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Jim Hannon <jmhannon@........> Subject: Re: Force-Balance Progress Date: Tue, 11 Mar 1997 19:17:03 -0600 Karl Cunningham wrote: > I rolled it off at 4Hz because > there are *many* mechanical resonances in the range of >20Hz which cause > peaking and phase shift in the feedback and cause the system to oscillate > if the bandwidth goes out further. I've spent quite a bit of time on these > resonances, and plan to work on that some more, but I if I want to do much > better I think I'll have to go to a different mechanical arrangement. > There's just too much flexure in the boom, suspension, and baseplate. For > instance, the base plate (1/2" aluminum 6"x24") resonated in tortion at > about 20Hz until I went to 4 leveling screws instead of 3. That, along > with stiffeners along the sides of the base plate, raised the resonance to > 50Hz or so. The method I've be using is to stiffen things up to drive the > resonances up in frequency (and away from the passband), or to dampen them > with foam. > > > Karl Cunningham > La Mesa, CA. > karlc@......... > Karl, Something I have been thinking about for another mechanical arrangment. Right now my seismograph is made of welded square steel tubing. Rectangular tubing is stiffer so what I propose is to make the frame of rectangular steel tubing and fill the tubes with concrete. -- Jim Hannon _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: ct@....... (Charlie Thompson) Subject: Seismo Poem from the Year 1911 Date: Wed, 12 Mar 1997 17:44:08 -0600 Bob Lewis in Plano, Texas suggested that I post this old poem he found. Bob writes: "I thought you might like this. It's the only poem I've ever seen about seismology. Maybe you could forward it to the guys in California. It is from a 1911 edition of the Bulletin of the American Seismological Society." From: BOB LEWIS Subj: Poem from 1911 "The Song of the Seismologist" I come from fields of fractured rock, From regions of upheaval, Where split and fault and seismic shock Attest a force primeval. I plant my instruments so fine On so-called Terra Firma And in that curious wiggly line I catch the seismic murmur. From records of a varied type I frame the weird equation. And when my integrals are ripe, I solve the whole creation. See, where these wiggles start to life, In north and east direction, This upward jog, that tells of strife. Whence I, by mere inspection, Can place my finger on the source Of that far-reaching seism; Lo! here, say I, was born the force That caused the cataclysm. I drop steel balls on rocky blocks- My rocking blocks fall over- I test the rush of the wave through rocks, And the strength of the shock discover. Now track I near, now track I wide, By many an installation- The secret of the Globe's inside Is mine by revelation. The tremors pass in drawn-out trail By paths brachistochronic, Emergence angles tell their tale Of wonderland Plutonic. Far in the depths where solar heat Can give no palpitation, I hark to the tune of the pulling Moon And tidal gravitation. On rocky shores the wavelets break Or even on sandy beaches, Six seconds each the time they take- And so the record teaches. The tremors come, the tremors go, They love the wintry weather, With periods fast and periods slow- perplexing altogether. But what care I, the seismist bold- I fear no complication; Each novel fact I easily fold Within my boiled equations. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Robert W. Teller" <mrlabs@..........> Subject: RE: Quake Watch Date: Thu, 13 Mar 1997 14:31:57 -0700 Bob, Sorry, but Quake Watch is being designed to operate in windows only. I = would be happy to supply anyone the serial port output of the A/D card = for the purpose of creating a DOS version. I tried to send this reply via e-mail, but my two attempts were returned = as undeliverable. Bob Teller, AA7OG -----Original Message----- From: RELJ%mimi@................ [SMTP:RELJ%mimi@................. Sent: Thursday, March 13, 1997 11:00 AM To: mrlabs@.......... Subject: Quake Watch From: BOB LEWIS WB5FDF RELJ =20 Subj: Quake Watch =20 I read about your Quake Watch the other day with interest. I have an = older Toshiba laptop (an XT) that I would like to use to acquire the seismic = data, freeing my 386 PC for other uses in my ham shack. I'm pretty sure that = the Toshiba will not run Windows since it has only 640K of RAM. It does = have a serial and a parallel port and a 3.5 inch floppy drive (no hard = drive). =20 I would like to be able to use the Toshiba to acquire the data, and use Winquake on my 386 machine to analyze what is recorded. I am using EMON now on the 386 which works fine but ties up the computer for other uses. =20 Is there any way your new Quake Watch might work? _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: dsevold@.............. (Dean Sevold) Subject: Lehman Suspension Wire Date: Thu, 13 Mar 97 19:07:15 PST Piano wire is available at most hobby stores that cater to the model aircraft builder. Splices can be made by forming, wrapping the parts with copper wire, and soldering, and, alternatively, there are sold small crimp-on connectors, and grommets for thimbles. .016" solid piano wire, that is, not stranded, has been used for control line wires (60 foot lengths) to fly a .35 to .60 cubic inch engine powered aircraft travelling 60 to 90 mph in circles, with 15 to 25 pound centripetal force on the lines. With proper eye splices, there is a very high safety factor. See your local hobby dealer or a friend who builds models. Dean Sevold _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Karl Cunningham <karlc@.........> Subject: Re: Force-Balance Progress Date: Thu, 13 Mar 1997 21:54:06 -0800 At 07:17 PM 3/11/97 -0600, you wrote: >Something I have been thinking about for another mechanical arrangment. >Right now my seismograph is made of welded square steel tubing. >Rectangular tubing is stiffer so what I propose is to make the frame of >rectangular steel tubing and fill the tubes with concrete. Jim -- I'm not sure how much energy absorbing concrete filling in steel tubes does. I'm sure it's better than without it. I wonder if dry sand would be any better; or a mixture of sand and oil or grease? There are viscoelastic rubber materials that are used to dampen vibrations on things like car metal panels. I wonder if these would be of use? Some people who know about keeping resonances down in structures are those who design telescope mounts, and they seem to be fond of filling metal tubes with concrete. I've seen articles about that is Sky & Telescope in the past. I'll see if I can dig one up. Karl Cunningham La Mesa, CA. karlc@......... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Barry Lotz <gbl@.......> Subject: Re: Force-Balance Progress Date: Thu, 13 Mar 1997 23:00:49 -0800 > I'm not sure how much energy absorbing concrete filling in steel tubes > does. I'm sure it's better than without it. I wonder if dry sand would be > any better; or a mixture of sand and oil or grease? > > There are viscoelastic rubber materials that are used to dampen vibrations > on things like car metal panels. I wonder if these would be of use? > > Some people who know about keeping resonances down in structures are those > Note: Building vibration isolators use a lead core. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Gaetan.Pasquier@............" <gapasqui@.............> Subject: Re: Force-Balance Progress Date: Fri, 14 Mar 1997 15:30:19 +0200 I would like not to receive your messages anymore but I already sent the message leave PSN-L many times without success. Could you help me to leave your list please. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Robert L Barns <75612.2635@..............> Subject: Bubble tiltmeter Date: 14 Mar 97 13:59:24 EST Hi gang, I would like to buy a Rockwell bubble transducer (a tiltmeter), Rockwell International part no 67380-301 or something similar. Any suggestions where to look? These were developed in the '50s and were used in large arrays in California. Bob Barns _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Mark Robinson <robotech@..........> Subject: Re: Bubble tiltmeter Date: Sat, 15 Mar 1997 13:57:00 -0800 Robert L Barns wrote: > > Hi gang, > I would like to buy a Rockwell bubble transducer (a tiltmeter), Rockwell > International part no 67380-301 or something similar. Any suggestions where to > look? > These were developed in the '50s and were used in large arrays in California. > Bob Barns I don't know exactly what the Rockwell part is like. Small curved tubes with electrodes and a fluid in them are used as electronic level sensors in Steadicams. They use them with LVDT (LDVT ?) chips to add a level to a video signal. Cinema Products Corporation Phone (310) 836 7991 Fax (310) 836 3112 Part number something like Z078-5204 Level Control Assy 78-5205 PCB MSC-150058 Level CG-10Q Good Luck Mark G Robinson | fax +64-9-849-7408 | Phone +64-9-846-3296 robotech@.......... | Box 8770, Auckland 1035, New Zealand ----------------------------------------------------------- 15 Mar 1956 "My Fair Lady" opens on Broadway starring Rex Harrison and Julie Andrews. 15 Mar 1975 Aristotle Onasis died. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: wcatino@............. Subject: re: Bubble Tiltmeter Date: Fri, 14 Mar 97 17:40:12 Bob Barns expressed an interest in a bubble tiltmeter (no e-mail address). I have an article I could scan describing the constructional details of a sensitive mercury tiltmeter that could be used as a seismometer. It uses the same sensing technique as the Lehman article I sent to Larry a while back. E-Mail me if you are interested. Walt (wcatino@.............. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane <cochrane@..............> Subject: Re: Force-Balance Progress Date: Fri, 14 Mar 1997 17:47:39 -0700 Greetings, At 09:57 PM 3/9/97 -0800, Karl Cunningham wrote: >Hi All -- > >I'm at the point of having my force-balance seismometer running. I been >using a borrowed laptop with a 12-bit A/D for data logging but haven't >written a conversion to the WinQuake file format yet. But, I am getting >some good-looking waveforms -- at least in the range of 0.1Hz to 5Hz. [snip] > >I tried to get a wideband velocity output over the range of 0.01Hz to 4Hz, >but had too much trouble with the noise and stability of the hi-pass filter >and integrator. I have been using integrators in my SG sensors and have had no problems with then if you do the following: The sensor has to be thermally stable. You need to fill the inside of the box, that covers the sensor, with something like foam rubber. You should also insulate the outside of the box. You need a high-pass filter before the integrator. I use a 1 uf mylar cap and a 10 meg resistor for the LF filter (See http://psn.quake.net/sgproc.gif). And another one after the integrator. I use LF412's op-amps (two amps in one 8 pin package) for almost all of my analog work. They are cheep and have good low noise / temp drift specs. I'm sure there are a lot of other op-amps out there that will work just as well. You need to feed enough background noise into the integrator so that it can swing + and - around 0 vdc. Any constant DC offset will cause problems. And, use a high quality cap in the feedback loop. I have been using 2 2.2 mylar caps and a 4.7 meg feedback resistor. >I cut back on the range, and at this point plan two >outputs -- one from 0.1Hz to 4Hz (already working), and the other from >0.01Hz to 0.5Hz (in a week or so). The longer-period output will have >higher gain up front and therefore less dynamic range but should still be >ok for teleseismic recording. The two output approach is a good way of recording local and teleseismic events. The none integrated output (my *.lc4 files) of my SG sensor produces a very similar seismogram to my Lehman (*.lc1 files). The two 3.6s a few days ago are a good example. The Lehman has a higher frequency response because it is measuring velocity. Dr. John Lahr posted a message a while back about using a differentiators (sp) to increase the freq response. It works, I tried it a while on my sensor. It increases the local ground noise (like my lehman is plagued with) so I am bypassing it for now. Also, I think some digital signal processing of the raw data can do some of the work for analog parts on a board. I have been working with Ed Cranswick to add integration display to WinQuake. I'm still play around with it put it seem to be working. The problem is I don't have a handle of the vertical display. WinQuake only displays counts from the A/D converter and can not reference it back to some real numbers (except the magnitude correction number used for ML calculation). This brings up the problem of the limitation of the current PSN event file format. We need a little more info (in the event file) on the type of sensor (acceleration, displacement or velocity) and the sensitivity, another hard thing to measure (except strong motion accelerometers, you can point them up or down and get a 1g force). For teleseismic events the output of the integrator can really bring out the low frequency waves (and noise of your sensor!). Since it also reduces the high frequencies of the local ground noise you can really increase the gain of this channel. Regards, Larry Cochrane Redwood City, PSN _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: wcatino@............. Subject: re: Tiltmeter - correction Date: Fri, 14 Mar 97 18:05:14 Whoops! I meant Gundersen-Shackeford, not Lehman! Sorry... walt (wcatino@.............. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Richard J. Goff" <rgoff@................> Subject: Design help Date: Fri, 14 Mar 1997 21:53:03 -0600 Hello all - Back in Jan., after corresponding with Larry C., I started building a SG seisometer. It, along with the difference amplifier, are working without problems. I'm now working on the amplifier and signal conditioning circuitry. I have chosen the National LMF60-100 IC which contains a 6-pole Butterworth LP filer. This chip is a scaled down (smaller die) version of the National MF-60 and also has two (2) spare OP amps. I've been able to get the entire system down to 2 IC's with an overall adjustable gain from 340 to 1080. (The diff. amp. + the rest) The LMF60 is a switched capacitor filter but the output has a clock feedthrough of 10 mv. This 10 mv. is constant and appears at the output if the signal level is 0 or if the signal is driven near the rails. The clock frequency is approximately 100 Hz. for a 3 dB corner of 1.5 Hz. I don't have an appreciation for the signal levels I will get from the SG sensor and this is why I solicit your help. If the 10 mv. is very small compared to signals I'll get from seismic events, I don't think I'll have any problems. The A/D could have errors of 10 mv., but if signal levels are about the same level as the clock feedthrough, I've got "BIG" problems and will have to do other things to get rid of the clock - OR scrap this idea. I'd rather not since this is such a beautiful filter requiring only two (2) external components for the RC clock oscillor. Please let me have your comments. Thanks - Dick Goff _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane <cochrane@..............> Subject: Re: Design help Date: Fri, 14 Mar 1997 20:44:36 -0700 At 09:53 PM 3/14/97 -0600, Richard J. Goff wrote: >Hello all - > >Back in Jan., after corresponding with Larry C., I started building a SG seisometer. >It, along with the difference amplifier, are working without problems. I'm now working >on the amplifier and signal conditioning circuitry. > >I have chosen the National LMF60-100 IC which contains a 6-pole Butterworth LP filer. >This chip is a scaled down (smaller die) version of the National MF-60 and also has two >(2) spare OP amps. I've been able to get the entire system down to 2 IC's with an >overall adjustable gain from 340 to 1080. (The diff. amp. + the rest) Its hard to say if this is a good gain setting range. It depends on how much signal you get out of your sensor plates. I have a gain of about 100 before the integrator. After the integrator you need to specify the gain at some frequency (the lower the frequency the higher the gain) so I'm not sure what the overall gain of my SG systems are (I've measured it, just done remember the numbers). After getting the sensor working just set the gain (see below on where the gain should go) to an expectable background level. > >The LMF60 is a switched capacitor filter but the output has a clock feedthrough of 10 >mv. This 10 mv. is constant and appears at the output if the signal level is 0 or if the >signal is driven near the rails. The clock frequency is approximately 100 Hz. for a 3 dB >corner of 1.5 Hz. > >I don't have an appreciation for the signal levels I will get from the SG sensor and >this is why I solicit your help. If the 10 mv. is very small compared to signals I'll >get from seismic events, I don't think I'll have any problems. The A/D could have errors >of 10 mv., but if signal levels are about the same level as the clock feedthrough, I've >got "BIG" problems and will have to do other things to get rid of the clock - OR scrap >this idea. I'd rather not since this is such a beautiful filter requiring only two (2) >external components for the RC clock oscillor. > Normally you need some post analog filter after a digital filter to remove the clock. You may only need to add a one pole (one resistor and cap) low-pass filter starting at 1.5 hz. This may remove enough of the clock for you. It depends on the number of bits your A/D converter has. A 12 bit chip with a +-5 volt max input works out to a ~2.5 millivolts per bit. A one pole filter should get you down below one bit. If you are using a higher bit A/D chip you might add a 2 pole equal value LP filter. They add the extra op-amps so you can build a post filter filter. If you need more gain in the system remember to add it before the LP filter. If you add it after the digital filter you will be amplifying the filter noise and the sensor signal. I would be interested in hearing more info on the filter chip. Especially the dynamic range. I use some digital filters (MAX 291) in my USGS demodulator board. These chips are 8 pole LP filters that work fine for 12 bit A/D systems. There are a little too noisy for 16 bit systems. The noise is not from the clock, just low frequency stuff in the band we are looking at. It must be possible to make a low-noise high dynamic range digital filter because every Compact Disk player as two of them <G>. Regards, Larry Cochrane Redwood City, PSN _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Charlie Plyler <cplyler@.............> Subject: Re: Design help Date: Sat, 15 Mar 1997 12:08:27 -0500 At 21:53 3/14/97 -0600, you wrote: >Hello all - > >Back in Jan., after corresponding with Larry C., I started building a SG seisometer. >It, along with the difference amplifier, are working without problems. I'm now working >on the amplifier and signal conditioning circuitry. > >I have chosen the National LMF60-100 IC which contains a 6-pole Butterworth LP filer. >This chip is a scaled down (smaller die) version of the National MF-60 and also has two >(2) spare OP amps. I've been able to get the entire system down to 2 IC's with an >overall adjustable gain from 340 to 1080. (The diff. amp. + the rest) > >The LMF60 is a switched capacitor filter but the output has a clock feedthrough of 10 >mv. This 10 mv. is constant and appears at the output if the signal level is 0 or if the >signal is driven near the rails. The clock frequency is approximately 100 Hz. for a 3 dB >corner of 1.5 Hz. > >I don't have an appreciation for the signal levels I will get from the SG sensor and >this is why I solicit your help. If the 10 mv. is very small compared to signals I'll >get from seismic events, I don't think I'll have any problems. The A/D could have errors >of 10 mv., but if signal levels are about the same level as the clock feedthrough, I've >got "BIG" problems and will have to do other things to get rid of the clock - OR scrap >this idea. I'd rather not since this is such a beautiful filter requiring only two (2) >external components for the RC clock oscillor. > >Please let me have your comments. > >Thanks - Dick Goff > >_____________________________________________________________________ Hello Dick, I too have been using this remarkable little chip in my filter circuits. A very simple way to get around this problem with the 10mv clock frequency is to insert a two pole analog lo-pass filter behind the LMF 60-100 chip with a c/o around 20hz. This keeps your frequency of interest extremely flat and also gets rid of the aliasing problems. A TLO82 op-amp is a good choice and is available from the "Shack". Rather than using seismic detectors, we have developed an electrical detection system monitoring voltage transients through the earth. By using extreme filtering methods we have been successful in detecting earthquakes and other natural and man made disturbances on a global scale. If you wish, I can send you a copy of the schematics we use so you may be able to convert some of the circuits for your own use. Charlie ELFRAD GROUP 35.41N / 80.494W _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Karl Cunningham <karlc@.........> Subject: Re: Force-Balance Progress Date: Sun, 16 Mar 1997 10:25:11 -0800 At 05:47 PM 3/14/97 -0700, Larry Cochrane wrote: >You need a high-pass filter before the integrator. I use a 1 uf mylar cap >and a 10 meg resistor for the LF filter (See >http://psn.quake.net/sgproc.gif). And another one after the integrator. I >use LF412's op-amps (two amps in one 8 pin package) for almost all of my >analog work. They are cheep and have good low noise / temp drift specs. I'm >sure there are a lot of other op-amps out there that will work just as well. > >You need to feed enough background noise into the integrator so that it can >swing + and - around 0 vdc. Any constant DC offset will cause problems. > >And, use a high quality cap in the feedback loop. I have been using 2 2.2 >mylar caps and a 4.7 meg feedback resistor. > Hi Larry -- Thanks for your suggestions about the conditioner design. I think my sensor is pretty thermally stable, but I need to do more testing on it. The problems I was having with the integrator went something like this. I was trying to cover the frequency range of 0.01Hz to 5Hz -- a 500:1 range, so the integrator had to cover a gain range of 500:1 (either increasing gain at low frequencies, decreasing it at high, or a combination). The input to the integrator is the acceleration output, which has a full-scale range of 20V (+/- 10V). There is a HPF between the two. If I took any gain before the integrator, I would loose dynamic range at the high-frequency end of things. This is something I didn't want to do, because I want to be able to see local events as much as I can without clipping; and after working so hard on the LVDT, I didn't want to throw away SNR in the electronics. So I let the integrator take the gain (500:1 at the 0.01Hz end). I am trying to maintain a noise level (at least in the electronics) below one bit of a 16-bit A/D, which, given the +/- 10V swing and 500:1 gain, means sub-microvolt stability out of the integrator op-amp. Also, if the high-pass filter was blocking any dc, the capacitance stability of the HPF capacitor becomes an issue. It's possible I could have made it work, but it seemed that two outputs would simplify things. Since I don't think I need as wide a dynamic range for telesiesmic events, I could take some of the gain before the integrator (where the impedances are lower), and then have the integrator reduce the gain at high frequencies rather than increase it at low frequencies. >Also, I think some digital signal processing of the raw data can do some of >the work for analog parts on a board. I agree. A laptop I have been borrowing has a 12-bit A/D and Labview on it. Labview is a data-collection and processing language. I have implemented software 3rd-order Bessel HP and LP filters (a simple function call in Labview) to see what the noise would look like if I actually built the filters in hardware. >We need a little more info >(in the event file) on the type of sensor (acceleration, displacement or >velocity) and the sensitivity, another hard thing to measure (except strong >motion accelerometers, you can point them up or down and get a 1g force). Sensitivity standards are something I've wondered about. If people share quantitative data, it should be apples/apples. Robert Barns' meter-calibrator idea could be used by some people to test the sensor. There is still sensor coupling to the ground, local ground response, and perhaps other things as well. I imagine coupling and ground response not only differ in amplitude from one site to another, but frequency-domain characteristics too. That sounds like a tough one. Karl Cunningham La Mesa, CA. karlc@......... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane <cochrane@..............> Subject: Re: Archives ?? Date: Sun, 16 Mar 1997 15:06:30 -0700 Hi Brian and Group, I have been meaning to do this. I have now made zip files of each PSN-L archive text file. Also, since this quarters file is getting really big, I divided it up info 2 files, and 1 zip file. Text file PSNL97QA.TXT contains message from January and February 1997. PSNL97Q1.TXT has March to current in it. I also made a zip file of PSNL97QA.TXT but the current archive file has no zip file. I could add a command to my system to ZIP the current archive file, but this will take a few days. I updated the Mailing List web page at http://psn.quake.net/maillist.html with links to the new zip files. Regards, Larry Cochrane Redwood City, PSN At 06:20 AM 3/16/97 -0800, Brian Chesire <BCChesire@................> wrote: >Hi Larry, >I'm new to the PSN-L and wanted download the some of the archives. I >get about a fourth to a third of each archive and then the system slows >down and times out. Any Ideas why? Also if you PKZIP'd them it would >save a lot of transfer time. >Thanks Brian > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane <cochrane@..............> Subject: New sensor online using ADXL05 chips, old sensor off line Date: Sun, 16 Mar 1997 23:18:17 -0700 Hi There, I have good news and I have bad news as they say.... Good news first. A while back Steve Hansen sent me two ADX05 Monolithic Accelerometer chips (Thanks Steve!). I finally got around to doing something with when. I breadboard the two chips and now have the sensor online. I took a little different approach with the two chips I have. I decided to use both in the same axes by setting them up in a push-pull configuration. What I did was feed one chip with a +5 volt source and the other with -5 VDC. For the -5 volt chip I connected ground to the +5 input pin and the -5 volts when to the ground pin (if you try this remember that the chip can is connected to the ground pin). I first had the chips oriented in the opposite direction. This didn't work right so I rotated one chip 180 degrees. After do that it work like it was suppose too. I took the pre-amp output of each chip and summed them together with two 10k resistors. I also placed a cap at the summing point to act as a 15hz low-pass filter. I did not use the spare op-amp in the chips. I was hoping that using two chips like this would help with linearity and have lower noise figure. Basically what's happening is I'm averaging two sensors, I think. Any thoughts on doing something like this? The output of the summing point gets high-pass filtered to remove any DC offset. From there the signal gets amplified and then into a 10hz 6 pole low-pass filter and then into the 16 bit A/D converter. I have the gain set so it has a +- 2G full scale output. This is the same as my (it actually belongs to the USGS) commercial Force Balanced Accelerometer I have online. They are both oriented N-S so I can compare them if or when we have a large enough event for them to pick up. The ADX05 chip is pretty noisy, a good low-pass filter helps a lot to remove some of it. The device is a little bit more sensitive then I thought it would be, BUT it is definitely a strong motion sensor. The background noise is constant day and night so there is no pickup of local ground noise like a high or medium gain sensor would have. Compared to the commercial FBA (again both set to ~+-2G) the ADX05 sensor has about 15x more background noise. The FBA sensor does not pickup any local ground noise either, so all of the noise is inside the ADX05 chips. Unlike the ADX05 sensor the FBA has almost no output when it's just sitting there. If definitely has a high dynamic range. I could cut down on the gain of the ADX05 sensor and make it a +-5G sensor. This would give the sensor a little bit more dynamic range. What kind of acceleration can one expect from a large event? I'll keep it the same as the commercial FBA for now. It makes it easier to compare the two. One thing that's kind neat about the FBA and ADX05 sensors. You can calibrate them using good old mother earth. By pointing the sensor up or down one can get a +-1G change in output. You don't have to move the sensor up and down to do this, just the force of gravity on the sensor as it sits there is all that is needed. Sure makes calibration pretty easy. Now for the bad news, after moving the short period vertical sensor I am using around, it stopped working. Its dead, gone of to see its maker (add the rest of Monty Pythons dead parrot scene substituting sensor for parrot<G>). I think the coil is screw up. It's not that big of a loss, it mostly picked up the local ground noise 99.99999% of the time. Anyways it frees up a channel for the new ADX05 sensor. So heres my current sensor to event file information. *.LC1 still my N-S Lehman *.LC2 was my short period vertical sensor. I will not use this ID since I have archived files using it. *.LC3 still my low frequency N-S SG sensor. The output data is integrated on this one. *.LC4 This is a high frequency (no integrator) output of my second SG sensor. It was pointed N-S so I could compare it with my Lehman. As of a few days ago I changed it to E-W so I would have one sensor pointing in that direction. *.LC5 Commercial FBA sensor pointed N-S. *.LC6 My new ADX05 strong motion sensor also pointed N-S. That's it. Hope everyone has a good week. Regards, Larry Cochrane Redwood City, PSN _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Richard J. Goff" <rgoff@................> Subject: Re: Design help Date: Sat, 15 Mar 1997 12:17:24 -0600 Charlie Plyler wrote: > > At 21:53 3/14/97 -0600, you wrote: > >Hello all - > > > >Back in Jan., after corresponding with Larry C., I started building a SG > seisometer. > >It, along with the difference amplifier, are working without problems. I'm > now working > >on the amplifier and signal conditioning circuitry. > > > >I have chosen the National LMF60-100 IC which contains a 6-pole Butterworth > LP filer. > >This chip is a scaled down (smaller die) version of the National MF-60 and > also has two > >(2) spare OP amps. I've been able to get the entire system down to 2 IC's > with an > >overall adjustable gain from 340 to 1080. (The diff. amp. + the rest) > > > >The LMF60 is a switched capacitor filter but the output has a clock > feedthrough of 10 > >mv. This 10 mv. is constant and appears at the output if the signal level > is 0 or if the > >signal is driven near the rails. The clock frequency is approximately 100 > Hz. for a 3 dB > >corner of 1.5 Hz. > > > >I don't have an appreciation for the signal levels I will get from the SG > sensor and > >this is why I solicit your help. If the 10 mv. is very small compared to > signals I'll > >get from seismic events, I don't think I'll have any problems. The A/D > could have errors > >of 10 mv., but if signal levels are about the same level as the clock > feedthrough, I've > >got "BIG" problems and will have to do other things to get rid of the clock > - OR scrap > >this idea. I'd rather not since this is such a beautiful filter requiring > only two (2) > >external components for the RC clock oscillor. > > > >Please let me have your comments. > > > >Thanks - Dick Goff > > > >_____________________________________________________________________ > > Hello Dick, > > I too have been using this remarkable little chip in my filter circuits. > A very simple way to get around this problem with the 10mv clock > frequency is to insert a two pole analog lo-pass filter behind the > LMF 60-100 chip with a c/o around 20hz. This keeps your frequency of > interest extremely flat and also gets rid of the aliasing problems. > A TLO82 op-amp is a good choice and is available from the "Shack". > > Rather than using seismic detectors, we have developed an electrical > detection system monitoring voltage transients through the earth. > By using extreme filtering methods we have been successful in detecting > earthquakes and other natural and man made disturbances on a global > scale. > > If you wish, I can send you a copy of the schematics we use so you > may be able to convert some of the circuits for your own use. > > > > > Charlie > ELFRAD GROUP > 35.41N / 80.494W > >Thanks Charlie - I'd appreciate a copy of your schematics. You can mail them to: Dick Goff 1169 Gooseberry Hill Shreveport, LA 71118 I'd still like a "feel" for the magnitude of the output voltage of a seismic event within an order a magnitude. From what I've seen, most A/D 's that are used are about 0-5 v. inputs. Most of the circuits I've seen have (Lehman's and SG's) have gains of ~ 500. Do most of the A/D 's use about a 0-5 v. input range and does an M5 quake register 50 mv., 500 mv. , 1 v., etc. I just want to get a "gut" feel of where I am. Thanks all for the replies. Dick Goff _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Richard J. Goff" <rgoff@................> Subject: Dynamic Range Date: Sat, 15 Mar 1997 12:25:03 -0600 Larry - The dynamic range of the National LMF-60 6 pole LP filter is 88 dB. You can download date sheets from <www.national.com>. Dick Goff _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Tolga BEKLER <tolga@..........................> Subject: Strainmeter Date: Mon, 17 Mar 1997 09:49:35 +0200 (EET) I am a research assistant in Bogazici University Kandilli Observayory & E/Q Research Enst. We have a e/q prediction studies in Marmara Region so I am trying to get ingormation about borehole type strainmeter. I would be glad if anyone send me info. and some physical aspects of it. Tolga Bekler _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane <cochrane@..............> Subject: Re: Design help Date: Mon, 17 Mar 1997 01:14:08 -0700 At 12:17 PM 3/15/97 -0600, Dick Goff wrote: >I'd still like a "feel" for the magnitude of the output voltage of a seismic event >within an order a magnitude. From what I've seen, most A/D 's that are used are >about 0-5 v. inputs. Most of the circuits I've seen have (Lehman's and SG's) have >gains of ~ 500. Do most of the A/D 's use about a 0-5 v. input range and does an >M5 quake register 50 mv., 500 mv. , 1 v., etc. I just want to get a "gut" feel >of where I am. Lets see if I can help, on the A/D card it depends on the manufacturer. My 12 or 16 bit A/D card has a fixed +-5V input range. The newer 12 bit PC-Lab 711 cards have a programmable gain input so you can have different input levels from +-5 V down to +-.3125. I recommend staying at the highest voltage range to keep the dynamic range as high as possible, especially if you have a long piece of wirer between the sensors amp card and the A/D converter. For the Amp gain I use a lot higher value them 500. I run my Amp at around 3.5K, and I have to keep it down because of all of the local ground noise. A lot depends the pickup coil. I use a 240VAC relay coil that has over 12k turns and a resistant of around 8.5k. The magnet has a 22 lb pull. I could easily increase the gain by two or three if I lived in a quieter location. Late at night I do start seeing the ~6 second micro seismic background noise so I couldn't increase it too much more then that. Now for the counts. First remember that the ML scale is based on the power of 10 and it measures maximum amplitude (or max A/D counts). If you had a sensor that produces a max peek count of say 500 for a ML3.0 100km away then a ML4.0, at the same distance, would produce a max count of 5000 (saturating a 12 bit system0 and a ML5.0 would produce 50K counts saturating a 16 bit system). I don't have any numbers for how the distance changes things. You can play around with WinQuake and see for your self how distance effects the numbers. Some real numbers, the two ML3.6's a few days ago just saturated my Lehman. The event was 37 km or 23 miles away. If my calculations are right then the coil produced a maximum output voltage of ~3.0mv for this event. A ML3.2 event (one at the Geysers up north from me) ~150km (94mi) away produced a max count of 2215 or .0002 mv at the coil. For teleseismic events I look at a resent 6.8 in Mexico, about 2900km (1800mi) away, produced a max count of around 2600, very close to the local ML3.2 event. Hope this helps, Regards, Larry Cochrane Redwood City, PSN _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Charlie Plyler <cplyler@.............> Subject: LMF60-100 Date: Tue, 18 Mar 1997 06:23:12 -0500 Hello all, Quite a few of you have requested a copy of the design schematics I use with our equipment concerning the LMF60-100 low pass filter. Although we are detecting natural and manmade events traveling through the earth by electrical devices, you may be able to modify the circuits to be used for seismic events. I have compressed the schematics to a gif format to about 35k which should be suitable for those with limited bandwith. If you would like to review them, just post a message to this group and I will email them to you privately. Charlie ELFRAD GROUP 35.41N / 80.494W _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Brian.Teravskis@............... Subject: Re: LMF60-100 Date: Tue, 18 Mar 1997 07:51:58 -0500 Charlie: I am interested in your schematic. At that size I would have no problem with you sending it directly. Thanks in advance, Brian -- Brian K. Teravskis Brian.Teravskis@............... ARS WD0EFL Apple Valley, MN _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Robert W. Teller" <mrlabs@..........> Subject: RE: LMF60-100 Date: Tue, 18 Mar 1997 07:17:16 -0700 Charlie, I would be very interested in obtaining your design schematics. Thanks for offering. Bob Teller -----Original Message----- From: Charlie Plyler [SMTP:cplyler@.............. Sent: Tuesday, March 18, 1997 4:23 AM To: PSN-L Mailing List Subject: LMF60-100 Hello all, Quite a few of you have requested a copy of the design schematics I use with our equipment concerning the LMF60-100 low pass filter. Although we are detecting natural and manmade events traveling through the earth by electrical devices, you may be able to modify the circuits to be used for seismic events. I have compressed the schematics to a gif format to about 35k which should be suitable for those with limited bandwith. If you would like to review them, just post a message to this group and I will email them to you privately. Charlie ELFRAD GROUP 35.41N / 80.494W _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Nick & Sophie Caporossi <nickcap@.............> Subject: RE: LMF60-100 Date: Tue, 18 Mar 97 10:40:27 -0500 -- [ From: Nick & Sophie Caporossi * EMC.Ver #2.5.02 ] -- Hi Charlie: I too would be interested in a copy of your design schematics. Thank you Nick Caporossi nickcap@............. 40 24.757N 74 23.435W > -----Original Message----- > From: Charlie Plyler [SMTP:cplyler@.............. > Sent: Tuesday, March 18, 1997 4:23 AM > To: PSN-L Mailing List > Subject: LMF60-100 > > Hello all, > > Quite a few of you have requested a copy of the design schematics I use with > our equipment concerning the LMF60-100 low pass filter. > > Although we are detecting natural and manmade events traveling through the > earth by electrical devices, you may be able to modify the circuits to be used > for seismic events. I have compressed the schematics to a gif format to about > 35k which should be suitable for those with limited bandwith. > > If you would like to review them, just post a message to this group and I will > email them to you privately. > > > Charlie > ELFRAD GROUP > 35.41N / 80.494W _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Nick & Sophie Caporossi <nickcap@.............> Subject: RE: LMF60-100 Date: Tue, 18 Mar 97 10:49:42 -0500 -- [ From: Nick & Sophie Caporossi * EMC.Ver #2.5.02 ] -- Hi Charlie: I too would be interested in a copy of your design schematics. Thank you Nick Caporossi nickcap@............. 40 24.757N 74 23.435W > -----Original Message----- > From: Charlie Plyler [SMTP:cplyler@.............. > Sent: Tuesday, March 18, 1997 4:23 AM > To: PSN-L Mailing List > Subject: LMF60-100 > > Hello all, > > Quite a few of you have requested a copy of the design schematics I use with > our equipment concerning the LMF60-100 low pass filter. > > Although we are detecting natural and manmade events traveling through the > earth by electrical devices, you may be able to modify the circuits to be used > for seismic events. I have compressed the schematics to a gif format to about > 35k which should be suitable for those with limited bandwith. > > If you would like to review them, just post a message to this group and I will > email them to you privately. > > > Charlie > ELFRAD GROUP > 35.41N / 80.494W ------- FORWARD, End of original message ------- _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Warren Shedrick" <warren@..........> Subject: Re: LMF60-100 Date: Tue, 18 Mar 1997 07:56:42 +0000 > Date: Tue, 18 Mar 1997 06:23:12 -0500 > To: PSN-L Mailing List <psn-l@.............> > From: Charlie Plyler <cplyler@.............> > Subject: LMF60-100 > Reply-to: PSN-L Mailing List <psn-l@.............> > Hello all, > > Quite a few of you have requested a copy of the design schematics > I use with our equipment concerning the LMF60-100 low pass filter. > > Although we are detecting natural and manmade events traveling > through the earth by electrical devices, you may be able to modify > the circuits to be used for seismic events. I have compressed the > schematics to a gif format to about 35k which should be suitable > for those with limited bandwith. > > If you would like to review them, just post a message to this > group and I will email them to you privately. > > > Charlie > ELFRAD GROUP > 35.41N / 80.494W > > > > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L > Mr. Plyler: I am interested in the schematic you mentioned. Please email Thank you Warren Shedrick > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Robert L Barns <75612.2635@..............> Subject: Rusting of Lehman wire Date: 18 Mar 97 11:13:46 EST Hi gang, One further thought on the rusting of piano wire in Lehman seismometers:Mine sits on the basement floor. The basement is rather leaky--the floor under the Lehman usually has standing water on it if we get an inch or more of rain (once or twice a month). Yet, my wire does not rust. I think that it is protected by the heater in the top of the 2" thick styrafoam box which encloses the Lehman. This heater dissapates about 15 watts and is enough to raise the temperature in the box a few degrees. A few degrees is enough to lower the relative humidity quite a bit and this stagnates the air in the box and avoids air currents around the Lehman. I remember hearing (long ago) that clean iron will not rust if the RH is < 80% but I'm not sure of this figure. Any salt (from your fingers or whatever) on the wire will permit rusting at lower RH's. "And now for something completely different..." There has been a mention of bolting seismometers to the floor. If strong local shocks are expected, I suppose that makes a little sense but in most cases, I think that is an unnecessary complication. The static coefficient of friction of steel feet on the seismometer sitting on almost anything, esp. concrete, is almost certainly > 0.8. This means that there can't be any sliding until the horizontal acceleration of the floor exceeds 0.8g. If 0.8g is exceeded, I suppose that there will be problems much more serious than a sliding sensor. Bob Barns _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Charlie Plyler <cplyler@.............> Subject: RE: LMF60-100 Date: Tue, 18 Mar 1997 11:40:24 -0500 Hello all, The response to my offer to make available of my use of the LMF60-100 low pass filter is almost overwhelming. If you don't mind, email requests directly to me at "ulf@............." and I will send them out as quick as possible. This will free up Larry's list and possibly expedite the transfer quicker. Thanks much, Charlie ELFRAD GROUP 35.41N / 80.494W _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Karl Cunningham <karlc@.........> Subject: Re: Rusting of Lehman wire Date: Tue, 18 Mar 1997 09:02:32 -0800 At 11:13 AM 3/18/97 EST, Robert Barns wrote: > I remember hearing (long ago) that clean iron will not rust if the RH is < 80% >but I'm not sure of this figure. Any salt (from your fingers or whatever) on >the wire will permit rusting at lower RH's. How about coating the wire with a very thin layer of thick grease. I don't think the grease would afftect the response significantly, and I think it would keep the wire from rusting pretty well. Karl Cunningham La Mesa, CA. karlc@......... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Karl Cunningham <karlc@.........> Subject: Re: LMF60-100 Date: Tue, 18 Mar 1997 09:03:52 -0800 At 06:23 AM 3/18/97 -0500, Charlie Plyer wrote: >If you would like to review them, just post a message to this >group and I will email them to you privately. Charlie -- Please send me a copy of the data too. Thanks. Karl Cunningham La Mesa, CA. karlc@......... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: watson@................ (Charles Watson) Subject: Re: Barstow 5.4 Date: Mon, 17 Mar 1997 21:38:06 -0800 Any good traces from the Barstow, Southern California, ML 5.4 quake this morning? -- ---/---- cpw _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: lahr@................. (Dr. John Lahr (USGS-GI Seismologist)) Subject: travel times Date: Tue, 18 Mar 1997 09:12:28 -0900 Bob Lewis asked me a question about travel times of Love and Rayleigh waves. He's used my travel time calculator page, but these surface waves are not included. Does anyone know a web site that has a good teleseismic travel time graph that can be printed out? Thanks, JCLahr The travel-time calculator is located at: http://www.giseis.alaska.edu/Input/lahr/artim.html ################################## John C. Lahr ################################# Seismologist ################################ U.S. Geological Survey ############################### c/o Geophysical Institute ############################## 903 Koyukuk Drive ~~~~~~~~~~~~~~ Get ~~~~~~~~~~ ############################# ########################################################### P.O. Box 757320 ################################ Fairbanks, AK 99775 ################################# Phone: (907) 474-7997 ################################## Fax: (907) 474-5618 ~~~~~~~~ the thrust? ~~~~~~~~~~~~~~ lahr@........ #################################### http://www.aeic.alaska.edu/Input/lahr/ _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Richard J. Goff" <rgoff@................> Subject: Thanks Date: Tue, 18 Mar 1997 12:33:03 -0600 Thanks Charlie P. and Latty C. for the help. I will use either a 1 pole or 2 pole Filter after the LMF-60-100 and set the corner at 10 Hz. I Guess the LMF-60 stirred some interest ! Dick Goff _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Bill Scolnik <wls@.........> Subject: Re: LMF60-100 Date: Tue, 18 Mar 1997 13:52:51 -0500 (EST) Charlie, I'd also like a copy of the schematic. Thanks, Bill Scolnik _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Dennis Leatart <ASTROSEEK@.........> Subject: Re: Barstow 5.4 Date: Tue, 18 Mar 1997 11:24:25 -0800 Charles and all: I got a very good trace of the quake from my vantage point here in Moorpark, CA. In fact, the initial waves went off scale-- However, did not pick up any of the aftershocks being reported. I am reducing the data now as we speak. Did anyone else get a good trace?--heard there was freeway damage just outside of Barstow?? -- _____ __ | \.-----.-----.-----.|__|.-----. | -- | -__| | || ||__ --| |_____/|_____|__|__|__|__||__||_____| _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: James Forbes <jforbes@.............> Subject: Re: LMF60-100 Date: Tue, 18 Mar 1997 17:41:14 -0500 Let me joint the crowd and ask for a copy of the schematics. Thanks At 07:56 AM 3/18/97 +0000, you wrote: >> Date: Tue, 18 Mar 1997 06:23:12 -0500 >> To: PSN-L Mailing List <psn-l@.............> >> From: Charlie Plyler <cplyler@.............> >> Subject: LMF60-100 >> Reply-to: PSN-L Mailing List <psn-l@.............> > >> Hello all, >> >> Quite a few of you have requested a copy of the design schematics >> I use with our equipment concerning the LMF60-100 low pass filter. >> >> Although we are detecting natural and manmade events traveling >> through the earth by electrical devices, you may be able to modify >> the circuits to be used for seismic events. I have compressed the >> schematics to a gif format to about 35k which should be suitable >> for those with limited bandwith. >> >> If you would like to review them, just post a message to this >> group and I will email them to you privately. >> >> >> Charlie >> ELFRAD GROUP >> 35.41N / 80.494W >> >> >> >> >> _____________________________________________________________________ >> >> Public Seismic Network Mailing List (PSN-L) >> >> To leave this list email listserver@............. with the body of the >> message: leave PSN-L >> >Mr. Plyler: >I am interested in the schematic you mentioned. Please email >Thank you >Warren Shedrick > > >_____________________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email listserver@............. with the body of the >message: leave PSN-L > > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane <cochrane@..............> Subject: Re: LMF60-100 ADMIN NOTE Please read. Date: Tue, 18 Mar 1997 15:39:55 -0700 At 06:23 AM 3/18/97 -0500, you wrote: >Hello all, >If you would like to review them, just post a message to this >group and I will email them to you privately. NO NO and NO, this is NOT the way to use this mailing list. Now everyone has to wade through a bunch of email message that have no usefully information. PLEASE, do use the list for things like this. It's just as easy to contact the person directly. Thanks, Larry Cochrane Redwood City, PSN BTW: I just ordered 4 chips though Digi-Key (1-800-344-4539), they have the -100's in stock. The -50 is back ordered, they should get more parts in 8 to 10 weeks. The -100 cost around $6.50 for 1 to 25 pieces. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Mark Robinson <robotech@..........> Subject: Re: LMF60-100 Date: Wed, 19 Mar 1997 12:10:13 -0800 Charlie Plyler wrote: > If you would like to review them, just post a message to this > group and I will email them to you privately. yes please ! Mark G Robinson | fax +64-9-849-7408 | Phone +64-9-846-3296 robotech@.......... | Box 8770, Auckland 1035, New Zealand ----------------------------------------------------------- 19 Mar 1932 Sydney Harbour bridge opened. 19 Mar 1967 Two lions escape from Wellington Zoo and roam the city. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: FCooper242@....... Subject: Re: Barstow 5.4 Date: Tue, 18 Mar 1997 19:41:13 -0500 (EST) Yes, Charles Got a good trace of the Barstow on my Esterline-Angus chart recorder. One of these days I will go a/d and can post such traces. Frank Cooper, Friendswood, Texas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: FCooper242@....... Subject: Re: Barstow 5.4 Date: Tue, 18 Mar 1997 19:42:19 -0500 (EST) Yes, Charles Got a good trace of the Barstow on my Esterline-Angus chart recorder. One of these days I will go a/d and can post such traces. Frank Cooper, Friendswood, Texas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Jim Cornelius <jimcor@..............> Subject: Re: LMF60-100 Date: Tue, 18 Mar 1997 18:36:13 -0700 Charlie Plyler wrote: > > Hello all, > > Quite a few of you have requested a copy of the design schematics > I use with our equipment concerning the LMF60-100 low pass filter. > > Although we are detecting natural and manmade events traveling > through the earth by electrical devices, you may be able to modify > the circuits to be used for seismic events. I have compressed the > schematics to a gif format to about 35k which should be suitable > for those with limited bandwith. > > If you would like to review them, just post a message to this > group and I will email them to you privately. > > Charlie > ELFRAD GROUP > 35.41N / 80.494W > Thanks for the offer, I'd appreciate a copy if you don't mind. Jim Cornelius -- Santa Fe, NM _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Charlie Plyler <cplyler@.............> Subject: Re: LMF60-100 ADMIN NOTE Please read. Date: Tue, 18 Mar 1997 20:38:43 -0500 At 15:39 3/18/97 -0700, you wrote: >NO NO and NO, this is NOT the way to use this mailing list. Now everyone has >to wade through a bunch of email message that have no usefully information. >PLEASE, do use the list for things like this. It's just as easy to contact >the person directly. > >Thanks, > >Larry Cochrane >Redwood City, PSN > >BTW: I just ordered 4 chips though Digi-Key (1-800-344-4539), they have the >-100's in stock. The -50 is back ordered, they should get more parts in 8 to >10 weeks. The -100 cost around $6.50 for 1 to 25 pieces. Sorry Larry, I realized my mistake as soon as I made it. I made a follow up post stating to please contact me privately for more info. Thanks, Charlie Charlie ELFRAD GROUP 35.41N / 80.494W _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Barry Lotz <gbl@.......> Subject: Re: New sensor online using ADXL05 chips, old sensor off line Date: Tue, 18 Mar 1997 19:14:42 -0800 Larry Cochrane wrote: > > This would give the sensor a little bit more dynamic range. What kind of > acceleration can one expect from a large event? I'll keep it the same as the > commercial FBA for now. It makes it easier to compare the two. Hi Larry- I'd say no more than 0.5 g in free field realisticly. I have heard of slightly more than 1 g on structures but I suspect that was due to structure response. Barry _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Brian Chesire <BCChesire@................> Subject: LMF60-100 Date: Tue, 18 Mar 1997 20:45:50 -0800 Please drop a copy my way. Thanks Brian _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Thomas Scott <tomscott@........> Subject: cardio-recorder Date: Wed, 19 Mar 1997 00:34:29 -0500 (EST) Hello All, I recently obtained various electronic devices (wife:"junk") and I have something that maybe somebody can use, maybe even me. It is from one of those combination treadmill/ECG units like you would find in a hospital. It appears to be a paper transport unit with 3 recording pen "thingies" that appear to work by heat or spark on fax-type paper. It also has a fourth "pen" that records one of two positions. It was manufactured by the Astro-Med division of Atlan-Tol Ind. Inc. Model W302XL-43. Anyone know what this is? Anyone want it? tomscott@........ _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Steve Hammond <shammond@..........> Subject: Re: Rusting of Lehman wire Date: Wed, 19 Mar 1997 00:42:48 -0800 (PST) Hi Bob, You are correct, if you use a large enough base to support the upright there is no need for bolting the unit to the floor. If I remember correctly, the 1956 Lehman article suggested a heavy wooden base. But in my design, it has nothing to do with sliding or the coefficient of friction. When I planned and built the seismic-house for the two Lehmans, I wanted to get them away from my shop area into a quiet spot on the property and when I did work around them, I wanted to be able to stand next to them without effecting the adjustments. When I set the foundation, I poured two 15" x 15" x 15" concrete piers and set three bolts in the top of the wet mud. I then set the forms to leave clearance between the piers and the floor, so that I could walk or stand next to the seismographs without effecting the devices. This is a years old idea and I liked it and included it in my overall design. I was then able to save a few buck by mounting the pipe flanges and 3/4" pipe uprights on 1ft. X 1.25ft. X 1/2in aluminum plate. The three bolts are set in a triangle pattern and pass through the base plate so I can level the units. For fine adjustment, there is two machine screws in the left and right outer edges of the aluminum plate that bottom into metal blocks. Just a slight turn on the machine screws with an bristol wrench and boom aligns left or right. > "And now for something completely different..." There has been a mention of > bolting seismometers to the floor. If strong local shocks are expected, I > suppose that makes a little sense but in most cases, I think that is an > unnecessary complication. The static coefficient of friction of steel feet on > the seismometer sitting on almost anything, esp. concrete, is almost certainly > > 0.8. This means that there can't be any sliding until the horizontal > acceleration of the floor exceeds 0.8g. If 0.8g is exceeded, I suppose that > there will be problems much more serious than a sliding sensor. > Bob Barns _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Dick Schmidt" <dicks@..........> Subject: Re: LMF60-100 Date: Wed, 19 Mar 1997 09:12:30 -0600 > At 07:56 AM 3/18/97 +0000, you wrote: > >> Date: Tue, 18 Mar 1997 06:23:12 -0500 > >> To: PSN-L Mailing List <psn-l@.............> > >> From: Charlie Plyler <cplyler@.............> > >> Subject: LMF60-100 > >> Reply-to: PSN-L Mailing List <psn-l@.............> > > > >> Hello all, > >> > >> Quite a few of you have requested a copy of the design schematics > >> I use with our equipment concerning the LMF60-100 low pass filter. > >> > >> Although we are detecting natural and manmade events traveling > >> through the earth by electrical devices, you may be able to modify > >> the circuits to be used for seismic events. I have compressed the > >> schematics to a gif format to about 35k which should be suitable > >> for those with limited bandwith. > >> > >> If you would like to review them, just post a message to this > >> group and I will email them to you privately. > >> > >> > >> Charlie > >> ELFRAD GROUP > >> 35.41N / 80.494W If it's not too much trouble, I'd like to receive a copy of the schematic too. Thanks much, Dick Schmidt Greendale WI USA dicks@.......... ************************************************ _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Dennis Leatart <ASTROSEEK@.........> Subject: Re: LMF60-100 Date: Wed, 19 Mar 1997 09:11:15 -0800 Dear Charlie Hope you have time to send one more, I would be very interested in the low pass filter of this type. Thanks in advance! -- _____ __ | \.-----.-----.-----.|__|.-----. | -- | -__| | || ||__ --| |_____/|_____|__|__|__|__||__||_____| _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: wizard@......... Subject: schematics Date: Wed, 19 Mar 1997 10:11:20 -0800 Charlie, Please add me to your list for the schematics. Thank You, Dick Morgret wizard@......... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Charlie Plyler <cplyler@.............> Subject: Re: schematics Date: Wed, 19 Mar 1997 13:43:43 -0500 Any one wishing the schematics of the LMF60-100 please, please email me privately at ulf@.............. This will free up this list. Thanks much Charlie _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Charles R. Patton" <patton@..........> Subject: Timing Marks for records Date: Wed, 19 Mar 1997 13:13:39 -0800 A while back a discussion started on using GPS for a source of timing marks for the seismic recordings. Question: how accurate do you really need this time? Currently several of the mail order places like Danmark, etc, are carrying a clock called the "Time Machine" manufactured by Oregon Scientific (actually a Hong Kong outfit) for around $80. It picks up the 60KHz WWV and extracts the time signals to set itself on time. I've done enough back engineering to realize that it will not be much better than about 0.1 second absolute accuracy as it depends on the 1 second data rate to synchronize its time set. Would this be accurate enough for your seismic time marks, or do you need the millisecond accuracy from the HF WWV's or GPS? If it is accurate enough, I might pursue finishing the back engineering enough to extract those time signals to use as a source for your PC or chart recorder timing. What do you think? Thanks, Charles R. Patton please use patton@......... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: JHammes@......................... Subject: Re[2]: LMF60-100 Date: Tue, 18 Mar 1997 14:30:25 -0800 ______________________________ Reply Separator _________________________________ Subject: Re: LMF60-100 Author: PSN-L Mailing List <psn-l@.............> at CCSMTP Date: 3/18/97 9:03 AM At 06:23 AM 3/18/97 -0500, Charlie Plyer wrote: >If you would like to review them, just post a message to this >group and I will email them to you privately. Charlie -- Please send me a copy of the data too. Thanks. Jerry Hammes jhammes@.................. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: JHammes@......................... Subject: Re[2]: LMF60-100 ADMIN NOTE Please read. Date: Tue, 18 Mar 1997 16:15:03 -0800 Larry wrote..... NO NO and NO, this is NOT the way to use this mailing list. Now everyone has to wade through a bunch of email message that have no usefully information. PLEASE, do use the list for things like this. It's just as easy to contact the person directly. Thanks, Larry Cochrane Redwood City, PSN BTW: I just ordered 4 chips though Digi-Key (1-800-344-4539), they have the -100's in stock. The -50 is back ordered, they should get more parts in 8 to 10 weeks. The -100 cost around $6.50 for 1 to 25 pieces. I wish to express support for Larry's request, lets stop misusing this forum before it gets spoiled, and its' unique qualities are lost. Jerry Hammes jhammes@.................. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Barry Lotz <gbl@.......> Subject: Re: Timing Marks for records Date: Wed, 19 Mar 1997 19:22:11 -0800 Charles R. Patton wrote: > > A while back a discussion started on using GPS for a source of timing > marks for the seismic recordings. Question: how accurate do you really > need this time? Currently several of the mail order places like > Danmark, etc, are carrying a clock called the "Time Machine" > manufactured by Oregon Scientific (actually a Hong Kong outfit) for > around $80. It picks up the 60KHz WWV and extracts the time signals to > set itself on time. I've done enough back engineering to realize that > it will not be much better than about 0.1 second absolute accuracy as it > depends on the 1 second data rate to synchronize its time set. Would > this be accurate enough for your seismic time marks, or do you need the > millisecond accuracy from the HF WWV's or GPS? If it is accurate > enough, I might pursue finishing the back engineering enough to extract > those time signals to use as a source for your PC or chart recorder > timing. What do you think? > Thanks, > Charles R. Patton > please use patton@......... > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L Hi Charles It would be plenty accurate for me. I don't see how if we have a more accurate time it will benefit proportionally. It beats the heck out of calling daily for the time, or programs that adjust the BIOS clock. This is what I currently use with reasonable success. You still have to occasionnally adjust the time. I don't think the travel time curves are intended to be that accurate. It seems that if everyone was on the same time reference that would be more important. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane <cochrane@..............> Subject: Re: New sensor online using ADXL05 chips. Date: Wed, 19 Mar 1997 22:09:41 -0700 At 07:14 PM 3/18/97 -0800, Barry Lotz wrote: > Hi Larry- > I'd say no more than 0.5 g in free field realisticly. I have heard >of slightly more than 1 g on structures but I suspect that was due to >structure Sounds a little low, if this is the case then the sensor is pretty useless. The average noise from the chip is around .005G that's only 40db, if .5G is the max it will see, of dynamic range. One could use a 8 bit A/D chip with that type of dynamic range. Anyone else have any G numbers for large events? I was inside a 3 story building (I was in the second floor) during the Loma Prieta event and it shook like hell. But as Barry wrote, I'm sure the structure had a lot to do with it. My strong motion sensors (and my other sensors) are in a spare bedroom. My house has one story and is sitting on a concrete slab sitting on the ground. No basement or crawl space under it. Regards, Larry Cochrane Redwood City, PSN _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Edward Cranswick <cranswick@........> Subject: Re: New sensor online using ADXL05 chips. Date: Wed, 19 Mar 1997 23:34:47 -0700 Larry Cochrane wrote: > > At 07:14 PM 3/18/97 -0800, Barry Lotz wrote: > > > Hi Larry- > > I'd say no more than 0.5 g in free field realisticly. I have heard > >of slightly more than 1 g on structures but I suspect that was due to > >structure > > Sounds a little low, if this is the case then the sensor is pretty useless. > The average noise from the chip is around .005G that's only 40db, if .5G is > the max it will see, of dynamic range. One could use a 8 bit A/D chip with > that type of dynamic range. > > Anyone else have any G numbers for large events? I was inside a 3 story > building (I was in the second floor) during the Loma Prieta event and it > shook like hell. But as Barry wrote, I'm sure the structure had a lot to do > with it. My strong motion sensors (and my other sensors) are in a spare > bedroom. My house has one story and is sitting on a concrete slab sitting on > the ground. No basement or crawl space under it. > > Regards, > Larry Cochrane > Redwood City, PSN Largest recorded acceleration is about 2.3 g vertical. During the 1994 Northridge EQ, 1.78 g EW horizontal was recorded at Tarzana in the San Fernando Valley, close to the epicenter. -Edward -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 1711 Illinois St cranswick@........ Golden, CO 80401 USA E.M. Forster said, "Only connect". _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane <cochrane@..............> Subject: Re: New sensor online using ADXL05 chips. Date: Wed, 19 Mar 1997 22:49:14 -0700 Thanks Edward, What was the magnitude of the event, I forget? Also do you know if the sensors where in structures? Larry At 11:34 PM 3/19/97 -0700, Edward Cranswick wrote: >Largest recorded acceleration is about 2.3 g vertical. During the 1994 >Northridge EQ, 1.78 g EW horizontal was recorded at Tarzana in the San >Fernando Valley, close to the epicenter. >-Edward >-- _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Edward Cranswick <cranswick@........> Subject: Re: New sensor online using ADXL05 chips. Date: Wed, 19 Mar 1997 23:58:26 -0700 Larry Cochrane wrote: > > Thanks Edward, > > What was the magnitude of the event, I forget? Also do you know if the > sensors where in structures? > > Larry > > At 11:34 PM 3/19/97 -0700, Edward Cranswick wrote: > >Largest recorded acceleration is about 2.3 g vertical. During the 1994 > >Northridge EQ, 1.78 g EW horizontal was recorded at Tarzana in the San > >Fernando Valley, close to the epicenter. > >-Edward > >-- The magnitude of the Northridge EQ was 6.7 MW (moment magnitude). -Edward -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 1711 Illinois St cranswick@........ Golden, CO 80401 USA E.M. Forster said, "Only connect". _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: David A Nelson <dann@........> Subject: New Zealand quake Date: Thu, 13 Mar 1997 23:00:16 +1200 hi all, here is the latest and yet another moderate event not to make it to the world quake listing:: 970313 0330 hrs (NZST) 970312 1530hrs (UTC) Mb 5.7 36.45S 179.65E, 246KD, 170 km NE of East Cape, Nth Is. NZ, Felt in Whakatane this is the largest New Zealand event so far this year. The seismicity has been well below avg. for Jan and Feb. Cheers Dave Dave A. Nelson 24 Jensen St., Green Is., Dunedin, South Is.. New Zealand. http://psn.quake.net/dave/home.htm ( world wide access ) http:/www.es.co.nz/~dann/home.html ( New Zealand access only ) SOD'SLAW-- When Something Does Go Wrong, There Is Sod All You Can Do AboutIt When The Last Of Ten Screws Has Been Removed From A Cover, It Will Be Discovered That The Wrong Cover Has Been Removed When The Last Of Ten Screws Has Been fitted back Into A Cover, It Will Be Discovered That The gasket Has Been Left Out _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "J. Lahr" <jlahr@............> Subject: Timing Marks for records Date: Wed, 19 Mar 1997 23:03:17 -0900 Charles writes: "A while back a discussion started on using GPS for a source of timing marks for the seismic recordings. Question: how accurate do you really need this time? " For short period seismology, it is best to keep the timing errors to less than .01 s. For long period work, the limit is about .1 s. I'm hoping that the GPS-bases TAC clock will meet the needs of the PSN. You can check out the current status at: http://www.tapr.org/tapr/html/tac2.html JCLahr *************************************** * John C. and Jan H. Lahr * * jlahr@............ * * P.O. Box 83245, Fairbanks, AK 99708 * * (907) 474-7997 * * http://www2.polarnet.com/~lahr * * http://giseis.alaska.edu/Input/lahr * *************************************** _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: David A Nelson <dann@........> Subject: gnd accelerations. Date: Thu, 20 Mar 1997 23:48:01 +1200 Larry, and all REMEMBER that 1.0g....ie the the acceleration due to gravity is 9.81 metres/sec/sec (/sec squared) ....up to 0.2 - 0.5g is reasonably common in a shallow M6 to 7 events on rock sites from studies in Taiwan on the strong motion array that Prof. Bolt was involved with. I have a video tape that I took of Prof. Bruce Bolt (Prof. of Seis. U of Cal. Berkely) when he did a talk out here a few yrs ago He was specifically talking about ground response in the bay area during the Loma Prieta event in '89 .... I will replay the tape and see if I can dig out some figures for you. He went on to discuss the response of the Golden Gate Bridge and the effort needed to seismically isolate it. It has in fact a natural period of 20 sec and is not really vulnerable to seismic activity..... damage from wind generated vibrations is much more likely he said Corolitis (sp?) ~5 km from the Loma Prieta rupture.... 0.6g horiz. San Fransisco area 0.2 - 0.3g on rock sites, S.F Airport 0.33g, Oakland 0.2 - 0.3g San Jose only 0.1g The June '92 Landers event Ms 7.5 produced a peak recorded accel. of 0.86g at a site near the rupture The first record of ground motion exceeding 1g (1.15g horizontal) was in the 1971 San Fernando Valley quake. There was 2.5 km between the Pacoima Dam recorder and the fault that moved. It had a peak vert. acceler. of 0.7g the Fault had a 2m hor. and a 1m vert. offset. the quake was Ms 6.5 The Chilean, Valparaiso event of 1985, just offshore, Ms 7.8 produced max. recorded horiz. gnd motion of 0.67g which was at San Antonio ~ 50 km SE of the Epic. Strong-motion seismometers recorded this event very well over a very wide area. they varied from 0.02g to 0.67g well there is some accumulated data to work with...... Cheers Dave BTW...... well there is a funny thing..... a whole week later my e-mail message about the NZ quake re-appeared .... must have got caught in a time warp or maybe it went through the Bermuda Triangle... A copy did actually appear last week but I don't know where this one came from.... one of those great unexplained mysteries of the universe. Dave A. Nelson 24 Jensen St., Green Is., Dunedin, South Is.. New Zealand. http://psn.quake.net/dave/home.htm ( world wide access ) http:/www.es.co.nz/~dann/home.html ( New Zealand access only ) SOD'SLAW-- When Something Does Go Wrong, There Is Sod All You Can Do AboutIt When The Last Of Ten Screws Has Been Removed From A Cover, It Will Be Discovered That The Wrong Cover Has Been Removed When The Last Of Ten Screws Has Been fitted back Into A Cover, It Will Be Discovered That The gasket Has Been Left Out _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Tolga BEKLER <tolga@..........................> Subject: strainmeter Date: Thu, 20 Mar 1997 16:19:48 +0200 (EET) hi all members of PSN-L I wrote a mail to all about strainmeter but i have not yet received any message from anybody. still I'm waiting to hear something Tolga Bekler bekler@........... tolga@.......................... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Phil Giannini" <phil_giannini@...........> Subject: data base Date: 20 Mar 1997 08:05:30 U REGARDING data base Hi Fellow Enthusiasts, Does anyone know of a location on the WEB or otherwise having a data base where-by you can enter a date, magnitude, or location and receive a listing of events for the desired criteria. Thanks in advance for any input. Phil /.SFN & Z _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: lahr@................. (Dr. John Lahr (USGS-GI Seismologist)) Subject: Re: New sensor online using ADXL05 chips. Date: Thu, 20 Mar 1997 10:18:46 -0900 The Northridge earthquake indicated the need for strong motion instruments able to record accelerations up to 2.0 g. Ed C. points out that the maximum so far recorded is 2.3 g vertical. The following is from an EQE web page (http://www.eqe.com/publications/northridge/geology.htm) Ground Shaking "Near-record strong ground motions were generated by the Northridge Earthquake. Recorded peak horizontal accelerations at the ground surface, at sites located within about 10 km of the earthquake rupture surface, ranged between 0.3g and 1.2g. These record-high ground motions within a metropolitan area caused severe structural damage within the San Fernando Valley. Most concentrated damage located outside the epicentral region appeared to be within areas of deep alluvial deposits, at valley margins, or on steep slopes and ridge crests. Ground motion amplification at many of these sites contributed to the heavy damage in these areas. With the exception of two strong-motion stations, recorded peak horizontal accelerations at sites from about 20 to 50 km away from the rupture zone ranged from 0.1g to 0.6g. The anomalies were peak horizontal ground accelerations of 1.0g and 1.8g recorded at Tarzana, about 16 km from the rupture zone, and 0.9g at Santa Monica, at a distance of about 30 km. The duration of strong motion was typically about 15 seconds." If you're going to record acceleration data, it would be too bad to have a nearby earthquake clip your system. Of course, it would be too bad to have a nearby earthquake at all, but that's always a possibility in a seismogenic zone. Be sure to bolt the accelerometer down, as it won't work properly while bouncing up and down on the ground. :-) JCLahr _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: lahr@................. (Dr. John Lahr (USGS-GI Seismologist)) Subject: Re: data base Date: Thu, 20 Mar 1997 10:39:48 -0900 > From null@................... Thu Mar 20 06:59 AKS 1997 > REGARDING data base > > Hi Fellow Enthusiasts, > > Does anyone know of a location on the WEB or otherwise having a data base > where-by you can enter a date, magnitude, or location and receive a listing of > events for the desired criteria. > > Thanks in advance for any input. Phil /.SFN & Z Try the NEIC page: http://wwwneic.cr.usgs.gov/neis/epic/epic.html JCLahr ################################## John C. Lahr ################################# Seismologist ################################ U.S. Geological Survey ############################### c/o Geophysical Institute ############################## 903 Koyukuk Drive ~~~~~~~~~~~~~~ Get ~~~~~~~~~~ ############################# ########################################################### P.O. Box 757320 ################################ Fairbanks, AK 99775 ################################# Phone: (907) 474-7997 ################################## Fax: (907) 474-5618 ~~~~~~~~ the thrust? ~~~~~~~~~~~~~~ lahr@........ #################################### http://www.aeic.alaska.edu/Input/lahr/ _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Mark Wilson mark@.............." <wilsonm@............> Subject: A little question Date: Thu, 20 Mar 1997 12:01:31 -0800 (PST) I have a Lehman that I built awhile back and I have put it back in service, but.. I am not sure if I am "tuning" it correctly. I have a question about the "period of swing". When I release the boom, is the period from start to finish? i.e. is the boom supposed to swing from release back to the release position in 4 to 8 seconds? Anyone out there have a step by step guide on the setup? Thanks.. *********************************************************************** --- mark@.............. --- http://www.markwilson.com --- wilsonm@............ ---==== DiscoverNet Network Operations http://www.discover.net ====--- *********************************************************************** _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: David A Nelson <dann@........> Subject: Re: strainmeter Date: Fri, 21 Mar 1997 11:33:21 +1200 Hi, Tolga, Prob. the main reason for no reply is that no-one amongst the group has seen let alone used one including the 3 professionals. (My apologies to them is they have) The only one I have seen was in a old horizontal mine shaft. It was a 3 metre long quartz/silica rod very finely supported on vertical uprights between two electrical contacts. Each electrical contact, one fixed to each end of the rod is also on a vertical upright that is solidly fixed to the ground. As the strain increases/decreases the quartz rod is compressedstretched producing the well known piezo-electric effect in the quartz. This effect can be measured as a change in its resonant frequency and/or its electrical conductivity. Well thats about all I know about them. Cheers Dave PS where in this wide world are you calling from. At 04:19 PM 3/20/97 +0200, you wrote: >hi all members of PSN-L >I wrote a mail to all about strainmeter but i have not yet received any >message from anybody. still I'm waiting to hear something > >Tolga Bekler >bekler@........... >tolga@.......................... > Dave A. Nelson 24 Jensen St., Green Is., Dunedin, South Is.. New Zealand. http://psn.quake.net/dave/home.htm ( world wide access ) http:/www.es.co.nz/~dann/home.html ( New Zealand access only ) SOD'SLAW-- When Something Does Go Wrong, There Is Sod All You Can Do AboutIt When The Last Of Ten Screws Has Been Removed From A Cover, It Will Be Discovered That The Wrong Cover Has Been Removed When The Last Of Ten Screws Has Been fitted back Into A Cover, It Will Be Discovered That The gasket Has Been Left Out _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane <cochrane@..............> Subject: Re: Timing Marks for records Date: Thu, 20 Mar 1997 17:39:17 -0700 Hi, At 01:13 PM 3/19/97 -0800, Charles R. Patton wrote: >A while back a discussion started on using GPS for a source of timing >marks for the seismic recordings. Question: how accurate do you really >need this time? I think what John Lahr said is what we should shoot for, 10ms for local stuff and .1 for teleseismic events. But I would be happy if we all where within +-1 second. When SDR is used with the WWV time option one can get +-10ms or better, if you have fair reception to one of the WWVH stations. Since the P wave travels at 6 to 8 km per second, every second that your systems time is off creates a 6-8km error in the data. >Currently several of the mail order places like >Danmark, etc, are carrying a clock called the "Time Machine" >manufactured by Oregon Scientific (actually a Hong Kong outfit) for >around $80. It picks up the 60KHz WWV and extracts the time signals to >set itself on time. I've done enough back engineering to realize that >it will not be much better than about 0.1 second absolute accuracy as it >depends on the 1 second data rate to synchronize its time set. Are your sure it picks up the 60k WWVB or does it use the regular WWVH at 2.5, 5, 10 or 15mhz? From what I understand is the WWVB can have a accuracies of a few 10s or 100s of usec, depending on how far away you are from one of the transmitting stations. The low frequency waves stay near the ground so there is less or no bouncing of the signal from the ionosphere like WWVH does. > Would >this be accurate enough for your seismic time marks, or do you need the >millisecond accuracy from the HF WWV's or GPS? If it is accurate >enough, I might pursue finishing the back engineering enough to extract >those time signals to use as a source for your PC or chart recorder >timing. What do you think? Let me know what you find out, if its something that SDR and use I could add it to the software. Barry Lotz <gbl@.......> wrote, > It would be plenty accurate for me. I don't see how if we have a more >accurate time it will benefit proportionally. It beats the heck out of >calling daily for the time, or programs that adjust the BIOS clock. This >is what I currently use with reasonable success. You still have to >occasionnally adjust the time. I don't think the travel time curves are >intended to be that accurate. It seems that if everyone was on the same >time reference that would be more important. The travel time tables can be very accurate. I'm always amazed at how close one can get the distance and time of origin for teleseismic and local events. For teleseismic events its not uncommon to get to within a few seconds of the published time of origin, and a few 100ths of seconds for local events. You know when you have a good P and S pick if the distance and time of origin are close. By having good timing, one can rely on the time of origin as a way for learning how to pick the P and S waves better. Regards, Larry Cochrane Redwood City PSN _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Jim Hannon <jmhannon@........> Subject: Re: New sensor online Date: Thu, 20 Mar 1997 20:33:40 -0600 The G forces in an earthquake have always been a question in my mind. Boy I sure wouldn't want to be in a quake at 2 g's. This discussion prompts me to tell a story. A few years ago one of our customers was complaning that the vibrations of his floating oil drilling platform was causing the radio's on the platform to fail. I was sent out to the platform to try and measure the vibration levels. It turns out that the vibrations in the radio room were not even measurable with the instrument we took along and absloutely no threat to the radios. This is even though when they started pulling the, several miles long, drill string up the whole platform would suddenly drop about 6 feet deeper into the water. I spent the night on the platform bobbing up and down. They were fighting a potential gas blowout and had to keep raising and lowering the drill string to force mud into the bore. I guess the point is that you can get a lot of motion without a lot a G force. -- Jim Hannon _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane <cochrane@..............> Subject: Re: A little question Date: Thu, 20 Mar 1997 19:35:32 -0700 Hi Mark and Others, The period of the sensors is usually done without any dampening. All you need to do is start the boom to move and time the time it takes to make one complete cycle (both positive and negative), or better yet time the time it takes to do several cycles and then divide the results by the number of cycles you used. After starting the boom moving you should wait one cycle before starting your timing. Keep doing this as you adjust your Lehman until you get the desired period you want, usually be 10 and 40 seconds. After getting the period adjusted then add the damping. This is from the operational manual for a Geotech long-period sensor: Observe the amplitude of the voltage (you will need to look at the output of your sensor to do this, I don't think you can eye-ball it) in both positive and negative deflections. Adjust the dampening until the ratio between the positive or initial and negative or second deflection is between 4 to 1 and 5 to 1. Lets see if I can draw this: ||| | | Max | | Positive | | | | ---------| | -------------- Max | | Negative ||| To adjust the damping I use a relay coil (with a long wire so I can run it into another room so I don't disturb the sensor) mounted near the magnet on the boom. I temporarily connect a power supply to the coil, or you can charge up a capacitor and dump it into the coil. This can give you a repeatable movement of the boom. Good luck, hope this helps. Larry Cochrane Redwood City, PSN At 12:01 PM 3/20/97 -0800, Mark Wilson wrote: >I have a Lehman that I built awhile back and I have put it back in >service, but.. I am not sure if I am "tuning" it correctly. > >I have a question about the "period of swing". >When I release the boom, is the period from start to finish? >i.e. is the boom supposed to swing from release back to the release >position in 4 to 8 seconds? >Anyone out there have a step by step guide on the setup? _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Charles R. Patton" <patton@.........> Subject: Re: Timing Marks for records Date: Thu, 20 Mar 1997 22:38:28 -0800 Re: the "Time Machine" 1) I missed a zero in the likely accuracy -- it is likely it could be set in the neighborhood of 10ms. As designed, it is very unlikely it could be set to 1ms as the rise and fall time of the pulse (modula- tion) detector is longer than this. 2) Yes, it is on 60KHz. 3) The unit uses a loopstick, 0.35" dia. x 4.8" long with a 0.5" long coil feeding a chip on board amplifier/modulation detector. This is fed through a three foot long 4 wire cable to the clock display unit. Power and ground are two of the wires, one of them sends the detected data (a 1 bps modulation) as it is detected and the fourth wire seems to be involved in a carrier detect notification (and/or perhaps part of the power down signaling as once the unit has detected a full sequence and set the display unit, it no longer detects the modula- tion.) 4) On the display unit is a crystal to run it as a clock without fur- ther need for RF detection. The instruction sheet says that 6 times every 24 hours it makes necessary adjustments. This has to be a part of battery conservation as only two AAA cells power the unit. So far it appears that no data stream is available out of the proces- sor on the display board. To take full advantage of the unit it would probably be necessary to tack onto the 20 or so LCD connections to decode the display driver signals. That is kind of painful. So the other route would be to make a new decoder that interfaces to the loop antenna module. At that point, $80 is a bit steep for just the anten- na section inasmuch as it is basically doing what was done in a Sig- netics application note in 1974 for the phase lock loop NE561B that was written by Don Lancaster. The note discusses how to use the 561B to recover the modulation from the 60KHz signal. So the basic concept is only 23 years old (at least!) A little bit of insight into the subject. Hope it helps. Later, when I get a bit more time, I intend to twiddle a couple of points labeled as test points on the board. It may be that the processor will go into a data test mode to allow easier testing at manufacturing time and thus put out the data in a more compact form. That would be optimum, but I won't hold my breath. Charles R. Patton Editor, Geo-Monitor patton@......... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: watson@................ (Charles Watson) Subject: MT for the Calico quake Date: Thu, 20 Mar 1997 10:46:49 -0800 An interesting Moment tensor solution was obtained by Berkeley for the recent Calico earthquake in Southern California: http://www.seismo.berkeley.edu/seismo/mt/1997/03/7062500 -- ---/---- Charles P. Watson, Consulting Geologist Advanced Geologic Exploration Seismo-Watch / Earthquake Information Services Voice: 702-852-0992 / Fax: 702-852-3226 mailto:watson@................ http://www.seismo-watch.com _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Barry Lotz <gbl@.......> Subject: Re: strainmeter Date: Thu, 20 Mar 1997 22:51:30 -0800 > As the strain increases/decreases the quartz > rod is compressedstretched producing the well known piezo-electric effect > in the quartz. This effect can be measured as a change in its resonant > frequency and/or its electrical conductivity. > In measuring strain in steel I use epoxied on strain gages composed of many passes of fine wire on a substrate. the above principle applys hear also. Usually a strain dependant resistor is best placed in a Wheatstone bridge and the bridge inbalance input to a differential amp. Barry _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Barry Lotz <gbl@.......> Subject: Re: A little question Date: Thu, 20 Mar 1997 23:11:15 -0800 Larry Cochrane wrote: > > Hi Mark and Others, > > The period of the sensors is usually done without any dampening. There is a slight difference between the damped and undamped natural frequency but I don't think we are talking about that degree of accuracy here. Wd = W*(1-(C/Ccr)^2)^0.5. For C/Ccr=0.7 , Wd=0.71*W<undamped>. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: David A Nelson <dann@........> Subject: Pgil. G.'s questioned event Date: Sat, 22 Mar 1997 11:39:41 +1200 Phil., the event you posted may have been the Mw6.2 in the Kermadecs the time you quoted wasnt too bad a match for a travel time across the pacific. I recorded it quite well on my drum recorder easy to pick out the 'P' and 'S' arrivals not so well recorded on the digital sys. So probab. won't bother posting my event file. 97/03/21 12:07:18 31.13S 179.36E 459.8 5.7Mb B KERMADEC ISLANDS REGION Mw 6.2 keep up the good work Dave Dave A. Nelson 24 Jensen St., Green Is., Dunedin, South Is.. New Zealand. http://psn.quake.net/dave/home.htm ( world wide access ) http:/www.es.co.nz/~dann/home.html ( New Zealand access only ) SOD'SLAW-- When Something Does Go Wrong, There Is Sod All You Can Do AboutIt When The Last Of Ten Screws Has Been Removed From A Cover, It Will Be Discovered That The Wrong Cover Has Been Removed When The Last Of Ten Screws Has Been fitted back Into A Cover, It Will Be Discovered That The gasket Has Been Left Out _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane <cochrane@..............> Subject: Re: A little question Date: Sat, 22 Mar 1997 14:26:51 -0700 At 11:11 PM 3/20/97 -0800, Barry Lotz wrote: >There is a slight difference between the damped and undamped natural >frequency but I don't think we are talking about that degree of accuracy >here. Wd = W*(1-(C/Ccr)^2)^0.5. For C/Ccr=0.7 , Wd=0.71*W<undamped>. > Hmm... I have always been told that dampen doesn't effect the period. If the sensor is critically dampened then the period drops by 1/3. That makes a 30 second period sensor a 21 sec sensor. That's a pretty big drop. Can someone explain how/why this happens? I'll have to play around with one of my sensors someday too see if I can see this effect. -Larry Redwood City, PSN _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Dennis Leatart <ASTROSEEK@.........> Subject: Unknown quake, Saturday, 12:04UT (4:04 PST)-teleseism? Date: Sat, 22 Mar 1997 14:41:30 -0800 Hi all!! Did anyone pick up a quake approximately 12:04UT March 22,1997? It recorded like a teleseism would from a long distance? Times do not seem to correlate to anything I could pick up anywhere on the net, and no one has posted an event???? -- _____ __ | \.-----.-----.-----.|__|.-----. | -- | -__| | || ||__ --| |_____/|_____|__|__|__|__||__||_____| _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: David A Nelson <dann@........> Subject: Re: Unknown quake, Saturday, 12:04UT (4:04 PST)-teleseism? Date: Sun, 23 Mar 1997 12:08:16 +1200 gidday Dennis, I did put a report on this e-mail list maybe you didn't read it..... it was in reply to Phil Giannini who also recorded something here is my message again.... Phil., the event you posted was the Mw6.2 in the Kermadecs the time you quoted wasnt too bad a match for a travel time across the pacific. I recorded it quite well on my drum recorder easy to pick out the 'P' and 'S' arrivals not so well recorded on the digital sys. So probab. won't bother posting my event file. 97/03/21 12:07:18 31.13S 179.36E 459.8 5.7Mb B KERMADEC ISLANDS REGION Mw 6.2 keep up the good work Dave At 02:41 PM 3/22/97 -0800, you wrote: >Hi all!! > >Did anyone pick up a quake approximately 12:04UT March 22,1997? It >recorded like a teleseism would from a long distance? Times do not seem >to correlate to anything I could pick up anywhere on the net, and no one >has posted an event???? >-- Dave A. Nelson 24 Jensen St., Green Is., Dunedin, South Is.. New Zealand. http://psn.quake.net/dave/home.htm ( world wide access ) http:/www.es.co.nz/~dann/home.html ( New Zealand access only ) SOD'SLAW-- When Something Does Go Wrong, There Is Sod All You Can Do AboutIt When The Last Of Ten Screws Has Been Removed From A Cover, It Will Be Discovered That The Wrong Cover Has Been Removed When The Last Of Ten Screws Has Been fitted back Into A Cover, It Will Be Discovered That The gasket Has Been Left Out _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Dennis Leatart <ASTROSEEK@.........> Subject: Re: Unknown quake, Saturday, 12:04UT (4:04 PST)-teleseism? Date: Sat, 22 Mar 1997 15:24:48 -0800 Hi Dave!! No, right time wrong date!! This was last night 3/22/97 12:04 UT!!! Not 3/21/97!!! I read your post and did not pick that one up on my vertical seismometer-- the closest time I could find was a 4.4 event that took place in Northern California at 11:36UT approximately-- I am going to have to check the times more precisely as my computer only gives an approximate time until I reduce the data. Occasionally, I get these "spurious events" as I call them. Just on the light side, my seismometer is located very close to our bathroom on one side of the house, so I get what I call "potty quakes" ( I intend to make a separate slab and housing for the seismometer in the near future)-- but no one was in the bathroom this time--I checked-also, noticed that my laser magnetic field detector was moving slightly during the event-- should not do this if the event was far away-- some kind of magnetic anomoly or sun flare????? --I don't think so-- this had all the markings of a real quake!! -- _____ __ | \.-----.-----.-----.|__|.-----. | -- | -__| | || ||__ --| |_____/|_____|__|__|__|__||__||_____| _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane <cochrane@..............> Subject: First strong motion data point Date: Sat, 22 Mar 1997 15:36:45 -0700 Hi, As you know I have been asking about G forces relating to strong motion sensors. The ML4.4 Hollister event last night was picked up on the Kinetics FBA-31 sensor I have. The max +- A/D counts where only 41. This works out to +- .0025 (2.5mG) of acceleration. You can check out the event file yourself by downloading the following file: 970322a.lc5. The P wave was just out of the background noise level, but the S can be clearly seen. This is the second moderate event around here, within less then two week, that has happened when I temporarily had the ADX05 sensor off line. The first was the two 3.6's about a week 1/2 ago. I had the sensor connected to one of my Amp/Filter cards that I was burning in. I had it online for several days after I built the new sensor. I disconnected the Amp to send it off to a school in Memphis, TN (Charlie Rond is helping to set up a sensor there) that day. I didn't have another amp ready to replace it. A few hours latter we had the two events. I felt them (barely), so it would have been a good test of the new sensor. I had the FBA31 online but I found a problem with some coupling between one of my SG sensors and the FBA31. I was sharing the same power supply between them, and, when the SG sensor would have a high output it was showing up on the FBA channel (some type of ground loop problem I think). I now have all my sensors with there own power supply, so I won't run into problems like this again (I hope). After the 3.6's I got another amp ready and was back online with the ADX05 sensor the next day. Yesterday I needed to remove the amp again so my brother (he does my PC layouts) could use it for some re-work on the artwork for the next batch of boards. He wanted to have a board to look at. Well a few hours later the 4.4 hit <G>, Murphy's Law is working well in Redwood City!. I'm pretty sure I would not have pickup anything do to the higher background noise of the ADX05 chips. Good thing I had the FBA31 up and running. The funny thing is I was in the process of building up another Amp/Filter board for the ADX05 when the 4.4 event happened. I got my LM60-100 filter chips yesterday, so I was breadboarding a new board just for this sensor. I was standing getting a part out of a drawer when the event hit, I did not feel it, even though I knew it was happening because my SDR alarms where going crazy. I now have the ADX05 sensor back online, so Northern California should be save for a while<G>. -Larry Redwood City, PSN _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: steve jones <stejones@..........> Subject: Discovery Channel tv program Date: Sat, 22 Mar 1997 19:44:55 -0800 I just finished watching an interesting show on The Discovery Channel about earthquakes and "earth lights" ...it talked about the appearance of "luminous events" in the areas of faults and seismic activity, sometimes shortly before earthquake activity...several proposed theories, but no hard answers yet...anyone else see this program? Any theories or information on the "earth light" phenomenon? 73, Steve KT4AY _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Richard J. Goff" <rgoff@................> Subject: Re: A little question Date: Sat, 22 Mar 1997 08:23:57 -0600 Larry Cochrane wrote: > > At 11:11 PM 3/20/97 -0800, Barry Lotz wrote: > > >There is a slight difference between the damped and undamped natural > >frequency but I don't think we are talking about that degree of accuracy > >here. Wd = W*(1-(C/Ccr)^2)^0.5. For C/Ccr=0.7 , Wd=0.71*W<undamped>. > > > > Hmm... I have always been told that dampen doesn't effect the period. If the > sensor is critically dampened then the period drops by 1/3. That makes a 30 > second period sensor a 21 sec sensor. That's a pretty big drop. Can someone > explain how/why this happens? I'll have to play around with one of my > sensors someday too see if I can see this effect. > > -Larry > Redwood City, PSN > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L Let me add my 2 cents to this - All harmonic oscillators such as vertical pendulums, horizontal pendulums, tuning forks, masses bobbing on the end of a spring, LC tank circuits are all subject to dampening since this isn't a frictionless world. The degree of dampening can be observed by watching the exponential decay of the amplitude with time. The amount of decay is determined by the dampening coefficient. When the coefficient is such that oscillations cease, then critical dampening has been reached anf f(t) is just an exponential decay from some peak amplitude (possibly an impulse) to zero. Between the frictionless case up to critical dampening, oscillations can be observed and these are constant frequency. In the case of a pendulum with small displacents, the frequency is only a function of its length and gravitional acceleration. Dick Goff _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: bfryer@............ (Bob Fryer) Subject: Re: Discovery Channel tv program Date: Sat, 22 Mar 1997 18:37:08 -0800 (PST) Hi Steve, "Electromagnetic Heresy," on my web page, tells of the work of the late Jerry Gallimore who detected some of the signals as early as 1973. There are many references to the electrical effects, on my page. Persinger's work has figured heavily in my investigations. If anyone has e-mail addresses for Russian geophysicists interested in these phenomena, please let me know as I will be in St. Petersburg and Moscow in September. Take care, Bob >I just finished watching an interesting show on The Discovery Channel >about earthquakes and "earth lights" ...it talked about the appearance >of "luminous events" in the areas of faults and seismic activity, >sometimes shortly before earthquake activity...several proposed >theories, but no hard answers yet...anyone else see this program? Any >theories or information on the "earth light" phenomenon? > >73, Steve KT4AY ----- earthquake WARNING research ----- --- animals, people, scientific evidence --- --- http://www.teleport.com/~bfryer --- _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Dennis Leatart <ASTROSEEK@.........> Subject: Re: Discovery Channel tv program Date: Sat, 22 Mar 1997 19:21:58 -0800 Hi Steve!!! Sorry I missed that program!!! I have heard and seen earthquake lights-- I would assume it has to do with the piezo-electric effect where ground pressure builds up on quartz crystals and produces electricity-- many igniters used in common household devices like barbeque lighters etc. produce this kind of electric spark. In the Northridge quake, I noticed a lot of flashing-- most of this was due however to transformers and electric wires overhead-- one of my friends was on the Simi freeway overlooking the valley when the earthquake hit and he thought for sure we had been "nuked" from all the flashing that was going on-- he was sure a lot of it was not due to electric wiring. It is an interesting subject!!!! -- _____ __ | \.-----.-----.-----.|__|.-----. | -- | -__| | || ||__ --| |_____/|_____|__|__|__|__||__||_____| _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: bfryer@............ (Bob Fryer) Subject: Re: Discovery Channel tv program Date: Sat, 22 Mar 1997 21:03:38 -0800 (PST) Hi Dennis, A friend reported seeing a "sheet of blue lightning" erupt from a small east-west trending creek bed moments before the P-wave from Northridge. He was only about 150' away; this was near Palmdale, on the north slope of the San Gabriels, nearly on the San Andreas FZ. He was in a trailer house, couldn't get to the window in time to see how extensive it was. He did think it lit up the whole side of the mountain. The main creeks do run north-south in that area. Some of the fault maps suggest a possible connection. Bob >Hi Steve!!! > >Sorry I missed that program!!! I have heard and seen earthquake >lights-- I would assume it has to do with the piezo-electric effect >where ground pressure builds up on quartz crystals and produces >electricity-- many igniters used in common household devices like >barbeque lighters etc. produce this kind of electric spark. In the >Northridge quake, I noticed a lot of flashing-- most of this was due >however to transformers and electric wires overhead-- one of my friends >was on the Simi freeway overlooking the valley when the earthquake hit >and he thought for sure we had been "nuked" from all the flashing that >was going on-- he was sure a lot of it was not due to electric wiring. >It is an interesting subject!!!! ----- earthquake WARNING research ----- --- animals, people, scientific evidence --- --- http://www.teleport.com/~bfryer --- _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Dennis Leatart <ASTROSEEK@.........> Subject: Re: Discovery Channel tv program Date: Sat, 22 Mar 1997 21:47:55 -0800 Hi bob! Wouldn't it be neat if you could a picture of something like this-- especially if you could get a spectragraph of the phenomena! Wow! I really think someday we will be able too-- I think predicting earthquakes is just a few years away! -- _____ __ | \.-----.-----.-----.|__|.-----. | -- | -__| | || ||__ --| |_____/|_____|__|__|__|__||__||_____| _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Barry Lotz <gbl@.......> Subject: Re: A little question Date: Sat, 22 Mar 1997 22:43:40 -0800 > All harmonic oscillators such as vertical pendulums, horizontal pendulums, > tuning forks, masses bobbing on the end of a spring, LC tank circuits are > all subject to dampening since this isn't a frictionless world. The degree > of dampening can be observed by watching the exponential decay of the > amplitude with time. The amount of decay is determined by the dampening > coefficient. When the coefficient is such that oscillations cease, then > critical dampening has been reached anf f(t) is just an exponential decay > from some peak amplitude (possibly an impulse) to zero. > > Between the frictionless case up to critical dampening, oscillations can > be observed and these are constant frequency. In the case of a pendulum with > small displacents, the frequency is only a function of its length and > gravitional acceleration. > > Dick Goff > 2 cents I disagree. For undercritically damped systems the damped frequency is lower than the undamped frequency. For low damped systems the difference is minimal and for highly damped systems the large amplitude decay makes it hard to observe. For example for a 20 hz undamped freq: damping % damped freq 5 19.97 10 19.90 30 19.08 50 17.32 70 14.28 _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: David A Nelson <dann@........> Subject: welcome #40 to the database and map Date: Sun, 23 Mar 1997 20:42:23 +1200 Hi all, I welcome Karl Cunningham from La Mesa, just out of San Diego to the PSN list.... He is now on the map and list.... Cheers Dave Dave A. Nelson 24 Jensen St., Green Is., Dunedin, South Is.. New Zealand. http://psn.quake.net/dave/home.htm ( world wide access ) http:/www.es.co.nz/~dann/home.html ( New Zealand access only ) SOD'SLAW-- When Something Does Go Wrong, There Is Sod All You Can Do AboutIt When The Last Of Ten Screws Has Been Removed From A Cover, It Will Be Discovered That The Wrong Cover Has Been Removed When The Last Of Ten Screws Has Been fitted back Into A Cover, It Will Be Discovered That The gasket Has Been Left Out _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Richard J. Goff" <rgoff@................> Subject: A little question Date: Sun, 23 Mar 1997 03:14:16 -0600 Barry & Larry - One of the more difficult (and painful) ways of learning something is by "opening your mouth and inserting your foot". I stand corrected !! After Larry's question, I looked at about 5 or 6 of my texts on mechanics and only found mention of it in one - so I guess it's a point sometimes overlooked. Had I analyzed the equations of motion, I might have discovered it. Even though, all of the texts that depicted dampening with a diagram, showed the decay with at constant frequency. I guess it's a point that is sometimes overlooked. Thanks for straightening me out. Dick Goff _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Tolga BEKLER <tolga@..........................> Subject: Re: strainmeter Date: Mon, 24 Mar 1997 13:15:44 +0200 (EET) Thank you very much David and Barry to reply my mail about strainmeter. Since we have e/q prediciton studies, I want to establish a strainmeter(s) along the North Anatolian Fault Zone. So still I'm waiting to hear about something about strainmeter not only physical aspects of it but some addresses (firms and/or internet) and institutes which thay have run strainmeters. Tolga Bekler Thanks for all members of PSN-L ISTANBUL WHERE THE CONTINENTS MEET _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: David A Nelson <dann@........> Subject: Re: strainmeter Date: Tue, 25 Mar 1997 03:18:14 +1200 Greetings Tolga, pleased to help out....... The Nth Anatolian Fault thats a large strike slip fault system from memory..... tell us all more about your activities. What is the sort of activity on the fault zone over recent years?. what kind of seismic recording gear is the observatory using..... drum recorder.... digital etc feel free to let us know about significant events in your area and joining in on discussions within the PSN group I am sure that we all would welcome new from a different part of the world Cheers Dave At 01:15 PM 3/24/97 +0200, you wrote: >Since we have e/q prediciton studies, I want to establish a strainmeter(s) >along the North Anatolian Fault Zone. >Tolga Bekler > >ISTANBUL WHERE THE CONTINENTS MEET > Dave A. Nelson 24 Jensen St., Green Is., Dunedin, South Is.. New Zealand. http://psn.quake.net/dave/home.htm ( world wide access ) http:/www.es.co.nz/~dann/home.html ( New Zealand access only ) SOD'SLAW-- When Something Does Go Wrong, There Is Sod All You Can Do AboutIt When The Last Of Ten Screws Has Been Removed From A Cover, It Will Be Discovered That The Wrong Cover Has Been Removed When The Last Of Ten Screws Has Been fitted back Into A Cover, It Will Be Discovered That The gasket Has Been Left Out _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Mark Wilson mark@.............." <wilsonm@............> Subject: Re: A little question Date: Mon, 24 Mar 1997 11:59:54 -0800 (PST) I would like to thank all of the responses to "A little question" I guess that was not too little of a question after all... :) *********************************************************************** --- mark@.............. --- http://www.markwilson.com --- wilsonm@............ ---==== DiscoverNet Network Operations http://www.discover.net ====--- *********************************************************************** _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Richard J. Goff" <rgoff@................> Subject: Leveling Screws Date: Mon, 24 Mar 1997 05:45:28 -0600 I'm working on leveling screws to finish the last few details on my sensor. From articles a couple of weeks ago, I searched out a company that does repairs on transents, etc. and was given a screw (w/ knob). It's metric with a fine thread but I can't identify it, find nuts, taps, etc. so I gave up. I have a friend that remembers everyting he's ever read and he gave me a clever solution which I don't remember seeing on the net. Take a shaft (1/4" for example}. Thread half of it 1/4-20 (NC) and thread the other half 1/4-28 (NF). Put a 1/4-20 nut and a 1/4-28 nut on the shaft. If you turn the shaft, not allowing the nuts to rotate, the distance between the nuts will change at the difference of the two thread pitches. For one revolution, this is: 1/20 - 1/28 = 1/70 or equivalent to 70 t.p.i. Dick Goff _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Roger Griggs <rdg8@.............> Subject: Re: Timing Marks for records Date: Mon, 24 Mar 1997 21:12:51 -0800 At 05:39 PM 3/20/97 -0700, you wrote: >I think what John Lahr said is what we should shoot for, 10ms for local >stuff and .1 for teleseismic events. But I would be happy if we all where >within +-1 second. When SDR is used with the WWV time option one can get >+-10ms or better, if you have fair reception to one of the WWVH stations. >Since the P wave travels at 6 to 8 km per second, every second that your >systems time is off creates a 6-8km error in the data. Hi, I am having to toy with this exact problem in our Electric Transmission Scada systems that keep your lights on in the better part of California. We try and sync our "remote transmitting units" at each substation to be within a second of the master station computer but we find that inadaqute due to our millisecond time stamps on each observed event. So I have been trying to setup a better time source that will get the units down in the 10 ms range. Our system is being upgraded to a NT platform from a Sun Unix box, (yes this is an upgrade believe it or not) and we are using a TrueTime GPS network time server that has 10 to 100 nano second accuracy. But to our horror, no matter how accurate your time source or how fast the cpu (Dell Pentium Pros a 200 mhz, there is a hidden, built in ladency in the NT software that updates the system clock at a rate of every 18 milliseconds! So this definately can put a wrench into a 10 millisecond target. Now I have the SDR board with the WWV option in my system and it reports, on the bottom line, that the delta of differance in time is usually less than 10 ms of WWV, but now I am having second thoughts as to it's accuracy with this unit being a slow 33mhz 386 or Larry has done some magic with the time ticks. Anyone have any tests that can be used to find our what the delay is or experience at the hardware level to shed some light on this problem? Regards Roger _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Karl Cunningham <karlc@.........> Subject: Re: Leveling Screws Date: Mon, 24 Mar 1997 21:20:10 -0800 At 05:45 AM 3/24/97 -0600, Dick Goff wrote: >I'm working on leveling screws to finish the last few details >on my sensor. From articles a couple of weeks ago, I searched >out a company that does repairs on transents, etc. and was >given a screw (w/ knob). It's metric with a fine thread but I can't >identify it, find nuts, taps, etc. so I gave up. If you want to use your leveling screws from the transit, here's something to try: Take a piece of plastic (nylon, or something else that's "mushy") and drill a hole in it just smaller than the OD of the screws. Then force the screw into the plastic, making threads as you go. Use the piece of plastic as a nut. Karl Cunningham La Mesa, CA. karlc@......... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: ct@....... (Charlie & Terri Thompson -- Buda MicroRanch ) Subject: Rare Texas Quake Date: Mon, 24 Mar 1997 23:38:09 -0600 Frank Cooper down in Houston suggested that I check my SDR data from 22:32 UTC...what I found was a nice recording of a RARE Texas quake....only 156 miles from me here in Buda! We get about 1 per year of these quakes. I uploaded the 3.8 quake for all to see...please subtract exactly 1 minute from my data due to an error on my part SDR was WWV-locked but 1 minute fast. Regards, Charlie Thompson Seismic Station .BUE _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane <cochrane@..............> Subject: Re: Rare Texas Quake Date: Mon, 24 Mar 1997 21:50:54 -0700 At 11:38 PM 3/24/97 -0600, Charlie wrote: >Frank Cooper down in Houston suggested that I check my SDR >data from 22:32 UTC...what I found was a nice recording >of a RARE Texas quake....only 156 miles from me here in >Buda! We get about 1 per year of these quakes. I >uploaded the 3.8 quake for all to see...please subtract >exactly 1 minute from my data due to an error on my part >SDR was WWV-locked but 1 minute fast. The current version of WinQuake, version 2.3, can correct the time of an event file. It's under the File menu item. I corrected Charlie's event file, so if you download it from my system DON'T subtract 60 seconds. If you got the file through the NewEvent mailing list you will need to correct the file yourself. Regards, Larry Cochrane Redwood City, PSN _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: watson@................ (Charles Watson) Subject: Re: Rare Texas Quake, Add History Date: Mon, 24 Mar 1997 10:50:01 -0800 Charlie, Texas activity is indeed rare. Today's quake was actually centered about 35 miles west-northwest of Corpus Cristi or about 10 miles northeast of Alice. Since 1976, there have been eight events in the San Antonio-Corpus Cristi area - most triggering near San Antonio. The largest registered M4.3 and occurred about 47 miles south-southeast of San Antonio near Karnes City on April 9, 1993. Today's M3.8 Lg quake is the furthest south event within this South Texas cluster. Of course, the Valentine region of southwest Texas is well known, with a M6.1 event in 1931 and the more recent Glass Mountains Mw 5.6 earthquake on April 13, 1995. -- ---/---- Charles P. Watson, Consulting Geologist Advanced Geologic Exploration Seismo-Watch / Earthquake Information Services Voice: 702-852-0992 / Fax: 702-852-3226 mailto:watson@................ http://www.seismo-watch.com _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Charlie Rond <rond@................> Subject: Re: First strong motion data point Date: Tue, 25 Mar 1997 04:38:19 -0600 Larry, I feel guilty that you missed recording an event because you sent us your parts. The only comfort is in the assurance that Murphy is alive and well there, as well as here. Reminds me of the night - quiet after days of quiet - when I shut down the system to do some tweaking. Satisfied and gratified, I turned it back on and found to my dismay, we were in the midst of a major teleseism, of which I captured the latter half. Charlie Rond -\/\--Public Seismic Network-Memphis rond@................ (901) 360-0302 [ free BBS ] http://gandlf.ceri.memphis.edu/~rond http://gandlf.ceri.memphis.edu/~rond/psn _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Robert L Barns <75612.2635@..............> Subject: EQNews rave review Date: 25 Mar 97 10:24:05 EST Hi gang, I just got the first issue of the successor to SeismoWatch. It is called 'EQNews-The Monthly Seismo-Watch Bulletin' (Vol 1. No. 1C, Dec. 1996) and is also published by Charles Watson. I am greatly impressed by the design and production quality of this--it is at least as good as SeismoWatch if not better. As before, the photos and graphics are outstanding. Even though it is a monthly (SeismoWatch was a weekly), I think that it is well worth the $60/yr. subscription price. I'm guessing, but I suspect that Charles will be willing to send a sample copy on request. The Web page is at http://www.seismo-watch.com The toll-free message/rquest line is 800-852-2960. Bob Barns _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: bzimmerman@............ Subject: Murphy doesn't live here Date: Tue, 25 Mar 1997 16:04:14 -0500 (EST) Apparently Murphy is not in Edinboro (Probably went to Florida for Spring Break with the rest of the students). I had our 2 new Lehmans off-line for most of the morning. Within 2 minutes of restarting SDR I picked up the 5.4 Western Brazil quake. I have been waiting for a chance to notify the group that our Lehmans were up and running and figured this was it. The systems were built by one of our students,Adam Hatton, for a senior project. Adam has made a few interesting adaptations to the Lehman design. The most significant change was to use CORIAN counter top material for the base and uprights. Adam checked the specs carefully and assures me that the CORIAN material will work better than steel or aluminum. We've had the systems up for a month now with out having to adjust/re-level. So far so good. Adam will be putting diagrams/materials lists on our Web page before the end of the semester. You can view images of the Lehmans at http://coop20.geos.edinboro.edu/~brianz/seismo.html. The N-S Lehman still isn't quite right. I think we need to adjust the dampening. The background levels are high and it is very sensitive to local vibrations. Dave could you update our PSN listing to show that the Lehmans our now on-line ? Brian S. Zimmerman Department of Geosciences Edinboro University of Pennsylvania Edinboro, PA 16444 Phone: (814) 732-2207 Email: BZimmerman@............ _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: watson@................ (Charles Watson) Subject: Re: EQNews rave review Date: Tue, 25 Mar 1997 01:16:46 -0800 Ah, gee, er, ah, gee, gosh...Thanks for the rave review Bob. I am glad people are getting the issues by now. The US Postal Service would not transfer our 2nd Class (Periodical) mailing permit and this and the next issue will have to be sent out 3rd (Standard) Class rate. Took about a eight days for Bob to get his issue. The cost per single issue is $6.50. It will not be practical to send it out for free, sorry. I have had to include it with the promotional packets because I have not made up the 2-Page flyers outlining the publication yet. So if you want a Sample Issue, please include the appropriate "donation". When I saw the first issue come off the press, I was excited!! On the inside page to the cover page, I have stated some of my ideas about expanding the issue from 16 pages to 32 pages. There is so much earthquake information available at the monthly level that I will have to expand the publication to properly cover the regions I have chosen to show. There is only so much one person can do, especially since I must have a second job to make ends meet. I am looking for assistance, both on the productioon line and financially. So....caugh, caugh...(put on the business hat) if anyone would like to contribute, please feel free to contact me. I have choosen the Cascadia 1700 earthquake as the feature "Quake of the Month" for the next issue and have obtained an excellent report from Alan R. Nelson of the Paleoseismology Group at the Denver US Geological Survey. Should be good issue! The december 1996 issue feartured a photo from Tom Fumal USGS Menlo Park on the San Andreas fault rupture studies at Swarthout Creek near Wrightwood. I do not have a digital image or report for a notable February quake yet and am looking for ideas and suggestions. Again thanks for the review Bob! How do you like that expanded Pacific Northwest page! There be data thar you just can't get shopping at the corner store... See ya! -- ---/---- Charles P. Watson, Consulting Geologist Advanced Geologic Exploration Seismo-Watch / Earthquake Information Services Voice: 702-852-0992 / Fax: 702-852-3226 mailto:watson@................ http://www.seismo-watch.com Robert L Barns wrote: > > Hi gang, > I just got the first issue of the successor to SeismoWatch. It is called > 'EQNews-The Monthly Seismo-Watch Bulletin' (Vol 1. No. 1C, Dec. 1996) and is > also published by Charles Watson. > I am greatly impressed by the design and production quality of this--it is at > least as good as SeismoWatch if not better. As before, the photos and graphics > are outstanding. > Even though it is a monthly (SeismoWatch was a weekly), I think that it is > well worth the $60/yr. subscription price. > I'm guessing, but I suspect that Charles will be willing to send a sample copy > on request. The Web page is at http://www.seismo-watch.com The toll-free > message/rquest line is 800-852-2960. > Bob Barns > > > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane <cochrane@..............> Subject: Re: Timing Marks for records Date: Tue, 25 Mar 1997 13:57:57 -0700 At 09:12 PM 3/24/97 -0800, Roger Griggs wrote: >Hi, [snip] > >But to our horror, no matter how accurate your time source or how fast the >cpu (Dell Pentium Pros a 200 mhz, there is a hidden, built in ladency in >the NT software that updates the system clock at a rate of every 18 >milliseconds! So this definately can put a wrench into a 10 millisecond >target. DOS, and regular Windows 3.1, does rely on the ~18 ms interrupt rate. NT, I think, does something different. I have played around with the NT (I use NT for all of my software development) time system. The low level time stuff deals with 1 millisecond steps, or something near this, but I'm not sure how it works. There is a NTP (Network Time Protocol) program, for NT, that can use the Internet to keep the system time within a few milliseconds, if you have a fast (T1) connection to the net. I used it to see if I could use a NT system connected up to the Internet as a time source for SDR. This method uses a comm port between the NT system and SDR. If worked pretty well, except for the 28K modem I use for my Internet connection. It added too much time latency, so I could only keep a ~100ms time accuracy. With a better connection, I'm sure it would improve it by a factor or 10, getting you closer to 10ms. I think NT emulates the 18ms time interrupt for DOS and old Windows programs. Your problem maybe the programs you got with your GPS system are DOS, or old Windows based, programs. The other problem is the time is still based on the clock on the motherboard, it will not be exactly the frequency needed to produce the ~18ms interrupt, and it can be very sensitive to temperature changes inside the computer. The NTP program I used could compensate for the frequency being off, but not the temperature drift. The DOS program, RightTime, can try to compensate for the temperature drift, if you have an accurate time source. > >Now I have the SDR board with the WWV option in my system and it reports, >on the bottom line, that the delta of differance in time is usually less >than 10 ms of >WWV, but now I am having second thoughts as to it's accuracy with this unit >being a slow 33mhz 386 or Larry has done some magic with the time ticks. No magic, I simply don't use the clock / timer on the motherboard! My A/D board, and the 711s PC-Lab's card that also works with SDR, both have a crystal oscillator and a programmable interrupt timer on them. SDR uses a 1ms interrupt generated by the A/D card. This is used for all timing within SDR. SDR only uses the system time when it first starts up, this is used to get the approximate time, and from then on it uses the 1ms interrupt for its time keeping. If the WWV option is used, SDR will samples the 1000hz tone decoder (only on my A/D board, but you can make a tone decoder and connect it up to the PC-Lab card) every millisecond for the 800 ms top of the minute mark from WWV. SDR averages 6 of these marks and uses the offset between the internal time of SDR and the minute mark to keep the time within a few milliseconds of the time mark received from WWV. I have said this before, 75% of the work in SDR was getting accurate timing. Keeping up with this 1ms rate is why SDR will only work in a pure DOS environment. SDR can not keep up with this rate, under Windows, without losing time. I could write a device driver for NT or Windows 95, this allows better interrupt handling, but this is a major project. And without some buffering of the data on the A/D board (a lot more parts, making my A/D board more expensive) it may still lose some interrupts ticks. Regards, Larry Cochrane Redwood City, PSN _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: frankcnd@.......... (Frank Condon) Subject: Re: EQNews rave review Date: xMessageSize=2000000 >The cost per single issue is $6.50. It will not be practical to send it out for >free, sorry. I have had to include it with the promotional packets because I have >not made up the 2-Page flyers outlining the publication yet. So if you want a >Sample Issue, please include the appropriate "donation". > >december 1996 issue feartured a photo from Tom Fumal USGS Menlo Park on the San >Andreas fault rupture studies at Swarthout Creek near Wrightwood. I do not have a >digital image or report for a notable February quake yet and am looking for ideas >and suggestions. > Hi Charles: I nominate the San Fernando Earthquake of February 9, 1971. Also, are there any December 1996 issues with the San andreas Article left to purchase? I live about fifteen miles away from Swarthout Creek and go by it each and every day on my way to work. It is a must read article for me! Thanks, Frank Condon... Mail to:frankcnd@.......... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Sam Toon <serr15@...............> Subject: Re: Timing Marks for records Date: Wed, 26 Mar 1997 09:19:25 GMT On Tue, 25 Mar 1997 13:57:57 -0700 Larry Cochrane wrote: > have a fast (T1) connection to the net. I used it to see if I could use a NT > system connected up to the Internet as a time source for SDR. This method > uses a comm port between the NT system and SDR. If worked pretty well, > except for the 28K modem I use for my Internet connection. Larry, Could you tell us how to do this, we have a NT system that we can keep the time accurate on using NTP to one of our central unix machines, which in turn is synchronised with an accurate time source somewhere else on the UK academic network. We would be interested in hooking up our SDR system to the NT machine so that it could keep accurate time. Thanks, Sam ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Sam Toon serr15@......... Microseismology Research Group http://www.liv.ac.uk/~serr15/Microseis/ Dept of Earth Sciences Tel: +44 (0)151 794 5157 University of Liverpool Fax: +44 (0)151 794 5157 P.O. Box 147, Liverpool, L69 3BX United Kingdom ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane <cochrane@..............> Subject: Re: Timing Marks for records Date: Wed, 26 Mar 1997 23:49:26 -0700 Hi Sam and others, The first thing to do is download the freeware port of NTP for NT. I have a copy of it on my backup system at: ftp://ftp.seismicnet.com/users/psn/software/ntxntpbin-gui.zip (~1meg file) If you don't have a 32 bit (for the long file names) unzip program you should also get: ftp://ftp.seismicnet.com/users/psn/software/unzip.exe After unziping the file, all you need to do is run the setup program. The setup program will ask you for one or two IP address of a NTP time server. After entering the IP numbers the setup program will do the rest. The NTP program runs as a service. At this point your NT system should have fairly accurate time, but your mileage may very.... Now you need to connect SDR up to your NT system using a serial cable. Remember to use a NULL mode or somehow swap the receive and transmit lines. You don't need any handshaking lines for this too work. In a few days I will release a small 32 bit command line program that will simply open a comm port and sit there waiting for a time request from SDR. When it gets the request, it reads the system time of the NT system and send it back to SDR. At that point SDR should be "locked" to the time reference. I will let you know when I have my time server ready. I already have it written but I need to do some cleanup work on it before I release it. Regards, Larry Cochrane Redwood City, PSN At 09:19 AM 3/26/97 GMT, Sam Toon wrote: >>On Tue, 25 Mar 1997 13:57:57 -0700 Larry Cochrane wrote: > >> have a fast (T1) connection to the net. I used it to see if I could use a >NT >> system connected up to the Internet as a time source for SDR. This method >> uses a comm port between the NT system and SDR. If worked pretty well, >> except for the 28K modem I use for my Internet connection. > >Larry, > Could you tell us how to do this, we have a NT system that we can >keep the time accurate on using NTP to one of our central unix machines, >which in turn is synchronised with an accurate time source somewhere else >on the UK academic network. We would be interested in hooking up our SDR >system to the NT machine so that it could keep accurate time. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Tony Carrasco <tcarrasc@................> Subject: I need direction! Date: Thu, 27 Mar 1997 11:09:40 -0800 (PST) Hello, I have been on the Public Seismic Network since February, just as an observer, now I need some help. I am a technician here at San Diego State University in the Geology Department. We have, in our department three drum seismographs, only one of which that is currently receiving any seismic information. The system at this time has no real scientific value for any of the Faculty in the department, and is set-up for student enjoyment only. I would like to see our system become computerized, giving the students a more "hands-on" learning experience using a program like WINQUAKE. I need some direction on how to achieve this goal. Currently the system is running off a phoneline we tap-off of Scripps Institute of Oceanography, which is in turn downcoming from Caltech. What is on the line is eight carrier frequencies modulated to give the data channels for different stations (680-3060 Hz). Currently we run the phoneline through a Kinemetrics Model DM-2 three channel discriminator, the output signal is then sent to our pen driver amplifiers and pens. As much as I like the drum system, and all its temperments, I think it is time for a change. Any help would be appreciated, thanks; Tony Carrasco <tcarrasc@................> _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Barry Lotz <gbl@.......> Subject: "swarm" Date: Thu, 27 Mar 1997 18:42:50 -0800 To all- Boy ! Fairfield Calif (38.15 N 121.93 W) sure had an "unusual" number of events around 3.0 today. To many to upload. Regards Barry _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Dennis Leatart <ASTROSEEK@.........> Subject: Re: "swarm" Date: Thu, 27 Mar 1997 19:45:16 -0800 Barry-- Can you give us anymore info. on these quake swarms in your area-- I heard on the news there were something like 14 events in the past two days-- is their any pattern? -- _____ __ | \.-----.-----.-----.|__|.-----. | -- | -__| | || ||__ --| |_____/|_____|__|__|__|__||__||_____| _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane <cochrane@..............> Subject: Re: "swarm" Date: Thu, 27 Mar 1997 20:06:15 -0700 At 07:45 PM 3/27/97 -0800, Dennis wrote: >Barry-- > >Can you give us anymore info. on these quake swarms in your area-- I >heard on the news there were something like 14 events in the past two >days-- is their any pattern? This is from finger quake@.................... 97/03/26 12:34:29 38.16N 121.93W 22.2 2.2Md 13 km SE of Fairfield, CA 97/03/26 14:01:42 38.17N 121.94W 18.1 2.1Md 12 km SE of Fairfield, CA 97/03/26 14:06:24 38.15N 121.93W 21.4 2.4Md 14 km SE of Fairfield, CA 97/03/26 15:34:59 38.15N 121.93W 21.1 2.8Md 14 km SE of Fairfield, CA 97/03/27 10:10:45 38.15N 121.94W 21.0 2.8Ml 14 km SE of Fairfield, CA 97/03/27 10:26:35 38.15N 121.94W 21.1 2.9Md 13 km SE of Fairfield, CA 97/03/27 11:11:24 38.15N 121.93W 21.4 2.8Md 14 km SE of Fairfield, CA 97/03/27 11:30:07 38.15N 121.94W 21.2 3.2Ml 13 km SE of Fairfield, CA 97/03/27 13:38:08 38.15N 121.93W 20.4 3.0Ml 14 km SE of Fairfield, CA 97/03/27 14:01:24 38.15N 121.94W 21.5 3.0Ml 14 km SE of Fairfield, CA 97/03/27 15:39:49 38.15N 121.94W 21.4 3.5Ml 14 km SE of Fairfield, CA 97/03/27 17:07:37 38.16N 121.92W 19.8 2.4Md 14 km SE of Fairfield, CA 97/03/27 17:16:42 38.16N 121.94W 20.9 2.7Ml 13 km SE of Fairfield, CA 97/03/27 18:01:43 38.15N 121.94W 21.4 3.0Ml 13 km SE of Fairfield, CA 97/03/27 20:40:00 38.15N 121.93W 20.9 2.3Md 14 km SE of Fairfield, CA 97/03/27 22:16:18 38.16N 121.94W 21.2 2.6Md 13 km SE of Fairfield, CA 97/03/27 22:47:53 38.15N 121.94W 21.2 3.3Ml 14 km SE of Fairfield, CA 97/03/27 22:53:07 38.15N 121.94W 21.5 3.1Ml 13 km SE of Fairfield, CA 97/03/27 22:56:27 38.17N 121.93W 20.3 2.1Md 12 km ESE of Fairfield, CA This is from the automatic picking system so the numbers may be off a little. Sure is filling up my ftp disk with a lot of event files. Anything over ~2.5 triggers both of my SDR systems, producing 10 even files. I have been filtering out some of the files, like the strong motion sensor. I haven't pickup anything on them yet. -Larry Cochrane Redwood City, PSN _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Karl Cunningham <karlc@.........> Subject: Re: "swarm" Date: Thu, 27 Mar 1997 20:57:13 -0800 And what's happening at Rat Island up North. There's been a whole raft of 4.3 to 5's over the last day or so (not to mention the first one at 5.4). Think of the hard disk space you'd need if you lived there! Karl Cunningham karlc@......... At 08:06 PM 3/27/97 -0700, Larry wrote: > >Sure is filling up my ftp disk with a lot of event files. Anything over ~2.5 >triggers both of my SDR systems, producing 10 even files. I have been >filtering out some of the files, like the strong motion sensor. I haven't >pickup anything on them yet. > >-Larry Cochrane >Redwood City, PSN _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane <cochrane@..............> Subject: Re: "swarm" Date: Thu, 27 Mar 1997 21:51:26 -0700 Must be the comet<G>... I forgot to say, the events are ~77km (46mi) NE of Redwood City. Are there any theories about how swarms like this happen? It certainly not random events when so many happen this close together. The local media has not done much reporting on the local swarm because of the 39 idiots (IMHO) how killed themselves near San Diego, Ca. We won't get much local news for the next few days while the media focuses on this event.... If it would have been a slower news day, I'm sure the media would be over at the local USGS interviewing someone. The events in the Rat Islands are aftershocks (I guess) from the 6.4 event there on the 26th. Larry Cochrane At 08:57 PM 3/27/97 -0800, you wrote: >And what's happening at Rat Island up North. There's been a whole raft of >4.3 to 5's over the last day or so (not to mention the first one at 5.4). >Think of the hard disk space you'd need if you lived there! > >Karl Cunningham >karlc@......... > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: David A Nelson <dann@........> Subject: Re: "swarm" Date: Fri, 28 Mar 1997 18:43:30 +1200 barry, pick out several of the best looking ones to upload thanks Dave At 06:42 PM 3/27/97 -0800, you wrote: >To all- > Boy ! Fairfield Calif (38.15 N 121.93 W) sure had an "unusual" number >of events around 3.0 today. To many to upload. > Regards > Barry Dave A. Nelson 24 Jensen St., Green Is., Dunedin, South Is.. New Zealand. http://psn.quake.net/dave/home.htm ( world wide access ) http:/www.es.co.nz/~dann/home.html ( New Zealand access only ) SOD'SLAW-- When Something Does Go Wrong, There Is Sod All You Can Do AboutIt When The Last Of Ten Screws Has Been Removed From A Cover, It Will Be Discovered That The Wrong Cover Has Been Removed When The Last Of Ten Screws Has Been fitted back Into A Cover, It Will Be Discovered That The gasket Has Been Left Out _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: watson@................ (Charles Watson) Subject: Re: "swarm" Date: Thu, 27 Mar 1997 10:52:06 -0800 I issued this bulletin earlier today regarding the Fairfield swarm: http://www.seismo-watch.com/EQS/AB/9703/A970327-073.SFdelta.html There has been a pair of M3.0s since. -- ---/---- Charles P. Watson, Consulting Geologist Advanced Geologic Exploration Seismo-Watch / Earthquake Information Services Voice: 702-852-0992 / Fax: 702-852-3226 mailto:watson@................ http://www.seismo-watch.com _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: David Wolny <dwolny@.......................> Subject: Re: "swarm" Date: Fri, 28 Mar 1997 12:32:59 -0700 (MST) On Thu, 27 Mar 1997, Larry Cochrane wrote: > > This is from finger quake@.................... > 97/03/26 12:34:29 38.16N 121.93W 22.2 2.2Md 13 km SE of Fairfield, CA > 97/03/26 14:01:42 38.17N 121.94W 18.1 2.1Md 12 km SE of Fairfield, CA > 97/03/26 14:06:24 38.15N 121.93W 21.4 2.4Md 14 km SE of Fairfield, CA > 97/03/26 15:34:59 38.15N 121.93W 21.1 2.8Md 14 km SE of Fairfield, CA > 97/03/27 10:10:45 38.15N 121.94W 21.0 2.8Ml 14 km SE of Fairfield, CA > 97/03/27 10:26:35 38.15N 121.94W 21.1 2.9Md 13 km SE of Fairfield, CA > 97/03/27 11:11:24 38.15N 121.93W 21.4 2.8Md 14 km SE of Fairfield, CA > 97/03/27 11:30:07 38.15N 121.94W 21.2 3.2Ml 13 km SE of Fairfield, CA > 97/03/27 13:38:08 38.15N 121.93W 20.4 3.0Ml 14 km SE of Fairfield, CA > 97/03/27 14:01:24 38.15N 121.94W 21.5 3.0Ml 14 km SE of Fairfield, CA > 97/03/27 15:39:49 38.15N 121.94W 21.4 3.5Ml 14 km SE of Fairfield, CA > 97/03/27 17:07:37 38.16N 121.92W 19.8 2.4Md 14 km SE of Fairfield, CA > 97/03/27 17:16:42 38.16N 121.94W 20.9 2.7Ml 13 km SE of Fairfield, CA > 97/03/27 18:01:43 38.15N 121.94W 21.4 3.0Ml 13 km SE of Fairfield, CA > 97/03/27 20:40:00 38.15N 121.93W 20.9 2.3Md 14 km SE of Fairfield, CA > 97/03/27 22:16:18 38.16N 121.94W 21.2 2.6Md 13 km SE of Fairfield, CA > 97/03/27 22:47:53 38.15N 121.94W 21.2 3.3Ml 14 km SE of Fairfield, CA > 97/03/27 22:53:07 38.15N 121.94W 21.5 3.1Ml 13 km SE of Fairfield, CA > 97/03/27 22:56:27 38.17N 121.93W 20.3 2.1Md 12 km ESE of Fairfield, CA > > This is from the automatic picking system so the numbers may be off a little. > > Sure is filling up my ftp disk with a lot of event files. Anything over ~2.5 > triggers both of my SDR systems, producing 10 even files. I have been > filtering out some of the files, like the strong motion sensor. I haven't > pickup anything on them yet. > > -Larry Cochrane > Redwood City, PSN > Greetings Larry, If the sequence of events stands as is after review, the depth, small area of focal point, and magnitudes look more reminiscent of something that would be seen associated with the Long Valley Caldera. This swarm seems to lack a definitive main shock. Unless you consider the main shock to be the 3.5 at 15:39 on the 27th. Sure got there slowly if the 3.5 stands as a main shock. Dave Wolny Grand Junction, Colo. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: watson@................ (Charles Watson) Subject: Re: "swarm" Date: Fri, 28 Mar 1997 00:47:48 -0800 Dave, Earthquake swarms by difinition do not need a main shock. They tend to tick on and off and consist a variety of events with comparable magnitudes within a "short" space of time. Although no one knows for sure, the swarms at Mammoth are beleived to be related to thermal activities associated to the Long Valley caldera. I would think any comparison between the Grizzly Island swarm in the San Francisco Delta with Mammoth Lakes seismicty would be..stretching it. The Grizzly Island sequence falls along a known seismic trend of reoccurring activity. Although the sequence appears unusual, consider the Rodgers Creek fault sequence that occurred in January/February. A number of quakes, including a trio of M3.0s, triggered a few miles east of Rohnart Park for several weeks - all at about the same hypocenter. In fact another M2.4 eveent was recorded there this past week. The Grizzly Island sequence is different, I admit, and raise considerable interest on where it may go from here. Be cool to set out some portables...It's too bad the Antioch-Vacaville-Winters trio of M6s in the 1890s weren't instrumented. :-( Could have told us a lot about how this sequence may go... Two guines for a M4? -- ---/---- Charlie _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Barry Lotz <gbl@.......> Subject: Re: "swarm" Date: Sat, 29 Mar 1997 14:41:49 -0800 Charles Watson wrote: > > > Two guines for a M4? > > -- > ---/---- You got my vote. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: watson@................ (Charles Watson) Subject: Thrust animation Date: Sun, 30 Mar 1997 10:11:10 -0800 Got this shareware web animation program called GifBuilder 0.5 a few months back and as I try to avoid the things I really need to do, like my taxes, I broke it out and fiddle-squarted around with it. Just for fun, I tried to show the motion of a thrust fault. Take a look: http://www.seismo-watch.com/HomeHTML/Animation/Thrust1.gif I used the new Macromedia Freehand 7.0 to make the graphic and just nudged the hanging wall block up a few knotches before saving it each time as a tiff file. Had to throw a few white blocks in blot out the background behind the trees and to size the top of the graphic. And just for fun, I had the nose of the thrust block break off and send tree and a bunch of dirt down the scarp for the final frame. Made the graphic a bit too small,as you will see, but cute never the less. Gosh, this animation stuff has a lot of potential. -- ---/---- Charlie _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: David A Nelson <dann@........> Subject: Re: Thrust animation Date: Mon, 31 Mar 1997 21:11:32 +1200 Charles, not bad at all, well done will we see a subduction zone next ???? Cheers Dave At 10:11 AM 3/30/97 -0800, you wrote: >Got this shareware web animation program called GifBuilder 0.5 a few >months back and as I try to avoid the things I really need to do, like >my taxes, I broke it out and fiddle-squarted around with it. > >Just for fun, I tried to show the motion of a thrust fault. Take a look: > >http://www.seismo-watch.com/HomeHTML/Animation/Thrust1.gif > Dave A. Nelson 24 Jensen St., Green Is., Dunedin, South Is.. New Zealand. http://psn.quake.net/dave/home.htm ( world wide access ) http:/www.es.co.nz/~dann/home.html ( New Zealand access only ) SOD'SLAW-- When Something Does Go Wrong, There Is Sod All You Can Do AboutIt When The Last Of Ten Screws Has Been Removed From A Cover, It Will Be Discovered That The Wrong Cover Has Been Removed When The Last Of Ten Screws Has Been fitted back Into A Cover, It Will Be Discovered That The gasket Has Been Left Out _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Edward Cranswick <cranswick@........> Subject: Re: seismologist TV stars Date: Mon, 31 Mar 1997 10:58:12 -0700 Steve- I believe that Beyond 2000 filmed at your house and the USGS in February 1991, during the Gulf War. -Edward Steve Hammond wrote: > > Hi Dave, That--- that was the first year we started the PSN in 1990. The > house in the tape is mine in San Jose. It was a lot of fun. The Beyond 2K > crew spent the day. I don't think my guarge will ever be that clean again. > The data they were showing was from the old FX1 seismograph. Watch it > again and you will understand why I never went into acting... > Regards, Steve > > On Sun, 2 Mar 1997, David A Nelson wrote: > > > to Steve Hammond and Edward Cranswick, > > > > I just recorded you guys on video tape today, Both of you were involved > > with an item on seismology on the BEYOND 2000 program. > > > > for the others info BEYOND 2000 is an Australian produced program which > > looks at scientific breakthroughs and general science items from around the > > world. > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 1711 Illinois St cranswick@........ Golden, CO 80401 USA E.M. Forster said, "Only connect". _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: lahr@................. (Dr. John Lahr (USGS-GI Seismologist)) Subject: Rat Islands Earthquakes Date: Mon, 31 Mar 1997 10:52:52 -0900 The continuing activity in the Rat Islands is quite interesting. This portion of the arc was ruptured by an MW 8.6 earthquake in 1957 which allowed a 900 km-wide portion of the Pacific plate to subduct a bit deeper beneath the Bearing Sea, which is part of the North American Plate. In 1986 a 225-km wide portion of the 1957 zone located south and east of Adak Island broke again in a magnitude MW 8.0 event. This left two portions of the 1957 break still unbroken: a 175-km wide zone on the west and a 500-km wide zone on the east. On June 10, 1996, a magnitude MW 7.9 earthquake extended the reruptured portion of the 1957 break another 125-km to the west, possibly falling short by about 50 km from rupturing all the way to the western limit of the 1957 break. The recent MW 6.6 event on March 26 at 02:08 UT and its aftershocks are located very near the western limit of the 1957 rupture zone. Is this it for the western end of the 1957 break, or will there be more action in the near future? What about rerupture of the eastern portion of the 1957 zone? Stay tuned to see what happens. (To be continued, on a geologic time scale.) JCLahr _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L)