Subject: Re: Big Quake From: twleiper@........ Date: Sat, 1 Apr 2000 11:48:17 -0500 Did anybody get a good trace on the mag 8.9 KERMADEC ISLANDS REGION event this morning? __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: R: Big Quake From: "Francesco" franuc@...... Date: Sat, 1 Apr 2000 19:23:05 +0200 Kermadec big quake? 1st April fish..............? ehehehe __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Big Quake From: John Hernlund hernlund@....... Date: Sat, 01 Apr 2000 12:24:01 -0700 (MST) On Sat, 1 Apr 2000 twleiper@........ wrote: > Did anybody get a good trace on the mag 8.9 KERMADEC ISLANDS REGION event > this morning? I haven't checked anything yet, but I was unable to find any reference to this event on the web. An 8.9 will be picked up by EVERYONE on the entire planet very strongly. In fact, the Earth would be oscillating for days after such a strong event in the low frequency modes. You might also expect strong tsunamis and other damage. Are you certain it was 8.9??? Where can I find more info??? John Hernlund E-mail: hernlund@....... WWW: http://www.public.asu.edu/~hernlund/ ****************************************************************************** __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Big Quake From: meredith lamb mlamb1@.......... Date: Sat, 01 Apr 2000 14:54:54 -0800 John Hernlund wrote: > On Sat, 1 Apr 2000 twleiper@........ wrote: > > Did anybody get a good trace on the mag 8.9 KERMADEC ISLANDS REGION event > > this morning? > > I haven't checked anything yet, but I was unable to find any reference to this > event on the web. An 8.9 will be picked up by EVERYONE on the entire planet > very strongly. In fact, the Earth would be oscillating for days after such a > strong event in the low frequency modes. You might also expect strong > tsunamis and other damage. Are you certain it was 8.9??? Where can I find > more info??? > > John Hernlund > E-mail: hernlund@....... > WWW: http://www.public.asu.edu/~hernlund/ > Well.....I certainly did....on my new "black hole seismograph". Unfortunately, its all theoretical as informatiion can't be retrieved.....but you can trust me here..... Meredith Lamb __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Big Quake From: Edward Cranswick cranswick@........ Date: Sat, 01 Apr 2000 15:06:22 -0700 Meredith- I understand you also recorded the recent M6.7 Parkfield earthquake on the same instrument. Would you like a job at the USGS? -Edward > Well.....I certainly did....on my new "black hole seismograph". > Unfortunately, its all theoretical as informatiion can't be > retrieved.....but you can trust me here..... > > Meredith Lamb -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 PO Box 25046, Federal Center cranswick@........ Denver, CO 80225-0046 USA E.M. Forster said, "Only connect". __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Big Quake From: twleiper@........ Date: Sat, 1 Apr 2000 17:38:17 -0500 John - I believe it was very nearly identical in magnitude and location to a similar event last April 1st. On Sat, 01 Apr 2000 12:24:01 -0700 (MST) John Hernlund writes: > On Sat, 1 Apr 2000 twleiper@........ wrote: > > Did anybody get a good trace on the mag 8.9 KERMADEC ISLANDS > REGION event > > this morning? > > I haven't checked anything yet, but I was unable to find any > reference to this > event on the web. An 8.9 will be picked up by EVERYONE on the > entire planet > very strongly. In fact, the Earth would be oscillating for days > after such a > strong event in the low frequency modes. You might also expect > strong > tsunamis and other damage. Are you certain it was 8.9??? Where can > I find > more info??? > > John Hernlund > E-mail: hernlund@....... > WWW: http://www.public.asu.edu/~hernlund/ > > ************************************************************************* ***** > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Big Quake From: ChrisAtUpw@....... Date: Sat, 1 Apr 2000 18:18:54 EST Tom, You really will have to get something done about that Beech Tree of yours. Chris __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Big Quake From: meredith lamb mlamb1@.......... Date: Sat, 01 Apr 2000 20:39:08 -0800 Edward Cranswick wrote: > Meredith- > I understand you also recorded the recent M6.7 Parkfield earthquake on the same > instrument. Would you like a job at the USGS? > -Edward > > > Well.....I certainly did....on my new "black hole seismograph". > > Unfortunately, its all theoretical as informatiion can't be > > retrieved.....but you can trust me here..... > > > > Meredith Lamb > Edward, Hey thanks Edward! Have my own job ideas with Ur Seismic Guessing Service (USGS). Figure I could start my own department called JIVE; Just Invalid Variable Entrys. Good thing too.....its hell standing on a streetcorner with a placard. :) Meredith __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Big Quake From: John Hernlund hernlund@....... Date: Mon, 03 Apr 2000 02:22:37 -0700 (MST) On Sat, 1 Apr 2000 twleiper@........ wrote: > John - I believe it was very nearly identical in magnitude and location > to a similar event last April 1st. Yes, and I probably fell for that one too!!! And will again next year of course. Ever Gullible, John Hernlund E-mail: hernlund@....... WWW: http://www.public.asu.edu/~hernlund/ ****************************************************************************** __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Cal Day at Berkeley University on 4/15/00 From: Larry Cochrane cochrane@.............. Date: Mon, 03 Apr 2000 13:25:28 -0700 Greeting, If you are in the SF Bay Area you might be interested in the open house at Berkeley Univ. The Seismo Lab will be open for tours and Professor Bruce Bolt will be giving a talk on "What Have the 1999 Earthquakes in Taiwan and Turkey Taught Us?". For more information see http://www.seismo.berkeley.edu/seismo/seismo.calday.html. Regards, Larry Cochrane Redwood City, PSN __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Geophone layout From: "Robert W. Avakian" ravakian@............ Date: Mon, 03 Apr 2000 19:00:56 -0500 So, how did things work out?? Bob Avakian Thomas wrote: > > Hi everyone, > > I am 4th year student working a project using geophones to measure ice > thicknes. Is there a special method to layout the geophones to get an > accurate profile an induced vibration? The purposal is to generate an > acoustic pulse through possibly several kilometers of ice and have the > geophones detect this pulse and derive the ice thickness. Would anyone have > suggestions on a detonation mechanism? I've heard people use 1 kg of > dynamite for 1 km of ice. > > As you can see, I am not too familiar with geophones but I do know they work > like an accelerator. If anyone knows of a good book, please suggest it > because none of our group members are geology people. > > Thanks alot for your time. > > Thomas Looi > Aerospace Engineering > University of Toronto > > _____________________________________________________________________ > > 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) Subject: Article on gravimeters From: George Bush gbush@....... Date: Tue, 04 Apr 2000 09:44:57 -0700 I just discovered an interesting article on the development of an absolute differential gravimeter that appeared in an unusual place. As a ametuer seismometer builder, I found the article fascinating to see what the big boys do. The article appeared in the March 2000 issue of "Laser Focus World," on pp20-24. For you non-subscribers the article can be seen on the web at: http://lfw.pennwellnet.com/home/articles.cfm?ARTICLE_ID=66006&VERSION_NUM=1& PUBLICATION_ID=12&Section=CurrentIssue Now I have had trouble emailing long URL's before, so if this isn't clickable, try to copy and paste it into the address box of your browser. And if that doesn't work you can go the the magazine's main web address http://lfw.pennwellnet.com/home/home.cfm and then select "current Issue" then World News" then the article "Interferometry, Fiber Coupling improves Gravimeters" George Bush Sea Ranch, CA, USA 38.74N, 123.5W __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Fwd: USGS: Geomagnetic Storm Alert From: The Lahrs JohnJan@........ Date: Thu, 06 Apr 2000 17:46:16 -0600 >------------- Begin Forwarded Message ------------- > >Date: Thu, 6 Apr 2000 18:01:09 -0400 >From: tharlow@........ >To: outreach@...................... >Subject: USGS: Geomagnetic Storm Alert > > >Media Advisory Address >U.S. Department of the Interior PO Box 25046, MS 150 >U.S. Geological Survey Denver, CO 80225 > > >Release Contact Phone E-mail >April 6, 2000 Don Herzog 303-273-8487 >herzog@........ >Geomagnetic Storm Alert > >The U.S. Geological Survey (USGS) reports a sudden increase in geomagnetic >activity that may signal the onset of a geomagnetic storm. While it is >geomagnetic storms that give rise to the beautiful Northern lights, they >can also pose a serious threat for commercial and military satellite >operators, power companies, astronauts, and they can even shorten the life >of oil pipelines in Alaska by increasing pipeline corrosion. > >A significant increase in geomagnetic activity was observed at about 12:45 >p.m. (E.T) on Thursday, April 6, 2000. Space Weather sources at NOAA & >NASA indicate that the likely cause of this increased activity is due to an >interplanetary shock wave that was detected by the ACE satellite at about >12:30 p.m. (E.T) today. Magnetic activity increased at all USGS magnetic >observatories about 15 minutes later and could be significant over the next >24-48 hours. If this geomagnetic activity continues, there is the >possibility for visible aurora at mid-latitudes. Plots of the data from >these observatories can be seen on-line at: >http://geomag.usgs.gov/frames/plots.htm > >Geomagnetic storms occur when plasma, a hot ionized gas of charged >particles produced by eruptions on the Sun, impacts the Earth's magnetic >field causing it to fluctuate wildly. These fluctuations cause currents to >flow in conductors on the ground and in space. Solar eruptions can produce >billions of tons of plasma traveling at speeds in excess of a million miles >an hour. > >The USGS provides valuable geomagnetic data to a wide variety of users and >organizations that are affected by geomagnetic storms. The agency operates >a network of 14 magnetic observatories that continuously monitor the >Earth's magnetic field. The data are collected in near-real time via >satellite to a downlink center located in Golden, Colo., and provided to >numerous customers including NOAA's Space Environment Center and the U.S. >Air Force Space Command Center. > >As the nation's largest water, earth and biological science, and civilian >mapping agency, the USGS works in cooperation with more than 2000 >organizations across the country to provide reliable, impartial, scientific >information to resource managers, planners, and other customers. This >information is gathered in every state by USGS scientists to minimize the >loss of life and property from natural disasters, to contribute to the >conservation and the sound economic and physical development of the >nation's natural resources, and to enhance the quality of life by >monitoring water, biological, energy, and mineral resources. > ### USGS ### > >This press release and in-depth information about USGS programs may be >found on the USGS home page: http://www.usgs.gov . To receive the latest >USGS news releases automatically by email, send a request to >listproc@................... . Specify the listserver(s) of interest from >the following names: water-pr; geologic-hazards-pr; biological-pr; >mapping-pr; products-pr; lecture-pr. In the body of the message write: >subscribe (name of listserver) (your name). Example: subscribe water-pr joe >smith. > > > >------------- End Forwarded Message ------------- * John C. and Jan H. Lahr * JohnJan@........ * 1925 Foothills Road * Golden, Colorado 80401-1718 * (303) 215-9913 * http://lahr.org/john-jan __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Fwd: Geomagnetic activity From: The Lahrs JohnJan@........ Date: Thu, 06 Apr 2000 17:47:27 -0600 >------------- Begin Forwarded Message ------------- >Date: Thu, 06 Apr 2000 16:22:41 -0600 >From: "Donald C. Herzog" >Subject: Geomagnetic activity > >April 6,2000 > >Team members: > >Sorry for the late notice, but we had a interplanetary shock wave hit late >this morning with an accompanying sharp increase in the solar wind >velocity, and a corresponding sharp increase in geomagnetic activity. The >magnetic field continues to be disturbed, and there could be aurora visible >at mid-latitudes tonight. > >Attached is a graphic showing the location of the aurora as of about 4 pm >local (Denver) time today. Red indicates intense auroral displays. You can >see that northern Russia and the Scandinavian countries are having auroral >sightings right now, and as it stands, it is likely that this will expand >into the northern US as we pass into the night. The best time for viewing >is around midnight, and look to the northern horizon. > >Don >------------- End Forwarded Message ------------- > >Content-Type: IMAGE/gif; name="aurora_040600.gif" >Content-Description: aurora_040600.gif >Content-MD5: EyEtFmyTyfY63dY31rP0lQ== > >Content-Type: TEXT/plain; name=NoName; charset=us-ascii >Content-Description: NoName >Content-MD5: oxOYuLYLDvySc7SuTsOAyg== > > >------------------------------------------------------- >Donald C. Herzog TEL: 303.273.8487 >U.S. Geological Survey FAX: 303.273.8600 >Box 25046 MS 966 herzog@................... >Denver Federal Center http://geomag.usgs.gov >Denver, CO 80225-0046 >USA * John C. and Jan H. Lahr * JohnJan@........ * 1925 Foothills Road * Golden, Colorado 80401-1718 * (303) 215-9913 * http://lahr.org/john-jan __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Wavelength of Surface Waves From: Paul Jebb pfjebb@.............. Date: Fri, 07 Apr 2000 15:00:58 -0400 Dear Members, I am trying to getting a feeling for the S- waves that our Lehman seismometer will detect. If the period of the boom must be adjusted to around 20 seconds or greater, what is the wavelength of these waves. My back-of-an-envelope estimate (v=fl) is in the order of 100 km. Is that reasonable? What is a typical amplitude for such a wave? Paul Jebb Newcomb Central School Dear Members,
I am trying to getting a feeling for the  S- waves that our Lehman seismometer will detect.  If the period of the boom must be adjusted to around 20 seconds or greater, what is the wavelength of these waves.  My back-of-an-envelope estimate (v=fl) is in the order of 100 km.  Is that reasonable?  What is a typical amplitude for such a wave?
Paul Jebb
Newcomb Central School Subject: Lehman Construction Questions... From: Brad Rogers rogers_psn@............. Date: 9 Apr 2000 07:23:30 -0700 I'm in the early stages of constructing a Lehman type seimometer, and have a few questions for the list.... Can anyone give me a good explaination of the tradeoffs involved between: 1) strength of the magnet used in the pickup on a Lehman seismometer, 2) the number of windings in the pickup coil, 3) the bit resolution of my A->D board? I have a 12 bit A->D board, and live in central New York state. Will I gain additional sensitivity by increasing the strength of the magnet used in the pickup? If I use a stronger magnet do I need to increase the number of windings in the coil? I have a couple magnet options, with one being a 24 pound pull, and the second being a 30 pound pull. The difference in cost is not great, but do I gain anything by using a stronger magnet? My second line of questioning is the construction of the boom. For teleseismic events I obviously want the longest period poss ible. Certainly the period can be lengthened by careful adjustment of the boom balance. But I'm also assuming that this delic ate balancing act can be simplified by: 1) slightly lengthening the boom, 2) getting the lead mass as close to the outside end of the boom as possible, and 3) putting the attachment point for the suspending wire as close to the outside end of the boom as possible. 4) I'm also assuming that I want to get the pickup coil as far out on the boom as possible, in order to increase its range of m otion. At least these things would seem to be intuitively true. Are they? Or am I missing something. Thanks, --Brad Rogers ____________________________________________________________________ For the largest MP3 index on the Web, go to http://mp3.altavista.com ____________________________________________________________________ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Lehman Construction Questions... From: Brad Rogers rogers_psn@............. Date: 9 Apr 2000 07:23:30 -0700 I'm in the early stages of constructing a Lehman type seimometer, and have a few questions for the list.... Can anyone give me a good explaination of the tradeoffs involved between: 1) strength of the magnet used in the pickup on a Lehman seismometer, 2) the number of windings in the pickup coil, 3) the bit resolution of my A->D board? I have a 12 bit A->D board, and live in central New York state. Will I gain additional sensitivity by increasing the strength of the magnet used in the pickup? If I use a stronger magnet do I need to increase the number of windings in the coil? I have a couple magnet options, with one being a 24 pound pull, and the second being a 30 pound pull. The difference in cost is not great, but do I gain anything by using a stronger magnet? My second line of questioning is the construction of the boom. For teleseismic events I obviously want the longest period poss ible. Certainly the period can be lengthened by careful adjustment of the boom balance. But I'm also assuming that this delic ate balancing act can be simplified by: 1) slightly lengthening the boom, 2) getting the lead mass as close to the outside end of the boom as possible, and 3) putting the attachment point for the suspending wire as close to the outside end of the boom as possible. 4) I'm also assuming that I want to get the pickup coil as far out on the boom as possible, in order to increase its range of m otion. At least these things would seem to be intuitively true. Are they? Or am I missing something. Thanks, --Brad Rogers ____________________________________________________________________ For the largest MP3 index on the Web, go to http://mp3.altavista.com ____________________________________________________________________ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: seis dynamic range From: S-T Morrissey sean@........... Date: Sun, 9 Apr 2000 14:56:04 -0500 (CDT) Paul, You correctly estimate of the wavelength of surface waves for a 20 second wave (0.05hz) with a velocity of 5 km/second as 100 km. (using v = f * l; or wavelength = velocity * period) Most people don't realize this. The longest waves seen are the fundamental free oscillations of the earth at 51 minutes, where the wavelength is the earths' circumference. Even near field P waves of 15 hz at 7.5 km/sec have wavelenghts of half a kilometer. You also asked about the dynamic range required of seismometers. Here is a repeat of a previous discussion on the subject. (August 99) The range of ground motions expected from earthquakes as recorded by a seismometer is hugh. Obviously if "you are there" at the fault scarp, you will need an accelerometer with a range up to 2gs. But most instrumental seismology follows general magnitude formulas of the classic form: M = log(A/T) + 1.66*log(distance) + constant. The constant is a regional variable, usually about -0.18. The distance is degrees (111 km per), A is the ground amplitude in nanometers, (a nanometer = 10^-9 meter; in older data it was called a millimicron.) and T is the period of the wave in seconds. For Ms calculations, A is the sustained peak-peak surface wave amplitude. You can plug in numbers for various scenarios. To answer your question about what will happen in the seismometer, solve for A: log(A/T) = Ms - 1.66*log(distance) + 0.18 A = T*log^-1(Ms -1.66*log(d) + 0.18.) The first step though is to convert the velocity output of the seismometer to displacement by dividing by omega, w = 2*pi/period. For the Turkey quake: the record here (St. Louis) was 150 microns/second at 24 seconds. 24 seconds is an w (omega) of 2*pi/24 = 0.262radian/sec. The velocity is converted to displacement by dividing by w, so 150/0.262 = 573 microns or 5.73x10^5 nanometers. (0.573 millimeters) (Every seismometer should have recorded this, and many clipped). So Ms = log(5.73x10^5/24) + 1.66*log(81deg) -0.18 = 7.37 (solving for A for a maximum magnitude of 8.0 at that distance would cause 2.46 millimeters of motion at St. Louis) But what did I record for the Ms = 5.8 aftershock? A = 24[log^-1(5.8 - 3.17 + 0.18) = 15 564 nanometers. (15.5 microns) This is a velocity (at 24 seconds) of 4.07 microns/second. With an output of 5.3mv/micron/sec, the record here was about 22 millivolts p-p, (or about 10 times the 6-second microseisms; at 0.5 microns p-p; at the time they were running more than 10 times that due to the hurricane). But what about a nearby quake? Say a Ms 4.0 in the next state? Putting numbers in the formula with distance = 3 degrees (200 miles) and T = 0.3 second, the seismometer will record 0.81 microns. For a magnitude 3, it will only sense 0.081 microns or 81 nanometers. (using the more accurate local Mblg(3hz) formula gives 43 nanometers) If M = 4 and is 1000km away, the motion at 1 second will be 398 nanometers. If M = 3 and is 1000km away, the motion at 1 second will be 40 nanometers. For a threshold event, say a 2.5 at 110 km with T = 0.22 sec (4.5hz), (this magnitude formula is revised for such local events, but we'll use it anyhow) the amplitude is 105 nanometers. (using the local Mblg formula gives 56 nanometers). To record these with useful signal-to-noise ratio requires a resolution of 1 nanometer from the seismometer. SO.... we need a displacement dynamic range of 1 nanometer to 1 millimeter, or 10^6. This is one reason seismometers prefer a velocity output. Looking at such numbers:. At 10 hz, 1 nanometer is 63nm/sec. At 1 hz, it is 6.3nm/sec. At 20 seconds (a broadband instrument) 1 millimeter is 314 microns/second. This is a velocity range of about 50 000 to 1, which is the same as the voltage output range. Until recently this range was difficult to handle with analog electronics, so multi-level recording was used. A 16-bit digitizer can realize this if noise is ignored. Providing for noise and instrumental drift increases the required range by a factor of 100 to 1000. So modern broadband stations use 24-bit digitizers with a resolution of 1 part on 16 777 216 with a least count value of 1.2 microvolts. For a seismometer with a VBB velocity output of 2000 volts/meter/second, the LSB represents 1.67 nanometers/sec. The maximum value is 10 millimeters/second p-p. Regards, Sean-Thomas __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: seis dynamic range From: "Kareem Lanier" kareemjupiter@............. Date: Sun, 9 Apr 2000 13:36:10 -0700 Paul, How do you get rid of all the local high-frequency noise? (My delimma) -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of S-T Morrissey Sent: Sunday, April 09, 2000 12:56 PM To: psn-l@.............. Subject: seis dynamic range Paul, You correctly estimate of the wavelength of surface waves for a 20 second wave (0.05hz) with a velocity of 5 km/second as 100 km. (using v = f * l; or wavelength = velocity * period) Most people don't realize this. The longest waves seen are the fundamental free oscillations of the earth at 51 minutes, where the wavelength is the earths' circumference. Even near field P waves of 15 hz at 7.5 km/sec have wavelenghts of half a kilometer. You also asked about the dynamic range required of seismometers. Here is a repeat of a previous discussion on the subject. (August 99) The range of ground motions expected from earthquakes as recorded by a seismometer is hugh. Obviously if "you are there" at the fault scarp, you will need an accelerometer with a range up to 2gs. But most instrumental seismology follows general magnitude formulas of the classic form: M = log(A/T) + 1.66*log(distance) + constant. The constant is a regional variable, usually about -0.18. The distance is degrees (111 km per), A is the ground amplitude in nanometers, (a nanometer = 10^-9 meter; in older data it was called a millimicron.) and T is the period of the wave in seconds. For Ms calculations, A is the sustained peak-peak surface wave amplitude. You can plug in numbers for various scenarios. To answer your question about what will happen in the seismometer, solve for A: log(A/T) = Ms - 1.66*log(distance) + 0.18 A = T*log^-1(Ms -1.66*log(d) + 0.18.) The first step though is to convert the velocity output of the seismometer to displacement by dividing by omega, w = 2*pi/period. For the Turkey quake: the record here (St. Louis) was 150 microns/second at 24 seconds. 24 seconds is an w (omega) of 2*pi/24 = 0.262radian/sec. The velocity is converted to displacement by dividing by w, so 150/0.262 = 573 microns or 5.73x10^5 nanometers. (0.573 millimeters) (Every seismometer should have recorded this, and many clipped). So Ms = log(5.73x10^5/24) + 1.66*log(81deg) -0.18 = 7.37 (solving for A for a maximum magnitude of 8.0 at that distance would cause 2.46 millimeters of motion at St. Louis) But what did I record for the Ms = 5.8 aftershock? A = 24[log^-1(5.8 - 3.17 + 0.18) = 15 564 nanometers. (15.5 microns) This is a velocity (at 24 seconds) of 4.07 microns/second. With an output of 5.3mv/micron/sec, the record here was about 22 millivolts p-p, (or about 10 times the 6-second microseisms; at 0.5 microns p-p; at the time they were running more than 10 times that due to the hurricane). But what about a nearby quake? Say a Ms 4.0 in the next state? Putting numbers in the formula with distance = 3 degrees (200 miles) and T = 0.3 second, the seismometer will record 0.81 microns. For a magnitude 3, it will only sense 0.081 microns or 81 nanometers. (using the more accurate local Mblg(3hz) formula gives 43 nanometers) If M = 4 and is 1000km away, the motion at 1 second will be 398 nanometers. If M = 3 and is 1000km away, the motion at 1 second will be 40 nanometers. For a threshold event, say a 2.5 at 110 km with T = 0.22 sec (4.5hz), (this magnitude formula is revised for such local events, but we'll use it anyhow) the amplitude is 105 nanometers. (using the local Mblg formula gives 56 nanometers). To record these with useful signal-to-noise ratio requires a resolution of 1 nanometer from the seismometer. SO.... we need a displacement dynamic range of 1 nanometer to 1 millimeter, or 10^6. This is one reason seismometers prefer a velocity output. Looking at such numbers:. At 10 hz, 1 nanometer is 63nm/sec. At 1 hz, it is 6.3nm/sec. At 20 seconds (a broadband instrument) 1 millimeter is 314 microns/second. This is a velocity range of about 50 000 to 1, which is the same as the voltage output range. Until recently this range was difficult to handle with analog electronics, so multi-level recording was used. A 16-bit digitizer can realize this if noise is ignored. Providing for noise and instrumental drift increases the required range by a factor of 100 to 1000. So modern broadband stations use 24-bit digitizers with a resolution of 1 part on 16 777 216 with a least count value of 1.2 microvolts. For a seismometer with a VBB velocity output of 2000 volts/meter/second, the LSB represents 1.67 nanometers/sec. The maximum value is 10 millimeters/second p-p. Regards, Sean-Thomas __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Lehman Construction Questions... From: BOB BARNS roybar@........ Date: Mon, 10 Apr 2000 10:39:43 -0400 Brad, About your questions about a Lehman: 1. The magnet-coil properties are not related to bit resolution. 16 bit resolution is better than 12 bit because of the greater dynamic range achieved. See Sean-Thomas discussion of the last few days about dynamic range. 2. The output of the coil is directly proportional to the strength of the magnet and the number of turns of the coil if the geometry is the same. Since gain in the amplifier is cheap, getting enough signal from the coil is rather easy if the geometry of the coil is appropriate for the magnet. 10,000 turns (pretty easy if #40 or finer wire is used) should be enough with a reasonable horse-shoe magnet. 3. There is no reason to balance the boom-the balance does not affect the period. The length of the period depends only on the geometry of the boom and its pivot points. Call the point of emergence of the suspension wire from the top support A and the pivot point at the end of the boom (the end opposite from the magnet or coil) B. The boom should be reasonably horizontal-say within +/- 10 deg. The period is determined by the angle between the vertical and the line between A and B. If the line A-B is vertical, the period is infinite, that is, there is no stable position for the boom. The period will be long (say 24 sec.) if the line A-B is slightly (say 0.25 deg.) inclined toward the far end of the boom. Since you are 'in central New York state', I am reasonably close-in Berkeley Heights, NJ, which is about 25 miles due west of Manhattan. You are welcome to come see my Lehman. If the above is not clear, I would be happy to discuss this on the 'phone 908-464-6785 any time. Bob Barns __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Wavelength of Surface Waves From: John Hernlund hernlund@....... Date: Mon, 10 Apr 2000 10:08:35 -0700 (MST) On Fri, 7 Apr 2000, Paul Jebb wrote: > Dear Members, > I am trying to getting a feeling for the S- waves that our Lehman > seismometer will detect. Do you mean surface waves or do you mean S-waves? These are two different concepts in that an S wave travels through the interior of a body while a surface wave travels along the surface of a body because of the way it snaps back when waves arrive at the edge. When an earthquake source occurs, waves are given off at many different frequencies and different amplitudes corresponding to each frequency. If you made a plot of the amplitude vs. the frequency of the source (the fourier transform) then you would see some type of specific shape. As the distance these waves travel increases, the amplitude vs. frequency plotted at each distance will begin to keel over to the right so that higher frequencies get lower and lower faster than lower frequencies do. If you use a logarithmic scale this tilt to the right should be like tilting a straight line. As the distance from the source increases then the straight line has a more negative slope. The shape of the initial amplitude vs. frequency plot is not know in general from the earthquake source. To simplify matters a little, we often use "impulse" sources in time. This is like a sharp hammer strike with a very short duration. So the activity on the fault itself would only have a spike if you looked at displacement vs. time. It turns out that the amplitude vs. frequency plot of an impulse source is a flat line where all the frequencies have the same amplitude. This means that the straight line will begin to tilt to the right as the waves travel away as described above. Now this scenario is simplified too much to account for everything that is seen in seismograms. So instead of using a single impulse, we can approximate the true source by adding a bunch of impulses that occur in different locations and at different times along the fault. In this way, a very accurate model can be made. So since we can model this source with a bunch of spikes, and we know how the magnitude vs. frequency changes over the distance travelled, you might have guessed that we can get a pretty accurate idea of what the actual seismogram should look like at any sight along the wave path. Because the amplitude-frequency is a fourier spectrum, you can perform an inverse fourier transform on it to see how the amplitude changes with time, which is what a seismogram is. These records are called synthetic seismograms, and can be used to compare with actual records to see how accurate your estimates for the source really are. There will be some variations in the real seismogram that cannot be accounted for by the source. These variations give you specific information about the material the waves travelled through. Also, the amount that the spectrum tilts to the right over a given distance is a measure of the "attenuation" of the wave. As you can imagine, people have come up with all kinds of line fitting methods to measure how much tilt has occurred. This is another way of mapping out the material the waves are passing through. Generally, hot materials attenuate more (tilt the frequency spectrum more per a given distance) than cool materials. This is because hot materials deform inelastically more easily than cool ones and take energy away from the seismic waves passing through them by rearranging some of their atoms. If you look in the literature, you can find a lot of interesting studies on this topic as well as maps of attenuation (also referred to a Q or quality factor, though high Q implies low attenuation). Indeed, you can take real seismograms and back up time to the initial source to get an estimate of what the real source actually looks like. This is a wonderful way to study active faults. You can tell where the most slip has occurred and even when it occurred. This has been done beautifully for the Taiwan earthquake. > If the period of the boom must be adjusted to around 20 seconds or greater, > what is the wavelength of these waves. My back-of-an-envelope estimate > (v=fl) is in the order of 100 km. Is that reasonable? Yes, this estimate always works, provided you know the velocity well enough. Mostly though, the velocity changes quite a bit in the intervening material, but again, this can also be measured by compiling many records from different locations. An interesting thing to think about is the way in which waves with different wavelength interact with objects they are passing through when the objects diameter is around the wavelength of the wave. If the diameter is much smaller, than the wave does not "see" the object other than its contribution to the mechanics of the whole interval. Higher frequencies can then see smaller objects, because the wavelength is shorter. But as waves travel, we have seen that the high frequencies die out. So what if this wave has travelled through the core? Then the shortest detectable wavelength is hundreds of kilometers, and no object smaller than that will be very detectable. This is a challenge for studying the structure and properties of the region just outside of the liquid outer core (also called D"). > What is a typical amplitude for such a wave? > Paul Jebb > Newcomb Central School Depends on the frequency... You get a blast of various frequencies, but the lower ones become most dominant as the distance travelled increases. This is probably more info than you needed, but perhaps it can explain how complicated the real world actually is and how we can use seismograms to explain it. John Hernlund E-mail: hernlund@....... WWW: http://www.public.asu.edu/~hernlund/ ****************************************************************************** __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: seis dynamic range From: Karl Cunningham karlc@....... Date: Mon, 10 Apr 2000 22:40:32 -0700 Sean-Thomas -- Thanks for the repeat and your great description of displacement and velocity vs distance and magnitude. Do these equations still hold in the very near field? My reason for asking is that there is some blasting going on about 1/4 mile away and about 200 feet higher in elevation from here, and I would like to be able to take advantage of what I record to the greatest extent I can. I am recording in both velocity and acceleration, and I am going to increase the digitizing rate to 100sps. I can appreciate that the coefficients of the equations probably depend on what's below the surface (in this case granite, hence the blasting). Would I be able to see echos from nearby discontinuities? All comments are welcome. Karl __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: seis dynamic range From: Paul Jebb pfjebb@.............. Date: Tue, 11 Apr 2000 10:42:17 -0400 Thanks for that note Sean, Wow! A wavelength the size of the earth. Paul S-T Morrissey wrote: > Paul, > > You correctly estimate of the wavelength of surface waves for a > 20 second wave (0.05hz) with a velocity of 5 km/second as 100 km. > (using v = f * l; or wavelength = velocity * period) > Most people don't realize this. The longest waves seen are the > fundamental free oscillations of the earth at 51 minutes, where the > wavelength is the earths' circumference. Even near field P waves > of 15 hz at 7.5 km/sec have wavelenghts of half a kilometer. > > You also asked about the dynamic range required of seismometers. > Here is a repeat of a previous discussion on the subject. (August 99) > > The range of ground motions expected from earthquakes as recorded > by a seismometer is hugh. Obviously if "you are there" at the fault > scarp, you will need an accelerometer with a range up to 2gs. > > But most instrumental seismology follows general magnitude formulas > of the classic form: > M = log(A/T) + 1.66*log(distance) + constant. > The constant is a regional variable, usually about -0.18. The distance > is degrees (111 km per), A is the ground amplitude in nanometers, > (a nanometer = 10^-9 meter; in older data it was called a millimicron.) > and T is the period of the wave in seconds. For Ms calculations, > A is the sustained peak-peak surface wave amplitude. > > You can plug in numbers for various scenarios. To answer your question > about what will happen in the seismometer, solve for A: > log(A/T) = Ms - 1.66*log(distance) + 0.18 > A = T*log^-1(Ms -1.66*log(d) + 0.18.) > > The first step though is to convert the velocity output of the seismometer > to displacement by dividing by omega, w = 2*pi/period. > > For the Turkey quake: the record here (St. Louis) was 150 microns/second > at 24 seconds. 24 seconds is an w (omega) of 2*pi/24 = 0.262radian/sec. > The velocity is converted to displacement by dividing by w, so > 150/0.262 = 573 microns or 5.73x10^5 nanometers. (0.573 millimeters) > (Every seismometer should have recorded this, and many clipped). > > So Ms = log(5.73x10^5/24) + 1.66*log(81deg) -0.18 = 7.37 > > (solving for A for a maximum magnitude of 8.0 at that distance would > cause 2.46 millimeters of motion at St. Louis) > > But what did I record for the Ms = 5.8 aftershock? > > A = 24[log^-1(5.8 - 3.17 + 0.18) = 15 564 nanometers. (15.5 microns) > > This is a velocity (at 24 seconds) of 4.07 microns/second. > With an output of 5.3mv/micron/sec, the record here was about 22 > millivolts p-p, (or about 10 times the 6-second microseisms; at 0.5 > microns p-p; at the time they were running more than 10 times that due to > the hurricane). > > But what about a nearby quake? Say a Ms 4.0 in the next state? Putting > numbers in the formula with distance = 3 degrees (200 miles) and > T = 0.3 second, the seismometer will record 0.81 microns. For a > magnitude 3, it will only sense 0.081 microns or 81 nanometers. > (using the more accurate local Mblg(3hz) formula gives 43 nanometers) > > If M = 4 and is 1000km away, the motion at 1 second will be 398 nanometers. > If M = 3 and is 1000km away, the motion at 1 second will be 40 nanometers. > > For a threshold event, say a 2.5 at 110 km with T = 0.22 sec (4.5hz), > (this magnitude formula is revised for such local events, but we'll > use it anyhow) the amplitude is 105 nanometers. (using the local > Mblg formula gives 56 nanometers). To record these with useful > signal-to-noise ratio requires a resolution of 1 nanometer from > the seismometer. > > SO.... we need a displacement dynamic range of 1 nanometer to 1 > millimeter, or 10^6. This is one reason seismometers prefer a velocity > output. Looking at such numbers:. > At 10 hz, 1 nanometer is 63nm/sec. At 1 hz, it is 6.3nm/sec. At 20 > seconds (a broadband instrument) 1 millimeter is 314 microns/second. > This is a velocity range of about 50 000 to 1, which is the same as > the voltage output range. > > Until recently this range was difficult to handle with analog > electronics, so multi-level recording was used. A 16-bit digitizer > can realize this if noise is ignored. Providing for noise and > instrumental drift increases the required range by a factor of > 100 to 1000. So modern broadband stations use 24-bit digitizers > with a resolution of 1 part on 16 777 216 with a least count value > of 1.2 microvolts. For a seismometer with a VBB velocity output of > 2000 volts/meter/second, the LSB represents 1.67 nanometers/sec. > The maximum value is 10 millimeters/second p-p. > > Regards, > Sean-Thomas > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: seis dynamic range From: Paul Jebb pfjebb@.............. Date: Tue, 11 Apr 2000 10:51:52 -0400 Kareem, I'm not sure, but I have a game plan for my set-up. We are still making mechanical adjustments. Larry Cochrane suggested that I control the time for the boom to die-back after a disturbance (move the boom 1 cm by hand or blowing on the boom) by changing the volume of oil surrounding the damper. A wave should die-out within a second (Larry Cochrane). I also have a gain control on my amplifier that we have to fiddle with. If you get any insights, please let me know Kareem. Paul Kareem Lanier wrote: > Paul, > How do you get rid of all the local high-frequency noise? (My delimma) > > -----Original Message----- > From: psn-l-request@.............. [mailto:psn-l-request@............... > On Behalf Of S-T Morrissey > Sent: Sunday, April 09, 2000 12:56 PM > To: psn-l@.............. > Subject: seis dynamic range > > Paul, > > You correctly estimate of the wavelength of surface waves for a > 20 second wave (0.05hz) with a velocity of 5 km/second as 100 km. > (using v = f * l; or wavelength = velocity * period) > Most people don't realize this. The longest waves seen are the > fundamental free oscillations of the earth at 51 minutes, where the > wavelength is the earths' circumference. Even near field P waves > of 15 hz at 7.5 km/sec have wavelenghts of half a kilometer. > > You also asked about the dynamic range required of seismometers. > Here is a repeat of a previous discussion on the subject. (August 99) > > The range of ground motions expected from earthquakes as recorded > by a seismometer is hugh. Obviously if "you are there" at the fault > scarp, you will need an accelerometer with a range up to 2gs. > > But most instrumental seismology follows general magnitude formulas > of the classic form: > M = log(A/T) + 1.66*log(distance) + constant. > The constant is a regional variable, usually about -0.18. The distance > is degrees (111 km per), A is the ground amplitude in nanometers, > (a nanometer = 10^-9 meter; in older data it was called a millimicron.) > and T is the period of the wave in seconds. For Ms calculations, > A is the sustained peak-peak surface wave amplitude. > > You can plug in numbers for various scenarios. To answer your question > about what will happen in the seismometer, solve for A: > log(A/T) = Ms - 1.66*log(distance) + 0.18 > A = T*log^-1(Ms -1.66*log(d) + 0.18.) > > The first step though is to convert the velocity output of the seismometer > to displacement by dividing by omega, w = 2*pi/period. > > For the Turkey quake: the record here (St. Louis) was 150 microns/second > at 24 seconds. 24 seconds is an w (omega) of 2*pi/24 = 0.262radian/sec. > The velocity is converted to displacement by dividing by w, so > 150/0.262 = 573 microns or 5.73x10^5 nanometers. (0.573 millimeters) > (Every seismometer should have recorded this, and many clipped). > > So Ms = log(5.73x10^5/24) + 1.66*log(81deg) -0.18 = 7.37 > > (solving for A for a maximum magnitude of 8.0 at that distance would > cause 2.46 millimeters of motion at St. Louis) > > But what did I record for the Ms = 5.8 aftershock? > > A = 24[log^-1(5.8 - 3.17 + 0.18) = 15 564 nanometers. (15.5 microns) > > This is a velocity (at 24 seconds) of 4.07 microns/second. > With an output of 5.3mv/micron/sec, the record here was about 22 > millivolts p-p, (or about 10 times the 6-second microseisms; at 0.5 > microns p-p; at the time they were running more than 10 times that due to > the hurricane). > > But what about a nearby quake? Say a Ms 4.0 in the next state? Putting > numbers in the formula with distance = 3 degrees (200 miles) and > T = 0.3 second, the seismometer will record 0.81 microns. For a > magnitude 3, it will only sense 0.081 microns or 81 nanometers. > (using the more accurate local Mblg(3hz) formula gives 43 nanometers) > > If M = 4 and is 1000km away, the motion at 1 second will be 398 nanometers. > If M = 3 and is 1000km away, the motion at 1 second will be 40 nanometers. > > For a threshold event, say a 2.5 at 110 km with T = 0.22 sec (4.5hz), > (this magnitude formula is revised for such local events, but we'll > use it anyhow) the amplitude is 105 nanometers. (using the local > Mblg formula gives 56 nanometers). To record these with useful > signal-to-noise ratio requires a resolution of 1 nanometer from > the seismometer. > > SO.... we need a displacement dynamic range of 1 nanometer to 1 > millimeter, or 10^6. This is one reason seismometers prefer a velocity > output. Looking at such numbers:. > At 10 hz, 1 nanometer is 63nm/sec. At 1 hz, it is 6.3nm/sec. At 20 > seconds (a broadband instrument) 1 millimeter is 314 microns/second. > This is a velocity range of about 50 000 to 1, which is the same as > the voltage output range. > > Until recently this range was difficult to handle with analog > electronics, so multi-level recording was used. A 16-bit digitizer > can realize this if noise is ignored. Providing for noise and > instrumental drift increases the required range by a factor of > 100 to 1000. So modern broadband stations use 24-bit digitizers > with a resolution of 1 part on 16 777 216 with a least count value > of 1.2 microvolts. For a seismometer with a VBB velocity output of > 2000 volts/meter/second, the LSB represents 1.67 nanometers/sec. > The maximum value is 10 millimeters/second p-p. > > Regards, > Sean-Thomas > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: My Seismometer From: "Darren Lamison-White" DLamisonWhite@............. Date: Tue, 11 Apr 2000 11:18:05 -0400 Hello My name is Darren Lamison-White. I am in the 8th grade my = seismometer has won first place in the junior division of the County = Science Fair=20 If you have anything else to say E-mail me at DLamisonWhite@.............
Hello My name is = Darren=20 Lamison-White. I am in the 8th grade my seismometer has won first place = in the=20 junior division of the County Science Fair
If you have = anything else to=20 say E-mail me at
DLamisonWhite@.............
Subject: Re: My Seismometer From: Paul Jebb pfjebb@.............. Date: Tue, 11 Apr 2000 11:44:43 -0400 Hey Darren, Congratulations! Good job on the first place finish! We are building a seismic station at our school here in the Adirondack mountains in central New York state. We haven't caught any quakes yet, but we will. Cheers, Paul Jebb Newcomb Central School Science Teacher Darren Lamison-White wrote: > Part 1.1 Type: Plain Text (text/plain) > Encoding: quoted-printable __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Filtering local noise From: S-T Morrissey sean@........... Date: Tue, 11 Apr 2000 22:20:45 -0500 (CDT) Paul and Kareem have brought up a question that has not been explicitly discussed, namely what to do about short period local or "cultural" noise. Seismology would be a lot easier sport if we didn't have to put up with ourselves and the noises of civilization. This includes everything from the dogs romping through the house, the school bus or Mack trucks on the street, and the freeway a kilometer away. This is why professional seismic stations are hidden in remote underground vaults rather than basements. Such noise has generally been dealt with by using low-pass active analog filters in the output of the seismometer. If a digitizer is used, its input circuitry probably includes a measure of "anti-aliasing" filtering, where the filter period is set to twice the sample interval. (A 10 hz waveform is minimally sampled by a 20 hz digitizer, which would then require a 10 hz low pass anti-alias filter.) For analog recording, the cosmetic appearance of the record becomes the determining factor. You cannot see the small P-wave if the record is full of noise bursts from passing cars. So the idea is to try to reduce the cultural noise to about the same level as longer period noises such as from tilting of the base of a horizontal or atmospheric pressure (vertical). Some amount of short period noise assures that the instrument is working. Also, the 6-second microseisms should be present. (this is true even for a long period sensor, not necessarily a broadband) So it is a matter of customizing the filters to the site. For my monitor here of the leaf spring vertical operating at 90 seconds, I use a 6-second passive notch filter to reduce the microseisms by about 100, and about 6 poles of low pass filtering the cut the traffic noise. I set the gain so I still see the local traffic noise at peaks of about a mm, the microseisms when there is a storm, and barometric noise of storms of 10 minutes period or more, while not having a record that is too messy. For utilizing low pass filters, simple one pole series resistor, shunt capacitor combinations can be used prior to almost any amplifier stage. More formal 2 and 4 pole active filters are generally employed. The preferred response is the uniform phase delay of the Bessel configuration. In a typical seismic system, the pre-amplifier at the seismometer usually has two two-pole filters at a net cutoff of about 20 hz, which is more than adequate for local short period instruments. The schematic of this preamplifier is on the web site. The filter is easily changed form 20 hz to 2 hz by using 10x the values of 4 resistors for use with broader response long period sensors. (This filter can be built with regular amplifiers like the LM308 if it doesn't have to be battery powered.) Additional filtering is found in the output of the telemetry discriminator (if used) and the digitizer input. Again, a phase linear response is used at about 20 hz for short period sensors like the L4-C, and 2 hz for a long period sensor. Most analog recorders provide several poles of additional, often switch selectable, filtering. Here one can play the tradeoffs of increasing the gain while lowering the frequency response to make the best of the cultural noise problem. I have seen some of the schematics suggested for use with the Lehman and SG designs, and they do include a measure of low pass filtering, even if it is scattered about. A more focused filter arrangement would be preferable. On the other hand, I see a number of amplifiers with a high value feedback resistor (for high gain) that is not bypassed with a capacitor to limit the gain at the noise frequencies. Since all our amplifiers operate at frequencies from DC to a few hz at most, we should be careful that higher frequencies, which are still sub-audio, are not amplified. Regards, Sean-Thomas __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: My Seismometer From: "steve hammond" shammon1@............. Date: Wed, 12 Apr 2000 22:47:00 -0700 Way to go Darren-- If you have a digital picture and more details, I = would be honored to post the information on the PSN web site in San = Jose, California http://pw2.netcom.com/~shammon1/psnsj.htm with other = PSN related information. Regards, Steve Hammond PSN San Jose, Aptos, California=20 -----Original Message----- From: Darren Lamison-White To: psn-l@.............. Date: Tuesday, April 11, 2000 8:19 AM Subject: My Seismometer =20 =20 Hello My name is Darren Lamison-White. I am in the 8th grade my = seismometer has won first place in the junior division of the County = Science Fair=20 If you have anything else to say E-mail me at DLamisonWhite@.............
Way to = go Darren-- If=20 you have a digital picture and more details, I would be honored to post = the=20 information on the PSN web site in San Jose, California http://pw2.netcom.com/= ~shammon1/psnsj.htm=20 with other PSN related information.
Regards, = Steve Hammond=20 PSN San Jose, Aptos, California 
-----Original = Message-----
From:=20 Darren Lamison-White <DLamisonWhite@.............>
To:=20 psn-l@.............. = <psn-l@..............>
D= ate:=20 Tuesday, April 11, 2000 8:19 AM
Subject: My=20 Seismometer

Hello My name = is Darren=20 Lamison-White. I am in the 8th grade my seismometer has won first = place in=20 the junior division of the County Science Fair
If you have = anything else=20 to say E-mail me at
DLamisonWhite@.............
Subject: mail From: john c cole johnccole@........ Date: Tue, 18 Apr 2000 06:15:16 -0500 Gentlemen For some reason I no longer get mail . I recently upgraded Juno . Could you put me back on? Thanks -- johnccole@........ ________________________________________________________________ YOU'RE PAYING TOO MUCH FOR THE INTERNET! Juno now offers FREE Internet Access! Try it today - there's no risk! For your FREE software, visit: http://dl.www.juno.com/get/tagj. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Filtering local noise From: "Tom Schmitt" tschmitt@.............. Date: Tue, 18 Apr 2000 08:46:38 -0400 This is a very late comment on the local noise question. In exploration seismic work geophone arrays were used to filter local noise. The signals from several geophnes would be summed. The noise would be out of phase at the geophones but the signal would be in phase. In reflection work that assumption is more justified than in earthquake or refraction seismology as in reflection the signal is coming more or less straight up. Has this ever been used in earthquake seismology? The usual answer to noise is a quiet location but with educational seismometers rather than research seismometers, location near the classroom is important. Second. There is a new chip that is up to a 6 pole analog filter. The configuration of the filter is set in a device similar to an EPROM burner. The software that comes with it has full design features such as simulation of amplitude and phase. Unfortunately I threw the flier away but I am trying to find the manufacturer through other channels. This could be helpful in designing filters for local noise. If anyone knows the web site of the manufacturer please let me know. I will continue to try to find it by other sources, Tom Schmitt tschmitt@.............. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Filtering local noise From: Karl Cunningham karlc@....... Date: Tue, 18 Apr 2000 08:19:24 -0700 Tom -- My $0.02... I don't think this is the filter you were using, but Maxim has a family of filters that don't need to be programmed but use an external clock to set the cutoff frequency. Often, the cutoff is 100:1 lower in frequency than the clock. There is very little attenuation at the clock frequency, so a simple analog filter is needed too. See http://dbserv.maxim-ic.com/pl_list.cfm?filter=f I can say about the ones you were using, but one problem with integrated filters such as Maxim's is drift and low-frequency noise. In these filters, the signal path goes through the IC. Some integrated filters are designed so that they are in parallel with and shunt a signal source to effect the desired filtering. That takes care of the drift problem but not the low-frequency noise. Karl At 08:46 AM 4/18/2000 -0400, you wrote: >Second. There is a new chip that is up to a 6 pole analog filter. The >configuration of the filter is set in a device similar to an EPROM burner. >The software that comes with it has full design features such as simulation >of amplitude and phase. Unfortunately I threw the flier away but I am >trying to find the manufacturer through other channels. This could be >helpful in designing filters for local noise. If anyone knows the web site >of the manufacturer please let me know. I will continue to try to find it >by other sources, __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: filter on ebay From: BOB BARNS roybar@........ Date: Wed, 19 Apr 2000 09:43:03 -0400 Hi gang, ebay (#308130108) has a Rockland Model 452 Dual Hi/Lo filter. The auction ends 4/20 and the current bid is $39. I don't know what frequency range this model covers. Bob Barns __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: preamplifier filter From: S-T Morrissey sean@........... Date: Thu, 20 Apr 2000 02:02:22 -0500 (CDT) To Cap and others who asked: The schematic of the seismic preamplifier with the 4-pole low pass Bessel filter can be found at: http://www.eas.slu.edu/People/STMorrissey/index.html under the section: stmmisc.html "PSN INFO ... SLU Seismic Network" I had previously posted the old 1980 pencil drawing, but about a year ago I redrew it and updated some details. I just got around to scanning the new drawing to the web page. regards, Sean-Thomas __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Filtering local noise From: ChrisAtUpw@....... Date: Thu, 20 Apr 2000 20:04:18 EDT Dear Tom Schmitt, You wrote :- > In exploration seismic work geophone arrays were used to filter local noise. > The signals from several geophones would be summed. The noise would be out > of phase at the geophones but the signal would be in phase. In reflection > work that assumption is more justified than in earthquake or refraction > seismology as in reflection the signal is coming more or less straight up. > Has this ever been used in earthquake seismology? Your letter raises several questions. How many and how widely spaced locations were you proposing for your recording stations? The wavelength of earthquake waves is likely to be VERY long when compared to explosive sounding signals / environmental noise and what you actually record at a particular site is effected by the wave path, which may have different properties from different directions. > The usual answer to noise is a quiet location but with > educational seismometers rather than research > seismometers, location near the classroom is important. If you can use your many observers to identify the various man made noise sources, there is no reason in principle why you should not place an auxiliary sensor(s) closer to sources and feed the relatively strong interfering signals back to provide compensation, but don't expect a perfect match. It is easier to do this using digital delays, rather than analogue delay lines. Can you record an environmental noise channel to help in identification and the seismograph channel? Could the identification / characterisation / avoidance of local sources be a worthwhile project? If the local noise is terrible, could you get on line data from some quiet location for your 'real earthquakes' and use your local set-up as a teaching / backup aid? > Second. There is a new chip that is up to a 6 pole analogue filter. The > configuration of the filter is set in a device similar to an EPROM burner. > The software that comes with it has full design features such as simulation > of amplitude and phase. Filters of this type are produced for use in hearing aids, to vary the audio characteristics over a wide band. In your application, it is probably better to use four pole Bessel filters, which are relatively easy and cheap to make with a couple of OPAs. When you go to six pole filters, the delay can get rather long. You may find that shifting the corner frequency downwards just a bit is actually preferable to adding more filter stages. If you have a two channel recording system, could you use it to compare the simultaneous results of various filter choices? If you initially use 'plug in' breadboard (with silver plated contacts), you can easily change the filter characteristics. Regards, Chris Chapman __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Filtering local noise From: "Tom Schmitt" tschmitt@.............. Date: Fri, 21 Apr 2000 09:00:22 -0400 ----- Original Message ----- From: To: Sent: Thursday, April 20, 2000 8:04 PM Subject: Re: Filtering local noise Dear Chris Thank you for your comments. I have left my original and your comments in this to make it easier to read. It is thus long and I apologize for that. > Dear Tom Schmitt, > > You wrote :- > > > In exploration seismic work geophone arrays were used to filter local > noise. > > The signals from several geophones would be summed. The noise would be out > > of phase at the geophones but the signal would be in phase. In reflection > > work that assumption is more justified than in earthquake or refraction > > seismology as in reflection the signal is coming more or less straight up. > > Has this ever been used in earthquake seismology? > > Your letter raises several questions. How many and how widely spaced > locations were you proposing for your recording stations? The wavelength of > earthquake waves is likely to be VERY long when compared to explosive > sounding signals / environmental noise and what you actually record at a > particular site is effected by the wave path, which may have different > properties from different directions. Well first I was hoping that one of the academic seismologists would answer with (1) that's impossable or (2) here is how to do it. Lacking that clear guidance :-) I will attempt some speculations. The period of the earthuakes is very long but the period of local noise is very short. If I remember Sean-Thomas was talking about 100 HZ notch filters to remove the local noise. At 5 km/sec for surface material and a frequency of 100hz the wavelength is 50 meters. Considering a wave propigating only in the x-z plane, and a seismometer located at 0,0 a second seismometer located at 25,0 would be 180 degrees out of phase for a 100 hz signal. Summing the two signals would result in zero ( minus the attenuation over 25 meters and local effects). > > > The usual answer to noise is a quiet location but with > > educational seismometers rather than research > > seismometers, location near the classroom is important. > > If you can use your many observers to identify the various man made noise > sources, there is no reason in principle why you should not place an > auxiliary sensor(s) closer to sources and feed the relatively strong > interfering signals back to provide compensation, but don't expect a perfect > match. It is easier to do this using digital delays, rather than analogue > delay lines. Can you record an environmental noise channel to help in > identification and the seismograph channel? Could the identification / > characterisation / avoidance of local sources be a worthwhile project? If the > local noise is terrible, could you get on line data from some quiet location > for your 'real earthquakes' and use your local set-up as a teaching / backup > aid? > The noise is usually diffuse in origin, thus having sensor near the noise probably will not work. The idea is to have enough sesors out there that the sum of them at any given time covers an intergal number of wave lengths of the noise. The sum is then zero. Since the signal is a much longer wave length it is not reduced by the summing. It would be prohibitively expensive to do this with long periond seismometers but your idea of noise monitors is good. One might be able to use exploration geopones to get the "noise", high pass those signals and sum them with the seismometer and reduce the noise. The news broadcsasters often use a second noise canceling microphone in noisey environments. The only reason for this is cosmetic or to look at local events. Also exploration work is much simpler in that one knows the source and noise characteristics better. Also that was an old technique in exploration, with vibroseis@ they may not have to do it any more. Also a quiet beats filtering any day. > > Second. There is a new chip that is up to a 6 pole analogue filter. The > > configuration of the filter is set in a device similar to an EPROM burner. > > The software that comes with it has full design features such as simulation > > of amplitude and phase. > > Filters of this type are produced for use in hearing aids, to vary the > audio characteristics over a wide band. In your application, it is probably > better to use four pole Bessel filters, which are relatively easy and cheap > to make with a couple of OPAs. When you go to six pole filters, the delay can > get rather long. You may find that shifting the corner frequency downwards > just a bit is actually preferable to adding more filter stages. If you have a > two channel recording system, could you use it to compare the simultaneous > results of various filter choices? If you initially use 'plug in' breadboard > (with silver plated contacts), you can easily change the filter > characteristics. > > Regards, > > Chris Chapman > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. I am going to send this whole thing to one of my academic friends to see what he says. I suspect some of these tricks might have been used in the good old days when we were monitoring the nuclear detonations of the former Soviet Union. There were some very long dedicated arrays focused to specific points in Asia. I do not have a machine right now, I hope to have one by the end of the Summer as I want that as a Summer science project for my daughters. I am working on a computer interface now. We live in a noisy environment which is why Sean Thomas' comments hit home. Thank you Tom Schmitt tschmitt@.............. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: seismic arrays From: S-T Morrissey sean@........... Date: Fri, 21 Apr 2000 15:03:35 -0500 (CDT) Tom, Chris, and company, You are quite correct in surmising that very sensitive arrays were deployed during the cold war to monitor Soviet nuclear tests. These had as many as 100 sensors in deep boreholes, with sensor spacings of kilometers or more. They could "beam" their sensitivity by summing the output of sensors with a time delay appropriate to the velocity of the propagation of the seismic wave across the array. Most of the science was top secret, run by the Air Force Geophysics Program (AFTAC), with the university involvement through ARPA (Advanced Research Projects Agency of DOD), and AFOSR (Air Force Office of Scientific Research). Some known installations were in Montana (the LASA: Large Aperture Seismic Array), at Yellowknife in central Canada, Grafenburg in Germany, and NORSAR in Norway. In a minimal example of how they worked, three sensors are aligned north , middle, and south , and a suspected test site in Kazakhstan is the source of a 1-second seismic pulse. The wavefront is lost in the noise as it passes the north sensor, but the array sensitivity is "tuned" to a velocity of a 1-second compressional wave (8 km/sec) propagating from the north. So the data from the north sensor is delayed by the appropriate time and then summed with the center seismometer data. This is repeated for the south sensor. Since the noise of each site is random, the summed signals increase the seismic wave amplitude by three times over the noise. Obviously much more improvement is made as more sensors are summed. And sensors along an arc at a constant radial distance from the source can be summed without any delays. So array geometry became a hot topic. Fortunately nuclear tests sites are difficult to move around or hide completely from satellites. This method makes many assumptions about wave paths, etc., and in the early '70s days of analog tape recorders, filters, and oscilloscopes, it was difficult to work with delays as large as a second. Digital analysis with analog triggers followed, and of course it is all digital now. As the arrays have been upgraded, the surplus scene has been flooded with used HS-10 seismometers, which were originally installed in 30 to 100 meter boreholes. Now the whole world is an array with the installation of several hundred broadband digital stations, with the focus of a major part of the newest instrumentation being verification of compliance with the CTBT (Comprehensive Test Ban Treaty). So arrays are not everyman's way to improve the signal to noise ratio. But, as they say, location is everything. Short period noise, like traffic, is generally outside our interest (is above 10hz), or attenuates rapidly, so 100 meters can make a big difference. But cultural noise generally does not interfere with 1 second and longer waves, so sharp filtering at the seismometer and/or at the recorder is very beneficial. From the VBB vertical seis in the basement here, I routinely see the 20 to 40 second surface waves of anything above a 5.5 that NEIS lists. But even with considerable filtering at 10 hz, I still recorded the Mblg 3.7 near Indianapolis on April 14, a distance of about 300 km from St. Louis. It did help that it was at night, after the local noise subsided. Regards, Sean-Thomas __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: seismic arrays From: Tobin Fricke tobin@....... Date: Fri, 21 Apr 2000 13:26:12 -0700 (PDT) My summer project last summer concerned seismic arrays in Alaska. As part of my project I wrote a program that takes the data from array stations and performs the "beamforming" process, outputting a slowness vector for the incident wavefield. If anyone's interested.. talk to me. Tobin __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Filtering local noise From: John Hernlund hernlund@....... Date: Sun, 23 Apr 2000 01:45:07 -0700 (MST) On Fri, 21 Apr 2000, Tom Schmitt wrote: > > > In exploration seismic work geophone arrays were used to filter local > > noise. > > > The signals from several geophones would be summed. The noise would be > out > > > of phase at the geophones but the signal would be in phase. In > reflection > > > work that assumption is more justified than in earthquake or refraction > > > seismology as in reflection the signal is coming more or less straight > up. > > > Has this ever been used in earthquake seismology? This technique is used in many variations. The buzz word for these types of techniques is "stacking" the data. For data on a single phase for many records you can average them, and because the noise is random it will be reduced. According to the mean value theorem of statistics, the noise should totally disappear as you average an infinite number of records. This is not, of course, possible, but the more the better. One of the cool things being done with stacking these days is to measure PP and SS precursors. These are the small reflections off the discontinuities in the Earth occurring at 670, 500 and 410 km depths which are interesting to study in terms of mineral phase transitions. A small part of the energy of the waves is reflected off these before the PP hits the surface, which is almost precisely between the quake location and the seismograph station. The result is a little wiggle one the seismogram just before the arrival of the main SS or PP phase. These are often too small to be seen for an individual event. By stacking enough seismograms for given "bounce points" the topography of these features can be mapped out really well. Also, the amplitude of the bumps tells you about the impedance of the boundary, which is useful in finding out what material change is occurring to produce it. > > Your letter raises several questions. How many and how widely spaced > > locations were you proposing for your recording stations? The wavelength > of > > earthquake waves is likely to be VERY long when compared to explosive > > sounding signals / environmental noise and what you actually record at a > > particular site is effected by the wave path, which may have different > > properties from different directions. > > Well first I was hoping that one of the academic seismologists would answer > with (1) that's impossable > or (2) here is how to do it. Lacking that clear guidance :-) I will attempt > some speculations. > > The period of the earthuakes is very long but the period of local noise is > very short. If I remember Sean-Thomas was talking about 100 HZ notch > filters to remove the local noise. At 5 km/sec for surface material and a > frequency of 100hz the wavelength is 50 meters. Considering a wave > propigating only in the x-z plane, and a seismometer located at 0,0 a second > seismometer located at 25,0 would be 180 degrees out of phase for a 100 hz > signal. Summing the two signals would result in zero ( minus the > attenuation over 25 meters and local effects). Correct, but you have many different frequencies to deal with. If the stations get too far apart, then the seismic waves will hit each one at a generally different time and phase. This can be dealt with using some fairly simple mathematics... The bottom line is that the detail of an object or structure you want to look at is never greater than the station spacing for a single teleseismic earthquake. Many earthquakes increase the resolution with all of the paths, but the rays that hit the seismometer are still travelling at a nearly vertical angle and the stations are far apart. Recent work has begun to develop using noise more creatively. For instance, atmospheric noise excites some of the Earth's free modes, and this can be very useful for some types of work. There are all kinds of cool numerical tricks for playing with this stuff. But if you just want a decent-looking seismogram for a teleseismic event then simply low-pass it... > > > The usual answer to noise is a quiet location but with > > > educational seismometers rather than research > > > seismometers, location near the classroom is important. > > > > If you can use your many observers to identify the various man made > noise > > sources, there is no reason in principle why you should not place an > > auxiliary sensor(s) closer to sources and feed the relatively strong > > interfering signals back to provide compensation, but don't expect a > perfect > > match. It is easier to do this using digital delays, rather than analogue > > delay lines. Can you record an environmental noise channel to help in > > identification and the seismograph channel? Could the identification / > > characterisation / avoidance of local sources be a worthwhile project? If > the > > local noise is terrible, could you get on line data from some quiet > location > > for your 'real earthquakes' and use your local set-up as a teaching / > backup > > aid? > > > > The noise is usually diffuse in origin, thus having sensor near the noise > probably will not work. The idea is to have enough sesors out there that > the sum of them at any given time covers an intergal number of wave lengths > of the noise. The sum is then zero. Since the signal is a much longer wave > length it is not reduced by the summing. No it is more complicated than that. One of the theories for dealing with noise uses the definition that noise is not correlated with itself. By removing the uncorrelated part of the seismogram, I think you can reduce some of the noise by up to a maximum estimate of 1/sqrt(2) (don't quote me on this value). Anyways, you can use a large array, and see the phase move across it. This is similar in principle to the new binocular telescopes being implemented around the world. In this scenario you assume that the noise at each location is completely random and different from the others. Then you can easily remove it. It is not about averaging necessarily, it is more about finding phases that cross the array which can be easily correlated. > It would be prohibitively expensive to do this with long periond > seismometers but your idea of noise monitors is good. One might be able to > use exploration geopones to get the "noise", high pass those signals and > sum them with the seismometer and reduce the noise. The news broadcsasters > often use a second noise canceling microphone in noisey environments. > > The only reason for this is cosmetic or to look at local events. Also > exploration work is much simpler in that one knows the source and noise > characteristics better. Also that was an old technique in exploration, > with vibroseis@ they may not have to do it any more. Also a quiet beats > filtering any day. Yikes, I think it is difficult and nearly impossible to extrapolate records over from a high frequency geophone to a low frequency instrument...better to just low pass and focus on distant events whose frequencies are lower than the poles on you filter. I don't think anybody learns much about the earth by putting a sophisticated broad band instrument right next to the earthquake source; this is where strong motion instruments are used instead. And when it is strong motion you are recording, the local noise is going to be small compared to recording distant events. > > > Second. There is a new chip that is up to a 6 pole analogue filter. > The > > > configuration of the filter is set in a device similar to an EPROM > burner. > > > The software that comes with it has full design features such as > simulation > > > of amplitude and phase. > > > > Filters of this type are produced for use in hearing aids, to vary the > > audio characteristics over a wide band. In your application, it is > probably > > better to use four pole Bessel filters, which are relatively easy and > cheap > > to make with a couple of OPAs. When you go to six pole filters, the delay > can > > get rather long. You may find that shifting the corner frequency downwards > > just a bit is actually preferable to adding more filter stages. If you > have a > > two channel recording system, could you use it to compare the simultaneous > > results of various filter choices? If you initially use 'plug in' > breadboard > > (with silver plated contacts), you can easily change the filter > > characteristics. > I am going to send this whole thing to one of my academic friends to see > what he says. > > I suspect some of these tricks might have been used in the good old days > when we were monitoring the nuclear detonations of the former Soviet Union. > There were some very long dedicated arrays focused to specific points in > Asia. > > I do not have a machine right now, I hope to have one by the end of the > Summer as I want that as a Summer science project for my daughters. I am > working on a computer interface now. We live in a noisy environment which > is why Sean Thomas' comments hit home. > Thank you > Tom Schmitt > tschmitt@.............. Tom, One sure way to test if something is noise or not, like a nuclear explosion is to forward model it. You then predict the groundmotion at each station where you can get records. This can be done fairly accurately by using either the travel-time tables or some mathematical model. You can either look directly at the seismograms or you can try and do a convolution of your predicted data with the actual records for each station. If the correlation is high for most of the records, then you can test it by using a given confidence interval (e.g. 95%). The more records you have, of course, the better you can decide. Many times, you add records and can correspondingly increase your confidence level. Also, you may want to statistically weight stations closer to the event more than ones further if it is a weak source. John Hernlund E-mail: hernlund@....... WWW: http://www.public.asu.edu/~hernlund/ ****************************************************************************** __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Anatomy of Seismograms From: Amy pstimson@......... Date: Sun, 23 Apr 2000 09:18:17 -0700 Anyone have a copy for sale or know of a link to same? Thanks, Paul Stimson __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Newcomb, NY Earthquake From: Paul Jebb pfjebb@.............. Date: Mon, 24 Apr 2000 11:43:02 -0400 Dear Members, On April 20th there was a 3.7 event here in Newcomb, almost directly below our school. In an unbeliveably bad stroke of luck, we were on vacation here and our seismometer totally missed the whole thing. If you have access to any seismic recordings for this event, I would love to get them. Can you help? Yours truly, Paul Jebb NCS __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Newcomb, NY Earthquake From: Paul Jebb pfjebb@.............. Date: Mon, 24 Apr 2000 13:23:41 -0400 Dear John, Thanks for that start. I took a cursory run to the IRIS site and at least got the depth down. I want to get a look at the actual seismograph output for this quake if I can. I'll run around there some more and see what I come up with. As for the local geology, Newcomb is located in the Adirondack mountains which is an anorthositic plug contiguous with the Canadian Shield. We do have a couple of faults running through Town but I am not sure of the exact layout. Yours truly, Paul Jebb John Hernlund wrote: > On Mon, 24 Apr 2000, Paul Jebb wrote: > > Dear Members, > > On April 20th there was a 3.7 event here in Newcomb, almost directly > > below our school. In an unbeliveably bad stroke of luck, we were on > > vacation here and our seismometer totally missed the whole thing. If > > you have access to any seismic recordings for this event, I would love > > to get them. > > Can you help? > > Yours truly, > > Paul Jebb > > NCS > > Paul, > What a bummer! These NE quakes are always quite interesting to see. What > is your geological setting there in Newcomb? I'd be interested to here more > about this (you can post to the list, because I am sure they are interested > too). As you may or may not know, all of the records of earthquake data from > the global seismic network are available for free on the web. I believe there > are quite a few stations around some of the ivy league schools in New England, > and you could probably get some of those. To obtain any record from any of > these stations, go to the site: http://www.iris.edu. IRIS is a university > consortium funded by NSF to study global seismology. They have quite a few > member institutions (including ASU, where I am). These seismograms are > recorded on the best, state-of-the-art equipment available today. > > John Hernlund > E-mail: hernlund@....... > WWW: http://www.public.asu.edu/~hernlund/ > > ****************************************************************************** __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Newcomb, NY Earthquake From: "Kareem Lanier" kareemjupiter@............. Date: Mon, 24 Apr 2000 21:16:13 -0700 Does anyone monitor telemetry signals coming from remote seismic stations? I need help doing this. I currently have a drum recorder and need either a discriminator or A to D card. -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of Paul Jebb Sent: Monday, April 24, 2000 10:24 AM To: John Hernlund; Seismic Network Subject: Re: Newcomb, NY Earthquake Dear John, Thanks for that start. I took a cursory run to the IRIS site and at least got the depth down. I want to get a look at the actual seismograph output for this quake if I can. I'll run around there some more and see what I come up with. As for the local geology, Newcomb is located in the Adirondack mountains which is an anorthositic plug contiguous with the Canadian Shield. We do have a couple of faults running through Town but I am not sure of the exact layout. Yours truly, Paul Jebb John Hernlund wrote: > On Mon, 24 Apr 2000, Paul Jebb wrote: > > Dear Members, > > On April 20th there was a 3.7 event here in Newcomb, almost directly > > below our school. In an unbeliveably bad stroke of luck, we were on > > vacation here and our seismometer totally missed the whole thing. If > > you have access to any seismic recordings for this event, I would love > > to get them. > > Can you help? > > Yours truly, > > Paul Jebb > > NCS > > Paul, > What a bummer! These NE quakes are always quite interesting to see. What > is your geological setting there in Newcomb? I'd be interested to here more > about this (you can post to the list, because I am sure they are interested > too). As you may or may not know, all of the records of earthquake data from > the global seismic network are available for free on the web. I believe there > are quite a few stations around some of the ivy league schools in New England, > and you could probably get some of those. To obtain any record from any of > these stations, go to the site: http://www.iris.edu. IRIS is a university > consortium funded by NSF to study global seismology. They have quite a few > member institutions (including ASU, where I am). These seismograms are > recorded on the best, state-of-the-art equipment available today. > > John Hernlund > E-mail: hernlund@....... > WWW: http://www.public.asu.edu/~hernlund/ > > **************************************************************************** ** __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Monitoring telemetry signals From: Larry Cochrane cochrane@.............. Date: Mon, 24 Apr 2000 22:13:05 -0700 Kareem, I and a few other PSN members monitor telemetry from remote sensors using my demodulator (discriminator) board. See http://www.seismicnet.com/telebrd.html for more information.The output of the demod board can drive a drum recorder or A/D card. Currently the *.CNI and *.CGP event files on my system (http://www.seismicnet.com) come from remote USGS sensors. At one point I had up to 5 channels recording remote senors. The problem is the USGS is slowly going digital around here (N. California) making my board obsolete. My board only works with the analog system commonly used to send analog data using a phone line or audio RF line. Regards, Larry Cochrane Redwood City, PSN At 09:16 PM 4/24/00 -0700, Kareem Lanier wrote: >Does anyone monitor telemetry signals coming from remote seismic stations? I >need help doing this. I currently have a drum recorder and need either a >discriminator or A to D card. > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: SDR & Windows98 From: "Rex Klopfenstein, Jr." rklopfen@......... Date: Tue, 25 Apr 2000 19:40:24 -0400 Has anybody used SDR with Windows98? Specifically can SDR & Win98 be used with network like Windows 95? -- Rex Klopfenstein, Jr. Bowling Green, OH rklopfen@......... http://www.wcnet.org/~rklopfen __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: SDR & Windows98 From: Larry Cochrane cochrane@.............. Date: Tue, 25 Apr 2000 16:55:17 -0700 Rex, Yes, you can use Win98 to run SDR with networking. As with 95, you do need to boot to the DOS only mode. If you have the network properly installed under Win98, the DOS only mode should be able to connect to your other Windows system(s) using the NET command. -Larry Cochrane Redwood City, PSN At 07:40 PM 4/25/00 -0400, you wrote: >Has anybody used SDR with Windows98? Specifically can SDR & Win98 be >used with network like Windows 95? > >-- >Rex Klopfenstein, Jr. >Bowling Green, OH >rklopfen@......... >http://www.wcnet.org/~rklopfen > > >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with >the body of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: SDR & Windows98 From: angel rodriguez angel@............ Date: Wed, 26 Apr 2000 16:11:49 -0500 Hello Rex, Tuesday, April 25, 2000, 6:40:24 PM, you wrote: RKJ> Has anybody used SDR with Windows98? Specifically can SDR & Win98 be RKJ> used with network like Windows 95? RKJ> -- RKJ> Rex Klopfenstein, Jr. RKJ> Bowling Green, OH RKJ> rklopfen@......... RKJ> http://www.wcnet.org/~rklopfen RKJ> __________________________________________________________ RKJ> Public Seismic Network Mailing List (PSN-L) RKJ> To leave this list email PSN-L-REQUEST@.............. with RKJ> the body of the message (first line only): unsubscribe RKJ> See http://www.seismicnet.com/maillist.html for more information. Hi, Yes, I use a das box to run SDR and the data and event files are sent to the W98 box. I do that cause the DOS box has very little memory and disk space. Both boxes are battery powered and off the grid. Best regards, angel mailto:angel@............ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Newcomb, NY Earthquake From: Bill Scolnik wls@......... Date: Thu, 27 Apr 2000 12:01:41 -0400 Paul, I checked my seismometer records this evening for April 20 and I show a trace at the right time for that quake. It's pretty deep in the noise, but with a little filtering the vertical trace is quite readable. I'd be happy to send you the file. Bill S At 11:43 AM 04/24/2000 , you wrote: >Dear Members, >On April 20th there was a 3.7 event here in Newcomb, almost directly >below our school. In an unbeliveably bad stroke of luck, we were on >vacation here and our seismometer totally missed the whole thing. If >you have access to any seismic recordings for this event, I would love >to get them. > >Can you help? > >Yours truly, >Paul Jebb >NCS > >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with >the body of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: [Fwd: Geology Labs On-Line, Virtual River Beta Release] From: Steve Hammond Shammon1@............. Date: Thu, 27 Apr 2000 10:31:44 -0700 FYI, if you do not already know, this is a high quality educational web site. Regards, Steve Hammond PSN Aptos California Colleagues, This is to notify you of the BETA release of a new activity for the Geology Labs On-Line project. VirtualRiver-Discharge. http://vcourseware.calstatela.edu/GeoLabs/ Follow the link to Virtual River. (You received this email because your address is in my database of people who may be interested in the "Virtual Labs" of the Geology Labs On-line project. If you received this email in error, please accept my apology and let me know so I can remove your address from the database.) I hope you will take a look at VirtualRiver and provide some feedback to me. It's designed as an interactive Web-based lab for introductory earth or environmental science courses at the university level. It may also be appropriate for some high school or middle school earth science classes. If you do review the activity, please note that there is a DEMONSTRATION version available (a link can be found on the first page) that gives you the opportunity for a quick overview. Can you use it? Did you find any bugs? Do you have any suggestions to improve it? VirtualRiver-Discharge and is one of three virtual labs we hope to eventually have available on the Web about rivers. It focuses on the determination of a stream's discharge using the "method of verticals." The next activity will be about flooding, hydrographs, flood recurrence intervals and flood probability. The final one will be concerned with erosion, load transport, and sediment deposition. VirtualRiver-Discharge, similar to previous virtual labs (Virtual Earthquake and Virtual Dating), requires students to interact with the content of a Web page (through Java Applets, JavaScripts, Dynamic HTML, and Shockwave Animations) in order to make careful observations and measurements, do simple calculations, and answer questions about their work. If the student correctly completes all aspects of the activity, a personalized "Certificate of Completion" is awarded to him/her. The certificate is proof positive that the student has completed the lab. Warning: Because VirtualRiver contains numerous Java Applets, there are certain "Technical Considerations and System Requirements" that need to be addressed. The site's first page contains a statement about these requirements. Thank you very much for your assistance in testing this activity. Gary Novak Department of Geological Sciences California State University at Los Angeles gnovak@..............
Colleagues,
This is to notify you of the BETA release of a new activity for the Geology Labs On-Line project. VirtualRiver-Discharge.
http://vcourseware.calstatela.ed u/GeoLabs/ Follow the link to Virtual River.

(You received this email because your address is in my database of people who may be interested in the "Virtual Labs" of the Geology Labs On-line project. If you received this email in error, please accept my apology and let me know so I can re move your address from the database.)

I hope you will take a look at VirtualRiver and provide some feedback to me. It's designed as an interactive Web-based l ab for introductory earth or environmental science courses at the university level. It may also be appropriate for some high sc hool or middle school earth science classes. If you do review the activity, please note that there is a DEMONSTRATION version a vailable (a link can be found on the first page) that gives you the opportunity for a quick overview.

Can you use it? Did you find any bugs? Do you have any suggestions to improve it?

VirtualRiver-Discharge and is one of three virtual labs we hope to eventually have available on the Web about riv ers. It focuses on the determination of a stream's discharge using the "method of verticals." The next activity will be about flooding, hydrographs, flood recurrence intervals and flood probability. The final one will be concerned with erosion, load transport, and sediment deposition.

VirtualRiver-Discharge, similar to previous virtual labs (Virtual Earthquake and Virtual Dating), r equires students to interact with the content of a Web page (through Java Applets, JavaScripts, Dynamic HTML, and Shockwave Ani mations) in order to make careful observations and measurements, do simple calculations, and answer questions about their work. If the student correctly completes all aspects of the activity, a personalized "Certificate of Completion" is awarde d to him/her. The certificate is proof positive that the student has completed the lab.

Warning: Because VirtualRiver contains numerous Java Applets, there are certain "Technical Considerations an d System Requirements" that need to be addressed. The site's first page contains a statement about these requirements.

Thank you very much for your assistance in testing this activity.

Gary Novak
Department of Geological Sciences
California State University at Los Angeles
gnovak@..............





Subject: Nerdess's in the PSN From: Edward Cranswick cranswick@........ Date: Fri, 28 Apr 2000 04:11:44 -0600 Kathy- When I made that remark about the members of the Public Seismic Network (PSN; see, e.g., ) largely consisting of men escaping into the garage from their wives, children, and families (an observation originally made by my friend, Benjamin Gardner, a USGS Volunteer for Science who did alot of work with the PSN in the early 1990's), I was not being mindlessly sexist. Over the last decade, I have kept my eye out for the appearance of women in the international group of amateur and not-so-amateur seismologists which now numbers over 300 members worldwide; but, unfortunately, most of them so far have been nerds, not nerdess's. -Edward -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 PO Box 25046, Federal Center cranswick@........ Denver, CO 80225-0046 USA E.M. Forster said, "Only connect". __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Nordic's in the PSN From: "Taylor, Victor" Victor.Taylor@......... Date: Fri, 28 Apr 2000 08:54:11 -0400 Go fishing, camping and trekking for your private time....Victoria > -----Original Message----- > From: cranswick@........ [SMTP:cranswick@......... > Sent: Friday, April 28, 2000 6:12 AM > To: haller@........ > Cc: sbohlen@......... bpgetcetc@.......... psn-l@.............. > Subject: Nerdess's in the PSN > > Kathy- > When I made that remark about the members of the Public Seismic > Network (PSN; see, e.g., ) largely consisting of > men escaping into the garage from their wives, children, and families > (an observation originally made by my friend, Benjamin Gardner, a USGS > Volunteer for Science who did alot of work with the PSN in the early > 1990's), I was not being mindlessly sexist. Over the last decade, I have > kept my eye out for the appearance of women in the international group > of amateur and not-so-amateur seismologists which now numbers over 300 > members worldwide; but, unfortunately, most of them so far have been > nerds, not nerdess's. > -Edward > > -- > Edward Cranswick Tel: 303-273-8609 > US Geological Survey, MS 966 Fax: 303-273-8600 > PO Box 25046, Federal Center cranswick@........ > Denver, CO 80225-0046 USA E.M. Forster said, "Only connect". > > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Anatomy of Seismograms From: ted@.......... Date: Fri, 28 Apr 2000 09:29:04 -0700 E-bay had a copy of "Principles Underlying the Interpretation of Seismograms", U.S. Dept. of Commerce Special Publication 254 (revised 1966 edition) for sale a few months ago. I think it went for about $65. However since the publication is out of print, the winning bidder was kind enough to send me a xerox copy of the book. If anyone on our list would like a copy of this document (about 50 pages), send me $5 to cover copying and shipping costs and I'll be glad to make you a copy. Address is 238 Highland St., Portsmouth, NH 03801. Regards, Ted __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Nordic's in the PSN From: ted@.......... Date: Fri, 28 Apr 2000 15:12:55 -0400 For years my plan has been that when the seismic station is online, recording and stable I will be able to leave the basement and go off to the mountains to fish, camp and trek, knowing that I'll capture any quakes that happen while I'm out there in the countryside doing healthy things. Unfortunately these three characteristics have never occured at the same time. :-( However I am now offering at a reduced rate to PSN members large lithographs of natural scenes to place in your basement or garage. Throw in a StairMaster and you won't hardly know the difference. Regards, Ted __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Nordic's in the PSN From: Steve Hammond Shammon1@............. Date: Fri, 28 Apr 2000 12:22:16 -0700 Hi Ed, -- sorry, but I think we had some really excellent Nerdess's in the group in the early days. While Ben was correct, the original six (Bruce, Al, Pete, Jan, Dick, and myself) consisted largely of men escaping into the garage to hack on their seismographs… it would be incorrect to represent the PSN as being void of women involvement during the first few years of existence. Need I remind you of the role that Dorothy Darby played in getting the PSN in Pasadena up and running or the results her actions had after relaying critical life saving information by radio during the early hours of the Northridge earthquake. Also, remember that in 1992 Carol Taylor at Anderson Elementary in San Jose had her fifth grade class on-line daily to the BBS in San Jose as they studied seismology and plate tectonics. Carol spent many of her own hours getting prepared to tech that initial group of students. Regards, Steve Hammond PSN Aptos, California Taylor, Victor wrote: > > Go fishing, camping and trekking for your private time....Victoria > > > -----Original Message----- > > From: cranswick@........ [SMTP:cranswick@......... > > Sent: Friday, April 28, 2000 6:12 AM > > To: haller@........ > > Cc: sbohlen@......... bpgetcetc@.......... psn-l@.............. > > Subject: Nerdess's in the PSN > > > > Kathy- > > When I made that remark about the members of the Public Seismic > > Network (PSN; see, e.g., ) largely consisting of > > men escaping into the garage from their wives, children, and families > > (an observation originally made by my friend, Benjamin Gardner, a USGS > > Volunteer for Science who did alot of work with the PSN in the early > > 1990's), I was not being mindlessly sexist. Over the last decade, I have > > kept my eye out for the appearance of women in the international group > > of amateur and not-so-amateur seismologists which now numbers over 300 > > members worldwide; but, unfortunately, most of them so far have been > > nerds, not nerdess's. > > -Edward > > > > -- > > Edward Cranswick Tel: 303-273-8609 > > US Geological Survey, MS 966 Fax: 303-273-8600 > > PO Box 25046, Federal Center cranswick@........ > > Denver, CO 80225-0046 USA E.M. Forster said, "Only connect". > > > > > > __________________________________________________________ > > > > Public Seismic Network Mailing List (PSN-L) > > > > To leave this list email PSN-L-REQUEST@.............. with > > the body of the message (first line only): unsubscribe > > See http://www.seismicnet.com/maillist.html for more information. > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Nordic's in the PSN From: "Taylor, Victor" Victor.Taylor@......... Date: Fri, 28 Apr 2000 15:49:25 -0400 Ted, I have found in my seismic studies that a very stable power supply, coupled to a battery bank, and utilizing a sola ac power line regulator leads to stability in the calibration, and operation of the system. It provides on line time during power outages. RF shielding around the seismic sensors removes transient EMF impulses. Computers are noisy and produce various intensities of RF noise depending on how hard they are running, more input and computing time means more RF noise. Optical fiber line with Photo Electronic coupling is useful over long runs. Build a system like this, install the sensors in a RF screen room, calibrate and collect data. Justify the expense as a tornado shelter. Buy a new fly rod and go fishing, camping and trekking with the whole household. > -----Original Message----- > From: ted@.......... [SMTP:ted@........... > Sent: Friday, April 28, 2000 3:13 PM > To: psn-l@.............. > Subject: RE: Nordic's in the PSN > > > > For years my plan has been that when the seismic station is online, > recording and stable I will be able to leave the basement and go off to > the > mountains to fish, camp and trek, knowing that I'll capture any quakes > that > happen while I'm out there in the countryside doing healthy things. > Unfortunately these three characteristics have never occured at the same > time. :-( > > However I am now offering at a reduced rate to PSN members large > lithographs of natural scenes to place in your basement or garage. Throw > in a StairMaster and you won't hardly know the difference. > > Regards, Ted > > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Fwd: New web page to look at! From: The Lahrs JohnJan@........ Date: Fri, 28 Apr 2000 17:56:43 -0600 Interesting site from the USGS Menlo Park. John >------------- Begin Forwarded Message ------------- > >X-Sender: reasen@................... >Date: Fri, 28 Apr 2000 14:02:44 -0700 >To: wehz@........................ >From: Paul Reasenberg >Subject: New web page to look at! > > >Hello All, > >There's a new web page I think you'll like! It presents Jim Luetgert's >real-time display of seismograms from our network in the "Helicorder" >format. Jim did a masterful job of writing the programs that keep these >displays fresh automatically. Some of you have seen these displays, but >most of you haven't yet. > >When you have a minute or two, take a look at > >http://quake.wr.usgs.gov/helicorders > >Both Jim (who did all the hard work) and I (who developed the web page) >would like your comments. I think Jim deserves a lot of credit for >creating this! > >Cheers, >Paul > > >-------------------------------------------------------------------- > >Paul A. Reasenberg Tel: 650-329-5002 >U.S. Geological Survey Fax: 650-329-5143 >345 Middlefield Road email: reasen@........ >Menlo Park, California 94025 > >Please note NEW EMAIL ADDRESS: reasen@........ > >Visit our website at http://quake.wr.usgs.gov/ > > > > >------------- End Forwarded Message ------------- John C. Lahr 1925 Foothills Road Golden, CO 80402 (303) 215-9913 http://lahr.org/john-jan/science.html __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Anatomy of Seismograms From: mbrewer mbrewer@...... Date: Fri, 28 Apr 2000 22:54:52 -0300 Ted, I would love to have a copy, but how do I get the $5 to you. It will cost me $4 to buy a bank draft. It is still a LOT less than $65. Would you happen to be coming to Bermuda soon? Regards, Martin -----Original Message----- From: ted@.......... [SMTP:ted@........... Sent: Friday, April 28, 2000 1:29 PM To: psn-l@.............. Subject: Re: Anatomy of Seismograms E-bay had a copy of "Principles Underlying the Interpretation of Seismograms", U.S. Dept. of Commerce Special Publication 254 (revised 1966 edition) for sale a few months ago. I think it went for about $65. However since the publication is out of print, the winning bidder was kind enough to send me a xerox copy of the book. If anyone on our list would like a copy of this document (about 50 pages), send me $5 to cover copying and shipping costs and I'll be glad to make you a copy. Address is 238 Highland St., Portsmouth, NH 03801. Regards, Ted __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Anatomy of Seismograms / Postage From: "Erich Kern" ekern@......... Date: Fri, 28 Apr 2000 19:38:24 -0700 Guys, The postage to Bermuda from the US at the "printed matter" air rate for 50 single sided pages (9 oz. with envelope) is $3.63. If it was going to Australia or NZ it would be $5.95 postage. If you do 50 pages with double sided copies, this still is 5 ounces with the envelope. The printed matter airmail postage to Bermuda is $2.35 or to Aus/ NZ would be $3.75 My guess is that Ted didn't include postage beyond US borders when he made the offer. Five bucks is a bargain any way you look at it. Regards, Erich Kern -----Original Message----- From: mbrewer To: 'psn-l@............... Date: Friday, April 28, 2000 7:24 PM Subject: RE: Anatomy of Seismograms Ted, I would love to have a copy, but how do I get the $5 to you. It will cost me $4 to buy a bank draft. It is still a LOT less than $65. Would you happen to be coming to Bermuda soon? Regards, Martin __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Article on gravimeters From: George Bush gbush@....... Date: Sat, 29 Apr 2000 09:42:15 -0700 I just discovered an interesting article on the development of an absolute differential gravimeter that appeared in an unusual place. As a ametuer seismometer builder, I found the article fascinating to see what the big boys do. The article appeared in the March 2000 issue of "Laser Focus World," on pp20-24. For you non-subscribers the article can be seen on the web at: http://lfw.pennwellnet.com/home/articles.cfm?ARTICLE_ID=66006&VERSION_NUM=1& PUBLICATION_ID=12&Section=CurrentIssue Now I have had trouble emailing long URL's before, so if this isn't clickable, try to copy and paste it into the address box of your browser. And if that doesn't work you can go the the magazine's main web address http://lfw.pennwellnet.com/home/home.cfm and then select "current Issue" then World News" then the article "Interferometry, Fiber Coupling improves Gravimeters" George Bush Sea Ranch, CA, USA 38.74N, 123.5W __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Anatomy of Seismograms / Postage From: ted@.......... Date: Sat, 29 Apr 2000 13:29:03 -0400 Erich is correct, that was USD 2.50 for copying and USD 2.50 for postage within US. Let's amend the offer to USD 5.00 for US addresses and USD 10.00 for outside the US. Any leftover money I will donate to Larry. Gee, if I had an e-business site you could all use your charge cards... Ted Blank (for those who want to write checks) "Erich Kern" @.............. on 04/28/2000 10:38:24 PM Please respond to psn-l@.............. Sent by: psn-l-request@.............. To: cc: Subject: Re: Anatomy of Seismograms / Postage Guys, The postage to Bermuda from the US at the "printed matter" air rate for 50 single sided pages (9 oz. with envelope) is $3.63. If it was going to Australia or NZ it would be $5.95 postage. If you do 50 pages with double sided copies, this still is 5 ounces with the envelope. The printed matter airmail postage to Bermuda is $2.35 or to Aus/ NZ would be $3.75 My guess is that Ted didn't include postage beyond US borders when he made the offer. Five bucks is a bargain any way you look at it. Regards, Erich Kern -----Original Message----- From: mbrewer To: 'psn-l@............... Date: Friday, April 28, 2000 7:24 PM Subject: RE: Anatomy of Seismograms Ted, I would love to have a copy, but how do I get the $5 to you. It will cost me $4 to buy a bank draft. It is still a LOT less than $65. Would you happen to be coming to Bermuda soon? Regards, Martin __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Seismogram Analysis From: meredith lamb mlamb1@.......... Date: Sat, 29 Apr 2000 11:57:21 -0700 Dennis Recla has sent a email, which he wishes forwarded to the PSN: I have copied the document Seismogram Analysis (Training Outline), 32 pages, which was prepared by the Laramie Analysis Facility Personnel as part of some government contracts to a PDF format file. Its old, vintage 1960, but a very basic description of examining seismograms to determine epicenters and travel times. Its about 1.3 mbyte, and I can email them to anyone who would like it, drop me a note, and I'll send out the copies. Don't want to put it out as a general post because of the size. I also have alot of the old Geotech/Geotechnical Corp manuals and such, which I can now covert to PDF formats. (depends on what is and what is not copyright protected). Reply to: recla@.......... Regards, Dennis Recla __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Nordic's in the PSN From: Edward Cranswick cranswick@........ Date: Sat, 29 Apr 2000 15:25:50 -0600 Victoria & Steve- I acknowledge your corrections. Of course, I see that the Earth, Gaia, is feminine, so that women tend to know what's going on anyway -- while men are busy putting instruments together to try and find out. -Edward Steve Hammond wrote: > Hi Ed, -- sorry, but I think we had some really excellent Nerdess's in > the group in the early days. While Ben was correct, the original six > (Bruce, Al, Pete, Jan, Dick, and myself) consisted largely of men > escaping into the garage to hack on their seismographs… it would be > incorrect to represent the PSN as being void of women involvement during > the first few years of existence. Need I remind you of the role that > Dorothy Darby played in getting the PSN in Pasadena up and running or > the results her actions had after relaying critical life saving > information by radio during the early hours of the Northridge > earthquake. Also, remember that in 1992 Carol Taylor at Anderson > Elementary in San Jose had her fifth grade class on-line daily to the > BBS in San Jose as they studied seismology and plate tectonics. Carol > spent many of her own hours getting prepared to tech that initial group > of students. > > Regards, Steve Hammond PSN Aptos, California > > Taylor, Victor wrote: > > > > Go fishing, camping and trekking for your private time....Victoria -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 PO Box 25046, Federal Center cranswick@........ Denver, CO 80225-0046 USA E.M. Forster said, "Only connect". __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Anatomy of Seismograms / Postage From: "Rex Klopfenstein, Jr." rklopfen@......... Date: Sat, 29 Apr 2000 18:02:35 -0400 I you send me your mailing address via private mail, I will be forwarding you a check! ted@.......... wrote: > Erich is correct, that was USD 2.50 for copying and USD 2.50 for postage > within US. > > Let's amend the offer to USD 5.00 for US addresses and USD 10.00 for > outside the US. Any leftover money I will donate to Larry. Gee, if I had > an e-business site you could all use your charge cards... > > Ted Blank (for those who want to write checks) > -- Rex Klopfenstein, Jr. Bowling Green, OH rklopfen@......... http://www.wcnet.org/~rklopfen __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Seismogram Analysis From: "Rex Klopfenstein, Jr." rklopfen@......... Date: Sat, 29 Apr 2000 18:05:41 -0400 Send me a copy!! Thanks meredith lamb wrote: > Dennis Recla has sent a email, which he wishes forwarded to > the PSN: > > I have copied the document Seismogram Analysis (Training > Outline), 32 pages, which was prepared by the Laramie > Analysis Facility Personnel as part of some government > contracts to a PDF format file. Its old, vintage 1960, but a > very basic description of examining seismograms to determine > epicenters and travel times. > > Its about 1.3 mbyte, and I can email them to anyone who > would like it, drop me a note, and I'll send out the copies. > Don't want to put it out as a general post because of the size. > > I also have alot of the old Geotech/Geotechnical Corp manuals > and such, which I can now covert to PDF formats. (depends > on what is and what is not copyright protected). > > Reply to: recla@.......... > > Regards, > > Dennis Recla > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. -- Rex Klopfenstein, Jr. Bowling Green, OH rklopfen@......... http://www.wcnet.org/~rklopfen __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Article on gravimeters From: John Hernlund hernlund@....... Date: Sat, 29 Apr 2000 19:58:10 -0700 (MST) On Sat, 29 Apr 2000, George Bush wrote: > I just discovered an interesting article on the development of an absolute > differential gravimeter that appeared in an unusual place. As a ametuer > seismometer builder, I found the article fascinating to see what the big > boys do. The article appeared in the March 2000 issue of "Laser Focus > World," on pp20-24. For you non-subscribers the article can be seen on the > web at: > http://lfw.pennwellnet.com/home/articles.cfm?ARTICLE_ID=66006&VERSION_NUM=1& > PUBLICATION_ID=12&Section=CurrentIssue > Now I have had trouble emailing long URL's before, so if this isn't > clickable, try to copy and paste it into the address box of your browser. > And if that doesn't work you can go the the magazine's main web address > http://lfw.pennwellnet.com/home/home.cfm > and then select "current Issue" then World News" then the article > "Interferometry, Fiber Coupling improves Gravimeters" > George Bush George, There was a horribly written article about an incredibly interesting subject a few years back in Scientific American. Even though the article did not belong in the magazine, you might be interested in reading it. It was about a gravity gradiometer that had been designed to help submarines "see" the topography on the ocean floor and avoid collision with sea mounts. They needed a passive method to see the ocean floor so that they would not be detected. Supposedly this thing worked great (too bad all the data they collected is classified). Anyways, the company that made it was allowed to contract its use out to some geophysical concerns, such as finding oil and natural gas resevoirs. The company takes a huge amount of money, throws this thing in a boat and drives around for a while. They take the data, reduce it, and then sell portions of it for commercial use. Nobody is allowed to buy one of these instruments, or use one for themselves. This is the reason it did not belong in the magazine: it was really an ad for the company. The exact technology is still classified, so it is like a magical black box. Anyways, this device produces higher resolution images for finding density anomalies than seismic methods, and does not require a whole lot of fancy deployment except for position tracking and recording instruments, and so is a lot easier to use than seismic arrays. I found this hard to believe when I first heard it, but then again I was only used to absolute vertical gravity measurements. So I had to find out about it a little further. The gravity gradient is the change in the gravity for each direction (down, east, north) within a given distance and with respect to each direction. So the downward component of gravity changes differently in the down, east and west directions, and likewise for the east and north components of gravity. This makes nine different combinations of gradients that can be examined. One of those nine components can tell you an awful lot more than an absolute gravity measurement, so just imagine having nine of them. Well, it turns out that some of the components are equal, and the total number of unique components is reduced to six. For example, the change in the down component of gravity with respect to north is equal to the change in the north component of gravity with respect to the down direction. In addition, the three terms where the component changes in each of its directions is regulated by the fact that a gravitational field is divergenceless, which means these three gradients must sum to 0. So that makes five unique components, from which the other four can be determined. All nine components are referred to as the "gravity gradient tensor." This machine is supposed to have rotatiing parts and sensors inside some kind of black spherical shell. It is very mysterious, and I would love to see inside one some day. I am sure everyone else would be interested too... I guess I would have to hijack one of their ships or something if I wanted to get it, but that won't happen any time soon. Perhaps the PSN could mount an expedition, and the media would try and figure out if PSN stood for some kind of terrorist organization or something. Anyhow, enjoy! John Hernlund E-mail: hernlund@....... WWW: http://www.public.asu.edu/~hernlund/ ****************************************************************************** __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Article on gravimeters From: "Tom Schmitt" tschmitt@.............. Date: Sun, 30 Apr 2000 14:40:05 -0400 John About fifteen years ago I went to a non-classified briefing about a land version of a gravity gradiometer. The Defense Mapping Agency had it. It was in a Winabago of some sort and had three disks that rotated at a fairly low rpm, a few Hz at most. The disks were less than a meter in diameter. The disks had two accelerometers on them. The acceleration as a function of position of the two accelerometers was reccorded and some sort of auto-correlation or FFT was done to get the direction and magnitude of the gradient. It was cute. Tom Schmitt tschmitt@.............. ----- Original Message ----- From: John Hernlund To: Sent: Saturday, April 29, 2000 10:58 PM Subject: Re: Article on gravimeters > > George Bush > > George, > There was a horribly written article about an incredibly interesting > subject a few years back in Scientific American. Even though the article did > not belong in the magazine, you might be interested in reading it. It was > about a gravity gradiometer that had been designed to help submarines "see" > the topography on the ocean floor and avoid collision with sea mounts. They > needed a passive method to see the ocean floor so that they would not be > detected. Supposedly this thing worked great (too bad all the data they > collected is classified). Anyways, the company that made it was allowed to > contract its use out to some geophysical concerns, such as finding oil and > natural gas resevoirs. The company takes a huge amount of money, throws this > thing in a boat and drives around for a while. They take the data, reduce it, > and then sell portions of it for commercial use. Nobody is allowed to buy > one of these instruments, or use one for themselves. This is the reason it > did not belong in the magazine: it was really an ad for the company. The > exact technology is still classified, so it is like a magical black box. > > Anyways, this device produces higher resolution images for finding density > anomalies than seismic methods, and does not require a whole lot of fancy > deployment except for position tracking and recording instruments, and so is a > lot easier to use than seismic arrays. I found this hard to believe when I > first heard it, but then again I was only used to absolute vertical gravity > measurements. So I had to find out about it a little further. > > The gravity gradient is the change in the gravity for each direction (down, > east, north) within a given distance and with respect to each direction. So > the downward component of gravity changes differently in the down, east and > west directions, and likewise for the east and north components of gravity. > This makes nine different combinations of gradients that can be examined. One > of those nine components can tell you an awful lot more than an absolute > gravity measurement, so just imagine having nine of them. Well, it turns out > that some of the components are equal, and the total number of unique > components is reduced to six. For example, the change in the down component > of gravity with respect to north is equal to the change in the north component > of gravity with respect to the down direction. In addition, the three terms > where the component changes in each of its directions is regulated by the fact > that a gravitational field is divergenceless, which means these three > gradients must sum to 0. So that makes five unique components, from which the > other four can be determined. All nine components are referred to as the > "gravity gradient tensor." > > This machine is supposed to have rotatiing parts and sensors inside some > kind of black spherical shell. It is very mysterious, and I would love to see > inside one some day. I am sure everyone else would be interested too... I > guess I would have to hijack one of their ships or something if I wanted to > get it, but that won't happen any time soon. Perhaps the PSN could mount an > expedition, and the media would try and figure out if PSN stood for some kind > of terrorist organization or something. > > Anyhow, enjoy! > > John Hernlund > E-mail: hernlund@....... > WWW: http://www.public.asu.edu/~hernlund/ > > **************************************************************************** ** > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Nordic's in the PSN From: Edward Cranswick cranswick@........ Date: Sun, 30 Apr 2000 16:56:20 -0600 Ted- > However I am now offering at a reduced rate to PSN members large > lithographs of natural scenes to place in your basement or garage. Throw > in a StairMaster and you won't hardly know the difference. You are a true IBM man! A credit to Big Blue! Of course, in my case, after FORTRAN programing on IBM 360/30, a 360/44, and a 360/50 for four years (1967-1971) in the family business, the research department of local state mental hospital, I ran off as a geology major to the oil fields of Oklahoma to work as a roustabout so that I could re-establish contact with the physical Earth . . . and that was the beginning of my life in the Earth sciences: I wanted to pursue geology to that I could see the world. Ironically, I ended up in seismology, the most mathematical techno-nerdy of the Earth sciences (at least it was then). I chased earthquakes, and so, unlike some of my more officebound seismological colleagues, I went out in the field and touched the Earth. But then, ironically again, I specialized in developing portable computer systems so that we could analyze the digital seismic waveforms recorded by our portable autonomous digital seismographs (PADSs) in near-realtime, i.e., while we were still in the field and data acquisition was still in process. So I can do everything on my field computer that I can do on my desktop back in the office -- it's like I never left the office . . . so why DID I leave the office . . . because I never saw the Earth. However, on my last trip to Turkey last December, I spent a couple of days in the field with the Turkish seismologist Naside Ozer who was operating 10 Reftek PASSCAL PADSs in the epicentral area of the 1999 Nov 12 Duzce Earthquake in cooperation with Lamont-Doherty Earth Observatory, Columbia University. Because I would only carry car batteries, and, unlike her students, I would not even measure battery voltages with a voltmeter, Naside told me that her 72-year-old father was a much better field assistant than I. However, unburdened by techno-nerdy concerns, I had one of the best experiences in my seismology career: seeing the structures -- the pull-apart basins and mountains, the fault ruptures and patterns of building damage -- of the North Anatolian Fault . . . I am grateful to Naside that she worked harder in the field than anyone I have ever seen and that she did such a brilliant job that included all the nerdy stuff . . . and left me to see the Earth. So there! -Edward ted@.......... wrote: > For years my plan has been that when the seismic station is online, > recording and stable I will be able to leave the basement and go off to the > mountains to fish, camp and trek, knowing that I'll capture any quakes that > happen while I'm out there in the countryside doing healthy things. > Unfortunately these three characteristics have never occured at the same > time. :-( -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 PO Box 25046, Federal Center cranswick@........ Denver, CO 80225-0046 USA E.M. Forster said, "Only connect". __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Articles on gravimeters From: "Ted Rogers" TedR@.................. Date: Mon, 1 May 2000 14:54:38 +1000 To whom it may interest I have been reading the comments on gravitation with great interest and it started me wondering about plumb lines and if at certain locations (assuming no interference/vibration) they hang truly vertical all the time - i.e. pointing directly through the centre of the earth, and even change due the core rotating at a different speed to the crust. Likewise if a skyscraper is truly vertical at one moment, could it not be vertical at another time as compared with a plumb line... I know the amount by which it would be out of plumb would be so insignificant as not to matter in the real world. I enjoy reading the discussions that the group put up and one day, GV, I hope to take a more active role in the earth sciences ------------ Ted Rogers. ---------- > From: Tom Schmitt > To: psn-l@.............. > Subject: Re: Article on gravimeters > Date: Monday, May 01, 2000 4:40 AM > > John > > About fifteen years ago I went to a non-classified briefing about a land > version of a gravity gradiometer. The Defense Mapping Agency had it. > > It was in a Winabago of some sort and had three disks that rotated at a > fairly low rpm, a few Hz at most. The disks were less than a meter in > diameter. The disks had two accelerometers on them. The acceleration as a > function of position of the two accelerometers was reccorded and some sort > of auto-correlation or FFT was done to get the direction and magnitude of > the gradient. > > It was cute. > > > Tom Schmitt > > tschmitt@.............. > > ----- Original Message ----- > From: John Hernlund > To: > Sent: Saturday, April 29, 2000 10:58 PM > Subject: Re: Article on gravimeters > > > George Bush > > > > George, > > There was a horribly written article about an incredibly interesting > > subject a few years back in Scientific American. Even though the article > did > > not belong in the magazine, you might be interested in reading it. It was > > about a gravity gradiometer that had been designed to help submarines > "see" > > the topography on the ocean floor and avoid collision with sea mounts. > They > > needed a passive method to see the ocean floor so that they would not be > > detected. Supposedly this thing worked great (too bad all the data they > > collected is classified). Anyways, the company that made it was allowed > to > > contract its use out to some geophysical concerns, such as finding oil and > > natural gas resevoirs. The company takes a huge amount of money, throws > this > > thing in a boat and drives around for a while. They take the data, reduce > it, > > and then sell portions of it for commercial use. Nobody is allowed to buy > > one of these instruments, or use one for themselves. This is the reason > it > > did not belong in the magazine: it was really an ad for the company. The > > exact technology is still classified, so it is like a magical black box. > > > > Anyways, this device produces higher resolution images for finding > density > > anomalies than seismic methods, and does not require a whole lot of fancy > > deployment except for position tracking and recording instruments, and so > is a > > lot easier to use than seismic arrays. I found this hard to believe when > I > > first heard it, but then again I was only used to absolute vertical > gravity > > measurements. So I had to find out about it a little further. > > > > The gravity gradient is the change in the gravity for each direction > (down, > > east, north) within a given distance and with respect to each direction. > So > > the downward component of gravity changes differently in the down, east > and > > west directions, and likewise for the east and north components of > gravity. > > This makes nine different combinations of gradients that can be examined. > One > > of those nine components can tell you an awful lot more than an absolute > > gravity measurement, so just imagine having nine of them. Well, it turns > out > > that some of the components are equal, and the total number of unique > > components is reduced to six. For example, the change in the down > component > > of gravity with respect to north is equal to the change in the north > component > > of gravity with respect to the down direction. In addition, the three > terms > > where the component changes in each of its directions is regulated by the > fact > > that a gravitational field is divergenceless, which means these three > > gradients must sum to 0. So that makes five unique components, from which > the > > other four can be determined. All nine components are referred to as the > > "gravity gradient tensor." > > > > This machine is supposed to have rotatiing parts and sensors inside > some > > kind of black spherical shell. It is very mysterious, and I would love to > see > > inside one some day. I am sure everyone else would be interested too... > I > > guess I would have to hijack one of their ships or something if I wanted > to > > get it, but that won't happen any time soon. Perhaps the PSN could mount > an > > expedition, and the media would try and figure out if PSN stood for some > kind > > of terrorist organization or something. > > > > Anyhow, enjoy! > > > > John Hernlund > > E-mail: hernlund@....... > > WWW: http://www.public.asu.edu/~hernlund/ > > > > > **************************************************************************** > ** > > > > __________________________________________________________ > > > > Public Seismic Network Mailing List (PSN-L) > > > > To leave this list email PSN-L-REQUEST@.............. with > > the body of the message (first line only): unsubscribe > > See http://www.seismicnet.com/maillist.html for more information. > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Dorothy Darby, the PSN Nerdess of Northridge From: Edward Cranswick cranswick@........ Date: Mon, 01 May 2000 02:37:14 -0600 Steve- Your comment, "Need I remind you of the role that Dorothy Darby played in getting the PSN in Pasadena up and running or the results her actions had after relaying critical life saving information by radio during the early hours of the Northridge earthquake," jogged my memory of the PSN presentation that Dorothy, her husband, Jerry, and you put together for the annual Seismological Society of America meeting at Pasadena in April 1994 following the Northridge Earthquake of 17 January 1994. Below is the abstract of that presentation (largely written by Ben Gardner, USGS Volunteer for Science, based on the material you all sent and last-minute phone conversations with you all). -Edward %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% THE PUBLIC SEISMIC NETWORK (PSN) OF PASADENA, HAM RADIO AND THE 17 JANUARY 1994 NORTHRIDGE EARTHQUAKE DARBY, D., DARBY, J., PSN, 841 Belvidere St., Pasadena, CA 91104, (818) 797-7509, ddarby@................. BBS (818) 797-0536; HAMMOND, S., PSN, 5847 Falon Way, San Jose, CA 95123, BBS (408) 226-0675 (Sponser: CRANSWICK, E.). By word of mouth via HAM radio, the Public Seismic Network has reached hundreds of people. In a crisis like the Northridge Earthquake, citizens need to play an organized role in assistance and communications; this is a motivation behind HAM radio networks. Linked to a PSN, HAM radio is a viable way of educating people about earthquakes and, during a quake, of passing on vital, realtime information. I learned of the PSN through amateur radio and contacted the PSN/San Jose BBS. We had already built a Lehman-type seismometer and had a chart recorder. We started operating a PSN BBS in Pasadena. I began a weekly net on amateur radio, giving out weekly earthquake data from both regional and world-wide events. PSN/Pasadena now has a user base of over 500. We are working on interaction with schools; several science teachers use the BBS. When the Northridge Earthquake struck, my role was to man the radio and take 'felt' reports; my husband handled the chart recorder and measured the P&S waves to calculate distances. My son, also a HAM, handled telephone calls. Within 5 minutes of taking those felt reports, we knew where the epicenter was. Those reporting 'rolling motion' were farther away, and those reporting 'sharp jolts' were closer. From experience of the 1991 Sierra Madre Earthquake, I knew that those at the epicenter would not be reporting in right away; they would be busy taking care of their own, or checking for damage and gas leaks. When those at the epicenter started reporting in, the reports turned to reports of fires and help needed. We became an emergency hotline, logging hundreds of calls within 72 hours. Calls came in asking for damage reports where relatives lived, for help needed in fighting fires, for advice about gas leaks, etc. Even as immediate needs were handled, we hoped to be of longterm use by putting information on the BBS as we got it. It may be still unclear how the seismic data can be used for research and to help us out. But the information helps the people listening. We had news media monitoring that frequency, and we had all the Emergency Operating Centers tuned into it. Police and fire agencies also monitor it. I may never know how many it helped, but we received many grateful responses. Darby, D., Darby, J., Hammond, S., 1994, The Public Seismic Network (PSN), Ham radio, and the 17 January 1994 Northridge Earthquake: Program for Northridge Abstracts, 89th Annual Meeting of the Seismological Society of America, 5-7 April 1994, Pasadena, California. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% Steve Hammond wrote: > Hi Ed, -- sorry, but I think we had some really excellent Nerdess's in > the group in the early days. While Ben was correct, the original six > (Bruce, Al, Pete, Jan, Dick, and myself) consisted largely of men > escaping into the garage to hack on their seismographs… it would be > incorrect to represent the PSN as being void of women involvement during > the first few years of existence. Need I remind you of the role that > Dorothy Darby played in getting the PSN in Pasadena up and running or > the results her actions had after relaying critical life saving > information by radio during the early hours of the Northridge > earthquake. Also, remember that in 1992 Carol Taylor at Anderson > Elementary in San Jose had her fifth grade class on-line daily to the > BBS in San Jose as they studied seismology and plate tectonics. Carol > spent many of her own hours getting prepared to tech that initial group > of students. > > Regards, Steve Hammond PSN Aptos, California > > Taylor, Victor wrote: > > > > Go fishing, camping and trekking for your private time....Victoria > > > > > -----Original Message----- > > > From: cranswick@........ [SMTP:cranswick@......... > > > Sent: Friday, April 28, 2000 6:12 AM > > > To: haller@........ > > > Cc: sbohlen@......... bpgetcetc@.......... psn-l@.............. > > > Subject: Nerdess's in the PSN > > > > > > Kathy- > > > When I made that remark about the members of the Public Seismic > > > Network (PSN; see, e.g., ) largely consisting of > > > men escaping into the garage from their wives, children, and families > > > (an observation originally made by my friend, Benjamin Gardner, a USGS > > > Volunteer for Science who did alot of work with the PSN in the early > > > 1990's), I was not being mindlessly sexist. Over the last decade, I have > > > kept my eye out for the appearance of women in the international group > > > of amateur and not-so-amateur seismologists which now numbers over 300 > > > members worldwide; but, unfortunately, most of them so far have been > > > nerds, not nerdess's. > > > -Edward -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 PO Box 25046, Federal Center cranswick@........ Denver, CO 80225-0046 USA E.M. Forster said, "Only connect". __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Articles on gravimeters From: "Tom Schmitt" tschmitt@.............. Date: Mon, 1 May 2000 09:09:12 -0400 Ted The stories about plumb bobs not hanging vertical are wonderful. The British Royal Surveyers in India found the plumb bobs leaning away from the mountains. They figured this out because the distance between two points was different when measured by astronomical and standard survey techniques. There is a little more to the story and this effect was known before that. However that is the example used in text books because the story is so good. (So were the surveyers, thousands of miles and they were worried about less than few meters errror if someone has a text book fill us in on the ammount of error they found). By the way, plumb bobs (lacking wind electostatic and or magnetic influences) always point in such a way to minimize their potential energy. Because of density variations in the earth, that may not be "down". The ammount of variation is slight and insignificant for most purposes. It is important for scientific purposes, it is important for very critical surveys is a few areas in the world, and it is very important for launching nuclear weapons at people. The later is why the Defense Maping Agency is concerned with it. The missles follow potential energy paths, which may be curved relative to other coordinates. If you want to hit dead on you need the shape of gravity field between where you are and where you want it to hit. Tom Schmitt tschmitt@.............. ----- Original Message ----- From: Ted Rogers To: Cc: Ted Rogers Sent: Monday, May 01, 2000 12:54 AM Subject: Re: Articles on gravimeters > To whom it may interest > > I have been reading the comments on gravitation with great interest and it > started me wondering about plumb lines and if at certain locations > (assuming no interference/vibration) they hang truly vertical all the time > - i.e. pointing directly through the centre of the earth, and even change > due the core rotating at a different speed to the crust. Likewise if a > skyscraper is truly vertical at one moment, could it not be vertical at > another time as compared with a plumb line... I know the amount by which it > would be out of plumb would be so insignificant as not to matter in the > real world. > > I enjoy reading the discussions that the group put up and one day, GV, I > hope to take a more active role in the earth sciences > > > ------------ > > Ted Rogers. > > > > ---------- > > From: Tom Schmitt > > To: psn-l@.............. > > Subject: Re: Article on gravimeters > > Date: Monday, May 01, 2000 4:40 AM > > > > John > > > > About fifteen years ago I went to a non-classified briefing about a land > > version of a gravity gradiometer. The Defense Mapping Agency had it. > > > > It was in a Winabago of some sort and had three disks that rotated at a > > fairly low rpm, a few Hz at most. The disks were less than a meter in > > diameter. The disks had two accelerometers on them. The acceleration > as a > > function of position of the two accelerometers was reccorded and some > sort > > of auto-correlation or FFT was done to get the direction and magnitude of > > the gradient. > > > > It was cute. > > > > > > Tom Schmitt > > > > tschmitt@.............. > > > > ----- Original Message ----- > > From: John Hernlund > > To: > > Sent: Saturday, April 29, 2000 10:58 PM > > Subject: Re: Article on gravimeters > > > > George Bush > > > > > > George, > > > There was a horribly written article about an incredibly interesting > > > subject a few years back in Scientific American. Even though the > article > > did > > > not belong in the magazine, you might be interested in reading it. It > was > > > about a gravity gradiometer that had been designed to help submarines > > "see" > > > the topography on the ocean floor and avoid collision with sea mounts. > > They > > > needed a passive method to see the ocean floor so that they would not > be > > > detected. Supposedly this thing worked great (too bad all the data > they > > > collected is classified). Anyways, the company that made it was > allowed > > to > > > contract its use out to some geophysical concerns, such as finding oil > and > > > natural gas resevoirs. The company takes a huge amount of money, > throws > > this > > > thing in a boat and drives around for a while. They take the data, > reduce > > it, > > > and then sell portions of it for commercial use. Nobody is allowed to > buy > > > one of these instruments, or use one for themselves. This is the > reason > > it > > > did not belong in the magazine: it was really an ad for the company. > The > > > exact technology is still classified, so it is like a magical black > box. > > > > > > Anyways, this device produces higher resolution images for finding > > density > > > anomalies than seismic methods, and does not require a whole lot of > fancy > > > deployment except for position tracking and recording instruments, and > so > > is a > > > lot easier to use than seismic arrays. I found this hard to believe > when > > I > > > first heard it, but then again I was only used to absolute vertical > > gravity > > > measurements. So I had to find out about it a little further. > > > > > > The gravity gradient is the change in the gravity for each direction > > (down, > > > east, north) within a given distance and with respect to each > direction. > > So > > > the downward component of gravity changes differently in the down, east > > and > > > west directions, and likewise for the east and north components of > > gravity. > > > This makes nine different combinations of gradients that can be > examined. > > One > > > of those nine components can tell you an awful lot more than an > absolute > > > gravity measurement, so just imagine having nine of them. Well, it > turns > > out > > > that some of the components are equal, and the total number of unique > > > components is reduced to six. For example, the change in the down > > component > > > of gravity with respect to north is equal to the change in the north > > component > > > of gravity with respect to the down direction. In addition, the three > > terms > > > where the component changes in each of its directions is regulated by > the > > fact > > > that a gravitational field is divergenceless, which means these three > > > gradients must sum to 0. So that makes five unique components, from > which > > the > > > other four can be determined. All nine components are referred to as > the > > > "gravity gradient tensor." > > > > > > This machine is supposed to have rotatiing parts and sensors inside > > some > > > kind of black spherical shell. It is very mysterious, and I would love > to > > see > > > inside one some day. I am sure everyone else would be interested > too... > > I > > > guess I would have to hijack one of their ships or something if I > wanted > > to > > > get it, but that won't happen any time soon. Perhaps the PSN could > mount > > an > > > expedition, and the media would try and figure out if PSN stood for > some > > kind > > > of terrorist organization or something. > > > > > > Anyhow, enjoy! > > > > > > John Hernlund > > > E-mail: hernlund@....... > > > WWW: http://www.public.asu.edu/~hernlund/ > > > > > > > > > **************************************************************************** > > > ** > > > > > > __________________________________________________________ > > > > > > Public Seismic Network Mailing List (PSN-L) > > > > > > To leave this list email PSN-L-REQUEST@.............. with > > > the body of the message (first line only): unsubscribe > > > See http://www.seismicnet.com/maillist.html for more information. > > > > __________________________________________________________ > > > > Public Seismic Network Mailing List (PSN-L) > > > > To leave this list email PSN-L-REQUEST@.............. with > > the body of the message (first line only): unsubscribe > > See http://www.seismicnet.com/maillist.html for more information. > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: PSN-L: Re: Seismogram Analysis From: walt_williams@........ Date: Mon, 1 May 2000 06:12:42 -0800 Hi, (and All), Could you please send me a copy as well? Thank you, Walt Williams, ================================== Organization for SETV Research (OSR) Northridge California, USA walt_williams@........ http://www.setv.org =================================== ------- Forwarded Message Follows ------- Date: Sat, 29 Apr 2000 18:05:41 -0400 From: "Rex Klopfenstein, Jr." To: psn-l@.............. Subject: Re: Seismogram Analysis Reply-to: psn-l@.............. Send me a copy!! Thanks meredith lamb wrote: > Dennis Recla has sent a email, which he wishes forwarded to > the PSN: > > I have copied the document Seismogram Analysis (Training > Outline), 32 pages, which was prepared by the Laramie > Analysis Facility Personnel as part of some government > contracts to a PDF format file. Its old, vintage 1960, but a > very basic description of examining seismograms to determine > epicenters and travel times. > > Its about 1.3 mbyte, and I can email them to anyone who > would like it, drop me a note, and I'll send out the copies. > Don't want to put it out as a general post because of the size. > > I also have alot of the old Geotech/Geotechnical Corp manuals > and such, which I can now covert to PDF formats. (depends > on what is and what is not copyright protected). > > Reply to: recla@.......... > > Regards, > > Dennis Recla > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. -- Rex Klopfenstein, Jr. Bowling Green, OH rklopfen@......... http://www.wcnet.org/~rklopfen __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Articles on gravimeters From: John Hernlund hernlund@....... Date: Mon, 01 May 2000 07:47:13 -0700 (MST) On Mon, 1 May 2000, Tom Schmitt wrote: > The stories about plumb bobs not hanging vertical are wonderful. The > British Royal Surveyers in India > found the plumb bobs leaning away from the mountains. They figured this out > because the distance between > two points was different when measured by astronomical and standard survey > techniques. There is a little more > to the story and this effect was known before that. However that is the > example used in text books because the > story is so good. (So were the surveyers, thousands of miles and they were > worried about less than few meters errror > if someone has a text book fill us in on the ammount of error they found). > > By the way, plumb bobs (lacking wind electostatic and or magnetic > influences) always point in such a way > to minimize their potential energy. Because of density variations in the > earth, that may not be "down". > The ammount of variation is slight and insignificant for most purposes. > It is important for scientific purposes, it is important for very critical > surveys is a few areas in the world, and it is very important for launching > nuclear weapons at people. The later is why the Defense Maping Agency is > concerned with it. The missles follow potential energy paths, which may be > curved relative to other coordinates. If you want to hit dead on you need > the shape of gravity field between where you are and where you want it to > hit. > Tom Schmitt > tschmitt@.............. Yes, these are some of the origins of the ideas of isostatic equilibrium. Many mountain ranges did not deflect a plumb as expected (i.e. toward the mountain), and the explanation had to include something about the density under the mountain range. Two theories came out, one that said that the mountain ranges had to be less dense than the lower country-side, and the other that said the root of the mountains containing less dense crustal rock had to be deeper than the low lowland crustal roots. The second explanation has proven to be the better one, because we find that the crustal root in mountainous zones is far deeper. This is like a boat sinking down further into the water under an increased load. Because the mantle is higher in viscosity than water of course the mountain range takes some time to sink to an equilibrium value. For mountain ranges which are growing very fast (like the Himalayas) an equilibrium is never achieved because the time for growth is much shorter than the time for sinking to equilibrium. Therefore you can use the deflection of the plumb to tell how fast the range is growing. The same effect is observed when removing material from the surface such as erosion and melting of glaciers, and people studying the latter have used the rate of uprising to calculate the viscosity of the mantle. All this came from the initial gravimeter studies... John Hernlund E-mail: hernlund@....... WWW: http://www.public.asu.edu/~hernlund/ ****************************************************************************** __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Origin time From: Paul Jebb pfjebb@.............. Date: Mon, 01 May 2000 13:16:16 -0400 Dear members: I have received several event files for the quake we got here in Newcomb, NY, on 4/20/00. I noticed that the origin time was different for each seismogram. Is the discrepancy due to differences in calibration of the clocks on the host computers? Special thanks to all of you who sent me event files of the quake. Yours truly, Paul Jebb Newcomb Central School __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Article on gravimeters From: George Bush gbush@....... Date: Mon, 01 May 2000 10:40:30 -0700 At 07:58 PM 4/29/00 -0700, you wrote: >George, > There was a horribly written article about an incredibly interesting >subject a few years back in Scientific American. Even though the article did >not belong in the magazine, you might be interested in reading it. It was >about a gravity gradiometer that had been designed to help submarines "see" >the topography on the ocean floor and avoid collision with sea mounts. They >needed a passive method to see the ocean floor so that they would not be >detected. Supposedly this thing worked great (too bad all the data they >collected is classified). Anyways, the company that made it was allowed to >contract its use out to some geophysical concerns, such as finding oil and >natural gas resevoirs. The company takes a huge amount of money, throws this >thing in a boat and drives around for a while. They take the data, reduce it, >and then sell portions of it for commercial use. Nobody is allowed to buy >one of these instruments, or use one for themselves. This is the reason it >did not belong in the magazine: it was really an ad for the company. The >exact technology is still classified, so it is like a magical black box. > ....snip... > John, Thanks for the interesting information. I have always thought that the measurment and understanding of gravity gradients was fascinating, I will try to find the Scientific American article. George __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: origin time, arrival time From: S-T Morrissey sean@........... Date: Mon, 1 May 2000 14:09:03 -0500 (CDT) Paul, I am getting the impression that you did not see the NEIS info about the 20 April quake? VIS: The following is from the United States Geological Survey, National Earthquake Information Center: Preliminary hypocenter for earthquake of 2000 Apr 20, NEW YORK: latitude 44.0 degrees north, longitude 74.3 degrees west, origin time 08 46 54.0 utc, depth shallow, magnitude 3.7 mbLg. The earthquake was felt in eastern New York and at Montpelier, Vermont. There have been no reports of damage. This is located in the same general area as a magnitude 5.1 earthquake on October 7, 1983, that caused minor damage and was felt in 12 U.S. states and 2 Canadian provinces. Stations used: NCB P 084656.2 HNH P 084720.5 LBNH P 084724.7 BINY P 084731.3 LSCT P 084734.9 WES P 084737.1 PAL P 084742.0 SSPA P 084800.5 MCWV P 084823.8 This is their calculation of the origin time based on the P arrival time at these 9 stations. Any additional arrival time data should only refine the origin time estimate. A single seismogram can only provide the unique arrival time at the station site; the reading is used with data from other stations, and a minimum of three are needed to calculate a hypocenter location, which results in the origin time estimate. A VERY approximate method we use with the wall maps is to use the P and S times to guess the distance of a station to an event, letting each 1 second difference to represent 8 kilometers of travel time. This lets us draw three circles on the wall map around the reporting stations, so their intersection is the epicenter guess. An origin time can also be guessed at with a single station P and S, again using 8 seconds/S-P time to get a distance, then figuring the P travel time. SO if S-P is 10 seconds, the event is about 80 km from the station (this is only good out to about 200 km). At a velocity of 5 km/second, the P wave took 16 seconds to get to the station, so the origin time is the P time minus 16 seconds. THis VERY approximate estimating can be improved by averaging the available data. MUCH better results are obtained using hypocenter programs that use recursive algorithms to minimize the error ellipses. Regards, Sean-Thomas __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Origin time From: Larry Cochrane cochrane@.............. Date: Mon, 01 May 2000 14:17:25 -0700 Paul, Part of the problem could be the computers time being off. If you are using WinQuake, and if the station is using SDR (my data logging software) with some type of time reference (GPS, WWV or WWVB), you should see an (L) next to the start time in the event window. The L indicates that SDR was locked to some time reference when the event file was created so the timing should be correct to within a few milliseconds, Regards, Larry Cochrane Redwood City, PSN At 01:16 PM 5/1/00 -0400, you wrote: >Dear members: >I have received several event files for the quake we got here in >Newcomb, NY, on 4/20/00. I noticed that the origin time was different >for each seismogram. Is the discrepancy due to differences in >calibration of the clocks on the host computers? > >Special thanks to all of you who sent me event files of the quake. > >Yours truly, >Paul Jebb >Newcomb Central School > > >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with >the body of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Speaking of gravimeters...and the earths weight... From: meredith lamb mlamb1@.......... Date: Mon, 01 May 2000 17:36:24 -0700 Hi all, Interesting this article came up on the Discovery web site, which coincides with gravimeters: http://www.discovery.com/news/briefs/20000501/space_earth.html It titled: Earth Loses Weight (a pun on diet weight watchers) Meredith Lamb __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Nordic's in the PSN From: John Hernlund hernlund@....... Date: Tue, 02 May 2000 23:39:37 -0700 (MST) On Sun, 30 Apr 2000, Edward Cranswick wrote: > Of course, in my case, after FORTRAN programing on IBM 360/30, a 360/44, > and a 360/50 for four years (1967-1971) in the family business, the research > department of local state mental hospital, I ran off as a geology major to the > oil fields of Oklahoma to work as a roustabout so that I could re-establish > contact with the physical Earth . . . and that was the beginning of my life in > the Earth sciences: I wanted to pursue geology to that I could see the world. > > Ironically, I ended up in seismology, the most mathematical techno-nerdy of > the Earth sciences (at least it was then). I chased earthquakes, and so, unlike > some of my more officebound seismological colleagues, I went out in the field > and touched the Earth. But then, ironically again, I specialized in developing > portable computer systems so that we could analyze the digital seismic > waveforms recorded by our portable autonomous digital seismographs (PADSs) in > near-realtime, i.e., while we were still in the field and data acquisition was > still in process. So I can do everything on my field computer that I can do on > my desktop back in the office -- it's like I never left the office . . . so why > DID I leave the office . . . because I never saw the Earth. We need more seismologists like you! I talked to a fellow who had done a dissertation on attenuation of seismic waves in some area of the upper mantle and when confronted with a chunk of olivine: he had no clue what it was! Of course, it behooves a seismo-guy or seismo-gal to know something about the rocks they are studying; actually to know A LOT about these rocks. Seismology is not well respected among my friends, who sometimes surmise that a lot of it is just chugging data into the same old routines to create tomographic images and such. Of course, there are too many seismologists who do just that, and it is not something we consider science because a technician at an MRI lab does the same thing and nobody calls them scientists. Therefore it follows that if seismology is a science, then these people are not really seismologists... John Hernlund E-mail: hernlund@....... WWW: http://www.public.asu.edu/~hernlund/ ****************************************************************************** __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: LaCoste and Romberg Meters From: juggie@................... (Nick Tile) Date: Wed, 3 May 2000 17:52 +0100 (BST) Hi guys, I got here a little differently to the rest of you - I used to do the field work, but never quite knew what I was doing :-) All this talk of gravity surveys reminds me of the days when I used to shoot seismic for a living - I never did, and still don't really understand how a La Coste and Romberg meter worked, but watching it working on a rolling ship, rolling 20 degrees port and starboard every few seconds, and pitching the same fore and aft was a very impressive experience... We once had a guy from LC & R on board running a course on the thing, but it was horribly complicated, and beyond understanding the basic principal that it was a fixed weight suspended on a zero length spring that would deflect by differing amounts according to the pull of gravity, I don't think anyone ever really understood it. Pity really cos we were surveying an area around Indonesia at the time which would have been interesting !!! I do recall that it used missile gyros that were very expensive to replace and screamed horribly when they expired, usually for several days. I should imagine that the device must be obsolete now, though I guess there were few enough of them for them to be eagerly grabbed if they ever were surplus. Had an interesting trip off Taiwan shortly after a big quake over there in the mid 80s, couldn't work for several days because of all the residual noise that swamped our somewhat puny signal. regards all, Nick __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Precise Frequencies derived from GPS From: "Mark Robinson" other@............... Date: Thu, 4 May 2000 15:09:43 +1200 I thought some members of the PSN community may be interested in this page : http://www.rt66.com/~shera/ It describes a unit which uses a phase locked loop locked to the GPS clock to give accuracies measured in parts in 10^12. My mind is unable to recall this being posted here before. regards all Mark Mark G Robinson | ZL2TOD | other@............... Box 8770, Auckland 1035, New Zealand Phone +64-9-846-3296, +64-9-817-4577 Pager +64-26-351-2770 ----------------------------------------------------------- 04 May 1863 Taranaki Maori retaliate against renewed european settlement and ambush a party of soldiers returning from Tataraimara 04 May 1891 Auther Conan-Doyle's character Sherlock Holmes died. 04 May 1953 Ernest Hemingway wins the Pulitzer Prize for "The Old Man and the Sea", William Inge wins for his play "The Picnic". 04 May 1968 The Big Mac is invented by a McDonald's Manager in Philadelphia. 04 May 1969 Radio Bosom, The Auckland University Student's Association Radio Station officially starts broadcasting. 04 May 1970 Four student vietnam war protestors are shot and killed at Kent State University. 04 May 1991 President Bush is admitted to hospital with arrythmia. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Minahassa Peninsula, Sulawesi quake From: meredith lamb mlamb1@.......... Date: Thu, 04 May 2000 00:25:03 -0700 Hi all, Still getting surface waves from this 7.3Ms quake, here in Denver, Colorado U.S.A., almost 2 hours after the event occurred at 04:21:17 U.T. Presume it overwhelmed the station in western Australia, which isn't too far away (~2-3 thousand miles), or pegged the seismo/s there. U.S.G.S. did a fine fast job putting the info on line. Meredith Lamb __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Minahasssa Peninsula From: Arie Verveer ajbv@............ Date: Thu, 04 May 2000 15:57:06 +0800 Hi Meredith, Got a great recording of the event, but with the "Big" Java trench between me and the quake, the values are much lower than they should be. The waves get reflected or refracted. The final wave that I record is about a magnitude lower than expected. Quakes either side of the trench record well. All the best Arie > U.S.G.S. did a fine fast job putting the info on line. I concur. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Minahasssa Peninsula From: meredith lamb mlamb1@.......... Date: Thu, 04 May 2000 03:59:25 -0700 Arie Verveer wrote: > Hi Meredith, > > Got a great recording of the event, but with the "Big" Java > trench between me and the quake, the values are much lower > than they should be. The waves get reflected or refracted. > The final wave that I record is about a magnitude lower than > > expected. Quakes either side of the trench record well. > > All the best > > Arie > Arie, You sure did, and with the S-G's too boot! Very interesting machine to use. Only had one S-G operating here, but it also did well for that big quake (ML5). The other S-G I'd replaced with an experimental unit....but that hung up prior to the quake of course....(alot of clenched teeth there....ha). Tony's in Hawaii recordings looks like works of art overall, real good, and it covers the span of time for most of the time. I'd expect just about everyone with long period capability will have events posted on this big one. Haven't heard of any tidal wave warning, or if it did any such. As remote an area as it is, it may take days to hear news from the area, in regard to damage and deaths resulting from it. Take care, Meredith Lamb __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re[2]: Anatomy of Seismograms From: angel rodriguez angel@............ Date: Thu, 4 May 2000 08:31:33 -0500 Hello ted, Friday, April 28, 2000, 11:29:04 AM, you wrote: tuic> E-bay had a copy of "Principles Underlying the Interpretation of tuic> Seismograms", U.S. Dept. of Commerce Special Publication 254 (revised 1966 tuic> edition) for sale a few months ago. I think it went for about $65. tuic> However since the publication is out of print, the winning bidder was kind tuic> enough to send me a xerox copy of the book. tuic> If anyone on our list would like a copy of this document (about 50 pages), tuic> send me $5 to cover copying and shipping costs and I'll be glad to make you tuic> a copy. Address is 238 Highland St., Portsmouth, NH 03801. tuic> Regards, Ted Hi Ted, I would like to get a copy of the "anatomy" book. Please send me your last name and I will send you a check ASAP. My name and address is: Angel Rodriguez 8318 Linden Ave No. Seattle, Wa. 98103 Best regards, angel mailto:angel@............ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: "Publication 254" requests From: ted@.......... Date: Thu, 4 May 2000 10:08:44 -0400 So far I have received 9 requests for copies of the "Anatomy of Seismograms" publication. I am going to wait another week or so for overseas requests (if any) to come in and then send them all out in a big batch. Please send any future communications about this pub directly to me, so we don't clutter up the list too much. Thanks. Regards, Ted Blank __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Virus Aleart From: Doug Crice dcrice@............ Date: Thu, 04 May 2000 07:14:51 -0700 PSN folks. I just received two copies of a virus this morning, both from geophysical contacts. Beware of a a message that says "Love Letter for You" with a .vbs extension (visual basic). My normal virus filter didn't see it, so it's very new. Doug Crice -- Doug Crice http://www.georadar.com 19623 Via Escuela Drive phone 408-867-3792 Saratoga, California 95070 USA fax 408-867-4900 __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: AZ quake swarm From: John Hernlund hernlund@....... Date: Thu, 04 May 2000 14:07:19 -0700 (MST) Got this at ASU, anybody else close enough to record these? May 4, 2000

EARTHQUAKE BULLETIN
North Rim and Painted Desert Earthquake Swarms

During the past two days earthquakes have been occurring on the North Rim of the Grand Canyon and in the Painted Desert region of northern Arizona.

The largest of these earthquakes was a magnitude 3.2 earthquake in the Painted Desert about 15 miles southwest of Tuba City and 19 miles east of Desert View at a depth of about 12 miles below the surface. The magnitude 3.2 Painted Desert earthquake occurred at 11:48 pm Wednesday night, May 3rd.

The North Rim earthquakes have been centered along Bright Angel Canyon about 9 miles northeast of the Grand Canyon Village. The largest of which is a magnitude 2.5 that occurred at 10:29 pm on Tuesday night May 2nd.

The earthquake swarms have occurred in a sparsely populated areas and no felt or damage reports have been received at the center.

The data for the earthquake are as follows:

     =95Painted Desert, Magnitude (ML) 3.2, Wednesday May 3, 2000 11:48 p.m. 36.09N x 111.51W
     =95North Rim, Magnitude (ML) 2.5, Tuesday May 2, 2000 10:29 p.m. 36.16N x 112.01W

If you felt the earthquake, or for additional information, please phone Doug Bausch at the Arizona Earthquake Information Center at (520) 523-7196.
Doug Bausch, Research Associate
Northern Arizona University, Geology Department
Bldg. 12, Room 100
Box 4099, Flagstaff, AZ  86011
Tel. (520) 523-7196, fax. (520) 523-9220
Douglas.Bausch@.......    http:= //vishnu.glg.nau.edu/aeic/aeic.html
****************************************************************** John Hernlund E-mail: hernlund@....... WWW: http://www.public.asu.edu/~hernlund/ ***************************************************************************= *** __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: PSN-L: .vbs scripts and spying From: walt_williams@........ Date: Thu, 4 May 2000 15:13:18 -0800 All, Programs which autoexecute .vbs scripts are at risk. Indeed there is a 'SPY' script which auto-downloads from WEBSITEs named, 'network.vbs'. This script downloads via java enabled webbrowsers. The script is dropped into three locations, c:/ c:/windows/ c:/windows/start menu/programs/startup The .vbs program is spawned by java, it attaches itself to the winsocket, and OLEs (pipes) MS products; grabs e-mail addresses from your MS e-mail programs (eg., outlook), and logs webbrowser surfing activity into the root in a file, 'networklog.log'. It then creates a peer to peer virtual hard-disk to a remote dynamically identified URL and uploads the logged information stored in 'network.log' file. At some pseudo random time in the future the .vbs script deletes the .log file and the .vbs spy script, 'erasing its tracks' I discovered this script when I rebooted my system one evening and an 'open' dialog request box appeared asking how I wanted to open the script. I don't use ANY products which auto-spawn .vbs and due to this, the script program failed to gather my personal information. This activity is patently illegal as it is unconstitutional and an invasion of privacy. This particular spy script has been floating around the InterNet about eight weeks. I have copies of the script, (functionally disabled) should anyone care to study how it works, it is interesting to see how the virtual hard disk is created without using LMHOSTS type tables. I rename the script extension to .sbv and then change the internal 'dim' statements to prevent accidental execution. Best Wishes, Walt Williams SETV/OSR ============================================ ------- Forwarded Message Follows ------- Date: Thu, 04 May 2000 07:14:51 -0700 From: Doug Crice Organization: GeoRadar Inc. To: PSN-L Mailing List Subject: Virus Aleart Reply-to: psn-l@.............. PSN folks. I just received two copies of a virus this morning, both from geophysical contacts. Beware of a a message that says "Love Letter for You" with a .vbs extension (visual basic). My normal virus filter didn't see it, so it's very new. Doug Crice -- Doug Crice http://www.georadar.com 19623 Via Escuela Drive phone 408-867-3792 Saratoga, California 95070 USA fax 408-867-4900 __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: News Report on the Minahassa Peninsula, Sulawesi quake From: Arie Verveer ajbv@............ Date: Fri, 05 May 2000 13:53:17 +0800 Hi, This news report may be of interest. - regarding the (00/05/04 04:21:17 0.90S 123.40E 33.0 7.3Ms A MINAHASSA PENINSULA, SULAWESI) quake. - Arie ------------------------------------------------- Nine dead in Indonesian earthquake. By news.com.au and AAP staff 05may00 14:17pm (AEST) AN earthquake that struck the central Indonesian island of Sulawesi has left nine people dead and hundreds of homes damaged. The earthquake struck yesterday morning with a magnitude of 6.5 said The Antara news agency. A wide stretch of eastern Sulawesi and the offshore islands of Peleng and Banggai were also affected. The death toll is expected to rise because coastal villages struck by a small tsunami wave that followed the earthquake have not yet reported due to communications problems. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: IASP91 table in Winquake From: RLLaney@....... Date: Sat, 6 May 2000 17:11:06 EDT Hello all: The recent quake on the Minahassa Peninsula, Sulawes reminded me of a question that I have had for some time about the use of the IASP91 table in Winquake. The teleseismic table in Winquake cannot be used to calculate the P and S wave arrivals for distances beyond about 12,000 km because beyond this distance the arrival location is in the "shadow" of the earth's core and arrivals are modified by travel through or along the boundary of the core (my location is about 15,000 km from the Minahassa event location). Thus, Winquake gives the error message "Can't place P and S markers" when one tries to calculate P and S wave arrivals beyond this distance using the teleseismic table. Yet if one uses the IASP91 table beyond the critical distance, P and S markers can be calculated. I guess I don't understand what the IASP91 table does that the teleseismic table doesn't do. Are the P and S wave arrivals that can be calculated using the IASP91 "real" beyond the critical distance? I noticed that my event record using the IASP91 table to calculate P and S arrivals and some of the other event records posted for the Minahassa quake showed 3 to 4 minutes difference between the calculated P wave arrival and what looked like the first arrival on the record. Can someone shed some light on this issue? Thanks, Bob Laney Herndon, VA __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: IASP91 table in Winquake From: The Lahrs JohnJan@........ Date: Sat, 06 May 2000 20:03:16 -0600 Hi Bob, I'm not sure of the working of Larry's program, but you can see the expected arrival times at your station for any earthquake by using this page: http://geohazards.cr.usgs.gov/tt/ There is also a travel time graph - an old one that is a bit hard to read - but your can see how P becomes P diffracted and then dies out. PKP is a few minutes later. John At 03:11 PM 5/6/00 , you wrote: > I guess I don't understand what the IASP91 >table does that the teleseismic table doesn't do. Are the P and S wave >arrivals that can be calculated using the IASP91 "real" beyond the critical >distance? I noticed that my event record using the IASP91 table to calculate >P and S arrivals and some of the other event records posted for the Minahassa >quake showed 3 to 4 minutes difference between the calculated P wave arrival >and what looked like the first arrival on the record. > >Can someone shed some light on this issue? > >Thanks, > >Bob Laney >Herndon, VA John C. Lahr 1925 Foothills Road Golden, CO 80402 (303) 215-9913 http://lahr.org/john-jan/science.html __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Article on gravimeters From: ChrisAtUpw@....... Date: Sun, 7 May 2000 13:25:22 EDT Dear Tom Schmitt, > About fifteen years ago I went to a non-classified briefing about a land > version of a gravity gradiometer. The Defense Mapping Agency had it. Were any details published? > It was in a Winabago of some sort What is that, please? > and had three disks that rotated at a fairly low rpm, a few Hz at most. > The disks were less than a meter in diameter. > The disks had two accelerometers on them. The acceleration as a > function of position of the two accelerometers was recorded and some sort > of auto-correlation or FFT was done to get the direction and magnitude of > the gradient. Did the disks all rotate at the same speed? Were they all the same diameter? Were they orientated at right angles to each other? Were they all mounted on the same frame? Were the two accelerometers diametrically opposed and on the same radius? Were they sensitive to forces in a radial direction or perpendicular to the disk? What sort of accelerometers were used? How were the signals and power transferred to the disks? How were the disks driven? Were air bearings used? Was there any automatic gravity alignment system? Naval gyro compasses and aircraft artificial horizons have them built in. I am trying to understand the principles / practical limitiations of a system which can detect the tiny changes in force that need to be measured against the noise background of even a large ship. Doing it in the horizontal plane sounds difficult enough. Doing it in the vertical plane would seem to be much more difficult. Doing it while the system is in motion sounds very dificult. Regards, Chris Chapman __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Article on gravimeters From: "Tom Schmitt" tschmitt@.............. Date: Sun, 7 May 2000 16:58:41 -0400 ----- Original Message ----- From: To: Sent: Sunday, May 07, 2000 1:25 PM Subject: Re: Article on gravimeters > Dear Tom Schmitt, > > > About fifteen years ago I went to a non-classified briefing about a land > > version of a gravity gradiometer. The Defense Mapping Agency had it. > > Were any details published? Not that I know of. It was a briefing. > > > It was in a Winabago of some sort > > What is that, please? A large recreational vehicle. A bus like thing with all sorts of gear in it. > > > and had three disks that rotated at a fairly low rpm, a few Hz at most. > > The disks were less than a meter in diameter. > > The disks had two accelerometers on them. The acceleration as a > > function of position of the two accelerometers was recorded and some sort > > of auto-correlation or FFT was done to get the direction and magnitude of > > the gradient. > > Did the disks all rotate at the same speed? Were they all the same > diameter? Were they orientated at right angles to each other? Were they all > mounted on the same frame? The all rotated at the same speed. Each disk had two accelerometers 180 degrees apart. At any time the acceleration on them was (1) an omega sqaured r term radially out ward. (2) the component of gravity resolved to the orientation of the line the two accelerometers were on. (3) any acceleration due to bumps in the road. The two accelerometrs per disk were necessary to compensate for any bumps. The difference between the readings of the two accelerometers gave the gradient of gravity in the direction the disk was pointing at that time. A bump would cause the same acceleration at both accelerometers and thus would cancel out when the gradient was measured. The axeses of rotation were 90 degrees to one another. They were all mounted to a very stiff platform. > Were the two accelerometers diametrically opposed and on the same radius? Yes above. > Were they sensitive to forces in a radial direction or perpendicular to the > disk? Yes above. What sort of accelerometers were used? That is the trick I am sure. Though the briefing was not classified they did not show us the parts manual! I suspect these were very special accelerometers. They had to be sensistive enough to measure the difference in g over a distance of one meter. > How were the signals and power transferred to the disks? > How were the disks driven? Were air bearings used? > Was there any automatic gravity alignment system? Naval gyro compasses > and aircraft artificial horizons have them built in. > I do not remember or was not told. > I am trying to understand the principles / practical limitiations of a > system which can detect the tiny changes in force that need to be measured > against the noise background of even a large ship. Doing it in the horizontal > plane sounds difficult enough. Doing it in the vertical plane would seem to > be much more difficult. Doing it while the system is in motion sounds very > dificult. > Honestly, I had trouble believing the thing worked. The physical principle is simple but how they got the system to work I do not know. I am sure they did a lot of post collection processing. They claimed that they could drive the thing at 30 miles an hour and get good data. About that time there was at least one sattelite launched at low altitude that had very good elevation measurements. I suspect that that technology replaced the land based measurements. However, my satelite geodesy is real rusty ( never was much good ) and that stuff was not discussed. > Regards, > > Chris Chapman > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Article on gravimeters From: John Hernlund hernlund@....... Date: Sun, 07 May 2000 21:38:01 -0700 (MST) On Sun, 7 May 2000, Tom Schmitt wrote: > > > and had three disks that rotated at a fairly low rpm, a few Hz at most. > > > The disks were less than a meter in diameter. > > > The disks had two accelerometers on them. The acceleration as a > > > function of position of the two accelerometers was recorded and some > sort > > > of auto-correlation or FFT was done to get the direction and magnitude > of > > > the gradient. > > Did the disks all rotate at the same speed? Were they all the same > > diameter? Were they orientated at right angles to each other? Were they > all > > mounted on the same frame? > > The all rotated at the same speed. Each disk had two accelerometers 180 > degrees apart. At any time the acceleration > on them was > > (1) an omega sqaured r term radially out ward. > > (2) the component of gravity resolved to the > orientation of the line the two > accelerometers were on. > > (3) any acceleration due to bumps in the road. > > The two accelerometrs per disk were necessary to compensate for any bumps. > The difference between > the readings of the two accelerometers gave the gradient of gravity in the > direction the disk was pointing at > that time. A bump would cause the same acceleration at both accelerometers > and thus would cancel out > when the gradient was measured. > > The axeses of rotation were 90 degrees to one another. > > They were all mounted to a very stiff platform. > What sort of accelerometers were used? > > That is the trick I am sure. Though the briefing was not classified they > did not show us the parts manual! > I suspect these were very special accelerometers. They had to be sensistive > enough to measure the difference in > g over a distance of one meter. I suspect some high tech piezo-electrics would do the trick. That would be the reason for rotating too I think. Recently some newer interesting materials have been developed that might be ideal for something like this. One is a lead niobate, which is a super dielectric and has an incredible piezoelectric potential. When the crystals are oriented correctly dielectric constants in the tens of thousands have been recorded. This certainly has an application in recording instrument technology. I don't think it is in wide spread use industrially, but we have been studying it at ASU. It will beat barium titanate as the super dielectric for sure, which might be what was available for these gravimeters. It would be fun to try and put one of these things together. The rotation sticks the gravimeters outward and keeps some pressure on them at all times I think. Because a piezo-electric transducer responds directly to changes in stress the rotation would produce an easy to study signal under ordinary circumstances. These transducers would not hold their charge for long, however, and the rotation would allow you to take the most useful information from them because it will always be changing. You could calibrate the loss of charge and everything else if you could find a good absolute gravity station with a vertical gradient measurement. You can totally predict the signal coming from them using simple mathematics. Because the data can be averaged over quite a few spins, the noise reduction could be done easily. The FFTs of both signals could be deconvoluted for the expected zero gradient response and then combined together. The left over portion (residual) of the signal could be used to get the gradient after the correlated deviations are removed (like from a bump in the road). The phase shift info would give you the direction of the gradient in the plane of the circle and the amplitude would give you the magnitude of the gradient. This would be quite a lot of fun to use! I think you could increase the confidence in the readings by modulating the frequency of rotation of the disk (i.e. speeding it up and slowing it down) because this would create another aspect of the response that can easily be used to back out the gravity gradient. > > How were the signals and power transferred to the disks? > > How were the disks driven? Were air bearings used? > > Was there any automatic gravity alignment system? Naval gyro compasses > > and aircraft artificial horizons have them built in. > I do not remember or was not told. Ahhhh, those are the real secrets for sure! It would be great to have magnetic bearings or something like that. Driving the thing would be tough because you would want to reduce the noise. Maybe some kind of nice electric motor with its own special bearings could be used. > > I am trying to understand the principles / practical limitiations of a > > system which can detect the tiny changes in force that need to be measured > > against the noise background of even a large ship. Doing it in the > horizontal > > plane sounds difficult enough. Doing it in the vertical plane would seem > to > > be much more difficult. Doing it while the system is in motion sounds very > > dificult. Yes, the horizontal gradient sounds far easier to me! Another thing that would be a pain in the but is the levelling, but the instruments might be able to use their own gyroscopic response to figure out this too. But this begins to look like an awful lot of computing and deconvolution to get the desired data. Maybe one could simply use the horizontal gradient in some cases. You could find a lot of interesting features in the subsurface just from this alone. I would love to try this some day, if I find the time. > Honestly, I had trouble believing the thing worked. The physical principle > is simple but how they got > the system to work I do not know. I am sure they did a lot of post > collection processing. Tens of millions of dollars in research money doesn't hurt either. > They claimed that they could drive the thing at 30 miles an hour and get > good data. That must have something to do with the speed of revolution and the number of averages needed to back out a gradient at the right resolution from the surface. > About that time there was at least one sattelite launched at low altitude > that had very good elevation measurements. I suspect that that technology > replaced the land based measurements. However, my satelite geodesy is real > rusty ( never was much good ) and that stuff was not discussed. It depends on what you want to look at. Instruments in orbit may be good for taking gravity data over large regions, but will not be sensitive to stuff close to the subsurface, which is usually what people are interested in. A good topography data set in the near future will allow for wonderful "terrain corrections" used for gravity interpretation. More powerful computers are also going to make instruments like this one more practical, because we might be able to make a low tech type and just have to average it over a longer time to get the needed data. The large amounts of data could then be deconvolved. After some time, we will have access to libraries of seismic and gravity data taken over the entire surface of the Earth, but probably long after we are all dead. John Hernlund E-mail: hernlund@....... WWW: http://www.public.asu.edu/~hernlund/ ****************************************************************************** __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Article on gravimeters From: John Hernlund hernlund@....... Date: Mon, 08 May 2000 01:11:29 -0700 (MST) Okay, I went through and did the math for the problem of two accelerometers (I know, I am definitely a nerd) in a rotating frame of reference. The two accelerometers are at opposite ends of the spinning frame, both at a radius of "r." The angular velocity of the frame is "w." To say that a gravity gradient exists is to say that there is a curvature in the gravitational potential "U" in the vicinity of the spinning disk. There are many ways to deal with this, but I let the gravitational potential take the form: U = K + 0.5*ax^2 + b*xy + 0.5*cy^2 + d*x + e*y Since this problem is being done in a plane, only x and y coordinates are needed. x and y could be east and north, or down and east, or which ever combination you want. The acceleration due to gravity is the gradient of the potential, which is (in vector form): g = [a*x + b*y + d,c*y + b*x +e] The gravity gradient is then (in matrix form): Dg = [ a b ] [ b c ] So we seek to find the values for a, b, and c only in the gradient determination. Saving you all the math, the signals from the two accelerometers (s1 and s2), when figured in terms of rotation, noise, and gravity can be added together to yield a very simple equation: S = s1 + s2 = 2r[w^2 - a*cos(wt)cos(wt) - 2b*sin(wt)cos(wt) -c*sin(wt)sin(wt)] The signals take this form if you adjust your time so that they lie on the x-axis at t = 0. Notice that the values for d and e, the values for the gravitational field itself, have cancelled out along with the noise. Lets modify this record further and let T = -S/(2r) + w^2 and the above equation becomes simply: T = a*cos(wt)cos(wt) + 2b*sin(wt)cos(wt) + c*sin(wt)sin(wt) Because we know what r, w, and t are in the data set we can fit the data to this formula and obtain values for a, b, and c. Viola! There is the gradient in that plane. (This assumes a negligible phase shift in the response for the instrument, but that could also be dealt with) The unanswered question, of course, is whether we can mount two accelerometers that are sensitive enough at the frequency w to make out exactly what a, b, and c are. The values for a, b, and c are very small I am sure. We can estimate what they would be in the vertical direction on the Earth by considering two points one meter apart at the surface. The gravity is given as g = -GM/r^2 (G = gravitational const., M is mass of Earth, and r is radius from Earth's center). The vertical gradient is the derivative with respect to the radius and is dg/dr = 2GM/r^3. Since the Earth's radius is about 6371 km, its mass 5.98E24 kg, and G is 6.67E-11 (SI units) the vertical gradient is about: 1.54E-6 s^-2. Lets say we want to detect a mountain that is 1 kilometer away (to its middle) has a density of about 3000 kg/m^3 (or 3 g/cc, about that of many rocks) and is one cubic kilometer in volume. We get about 2E-7 s^-2. That value is about one-tenth of the value of the vertical gradient, and is larger than I expected. This is because of the 1/r^3 form of the equation for the gradient. This type of instrument will be extremely sensitive to things that are close. The gradient direction will also tend to point towards high density bodies and away from low density objects. This would be great for finding salt domes and such. Anyways, I think that this is definitely possible. I am almost itching to try it myself. The key does seem to be finding a couple of accelerometers that are sensitive enough, and also rugged enough to take the beating they are sure to get. High performance piezo-electric accelerometers would be perfect for the task but also very expensive or impossible to find for the sensitivity required. One pair on a single spinning frame is all that is needed I think, because it could be made to tilt in any general direction. Surely though, the bear is probably lurking in the details. John Hernlund E-mail: hernlund@....... WWW: http://www.public.asu.edu/~hernlund/ ****************************************************************************** __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Article on gravimeters From: offutt@............ (Warren Offutt) Date: Mon, 8 May 2000 06:49:03 -0600 (MDT) Compliments to John Hernlund for a very nice and well done analysis of the rotating pair of accelerometers. I'd like to add that, as far as instrumentation is concerned, it is] much easier to obtain stable high gain in a passband that is not centered at baseband ... in other words, a high gain, stable AC amplifier is easier to achieve than a high gain stable DC amplifier, and the rotating frame has the benefit of moving at least part of the spectrum of interest up out of the baseband ... John, I admire what you have done. Regards to all warren __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Precise Frequencies derived from GPS From: Bob Smith bobsmith5@........ Date: Mon, 08 May 2000 10:19:54 -0400 Hello All -- I have been a lurker here for several weeks because seismology is a latent interest. As I am not a currently active seismologist so I am not sure what sort of timing requirements are needed to correlate independent observations. My gut feel is that something in the one millisecond region is adequate. Anyway, Mark's pointer to the work by Brooks Shera is very relevant. His GPS derived, phase locked oscillator control will certainly lead to an excellent frequency reference, and thus, a very stable time base. Perhaps of more interest to the PSN may be the work in direct GPS timing lead by Dr. Thomas A. Clark of the Goddard Space Flight Center and well known radio amateur (W3IWI) in the development of low cost GPS timing references. It is my understanding that using GPS as a time reference, you can achieve sub-microsecond clock accuracy's with relative ease. For those interested in following these interesting developments I recommend that they explore the TAPR (Tuscon Amateur Packet Research organization) web site at http://www.tapr.org There you will find information on the TAC-2 (Totally Accurate Clock) developed by Dr. Clark and the TAC-32 companion PC software by another dedicated radio amateur that derives a very stable time base directly from GPS signals. Interested parties should also follow links to the TAPR SIGs (Special Interest Groups) and join the TACGPS email list. Also by linking to http://www.time.gov you will reach the NIST time standards home page with has many interesting links to information on precision timekeeping and frequency standards. Best wishes, Bob Smith Mark Robinson wrote: > > I thought some members of the PSN community may be interested in this page : > > http://www.rt66.com/~shera/ > > It describes a unit which uses a phase locked loop locked to the GPS clock > to give accuracies measured in parts in 10^12. > > My mind is unable to recall this being posted here before. > > regards all > > Mark > > Mark G Robinson | ZL2TOD | other@............... > Box 8770, Auckland 1035, New Zealand > Phone +64-9-846-3296, +64-9-817-4577 Pager +64-26-351-2770 > ----------------------------------------------------------- > 04 May 1863 Taranaki Maori retaliate against renewed european settlement and > ambush a party of soldiers returning from Tataraimara > 04 May 1891 Auther Conan-Doyle's character Sherlock Holmes died. > 04 May 1953 Ernest Hemingway wins the Pulitzer Prize for "The Old Man and > the > Sea", William Inge wins for his play "The Picnic". > 04 May 1968 The Big Mac is invented by a McDonald's Manager in Philadelphia. > 04 May 1969 Radio Bosom, The Auckland University Student's Association Radio > Station officially starts broadcasting. > 04 May 1970 Four student vietnam war protestors are shot and killed at Kent > State University. > 04 May 1991 President Bush is admitted to hospital with arrythmia. > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. -- --------- Avoid computer viruses -- Practice safe hex ------------- * * Specializing in small, cost effective embedded control systems * * Robert L. (Bob) Smith Smith Machine Works, Inc. internet bobsmith5@.............. Lumlay Road landline 804/745-1065 Richmond, Virginia 23236+1004 __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: IASP91 table in Winquake From: Larry Cochrane cochrane@.............. Date: Mon, 08 May 2000 15:09:21 -0700 Bob, When I added the IASP91 tables to WinQuake I was surprised to see the P and S wave tables went out farther then the JB tables. Since the P wave goes into a shadow at around 106 deg (1 deg = ~111km) I'm not sure what the tables represent past this distance. -Larry Cochrane Redwood City, PSN At 05:11 PM 5/6/00 EDT, you wrote: >Hello all: > >The recent quake on the Minahassa Peninsula, Sulawes reminded me of a >question that I have had for some time about the use of the IASP91 table in >Winquake. > >The teleseismic table in Winquake cannot be used to calculate the P and S >wave arrivals for distances beyond about 12,000 km because beyond this >distance the arrival location is in the "shadow" of the earth's core and >arrivals are modified by travel through or along the boundary of the core (my >location is about 15,000 km from the Minahassa event location). Thus, >Winquake gives the error message "Can't place P and S markers" when one tries >to calculate P and S wave arrivals beyond this distance using the teleseismic >table. Yet if one uses the IASP91 table beyond the critical distance, P and >S markers can be calculated. I guess I don't understand what the IASP91 >table does that the teleseismic table doesn't do. Are the P and S wave >arrivals that can be calculated using the IASP91 "real" beyond the critical >distance? I noticed that my event record using the IASP91 table to calculate >P and S arrivals and some of the other event records posted for the Minahassa >quake showed 3 to 4 minutes difference between the calculated P wave arrival >and what looked like the first arrival on the record. > >Can someone shed some light on this issue? > >Thanks, > >Bob Laney >Herndon, VA >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with >the body of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Article on gravimeters From: "Charles R. Patton" charles.r.patton@........ Date: Mon, 08 May 2000 15:23:27 -0700 Good work, John. A few comments. Ball bearings in today=92s hard disk drives are in the 10 u inch runout class or so. Hydrodynamic, gas or liquid, bearings are required below this. The trade is between viscous drag =96 power consumption =96 and start/stop performance. Gas, generally air, applications usually have a compressed air supply to run from. Someone mentioned bumps cancel out. Not so. The bump looks just like acceleration and acceleration is indistinguishable from gravity. The difference is only in the frequency range, gravity is DC, while the bump is transitory so can be integrated out with a sufficiently time. A corollary of this is that the bearing defects =96 imperfections in the balls and races =96 show up as a frequency spectrum in the accelerometers= also and would have to be removed in the same way, by integration. John comments about lead niobate, and barium titanate strike to the heart of the matter. Piezo accelerometers do not have DC response but are stable and require high input impedance amplifiers to achieve low frequencies. I touched on this subject in a note to PSN 8/17/97: * Re: Piezo accelerometers for seismic work. Highly unlikely. I have used extensively piezo-ceramic accelerometers of approximately the size in the web site (http://www.oceana.inter.net) illustration (cantilever beam types in SMT 1206 like packages from TDK, Murata, and others.) All of these have sensitivities of around 1 to 2 mV /g. They have typical capacities of around 200 pF. So in order to bias the front end preamp you have to parallel them with resistors of 10 M or more. This then sets the low frequency rolloff, i.e.: f =3D 1 / (2PiRC) =3D 1/(6.28*200e-12*1e7)=3D79.6 Hz So you have an extremely high cutoff problem first of all. Couple that with the fact you've got the 10 M resistor generating a noise voltage of approximately 300+ nV, you are left with a minimum sensitivity of only g*300nV/1mV=3D300 ug at 80Hz and falling from there. If you want to fight the problem of the resistor versus cutoff frequency the noise will only go up. So you're kind of in a catch 22. I don't anticipate that this is a good approach. So higher capacity can lead to lower frequency response. Today, SMT (surface mounting) capacitors (caps) use multi-layer technology to achieve high capacitance values. This technique is just now moving into the piezo accelerometers mentioned above. The caps and accelerometers use identical materials with the main differences being in the construction to utilize a =93proof mass=94 to put stress into the ceramic= during acceleration and the =93poling=94 of the ceramic. Poling requires= taking the ceramic to its Curie point, applying a high voltage to its electrodes, then cooling the part off while the voltage is applied. One variations of the proof mass and higher strain (as it is the strain which generates voltage) is the cantilever mentioned above. One other point needs making. The ceramic materials have high piezoelectric coefficients, but also have temperature and mechanical instability problems in high resolution applications which is why the expensive (repeatable, calibrated) applications use quartz accelerometers. But those accelerometers are relatively low capacity and output. A proof mass on a diaphragm to form a variable capacitance is a possibility and would have DC response, but since the given was spinning disks, one has to assume this avenue did not have the performance required, so AC accelerometers were being used. For those of an experimental bent. Take an SMT cap, 0.01 to 0.1 uF and mount it on a PCB. Ground one end and feed the other end through a 1 Mohm resistor from 5 to 10 VDC or so. This biasing supplies substitutes in some measure for the poling. Monitor the junction with an oscilloscope. Tap or bend the PCB and you should observe 10=92s of mV on= the scope. Practical hints on the cap selection: the higher the capacity, the smaller the package, and the lower the voltage is generally better. This is because this will tend to lead to caps with the high K dielectrics, which are the more sensitive in this mode. Plug the numbers here into the formula above and you=92ll find that low frequency response becomes much easier to achieve with these high capacities. Engineering folklore tells of unaware engineers who chased microphonic boards for many hours due to this phenomenon. Anyway, back to the spinning disk gravimeter. Piezo accelerometers are stable and will still have repeatable output for delta G=92s in the midst= of the constant G=92s even in the several hundred range such as the centripetal acceleration you could generate on a spinning disk. You could use magnetic accelerometers, which after all, is what the geophones are. But again, the standard magnetic units also don=92t have DC response. So the use of the spinning disk to convert the DC gradient to AC is an excellent way around the DC problems. Additionally it provides two other benefits: by going to AC it helps move the amplifier away from the 1/F noise problem and it makes possible sensing the absolute value of the G field. A thought experiment: In the following I=92ll use Ge for earth acceleration and Ga for centripetal acceleration. With a reasonably low rotation rate that yields a 1 G centripetal acceleration in the accelerometers set the disk vertical so the accelerometer will be subjected to a cycle of Ga (0) , Ga minus- Ge (90), Ga (180), Ga plus Ge (270) in a sine wave fashion. If we subtract the 0 and 180 degree values from the 90 and 270 degree positions we are left with a sine wave representative of 2 times the Ge value. The maximum phase position is the angle of the Ge component. The Ga value is an absolute calibration because we can measure rotation rate and positions to PPM levels. The bearings are probably air spindles, in order to get below the 10 u in runout, which would show up as equivalent accelerations (G variations.) It would be an interesting gadget. Regards, Charles R. Patton, Owner Synergy Co. =93Creative, Cost Effective EMI, ESD and Analog Design Solutions=94 21490 Camino Arriba Murrieta, CA 92562 Phone: 909-698-9657 Fax: 909-698-0224 Email: charles.r.patton@........ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Article on gravimeters From: John Hernlund hernlund@....... Date: Mon, 08 May 2000 16:12:48 -0700 (MST) On Mon, 8 May 2000, Charles R. Patton wrote: > Good work, John. Thanks, just a half hour out of my day. I'll post the whole derivation som= e day soon when I can recall what "time" means. The point of my analysis was= to get only at the gradient, not the absolute field. The absolute field is no= ise for gradient determination. I think the idea though is that the gradient i= s far more useful in "resolving" sub-surface structures. I am still skeptica= l about the claim that these out perform seismic reflection techniques in ter= ms of time and quality though. Who knows, maybe they are right. I can think = of a million academic applications for this thing once it reaches the relative= ly poor and destitute realm of science (as compared to defense and oil of course). > Someone mentioned bumps cancel out. Not so. The bump looks just like > acceleration and acceleration is indistinguishable from gravity. The > difference is only in the frequency range, gravity is DC, while the bump > is transitory so can be integrated out with a sufficiently time. The noise and main component of the field only cancel in the summed signals from the two devices. But this requires a rigid frame and two acceleromete= rs acting at very precisely the same response and output sensitivity; a great mechanical feat in its own right. I think you could deal with a little bit= of play in the mathematical analysis, but it would be nice to build something that works right in the first place. A very small error in the two radii o= f the accelerometers would be devastating for these measurements, so some kin= d of control would be needed on this parameter as the instrument deforms over time. > A corollary of this is that the bearing defects =96 imperfections in the > balls and races =96 show up as a frequency spectrum in the accelerometers > also and would have to be removed in the same way, by integration. Or addition of the signals... A spectral analysis of each would provide mo= re information about the absolute field, but the summed signals would be neede= d for the gradients. =20 > John comments about lead niobate, and barium titanate strike to the > heart of the matter. Piezo accelerometers do not have DC response but > are stable and require high input impedance amplifiers to achieve low > frequencies. I touched on this subject in a note to PSN 8/17/97: This is great info. I figured somebody else around here would know more ab= out the actual instrumentation than I do. Another problem with lead niobate an= d other "perovskite structure" piezo-electrics is that they are "ferri-electr= ic" meaning that they act like iron in a magnetic field, only this is applied t= o an electric field. This will give them a definite phase shift in their response which is also a problem to be worked out mathematically. > * Re: Piezo accelerometers for seismic work. Highly unlikely. I have > used extensively piezo-ceramic accelerometers of approximately the size > in the web site (http://www.oceana.inter.net) illustration (cantilever > beam types in SMT 1206 like packages from TDK, Murata, and others.) > All of these have sensitivities of around 1 to 2 mV /g. They have > typical capacities of around 200 pF. So in order to bias the front end > preamp you have to parallel them with resistors of 10 M or more. This > then sets the low frequency rolloff, i.e.: > f =3D 1 / (2PiRC) =3D 1/(6.28*200e-12*1e7)=3D79.6 Hz > So you have an extremely high cutoff problem first of all. Couple that > with the fact you've got the 10 M resistor generating a noise voltage of > approximately 300+ nV, you are left with a minimum sensitivity of only > g*300nV/1mV=3D300 ug at 80Hz and falling from there. > If you want to fight the problem of the resistor versus cutoff frequency > the noise will only go up. So you're kind of in a catch 22. I don't > anticipate that this is a good approach. >=20 > So higher capacity can lead to lower frequency response. Today, SMT > (surface mounting) capacitors (caps) use multi-layer technology to > achieve high capacitance values. This technique is just now moving into > the piezo accelerometers mentioned above. The caps and accelerometers > use identical materials with the main differences being in the > construction to utilize a =93proof mass=94 to put stress into the ceramic > during acceleration and the =93poling=94 of the ceramic. Poling requires > taking the ceramic to its Curie point, applying a high voltage to its > electrodes, then cooling the part off while the voltage is applied. One > variations of the proof mass and higher strain (as it is the strain > which generates voltage) is the cantilever mentioned above. One other > point needs making. The ceramic materials have high piezoelectric > coefficients, but also have temperature and mechanical instability > problems in high resolution applications which is why the expensive > (repeatable, calibrated) applications use quartz accelerometers. But > those accelerometers are relatively low capacity and output. A proof > mass on a diaphragm to form a variable capacitance is a possibility and > would have DC response, but since the given was spinning disks, one has > to assume this avenue did not have the performance required, so AC > accelerometers were being used. >=20 > For those of an experimental bent. Take an SMT cap, 0.01 to 0.1 uF and > mount it on a PCB. Ground one end and feed the other end through a 1 > Mohm resistor from 5 to 10 VDC or so. This biasing supplies substitutes > in some measure for the poling. Monitor the junction with an > oscilloscope. Tap or bend the PCB and you should observe 10=92s of mV on > the scope. Practical hints on the cap selection: the higher the > capacity, the smaller the package, and the lower the voltage is > generally better. This is because this will tend to lead to caps with > the high K dielectrics, which are the more sensitive in this mode. Plug > the numbers here into the formula above and you=92ll find that low > frequency response becomes much easier to achieve with these high > capacities. Engineering folklore tells of unaware engineers who chased > microphonic boards for many hours due to this phenomenon. >=20 > Anyway, back to the spinning disk gravimeter. Piezo accelerometers are > stable and will still have repeatable output for delta G=92s in the midst > of the constant G=92s even in the several hundred range such as the > centripetal acceleration you could generate on a spinning disk. You > could use magnetic accelerometers, which after all, is what the > geophones are. But again, the standard magnetic units also don=92t have > DC response. So the use of the spinning disk to convert the DC gradient > to AC is an excellent way around the DC problems. Additionally it > provides two other benefits: by going to AC it helps move the amplifier > away from the 1/F noise problem and it makes possible sensing the > absolute value of the G field. >=20 > A thought experiment: In the following I=92ll use Ge for earth > acceleration and Ga for centripetal acceleration. With a reasonably low > rotation rate that yields a 1 G centripetal acceleration in the > accelerometers set the disk vertical so the accelerometer will be > subjected to a cycle of Ga (0) , Ga minus- Ge (90), Ga (180), Ga plus > Ge (270) in a sine wave fashion. If we subtract the 0 and 180 degree > values from the 90 and 270 degree positions we are left with a sine wave > representative of 2 times the Ge value. The maximum phase position is > the angle of the Ge component. The Ga value is an absolute calibration > because we can measure rotation rate and positions to PPM levels. The > bearings are probably air spindles, in order to get below the 10 u in > runout, which would show up as equivalent accelerations (G > variations.) It would be an interesting gadget. Indeed! John Hernlund E-mail: hernlund@....... WWW: http://www.public.asu.edu/~hernlund/ ***************************************************************************= *** __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Article on gravimeters From: ChrisAtUpw@....... Date: Mon, 8 May 2000 21:40:48 EDT In a message dated 08/05/00 05:39:38 GMT Daylight Time, hernlund@....... writes: > > > What sort of accelerometers were used? > > I suspect these were very special accelerometers. They had to be > > sensitive enough to measure the difference in > > g over a distance of one meter. > I suspect some high tech piezo-electrics would do the trick. That > would be the reason for rotating too I think. Recently some newer > interesting materials have been developed..... I have been looking at piezo-electrics for seismograph applications. One limiting factor seems to be the large changes in properties / drift with temperature. (The 50 nF types do, however, ease the input impedance / cutoff frequency problems considerably and 0.1 Hz is quite easily achieved. >3 V output per g also helps a lot.) Remembering the problems with spring materials in seismographs and that the accelerometers will be rotating quite fast, the 'obvious' solution of a mass + spring + LVDT + damping doesn't seem very hopeful, either. Maybe quartz could provide the stability? What is the best linearity / stability / sensitivity / lowest noise that can be obtained? Do any sensors directly give a frequency or frequency modulated output? > The rotation sticks the gravimeters outward and keeps some pressure on them > at all times I think. OK, let's consider a disk of 1 m diameter rotating in the vertical plane. To keep the pressure in the same direction and avoid any 'passing through zero' effects, we need a rotation of > 42 RPM. The 1 & 3g level is ~ 60 RPM, so we probably operate in between. > Because a piezo-electric transducer responds directly to > changes in stress the rotation would produce an easy to study signal under > ordinary circumstances. These transducers would not hold their charge for > long, however, and the rotation would allow you to take the most useful > information from them because it will always be changing. You could > calibrate the loss of charge and everything else if you could find a good > absolute gravity station with a vertical gradient measurement. You can > totally predict the signal coming from them using simple mathematics. Only if the response, amplifiers etc. are absolutely linear, otherwise you will see 'errors'. You are subtracting large voltages and looking for very small remainders. This is not neccessarily disastrous, but will make the detection of small signals more difficult. Charge leakage should not be a problem, since you are only looking for changes in potential. I don't know how you cope with bumps in the road. I suspect that a very good 'soft' vehicle suspension system would be needed. When you set down you coffee mug on the table, it gets a shock of 10 to 100g. You need to design out that problem as far as possible! By rotating the disks, only the changes in signal levels need to be considered and the signals from a series of rotations can be averaged. > Because the data can be averaged over quite a few spins, the noise reduction > could be done easily. I'm not so sure of 'easily'? You have to get the signal in the first place and we are talking about ppm 'g' level changes. It's OK in the horizontal plane, but in the vertical plane you are seeing signals changing from 0 to 2 g minimum. To reduce noise by x2, you need four samples. To reduce it by x4, you need sixteen samples.... It depends on how long you can wait to get your answer. If the signal is buried in noise and for this application we can reasonably assume that the best possible sensitivity is required, phased 'Boxcar' detectors might be a better option. They are very good at digging signals out of noise. Chopping up a very low level signal and feeding it into a computer can result in a 'garbage in / garbage out' situation. > The FFTs of both signals could be deconvoluted for the > expected zero gradient response and then combined together. The left over > portion (residual) of the signal could be used to get the gradient after the > correlated deviations are removed (like from a bump in the road). The phase > shift info would give you the direction of the gradient in the plane of the > circle and the amplitude would give you the magnitude of the gradient. This > would be quite a lot of fun to use! I think you could increase the > confidence > in the readings by modulating the frequency of rotation of the disk (i.e. > speeding it up and slowing it down) because this would create another aspect > of the response that can easily be used to back out the gravity gradient. Holding the rotation speed constant to ppm levels sounds hard enough. Changing it in a known way with a known phase sounds like a problem which I would wish to avoid. > > > How were the signals and power transferred to the disks? > > > How were the disks driven? Were air bearings used? > > > Was there any automatic gravity alignment system? Naval gyro > > > compasses and aircraft artificial horizons have them built in. > > I do not remember or was not told. > Ahhhh, those are the real secrets for sure! It would be great to have > magnetic bearings or something like that. Driving the thing would be tough > because you would want to reduce the noise. Maybe some kind of nice > electric motor with its own special bearings could be used. Aren't magnetic bearings essentially low load devices? We are talking about 1 metre discs with electronics on board, which need to be rigid and have an appreciable moment of inertia..... you can't make one weighing just a few ounces. You would not need high pressures for air bearings at these speeds / loads. They tend to be 'cleaner' than fluid bearings. It might just be worth trying out precision ball bearings. Thinking laterally, the record industry used two successful drive designs for vinyl disk record players. One was a flat rubber belt pulley drive system, but this could give problems with slippage, phase and accurate rotor speeds. The other was a direct drive stepper motor - which doesn't require separate bearings and whose speed can be crystal controlled. These also operate in the required speed range..... round about 45 RPM. The rotation sensing would probably be optical. > > Honestly, I had trouble believing the thing worked. The physical > > principle is simple but how they got the system to work I do not know. > > I am sure they did a lot of post collection processing. > > They claimed that they could drive the thing at 30 miles an hour and get > > good data. Your roads must be a lot better than ours...! > That must have something to do with the speed of revolution and the number > of averages needed to back out a gradient at the right resolution from the > surface. This is why I think that they can't have digitised the raw data and then processed it. It must be quite a complex analogue process. Even 16 bit resolution is a long way from 1 ppm. Balancing up signals to ppm accuracy is not a trivial task. > Instruments in orbit may be good for > taking gravity data over large regions, but will not be sensitive to stuff > close to the subsurface, which is usually what people are interested in. A > good topography data set in the near future will allow for wonderful " > terrain corrections" used for gravity interpretation. More powerful computers > are also going to make instruments like this one more practical, because > we might be able to make a low tech type and just have to average it over a > longer time to get the needed data. The large amounts of data could then > be deconvolved. Adding a powerful computer won't do much for a poor S/N ratio. There is only so much 'information' in the system - and so much noise. If you want better data, you have to either improve the S/N ratio or wait for it. Thanks for the analysis of the two accelerometer signals - a VERY useful contribution! Regards, Chris Chapman __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Article on gravimeters From: George Harris gjharris@............. Date: Mon, 08 May 2000 21:12:20 -0400 John Hernlund wrote: > On Mon, 8 May 2000, Charles R. Patton wrote: > > Good work, John. > > Thanks, just a half hour out of my day. I'll post the whole derivation some > day soon when I can recall what "time" means. The point of my analysis was to > get only at the gradient, not the absolute field. The absolute field is noise > for gradient determination. I think the idea though is that the gradient is > far more useful in "resolving" sub-surface structures. I am still skeptical > about the claim that these out perform seismic reflection techniques in terms > of time and quality though. Who knows, maybe they are right. I can think of > a million academic applications for this thing once it reaches the relatively > poor and destitute realm of science (as compared to defense and oil of > course).PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. George Harris suggests: Based on experience with inertial navigation and air bearings, I believe that I can sow some light on what was probably used in the rotating gradiometer. First, as some may know, inertial navigation depends on the use of very precise gyros to stabilize a platform about all three axes. Mounted on the platform are two very precise calibrated accelerometers which measure the two compnents of the horizontal acceleration. The outputs of these acceleromaters is doubly integrated, and used to correct the vertical orientation of the platform by precessing the gyros. Back in the 50's, such a platform could be stabilized to something like a minute per hour or less. By now they should be much better. On this platform, supported in a precision air bearing, would be a second platform which could be rotated at a desired speed. This would have two of the same accelerometers (or perhaps four) with pairs on opposite sides of the platform. When rotated, they would show identical accelerations as long as the vertical did not move. A motion of the vertical would affect the opposite acclerometers in opposite direction, one acceleration would be slightly increased the other decreased. By subtracting the two, the vertical shift would be known. Any lateral acceleration would also affect the diference, but this would be at a frequency other than the rotation frequency. Proper data analysis should be able to separate out the differences which are at the rotation frequency, and these would be the gradient changes. With GPS, the whole thing should be much easier. In the original system, long term corrections were applied by looking at the stars. Yes, they can be seen in the daytime if you know about where to look with. with proper sensors! A precise GPS system should be able to cancel out most of the lateral acceleration by doing a double differentiation on the GPS position and subtracting from the measured acceleration. The whole thing sounds like a fascinatimg, expensive program. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Article on gravimeters From: "Tom Schmitt" tschmitt@.............. Date: Tue, 9 May 2000 10:58:54 -0400 A couple of comments. I am begining to remember more about the device that was talked about at the meeting. Some one said tens of millions of dollars. I suspect that would be a minimum. The device relied alot on technology that the Navy had been working on for decades. They had very precise accerometers in the 1950's. Nuclear subs have used inertial navigation since the begining and that was in the 1950's. The gradiometer had GPS though, that was before the commercial units ( this was in 1984 or 1985). The rotating accelerometers were on an inertial table. That is a table that had three gyros and at least two accelerometers on it. This is importantant because basically what the device does is measure the direction of the vector we call "DOWN". The magnitude measured is the difference in g over twice the rotational vector. For the direction of down to have any special meaning ( we can measure that with a rock :) ) we have to compare it to the direction that we think down should be. We know what direction it should be from our assumtion of the shape of the earth ( the elipsoid ). Now the second tricky part is having an independent frame of reference at the site which tells us where down is based on the elipsoid. That is where the inertial table comes in. The gyros etc keep track of the presice orientation of the table with respect to an inital calibration points ( more likely points along the way previously established by classical geodetic methods). Bumps by the way are canceled out more or less. The sudden acceleration due to a bump is more or less the same at both accelrometers. Since it is the difference between acceleration at the two units that is calculated, the bumps tend to camcel. Tend to because they would have to have the same responce at the range of acceleration tey are subjected to and the disk would have to be perfectly stiff ( relative to the integration time of the measurement). I was interested in teh device because at the time I had considerable interest in the 1886 Charleston earthquake. I wanted to get it down to Charleston to see if there was any basement expression of the faults Paradeep Talwani an Don Calhoun had propsed in the Charleston Area. Tom Schmitt tschmitt@.............. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Article on gravimeters From: John Hernlund hernlund@....... Date: Tue, 09 May 2000 08:50:21 -0700 (MST) On Tue, 9 May 2000, Tom Schmitt wrote: > I am begining to remember more about the device that was talked about at the > meeting. > > Some one said tens of millions of dollars. I suspect that would be a > minimum. The device > relied alot on technology that the Navy had been working on for decades. > They had very precise > accerometers in the 1950's. Nuclear subs have used inertial navigation > since the begining and that > was in the 1950's. The gradiometer had GPS though, that was before the > commercial units > ( this was in 1984 or 1985). > Tom Schmitt > tschmitt@.............. Thanks for the extra info Tom. I figured something like this would be prohibitively expensive for our type of group. Maybe we can ask Bill Gates for the money. Anyways, it seems that the only way we will ever find these things in our hands is through either the generosity of the government (i.e. donation of older instruments) or incredible advancements in accelerometer technology. Though the latter is certain to occur, we may all be dead by the time it could apply to this problem for a small cost. I am wondering if a large university collaboration could be developed some time in the future to appropriate one of these instruments and do something like this new USArray deal; truck it all over the US. The other solution might be to have S-T figure out a way to build this thing from hardware store parts! :-) John Hernlund E-mail: hernlund@....... WWW: http://www.public.asu.edu/~hernlund/ ****************************************************************************** __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Article on gravimeters From: ChrisAtUpw@....... Date: Tue, 9 May 2000 20:15:31 EDT Dear Mr.Harris, Thank you for a very interesting letter. > First, as some may know, inertial navigation depends on the use of very > precise gyros to stabilise a platform about all three axes. Were they using all air bearings and quartz controlled synchronous motors, please? Was the angle sensing LVDT, LCDT, optical fringe or what? > Mounted on the platform are two very precise calibrated accelerometers > which measure the two components of the horizontal acceleration. What principle was used for measuring accelerations and were they low range absolute units, rather than 'AC' / piezo etc. types, please? > The outputs of these accelerometers is doubly > integrated, and used to correct the vertical orientation of the platform by > precessing the gyros. Back in the 50's, such a platform could be stabilised > to something like a minute per hour or less. It sounds impressive. Do you know if there are any inertial platforms going cheap on the used equipment market? Getting one might be a good start to developing a gradiometer! Regards, Chris Chapman __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Article on gravimeters From: George Harris gjharris@............. Date: Fri, 12 May 2000 09:36:28 -0400 ChrisAtUpw@....... wrote: > Dear Mr.Harris, > > Thank you for a very interesting letter. > > > First, as some may know, inertial navigation depends on the use of very > > precise gyros to stabilise a platform about all three axes. > Were they using all air bearings and quartz controlled synchronous > motors, please? You would not believe what the gyros looked like! Each one was a cylinder about 5 inches in diameter and 8 inches long. The rotor was floated in a can in a dense fluid. The pivots were small jewel bearings. > > Was the angle sensing LVDT, LCDT, optical fringe or what? > The acceleration sensing and precession torquing was done with an item called a microsyn. It is a small rotary magnetic assembly similar to the linear ones in principal. > > > Mounted on the platform are two very precise calibrated accelerometers > > which measure the two components of the horizontal acceleration. > What principle was used for measuring accelerations and were they low > range absolute units, rather than 'AC' / piezo etc. types, please? > > > The outputs of these accelerometers is doubly > > integrated, and used to correct the vertical orientation of the platform by > > precessing the gyros. Back in the 50's, such a platform could be > stabilised > > to something like a minute per hour or less. > It sounds impressive. Do you know if there are any inertial platforms > going cheap on the used equipment market? Getting one might be a good start > to developing a gradiometer! > It is my understanding that the airlines use inertial sensors now. It should be a good place to start. I wrote the first major military proposal for an inertial system for GM, and I believe that they made the systems for commercial use later. > > Regards, > > Chris Chapman > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Article on gravimeters From: ChrisAtUpw@....... Date: Fri, 12 May 2000 23:05:07 EDT In a message dated 12/05/00 17:39:45 GMT Daylight Time, gjharris@............. writes: > You would not believe what the gyros looked like! Each one was a cylinder > about 5 inches in diameter and 8 inches long. The rotor was floated in a can > in a dense fluid. The pivots were small jewel bearings. That sounds about right. And the rotor speed was controlled by two stages of centrifugal contacts..... which oscillated and needed precise setting. > The acceleration sensing and precession torquing was done with an item > called a microsyn. It is a small rotary magnetic assembly similar to the > linear ones in principal. My forgettory needs an overhaul ! I just remember selsyns, magsyns, magslips, synchro resolvers, twin triodes, vibrating capacitors, chopper stabilised amplifiers and then things got hi-tech with Hall Effect multipliers. Engineers used slide rules, or math tables, or maybe a Monroe Electric Adding Machine. And it took half an hour with a programme on punched paper cards to invert an eight by eight matrix, using a computer the size of a large living room..... with valves in it.... Gee..... that was long ago..... it was another world ! And then Germanium transistors came along..... Thanks for reviving the memories..... Chris __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Article on gravimeters From: Ed Thelen ethelen@........ Date: Fri, 12 May 2000 20:27:51 -0700 ChrisAtUpw@....... wrote: > > In a message dated 12/05/00 17:39:45 GMT Daylight Time, > gjharris@............. writes: > > > You would not believe what the gyros looked like! Each one was a cylinder > > about 5 inches in diameter and 8 inches long. The rotor was floated in a can > > in a dense fluid. The pivots were small jewel bearings. > > That sounds about right. And the rotor speed was controlled by two stages > of centrifugal contacts..... which oscillated and needed precise setting. > Oh Nay - 400 cycle synchronous motors, with the solid steel rotor (magnetizable by the stator current) on the outside which supplied the angular momentum. Honeywell used a quartz crystal oscillator with divide circuitry to obtain a "fixed" stable 400 Hz. The density of the fluid used to float the inner gyro unit, (float to nullify off axis torques) was quite temperature sensitive. So, it took a warm up period (like 20 minutes) for the thermostatically controlled heater (in that can you mention) to get to the fluid to the correct temperature (and density). Some MIT cat (Draper?) got the floatation idea, and it was a winner. All above circa 1957, gyros used for the Vanguard rocket. (The guidance system worked, the propulsion system was designed to give low g's on lift off, so that the Soviets would not think this was a war rocket. Unfortunately, the marginally adequate lift thrust hiccuped, and the Vanguard was vanquished :-(( ---------- Where were we - oh - yes, pendulous gyros to measure acceleration - yes - sorry - __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Wielandt article updates From: Brett Nordgren bnordgren@.............. Date: Mon, 15 May 2000 23:20:06 -0400 About ten days ago, Prof. Erhard Wielandt, who has pioneered the development of force-feedback seismometers, updated his online paper titled "Seismic Sensors and Their Calibration", which may be found at http://www.geophys.uni-stuttgart.de/seismometry/man_html/index.html This an excellent overview of the issues involved in the design of feedback seismometers. He has also revised and expanded his article "Seismometry" at http://www.geophys.uni-stuttgart.de/seismometry/hbk_html/index.html Enjoy. Brett Nordgren __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: 1938 amateur seismology article From: "Frank Cooper" fxc@....... Date: Tue, 16 May 2000 22:47:37 -0500 Hi, I have included a five page1938 article on how to construct your own seismograph from Modern Mechanix on my web page at: http://freeweb.pdq.net/fxc/ The web page SEISMOLOGY IN FRIENDSWOOD, TEXAS, USA, will take several minutes to download. I think many PSN members will be interested in the 1938 methods of constructing an amateur seismograph. How different it is today! Regards, Frank Cooper, Friendswood, Texas __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: 1938 amateur seismology article From: ted@.......... Date: Wed, 17 May 2000 07:58:38 -0400 Frank, Thanks for posting this fascinating article. No errors in the circuit diagrams either! :-) This guy was clearly a tinkerer in the mold of the Wright brothers. Ted Blank "Frank Cooper" @.............. on 05/16/2000 11:47:37 PM Please respond to psn-l@.............. Sent by: psn-l-request@.............. To: cc: Subject: 1938 amateur seismology article Hi, I have included a five page1938 article on how to construct your own seismograph from Modern Mechanix on my web page at: http://freeweb.pdq.net/fxc/ The web page SEISMOLOGY IN FRIENDSWOOD, TEXAS, USA, will take several minutes to download. I think many PSN members will be interested in the 1938 methods of constructing an amateur seismograph. How different it is today! Regards, Frank Cooper, Friendswood, Texas __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Frequency of Channels- BH* - LH* From: Arie Verveer ajbv@............ Date: Thu, 18 May 2000 13:18:02 +0800 Hi, Just a small question, does anyone know what are the frequency ranges when referring to Broardband or Long period seismographs. My guess is the BH* channels are 1 hz - to 20 hz ????? BHZ, BHE, BHN - Broardband LHZ, LHE, LHZ - Long Period By the way is there any other designations? Thanks Arie __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Mount Hood in Volcanoe in Oregon questions From: meredith lamb mlamb1@.......... Date: Thu, 18 May 2000 14:03:47 -0700 Hi all, My sister in Oregon has noted on TV news, some notes of Mount Hood area "experiencing small quakes lately". My question is.... this new; or just more or less normal sporadic quakes in its area? Thanks, Meredith Lamb __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Mount Hood in Volcanoe in Oregon questions From: "Johnston, Michael K" michael.k.johnston@......... Date: Thu, 18 May 2000 13:46:58 -0700 Meredith, You can query the catalog at: http://www.geophys.washington.edu/SEIS/PNSN/CATALOG_SEARCH/cat.search.html I know because of the anniversary of Mount St. Helens, there has been an increase in news coverage in the Seattle area. -Mike Johnston -----Original Message----- From: meredith lamb [mailto:mlamb1@........... Sent: Thursday, May 18, 2000 2:04 PM To: psn-l@.............. Subject: Mount Hood in Volcanoe in Oregon questions Hi all, My sister in Oregon has noted on TV news, some notes of Mount Hood area "experiencing small quakes lately". My question is.... this new; or just more or less normal sporadic quakes in its area? Thanks, Meredith Lamb __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Mount Hood in Volcanoe in Oregon questions From: Canie Brooks canie@........... Date: Thu, 18 May 2000 14:24:00 -0700 Here's a link for current seismicity at Mt Hood: http://www.geophys.washington.edu/SEIS/PNSN/HOOD/hoodrec_eqs.html Canie At 01:46 PM 5/18/00 -0700, Johnston, Michael K wrote: >Meredith, > >You can query the catalog at: >http://www.geophys.washington.edu/SEIS/PNSN/CATALOG_SEARCH/cat.search.html >I know because of the anniversary of Mount St. Helens, there has been an >increase in news coverage in the Seattle area. > >-Mike Johnston __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Frequency of Channels- BH* - LH* From: Larry Cochrane cochrane@.............. Date: Thu, 18 May 2000 17:20:24 -0700 Arie, The different channels all come from the same sensor. The only difference is the sample rate and low-pass filter point. The BH* channels are normally sampled at 20 or 40 SPS and the LH* channels at 1 SPS. There is also a VH* channel with a sample rate of .1 SPS. On my Broadband request system I receive this channel but throw away the data since is not very useful for earthquake monitoring. -Larry Cochrane Redwood City, PSN At 01:18 PM 5/18/00 +0800, you wrote: >Hi, Just a small question, does anyone know what are the >frequency ranges >when referring to Broardband or Long period seismographs. My >guess is >the BH* channels are 1 hz - to 20 hz ????? > >BHZ, BHE, BHN - Broardband >LHZ, LHE, LHZ - Long Period > >By the way is there any other designations? > >Thanks Arie > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Mount Hood Volcano in Oregon questions From: meredith lamb mlamb1@.......... Date: Thu, 18 May 2000 19:17:28 -0700 Canie Brooks wrote: > Here's a link for current seismicity at Mt Hood: > http://www.geophys.washington.edu/SEIS/PNSN/HOOD/hoodrec_eqs.html > > Canie > > At 01:46 PM 5/18/00 -0700, Johnston, Michael K wrote: > >Meredith, > > > >You can query the catalog at: > >http://www.geophys.washington.edu/SEIS/PNSN/CATALOG_SEARCH/cat.search.html > >I know because of the anniversary of Mount St. Helens, there has been an > >increase in news coverage in the Seattle area. > > > >-Mike Johnston > Mike and Canie, Thanks for the web site reference; its actually quite detailed. Interesting about the 12 quakes since 5/14/00 through 5/18/00. I've never hit it up before. I see that it has alot of variety on: http://www.geophys.washington.edu/SEIS/PNSN/HOOD/ Meredith Lamb __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Mount Hood in Volcanoe in Oregon questions From: Bob Fryer bfryer@............ Date: hello Meredith, This is normal, and sporadic, activity for Mt. Hood. Hood was THE mountain for Oregonians -- until May 18th, 1980. Now when we talk about 'the mountain,' we gotta be more specific. When I go out to get the newspaper in the morning, I'll check to see if Hood is still there -- 50 miles east of me -- just to be sure.... What's left of St Helens is 'bout 50 miles North of me.... That which I didn't see heading for Montana. Take care, Bob F >Hi all, > >My sister in Oregon has noted on TV news, some notes of >Mount Hood area "experiencing small quakes lately". > >My question is.... this new; or just more or less normal sporadic >quakes in its area? > >Thanks, > >Meredith Lamb ----- earthquake WARNING research ----- --- animals, people, scientific evidence --- --- http://www.teleport.com/~bfryer --- __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Mount Hood in Volcanoe in Oregon questions From: meredith lamb mlamb1@.......... Date: Fri, 19 May 2000 00:47:46 -0700 Bob Fryer wrote: > hello Meredith, > > This is normal, and sporadic, activity for Mt. Hood. Hood was THE mountain > for Oregonians -- until May 18th, 1980. > > Now when we talk about 'the mountain,' we gotta be more specific. When I > go out to get the newspaper in the morning, I'll check to see if Hood is > still there -- 50 miles east of me -- just to be sure.... > > What's left of St Helens is 'bout 50 miles North of me.... That which I > didn't see heading for Montana. > > Take care, > Bob F > Bob, OK on the sporadic seismic appearances around Mt. Hood, I didn't delve too deeply into the University of Washington web site, in regards to it. I think alot of people regard it as potentially very dangerious though. Ahhh yesss, Mt St. Helens....I made a trip there around 85, such a pile of huge logs for many miles. Rather unforgettable when it blew in 80. The learning channel on TV had a hour program on it tonight, which I've seen before, but watched again anyway. Think the same channel had a show about Kratatoa volcanoe and where they attributed alot of the dark ages to its effects on Wednesday or Tuesday night. The Columbia river is a sight to see for anyone also, huge layers of lava all along the route. Of course the dams with their "fish ladders" viewing rooms is another must see. The forests there in Oregon and Washington put the forests of Colorado to shame....its so dense just about everywhere, one could get lost just 50 foot into some of the areas. Take care also, Meredith Lamb __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Seismograph From: Doug Crice dcrice@............ Date: Fri, 19 May 2000 09:30:13 -0700 You earthquake enthusiasts will want to take a look at this seismograph on ebay at http://cgi.ebay.com/aw-cgi/eBayISAPI.dll?ViewItem&item=333640427 The small bag contains sand which provides double duty as a damping medium and recording medium. -- Doug Crice http://www.georadar.com 19623 Via Escuela Drive phone 408-867-3792 Saratoga, California 95070 USA fax 408-867-4900 __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Broadband station response From: S-T Morrissey sean@........... Date: Fri, 19 May 2000 12:34:39 -0500 (CDT) Here is some additional information on the channel designations at a broadgand station using SEED name conventions: (SEED = Standard for the Exchange of Earthquake Data ). Note that the SEED names are different from the former channel streem descriptor names: ie VBB-Z is BHZ, LP-Z is LHZ, VLP-? is VH?, VSP-? is SH?, etc. The names do not exactly specify the sample rate, but the conventions of the IRIS stations are preferred. here is the file vbb_system_description from CCM: ---------------------------------------------------------------------- File USR/GSN/DP_LOGS/ VBB_SYSTEM_DESCRIPTION at station CCM: (This is the response to the "r" command in any data retrieval mode.) Station : CCM Cathedral Cave, Missouri Lat: 38.0557 N Lon:-91.2446 W Elev:222.5m (51 meters below the local surface) Components: Z : + = ground motion up N : + = ground motion north E : + = ground motion east Digitizer: Quanterra Q980 split system (9 24-bit channels). SEED NAMES: BHZ,BHN,BHE: Streams: VBB : 20 SPS: on 24-bit channels, from Streckeisen STS-1 seismometers. Instrument response is flat to velocity from 10 Hz to 360 sec; Sensitivities are Z = 2278 Vsec/m; N = 2142 Vsec/m; E = 2058 Vsec/m. Recorded continuously on line and on tape. LHZ,LHN,LHE: LP : 1 SPS: derived by constant-time-delay Finite Impulse Response (FIR) digital filter from VBB stream in real time, cutoff at 2.7 S period. 4x Gain. Recorded continuously. VHZ,VHN,VHE: VLP : 0.1 SPS: derived by FIR filter from LP stream in real time, cutoff at 27 S period. 4x Gain. Recorded continuously. UHZ,UHN,UHE: ULP : 0.01 SPS: derived by FIR filter from VLP stream in real time, cutoff at 270 S period. Recorded continuously. Micro-Barometer Data, as of 24 Feb. 1995: U data is direct barometer at 419.43 counts/Pascal; V data is 3600 sec high pass of U; W data is 100 sec high pass of U. BHU,BHV,BHW: U,V,W VBB: 20 SPS: on 24-bit channels, same response as STS-1s LHU,LHV,LHW; VHU,VHV,VHW; UHU,UHV,UHW: LP, VLP, and ULP barometric data also recorded continuously. Very high gain, short period channels for the CTBT (Comprehensive Test Ban Treaty) from a separate set of 1 hz seismometers: SHZ,SHN,SHE: VSP : 40 SPS: on 24-bit channels, from GS-13 seismometers. Recording continuously but NOT event detected. (The amplifiers for the GS-13's are flat to 25 hz.) EHZ,EHN,EHE: ESP : 80 SPS: on 24-bit channels, from GS-13 seismometers. Event recorded only. (online buffers; not on tape) Various SOH channels are also recorded, including STS-1 mass position (VMZ,VMN,VME), DA supply voltage (VE1,UE1), average free packets (AFP), clock drift and corrections (ACD, AFC), and DA instrument temperature (VKI). Note: FIR filter delays are accounted for in the header reported with the data. Response: Basic response for the LP, VLP, and ULP channels is flat to ground velocity from the FIR filter upper cutoff to the second-order lower corner at 360 S period. _________________________________________ Regards, Sean-Thomas __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Fixed-end leafspring analysis From: Brett Nordgren bnordgren@.............. Date: Sat, 20 May 2000 14:47:57 -0400 To the hardware builders, Just put up the first pass of the mechanical analysis of a fixed-end leafspring as used in the STS-1 vertical. It's a multi-worksheet Excel 97 workbook, plus Word 97 doc file and a bunch of helpful Microsoft Knowledge Base Excel troubleshooting articles in html. 754k - 42 files Doc file only, as included in above file, but in .pdf form. 106k Also included is an update to Put on an addendum to take note of Sean-Thomas' concerns regarding op-amp noise. To be found at: http://members.home.net/nordgren/public/ Good luck, Brett Nordgren bnordgren@.............. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Fixed-end leafspring analysis From: "OguzCem Candir" oguzcem@........... Date: Sat, 20 May 2000 22:36:51 +0300 Dear Mr Nordgren, Is there any possibilty to get the same explanations below, for a horizontal Lehman seismometer. First problem is how the boom comes to its original position without any spring or damping only with its steel wire, and what is the spring constant (k) of the system. Also what is the equation of motion of the system. Best regards, Oguz Cem Candir BS MechEng ----- Original Message ----- From: Brett Nordgren To: Sent: Saturday, May 20, 2000 9:47 PM Subject: Fixed-end leafspring analysis > To the hardware builders, > > Just put up the first pass of the mechanical analysis of a fixed-end > leafspring as used in the STS-1 vertical. It's a multi-worksheet Excel 97 > workbook, plus Word 97 doc file and a bunch of helpful Microsoft Knowledge > Base Excel troubleshooting articles in html. > 754k - 42 files > > Doc file only, as included in above file, but in .pdf form. > 106k > > Also included is an update to > > Put on an addendum to take note of Sean-Thomas' concerns regarding op-amp > noise. > > To be found at: > > http://members.home.net/nordgren/public/ > > Good luck, > > Brett Nordgren > bnordgren@.............. > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Strain meters? From: Jim ODonnell jimo17@........ Date: Sat, 20 May 2000 12:44:55 -0700 Sean Thomas et al,.. A student at UNLV would like to measure movement across some fissures in Las Vegas. The fissures are cracks in the soil (deep alluvium) about 10m long in an area of mapped faulting. I was wondering if strain meters would do the trick, the cheaper the better,and can you recommend or suggest any methods or devices that would work? Jim O'Donnell Registered Geologist No. 1240, State of California, 1970 Registered Geophysicist No. 158, State of California, 1974 702 293-5664 jimo17@........ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Strain meters? From: "Robert W. Avakian" ravakian@............ Date: Sat, 20 May 2000 17:51:08 -0500 If the measurement need not be continuous, optical methods may be cheaper and easier. A couple of concrete piers and an inexpensive laser could be used with great effect I would think. Strain meters need to be fixed rigidly at both ends do they not? A problem in loose soils. Jim ODonnell wrote: > > Sean Thomas et al,.. > > A student at UNLV would like to measure movement across some fissures in > Las Vegas. The fissures are cracks in the soil (deep alluvium) about 10m > long in an area of mapped faulting. I was wondering if strain meters > would do the trick, the cheaper the better,and can you recommend or > suggest any methods or devices that would work? > > Jim O'Donnell > Registered Geologist No. 1240, State of California, 1970 > Registered Geophysicist No. 158, State of California, 1974 > 702 293-5664 > jimo17@........ > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: The revised and corrected "zero force" hinge From: ChrisAtUpw@....... Date: Sat, 20 May 2000 22:23:17 EDT Dear Brett Nordgren, The 'zero force' hinge analysis given in zerohng2.pdf as referred to the rolling cylinders, may be easier to understand if you think of it in a different manner. Consider two equal diameter pulleys with fixed parallel axes of rotation having a crossed belt running around them, giving contra-rotation. When you turn one pulley, the other moves through the same angle, but in the opposite sense. If you now fix one pulley and allow the axis of the other to rotate around it, the moving pulley rotates twice while going once around the fixed pulley. The position of the crossover of the belt moves in a circle half way between the pulleys. This analysis can be extended to circles of different diameter with different 'belt' lengths. The slight 'catch' about this 'zero force' design is that unless the belt is 'completely flexible', bending the belt over the pulleys involves a force which tends to pull the pulleys together - the natural shape of the 'straight bit' forming the hinge is actually 'S' shaped. Regards, Chris Chapman __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: strainmeters/creepmeters From: S-T Morrissey sean@........... Date: Sat, 20 May 2000 21:43:10 -0500 (CDT) Jim, The first task when considering strainmeters or tiltmeters is just what range of strain or displacement is expected over what period of time. If you have an active fault crossing a paved road, a linear line of nails makes a great creepmeter for movements of centimeters per year. For continuous measurements a taught wire (often of Invar or carbon fiber) is stretched across the fault at an oblique angle inside a large (eg 6") ABS pipe between buried concrete vaults (pre- cast septic tanks are used). Often several fiber creepmeters are installed in parallel using the same pipe, vaults, and monuments. Extra fibers are set aside as spares, and using different wires or fibers allows temperature compensation. One end of the wire or fiber is anchored to a large a monument in as deep a hole as you can afford, and the free end is coupled to a displacement transducer anchored to a similar monument. In hard rock sites, earth- tide resolution has been achieved at 10^-7 strain. Otherwise surface hydrology limits useful long term measurements, unless large movements are expected, such as 2 to 3 cm/year at Parkfield and Hollister in CA. Much work has been done trying to get reproducible data, especially in surface installations, over time periods of tectonic interest, like YEARS. After a number of wishful claims of success, surface strain or creep measurements have faded away except in locations with very active tectonics. There are no cheap or easy ways to do this. Among the best strainmeters are the 750 meter baseline laser interferometer systems at Pinon Flat that operate in evacuated tubes and have massive end monuments with "optical anchors" thru the decomposed granite of the surface to virgin rock 20 meters down. They have achieved stability of better than 10^-6 / year but at great expense and effort. GPS measurements are also used, but over longer distances, and expected tectonic deformations and fault creep have been seen. But even here the wide area data does not agree with the on-fault creep data because the fault is at depth and its movement is better integrated over a large area of the surface rather than being localized at a surface fault. A classical reference on the subject can be found in: Agnew, D.C., "Strainmeters and Tiltmeters", Reviews of Geophysics, vol 24, No 3, 579-634, 1986 _______________ Regards, Sean-Thomas __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: The revised and corrected "zero force" hinge From: Brett Nordgren bnordgren@.............. Date: Sat, 20 May 2000 23:22:57 -0400 At 10:23 PM 5/20/2000 -0400, you wrote: > The slight 'catch' about this 'zero force' design is that unless the > belt >is 'completely flexible', bending the belt over the pulleys involves a force >which tends to pull the pulleys together - the natural shape of the 'straight >bit' forming the hinge is actually 'S' shaped. > > Regards, > > Chris Chapman Chris, Thanks for the nice explanation. It is a weird configuration to visualize. I think because of symetry, there should actually be zero residual moment. If you didn't mark the ends of the cylinders, you wouldn't be able to tell how much it had rotated. The flexures would all continue to have the same shape, whatever it was. In effect, as one flexure winds up, another is unwinding in exactly the opposite way. Think everything cancels out. Although, thinking about it, it's probable that the effect you're describing might well allow the axis of rotation to shift very slightly depending on the direction of the force on the hinge. That may be the problem. I'm hoping it's a pretty small effect. Regards, Brett __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: strainmeters/creepmeters From: Ed Thelen ethelen@........ Date: Sat, 20 May 2000 21:53:43 -0700 re: following message - 20 years ago, creep measurements were plagued by many surprising (to clean handed city dwellers and college students) problems. I visited an installation near Hollister, CA one weekend. The maintenance technician was there, and doing the usual: - cleaning out crickets, and even mice that had burrowed through the cracks and other real separations between various walls, tubes, holes for wires, ... - manually clearing out mud from the wires and strain gauge heads due to a "once in a hundred year storm", which seemed to come every year or so. - re-adjusting the time standard by comparing the phase of the 400 wave from the on site time unit and the 400 cycle wave from the WWV receiver using a big vacuum tube osciloscope. This was before GPS and similar technologies - - ah - for the good old days ;-) Enjoy Ed Thelen S-T Morrissey wrote: > > Jim, > > The first task when considering strainmeters or tiltmeters is just > what range of strain or displacement is expected over what period of > time. If you have an active fault crossing a paved road, a linear > line of nails makes a great creepmeter for movements of centimeters > per year. For continuous measurements a taught wire (often of Invar > or carbon fiber) is stretched across the fault at an oblique angle > inside a large (eg 6") ABS pipe between buried concrete vaults (pre- > cast septic tanks are used). Often several fiber creepmeters are installed > in parallel using the same pipe, vaults, and monuments. Extra fibers > are set aside as spares, and using different wires or fibers allows > temperature compensation. > One end of the wire or fiber is anchored to a large a monument in as deep > a hole as you can afford, and the free end is coupled to a displacement > transducer anchored to a similar monument. In hard rock sites, earth- > tide resolution has been achieved at 10^-7 strain. Otherwise surface > hydrology limits useful long term measurements, unless large movements > are expected, such as 2 to 3 cm/year at Parkfield and Hollister in CA. > Much work has been done trying to get reproducible data, especially > in surface installations, over time periods of tectonic interest, like > YEARS. After a number of wishful claims of success, surface strain > or creep measurements have faded away except in locations with very > active tectonics. There are no cheap or easy ways to do this. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Strain meters? From: Karl Cunningham karlc@....... Date: Sun, 21 May 2000 00:14:09 -0700 Jim -- I'm not sure what the magnitude of the expected strain is or how protected the area is from vandalism, but here's some suggestions: A frequently-used and very inexpensive method to measure horizontal strain across a fault is to drive stakes at A and B (one on each side of the fault, perhaps a meter on each side) and perhaps 5 meters apart along the fault: stake-A C-stake ========================================================fault stake-D B-stake Anchor a wire to one of the stakes and stretch it along to the other one, where it is attached by an extension spring. Measuring the length of the spring with a caliper, and compensating for change in the length of the wire due to thermal expansion, gives a measure of strain along the fault. A variation is to drive four stakes and to measure A-B, A-D, C-B, and D-C. This gives a vector of movement and also gives redundant measurements for checking. For more cost, a quartz fiber instead of the wire will improve temperature stability, and use of an LVDT instead of the calipers will improve measurement resolution and stability. And you can build a shelter over the apparatus to improve things even more. Regards, Karl Cunningham karlc@....... At 12:44 5/20/2000 -0700, you wrote: >Sean Thomas et al,.. > >A student at UNLV would like to measure movement across some fissures in >Las Vegas. The fissures are cracks in the soil (deep alluvium) about 10m >long in an area of mapped faulting. I was wondering if strain meters >would do the trick, the cheaper the better,and can you recommend or >suggest any methods or devices that would work? __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Zero force hinge From: ChrisAtUpw@....... Date: Sun, 21 May 2000 11:57:03 EDT Dear Brett Nordgren, Thanks for your EMail about the hinge design. > As you rotate the cylinders, the total length of flexure material in > contact with the cylinders remains constant. Whatever unwinds from one, > winds up on the other. Then, because the force on the hinge is constant, > the "s" curves will be exactly the same shape..... > Therefore there is no net change of the strain energy in the flexures as > the cylinders rotate. Therefore there can be no moments resisting the > rotation, or conservation of energy would be violated for the system. That was what I had concluded. > I'm pretty sure the same analysis works when the cylinders are of different > sizes, but it requires a slightly more involved argument. The track of the intersection point of a fixed length belt around two cylinders must always lie on a circle. One cylinder will rotate with regard to the other in the ratio 2x their diameters. If you want a very small sideways movement, use a large fixed cylinder and a small rotating one. The movement between the cylinder axes under changing lateral forces, can be fairly accurately calculated. It is the extension of bent beam with a directional load parallel to the tip section, with a correction allow for small changes in the position of the contact point of on the cylinder. There will be a minimum load which just keeps the flexing belt in contact around the cylinder - the natural shape of a crossed belt is a couple of 'tear shapes'. If you have flexures with fixed ends, the curve of the intersection approximates to an ellipse - the lengths of the two crossover foils is constant, the bend points are 'fixed' and the sum of the distances on one side between the crossover and the fixing points must be constant - hence it is an ellipse. Then you have to add in the four beam bending corrections at the ends. For hinge design for seiesmographs, any pair of hinges should have the same geometry and similar, if not identical, loading per unit length. Regards, Chris Chapman __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Worlds deepest rocks surface in Pacific From: meredith lamb mlamb1@.......... Date: Sun, 21 May 2000 13:13:46 -0700 Noted a interesting article on the web: http://www.discovery.com/news/briefs/20000518/geology_deeprock.html >From my point of view....I can't really understand how they could have gotten to the surface from the between the upper and lower mantle intact, and, from the Pacific basin itself? Meredith Lamb __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Strain meters? From: Bob Smith bobsmith5@........ Date: Sun, 21 May 2000 16:50:57 -0400 Hello all --- Having no idea of the range of motion and resolution/repeatability you are looking for I'm not sure that this approach will be of any use. In the '80s and 90's I worked several years for a client that built medical X-Ray systems. Such a machine is essentially a low precision robot or industrial grade positioning system. An essential element of the control system was a linear sensor to measure the position of various arms and slides that held the X-Ray tube and imaging device. We looked at a number of devices: 1. Laser interferometers (too expensive). 2. LVDTs (limited range of travel) 3. Gray coded sensor bars and optical sensors (too expensive and clumsy to get the desired resolution). 4. Optical encoders such as used on precision milling machines (Technically good solution, but too expensive for a multi-axis system and very sensitive to mechanical alignment. 5. And a million other ideas, some of them pretty loony :-) . The final solution was a Rube Goldberg inspired device affectionately known as a "string pot". It consisted of a grooved or threaded drum around which a small stainless steel aircraft cable (about 0.032" diam) was wound. The drum and cable arrangement was pre loaded by a clock type spring motor. The tension was quite high, probably around 15-20 pounds force. (The thing could produce quite a nasty cut/burn if you let it get away while pulled well out against the string :-( ). Finally the drum drove a ten turn potentiometer through a pair of gears. The position of the potentiometer shaft was measured by a twelve or fourteen bit A/D converter. Performance -- Range of motion - Typically 250 to 1000 mm depending on drum diameter and gear ratios. (Range of motion is virtually unlimited as it is controled by the drum diameter and gear ratios.) Resolution - Reliably better than 1 part per 1000 of total travel. Repeatability - Excellent, essentially equal to resolution. Absolute accuracy - also 1 part per 1000 after calibration. Suitability for this application??? 1. Temperature stability was not evaluated (working in a hospital environment has some advantages). 2. Micro controller (A/D) interfacing required. If anyone is interested, I can provide more details on this wacky device. Best wishes, Bob Smith Jim ODonnell wrote: > > Sean Thomas et al,.. > > A student at UNLV would like to measure movement across some fissures in > Las Vegas. The fissures are cracks in the soil (deep alluvium) about 10m > long in an area of mapped faulting. I was wondering if strain meters > would do the trick, the cheaper the better,and can you recommend or > suggest any methods or devices that would work? > > Jim O'Donnell > Registered Geologist No. 1240, State of California, 1970 > Registered Geophysicist No. 158, State of California, 1974 > 702 293-5664 > jimo17@........ > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. -- --------- Avoid computer viruses -- Practice safe hex ------------- * * Specializing in small, cost effective embedded control systems * * Robert L. (Bob) Smith Smith Machine Works, Inc. internet bobsmith5@.............. Lumlay Road landline 804/745-1065 Richmond, Virginia 23236+1004 __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Web Ring From: Wayne Abraham J73WA abrahamw@........ Date: Sun, 21 May 2000 18:23:47 -0400 Hello fellow PSN members Over the past 18 months since I have been a member of the PSN, I have noticed that there are many members of this fabulous group who have pretty impressive websites detailing many aspects of his great hobby. Many questions are answered by providing links to each other's websites. I have also noticed that apart from a few links on Larry's website, there is no real way of harnessing these resources into a comprehensive list of PSN related websites with their descriptions. For this reason, I have just started a Public Seismic Network WebRing. You may visit the ring at: http://nav.webring.org/cgi-bin/navcgi?ring=psn;id=1;next5 A link to the Ring is also provided at the bottom of my website http://www.freeyellow.com/members6/dominicapsn/page1.html If you have own a website relevant to PSN interests and would like to join the ring, you may do so at: http://edit.webring.org/cgi-bin/membercgi?ring=psn;addform If you have any comments or question, please do not clutter the list with them. You may email me direct at: mailto:abrahamw@.................... WebRing feedback. Thanks for your time, Wayne -- Wayne Abraham 1430 Rodney Street Portsmouth, Dominica abrahamw@........ http://www.freeyellow.com/members6/dominicapsn/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Special Pub 254 on it's way From: ted@.......... Date: Sun, 21 May 2000 19:23:21 -0400 Some of you may have already received your copies of Interpretation of Seismograms. All copies have gone out. I got 19 requests and received a total of $113. Copying was $53 and postage was $28 so I'm sending a check for $32 to Larry. Happy reading everybody. Regards, Ted Blank __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: AutoDRM-Winquake-Hypoellipse From: Arie Verveer ajbv@............ Date: Mon, 22 May 2000 15:22:51 +0800 Hi, I've just updated my webpage with a better example on how to use the AutoDRM request manager. It also contains an example o n how I used Hypoellipse to find a quakes position from the AutoDRM info. If you find any errors please let me know. This all came about, due to the closure of our states geophysical observatory. So if you want info on smaller quakes then calculate it yourself. Hmmmmm. But armed with "GseToPsn", "Winquake" and "Hypoellipse" that should be no problem. Arie __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Special Pub 254 on it's way - New Mail Server From: Larry Cochrane cochrane@.............. Date: Mon, 22 May 2000 01:58:56 -0700 At 07:23 PM 5/21/00 -0400, you wrote: >Some of you may have already received your copies of Interpretation of >Seismograms. All copies have gone out. I got 19 requests and received a >total of $113. Copying was $53 and postage was $28 so I'm sending a check >for $32 to Larry. Happy reading everybody. > >Regards, >Ted Blank Thanks Ted, The money will go towards the new mail server I purchased last month. I needed to replace the mail server we have been using for years do to spammers hijacking the server. The old version of NTMail, the mail server I had been using, would not allow me to block the spammers from using my system. Upgrading to the new version NTMail would have cost over $1K so I started looking for a cheaper server. After trying some cheaper servers that didn't work, or did not have the features I needed, I ended up with MailSite (see www.rockliffe.com). It was a little cheaper then the new version of NTMail and after contacting the company and explaining that their server would be used for the PSN and a few other mailboxes for my personal usage they lowered the price to $800.00. Still a lot of money, but I couldn't spend any more time looking for another server. When the spammers hit my system, my system was temporary placed on a blacklist as an open mail server. Some ISP's use this list to block email so I needed to get something work quickly so everyone would receiver messages sent from my system. It was also taking a lot of my time evaluating servers so when I found this server that had every I needed including blocking spammers I went for it. Regards, Larry Cochrane Redwood City, PSN __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Strain meters? From: Danie Overbeek danieo@............ Date: Mon, 22 May 2000 11:21:09 +0000 Hooray for Bob Smith's sensible engineering solution to displacement measuring. The cable over spring loaded pulley was used successfully as early as the 1930's in the Sperry A-2 automatic pilot feedback system. Cheers all string and pulley experimenters Danie Overbeek. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: The revised and corrected "zero force" hinge From: "George Harris" gjharris@............. Date: Mon, 22 May 2000 11:02:00 -0700 > > The slight 'catch' about this 'zero force' design is that unless the > > belt > >is 'completely flexible', bending the belt over the pulleys involves a force > >which tends to pull the pulleys together - the natural shape of the 'straight > >bit' forming the hinge is actually 'S' shaped. > > > > Regards, > > > > Chris Chapman > > > Chris, > Thanks for the nice explanation. It is a weird configuration to visualize. > > I think because of symetry, there should actually be zero residual > moment. If you didn't mark the ends of the cylinders, you wouldn't be able > to tell how much it had rotated. The flexures would all continue to have > the same shape, whatever it was. In effect, as one flexure winds up, > another is unwinding in exactly the opposite way. Think everything cancels > out. The above comment is correct. If the flexures are not bent prior to wrapping them around a cylinder, there is no energy required to move the hinge. As one flexure is bent, the other is unbent in exactly an equal amount. The secret to making the stiffness high is to make the flexures as thin as possible. As stated in the first message, there is a slight "s" shape between the cylinders. As the force on the hinge increases, these "s" shapes straighten out and get stiffer. I have been using this type of hinge on both verticals and horizontals for a couple of years, and they perform very well. My preferred configuration is 1/2 inch cylinders with .002 high strength material for the bands. George Harris __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: PSN mail server pledge drive. Re: Special Pub 254 on it's way - New Mail Server From: Steve Hammond Shammon1@............. Date: Mon, 22 May 2000 13:28:01 -0700 Wow, $800 for a mail server! That is a lot more than what Wildcat and a modem cost for the old PSN BBS systems... Larry, I remember pledging a check at the meeting. Larry I pledge $30 for the new mail server kuz that's what I can afford right now. I'll mail you the check today. Regards, Steve Hammond PSN San Jose Larry Cochrane wrote: > > At 07:23 PM 5/21/00 -0400, you wrote: > >Some of you may have already received your copies of Interpretation of > >Seismograms. All copies have gone out. I got 19 requests and received a > >total of $113. Copying was $53 and postage was $28 so I'm sending a check > >for $32 to Larry. Happy reading everybody. > > > >Regards, > >Ted Blank > > Thanks Ted, > > The money will go towards the new mail server I purchased last month. I > needed to replace the mail server we have been using for years do to > spammers hijacking the server. The old version of NTMail, the mail server I > had been using, would not allow me to block the spammers from using my > system. Upgrading to the new version NTMail would have cost over $1K so I > started looking for a cheaper server. After trying some cheaper servers > that didn't work, or did not have the features I needed, I ended up with > MailSite (see www.rockliffe.com). It was a little cheaper then the new > version of NTMail and after contacting the company and explaining that > their server would be used for the PSN and a few other mailboxes for my > personal usage they lowered the price to $800.00. Still a lot of money, but > I couldn't spend any more time looking for another server. > > When the spammers hit my system, my system was temporary placed on a > blacklist as an open mail server. Some ISP's use this list to block email so > I needed to get something work quickly so everyone would receiver messages > sent from my system. It was also taking a lot of my time evaluating servers > so when I found this server that had every I needed including blocking > spammers I went for it. > > Regards, > Larry Cochrane > Redwood City, PSN > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Special Pub 254 on it's way - New Mail Server From: "Rex Klopfenstein, Jr." rklopfen@......... Date: Mon, 22 May 2000 19:02:36 -0400 I will send you a check for $25. It will be after Memorial Day, we are going to DC for the weekend. Larry Cochrane wrote: > At 07:23 PM 5/21/00 -0400, you wrote: > >Some of you may have already received your copies of Interpretation of > >Seismograms. All copies have gone out. I got 19 requests and received a > >total of $113. Copying was $53 and postage was $28 so I'm sending a check > >for $32 to Larry. Happy reading everybody. > > > >Regards, > >Ted Blank > > Thanks Ted, > > The money will go towards the new mail server I purchased last month. I > needed to replace the mail server we have been using for years do to > spammers hijacking the server. The old version of NTMail, the mail server I > had been using, would not allow me to block the spammers from using my > system. Upgrading to the new version NTMail would have cost over $1K so I > started looking for a cheaper server. After trying some cheaper servers > that didn't work, or did not have the features I needed, I ended up with > MailSite (see www.rockliffe.com). It was a little cheaper then the new > version of NTMail and after contacting the company and explaining that > their server would be used for the PSN and a few other mailboxes for my > personal usage they lowered the price to $800.00. Still a lot of money, but > I couldn't spend any more time looking for another server. > > When the spammers hit my system, my system was temporary placed on a > blacklist as an open mail server. Some ISP's use this list to block email so > I needed to get something work quickly so everyone would receiver messages > sent from my system. It was also taking a lot of my time evaluating servers > so when I found this server that had every I needed including blocking > spammers I went for it. > > Regards, > Larry Cochrane > Redwood City, PSN > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. -- Rex Klopfenstein, Jr. Bowling Green, OH rklopfen@......... http://www.wcnet.org/~rklopfen __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: PSN mail server pledge drive From: Jim ODonnell jimo17@........ Date: Mon, 22 May 2000 16:15:56 -0700 My $25 check will be in the mail tomorrow... Many thanks to Larry... Also received my copy of, 'Interpretation of Seismograms' today. Actually I recognized it, as I was working for ESSA in 1966 .....Jim __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: AutoDRM, Winquake, Hypoellipse From: Arie Verveer ajbv@............ Date: Tue, 23 May 2000 07:31:27 +0800 Sorry I forgot to mention the web site: http://www.iinet.net.au/~ajbv - Arie > Hi, I've just updated my webpage with a better example on how to use the AutoDRM request manager. > It also contains an example on how I used Hypoellipse to find a quakes position from the AutoDRM info. > If you find any errors please let me know. > > This all came about, due to the closure of our states geophysical observatory. So > if you want info on smaller quakes then calculate it yourself. Hmmmmm. > > But armed with "GseToPsn", "Winquake" and "Hypoellipse" that should be no problem. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: AutoDRM Sites Link From: Arie Verveer ajbv@............ Date: Tue, 23 May 2000 20:13:19 +0800 Hi All , It appears that the PIDC facility ( http://www.pidc.org/dataprodbox/prod.html ) is closed down for new events after 20/feb/2000. For those who are interested in the AutoDRM to gather data then I would recommend the site at http://seismo.ethz.ch/waves4u/ This gives you a list of AutoDRM's and links to stations. Actually the site at http://seismo.ethz.ch/waves4u/ is well worth exploring. Arie __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Lehman sensitivity, etc From: The Lahrs JohnJan@........ Date: Mon, 22 May 2000 21:50:01 -0600 Dear Oben, I'm glad to hear that you are building a seismic system. The best source of technical information is the Public Seismic Network, through the archives of their Email messages, through web sites, or by asking questions. Sean-Thomas Morrissey , for example, is one of the experts in seismological instrumentation who is in the PSN and he often provides answers to PSN questions. To join, please see this page to join the group: http://www.seismicnet.com/maillist.html Best of luck with your new instrument. Yours, John At 09:16 AM 5/16/00 , you wrote: >Hello Mr. Lahr, >As senio students in Mechanical Engineering Department at Bogazici >University, Istanbul in Turkey, we are working on building a Lehman type >seismometer. We are almost done with the construction but we need >information on the governing equations, transfer functions and >sensitivity, and etc. about the Lehman type seismometer in general. We >will appreciate your invaluable experience and knowledge on this subject. >Thank you for your kind interest, >Best regards, >Oben Ceryan >Oguz Cem Candir >________________________________________________________________________ >Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com John C. Lahr 1925 Foothills Road Golden, CO 80402 (303) 215-9913 http://lahr.org/john-jan/science.html __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: seismometer info From: S-T Morrissey sean@........... Date: Tue, 23 May 2000 14:22:25 -0500 (CDT) Oben, Oquz, and company, Regarding your request for general information about seismometer design and engineering: recently Brett Nordgren posted the urls of revised articles by Erhard Wielandt, who is one of the pioneers of broadband technology. The articles cover similar material in a quite generalized review. But perhaps the greatest value in them is the bibliography included with each, particularly the /hbk_html/... article. This list includes the full reference information for important technical articles by Peterson, Rogers, Aki and Richards, Riedesel and co., as well as the classics by Agnew, Benioff and Press, and LaCoste, to name a few. look at: //www.geophys.uni-stuttgart.de/seismometry/man_html/index.html and: //www.geophys.uni-stuttgart.de/seismometry/hbk_html/index.html Also, regarding the Lehman design specifically, the PSN maintains an archive of the many discussions about its design and performance, as John Lahr has pointed out. I have not been particularly involved with the Lehman discussions because it is a horizontal sensor with inherent limitations in what earthquake waveforms it is sensitive to (limited P-wave use) and its' generally order of magnitude greater sensitivity to tilt noise of the pier. I encourage everyone to build vertical sensors. The Wielandt articles do address the noise problems with a long period or broadband horizontal sensor. Look at the referenced papers by Rogers for more complex equations and functions. Regards, Sean-Thomas __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: New Mail Server From: The Lahrs JohnJan@........ Date: Wed, 24 May 2000 07:58:46 -0600 Hi Larry, Thanks for keeping the PSN Email system going! I've put a check for $30 in an envelope with your name on it. Now I just need your address. Cheers, John At 02:58 AM 5/22/00 , you wrote: >The money will go towards the new mail server I purchased last month. ...... John C. Lahr 1925 Foothills Road Golden, CO 80402 (303) 215-9913 http://lahr.org/john-jan/science.html __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: F.E.S.N.- SEISMO WAP FREE SERVICE From: "Giovanni Rotta" rottag@.......... Date: Wed, 24 May 2000 20:21:06 +0200 Dear friends, I have the pleasure to present to you the new Friuli Experimental = Seismic Network' (Italy) www.fesn.org free service SeismoWap: with your = cellular phone you can connect the net and the FESN' Archive of the = Events to read the last events recorded. To be able to connect the net = by your cellular phone you need to contact your phone provider to = emprove it. The FESN SeismoWap' net address is www.fesn.org/main.asp ; This free service is offered by the Skipper Soft S.r.l. = www.skippersoft.com=20 Have our best regards, =20 Giovanni Rotta =20 Giovanni Rotta Via F. Pizzigoni, 10 33010 Resia (Udine) I Lat. 46.368 N Long. 13.299 E rottag@.......... http://www.fesn.org
Dear friends,
I have the pleasure to present = to you the=20 new Friuli = Experimental=20 Seismic Network' (Italy) www.fesn.org free=20 service SeismoWap: with = your=20 cellular phone you can connect the net and the FESN' Archive of the = Events to=20 read the last events recorded. To be able to connect the net by your = cellular=20 phone you need to contact your phone provider to emprove it. The = FESN=20 SeismoWap' net address is www.fesn.org/main.asp = ;
 
This free service is offered by the Skipper = Soft=20 S.r.l. www.skippersoft.com=20
Have our best regards,
 
Giovanni Rotta
 
Giovanni Rotta
Via F. Pizzigoni, 10
33010 = Resia=20 (Udine) I
Lat. 46.368 N  Long. 13.299 E
rottag@..........
http://www.fesn.org




<= BR>



Subject: Re: New Mail Server From: Larry Cochrane cochrane@.............. Date: Wed, 24 May 2000 14:03:57 -0700 Thanks John, Heres my address: Larry Cochrane 24 Garden St. Redwood City, CA 94063 -Larry At 07:58 AM 5/24/00 -0600, you wrote: >Hi Larry, > >Thanks for keeping the PSN Email system going! I've put a check for $30 in an >envelope with your name on it. Now I just need your address. > >Cheers, >John > >At 02:58 AM 5/22/00 , you wrote: > >>The money will go towards the new mail server I purchased last month. >..... > >John C. Lahr >1925 Foothills Road >Golden, CO 80402 >(303) 215-9913 >http://lahr.org/john-jan/science.html __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: DSL From: Larry Cochrane cochrane@.............. Date: Wed, 24 May 2000 19:21:26 -0700 Hi Barry, There are several ways to network other systems to your DSL line. The simplest way is to get multiple static IP address from your ISP. This costs more but setup is the easiest. I have PacBell enhanced service that gives you 5 static IP address. The cost is $80.00 per month. In this configuration all you need is a ethernet hub. The DSL modem connects to the hub as well as your computer systems. Each system is then giver their own IP address. You do need to worry about security since all of the systems are connected to the Internet whenever the system is on. You can also buy a router / gateway / firewall / hub box that can use one IP address and allow other systems on your private network to access the Internet. As with the configuration above, the DSL modem connects to the router as well as all of your systems. One advantage with this option is better security since the router box acts as a firewall. And one other way of doing it is to use one of your computer systems to act as a router / gateway. In this configuration one computer acts as the router. There are several programs that you can buy that will do the IP routing, one is called WinGate. The problem with #2 and #3 is setup. Configuring everything so that it works properly is very difficult if you haven't done it before. I'm CC'ing the PSN, maybe others can use this info or offer other suggestions. -Larry At 07:51 PM 5/23/00 -0700, Barry wrote: >Hi Larry > I have a (mostly) non seismic question. I was considering getting a >DSL service but the phone company says it's designed for a single line >to one computer. They were not helpful wrt networking. I know a >reasonable amount about electronics and computer languages and older >hardware, but what I know about connecting computers together you can >fit on a pin head. Any help with literature references I can read would >be appreciated. Also do you think or know if I could hook my and my >son's computer to the same DSL line? >Regards >Barry > > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Internet connection sharing From: ted@.......... Date: Wed, 24 May 2000 23:11:14 -0400 The answer is "you bet." I have one PC which has a cable modem connection to the internet, and I run software called SyGate ($39.95) from www.sybergen.com. This allows any computer on our home ethernet lan to share the one high-speed internet connection, which in Barry's case would be DSL. The LAN has also had lots of side benefits, like ability to share printers, copy files quickly and (soon) let me view newly captured quake files on the basement PC from my office. I tried WinGate for several weeks, and never had any luck. SyGate installed cleanly and intuitively and worked the first time. Their web-based help site is great with actual screen shots of how you should set up the network panels in each machine. I highly recommend it. 30 day free trial as well. Machine with DSL connection is installed as "server", all the rest are installed as "client". The main secret to getting this stuff working is knowing about one web site - www.timhiggins.com. One trip through this site and you will be a networking guru, no kidding. :-) One critical piece of information I got here to make the intial LAN install a success is to install the NetBEUI protocol on all the lan-attached PCs, even if you are only going to use TCP/IP. (Take that Bill Gates, thought nobody would figure that out didn't ya?) The PC with the DSL connection needs *two* ethernet cards. Make sure they are different manufacturers. Why? Tim Higgins says so...but it also makes it easier to tell them apart since they have to be configured differently. The one attached to the DSL modem is typically set to "get an IP address automatically". (This is the one whose NIC address you have to give to the ISP.) The second ethernet card is attached to the home LAN hub, and is set to static IP address 192.168.0.1. All the other machines in your house are set to 192.168.0.2, 3, 4, etc. You tell the other machines to use the ..1 machine as the gateway in the SyGate client software settings on each machine. That's it, everybody now has a high-speed internet connection. Windows 98 second edition has a similar feature called ICS or Internet Connection Sharing. However I decided that I did not want to use anything designed by the same people who designed the Win 95 networking control panels. So my 40 bucks bought me a bit of tranquility, something that doesn't often go along with network debugging. Fundamental advice which I found very helpful as well: (1) get your home LAN working as a local LAN, including the DSL-attached machine (but without setting up any internet sharing support). (2) add the internet sharing support to the working LAN. You'll never get it to work if you try to do it all at once. Other solutions for networking your home computers are now common. Some use home wiring, some use mysterious "radio" waves (but who believes in that stuff though). I went with ethernet cards and 10baseT (8-wire RJ45) cables, mostly because industry uses this and it works. If you buy a hub, make sure it can support both 10 and 100 Mb/sec rates, and that plugging one 10 Mb card in doesn't slow the whole thing down (i.e. each port speed is independent of the others). Sometimes you have to open the box and read the manual to find this out. I have the NetGear DS104 Dual Speed Hub with 4 ports. Very happy with it, except I wish I'd bought one with 6 ports. I run the CAT5 cable outside the house and bring it in through holds drilled in the baseboard. I know it's not built for that but it works fine. Just buy a color that goes with your house. :-) All my phone service is done this way too, and you can get 4 phone lines in one CAT5 cable with top quality signals. Router/firewall box is a good idea too, but they are about $500. OK, time to kick the dog out of the bed. Regards, Ted IBM Global Services - Performance Management and Capacity Planning at the Washington Systems Center 238 Highland St., Portsmouth, NH 03801 Phone: 8-253-9969 Outside: (603) 433-9201 Fax: (603) 433-9190 Pager: 1-800-759-8888 PIN 1151100 Text page: http://www.skytel.com/Paging/index.html pin# 1151100 Notes: Ted Blank/Santa Teresa/IBM@IBMUS Internet: ted@.......... Larry Cochrane @.............. on 05/24/2000 10:21:26 PM Please respond to psn-l@.............. Sent by: psn-l-request@.............. To: barry lotz cc: psn-l@.............. Subject: Re: DSL Hi Barry, There are several ways to network other systems to your DSL line. The simplest way is to get multiple static IP address from your ISP. This costs more but setup is the easiest. I have PacBell enhanced service that gives you 5 static IP address. The cost is $80.00 per month. In this configuration all you need is a ethernet hub. The DSL modem connects to the hub as well as your computer systems. Each system is then giver their own IP address. You do need to worry about security since all of the systems are connected to the Internet whenever the system is on. You can also buy a router / gateway / firewall / hub box that can use one IP address and allow other systems on your private network to access the Internet. As with the configuration above, the DSL modem connects to the router as well as all of your systems. One advantage with this option is better security since the router box acts as a firewall. And one other way of doing it is to use one of your computer systems to act as a router / gateway. In this configuration one computer acts as the router. There are several programs that you can buy that will do the IP routing, one is called WinGate. The problem with #2 and #3 is setup. Configuring everything so that it works properly is very difficult if you haven't done it before. I'm CC'ing the PSN, maybe others can use this info or offer other suggestions. -Larry At 07:51 PM 5/23/00 -0700, Barry wrote: >Hi Larry > I have a (mostly) non seismic question. I was considering getting a >DSL service but the phone company says it's designed for a single line >to one computer. They were not helpful wrt networking. I know a >reasonable amount about electronics and computer languages and older >hardware, but what I know about connecting computers together you can >fit on a pin head. Any help with literature references I can read would >be appreciated. Also do you think or know if I could hook my and my >son's computer to the same DSL line? >Regards >Barry > > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: DSL From: "Eric D. Fehr" fehr@............ Date: Wed, 24 May 2000 20:32:18 -0700 Windows 98 Second Edition and up also do a simple form of #3, aka NAT (Network Address Translation, where one IP address is shared by all of the computers on your network) & DHCP (which handles the provision & distribution of the local IP addresses for your local network computers, so that you don't have to configure the IP address, gateway, etc, yourself), when "Internet Connection Sharing" is enabled. The standard configuration with it is fairly easy to set up and use, but making changes to the typical configuration (which is rarely required in the average home environment) requires changes to your registry. You could alternately have a UNIX box as your firewall, running natd. It all depends on your level of technical expertise. I would imagine that there are some good tutorials out there for "Internet Connection Sharing" with Windows, a quick consultation with your favorite search engine should help guide the way. As mentioned, there are some good products out there that will act as both a network hub and router, and the price on these is falling all the time. Last I saw was a 10Mbps hub with built in router, DHCP server, & firewall, from Linksys, for about the same price as their 100Mbps switch. I believe it was sub-$200 Canadian, which would be in the $100-150 range US. Eric At 07:21 PM 5/24/00 -0700, you wrote: >Hi Barry, > >There are several ways to network other systems to your DSL line. The >simplest way is to get multiple static IP address from your ISP. This costs >more but setup is the easiest. I have PacBell enhanced service that gives >you 5 static IP address. The cost is $80.00 per month. In this >configuration all you need is a ethernet hub. The DSL modem connects to the >hub as well as your computer systems. Each system is then giver their own >IP address. You do need to worry about security since all of the systems >are connected to the Internet whenever the system is on. > >You can also buy a router / gateway / firewall / hub box that can use one >IP address and allow other systems on your private network to access the >Internet. As with the configuration above, the DSL modem connects to the >router as well as all of your systems. One advantage with this option is >better security since the router box acts as a firewall. > >And one other way of doing it is to use one of your computer systems to act >as a router / gateway. In this configuration one computer acts as the >router. There are several programs that you can buy that will do the IP >routing, one is called WinGate. > >The problem with #2 and #3 is setup. Configuring everything so that it >works properly is very difficult if you haven't done it before. > >I'm CC'ing the PSN, maybe others can use this info or offer other suggestions. > >-Larry > >At 07:51 PM 5/23/00 -0700, Barry wrote: > >Hi Larry > > I have a (mostly) non seismic question. I was considering getting a > >DSL service but the phone company says it's designed for a single line > >to one computer. They were not helpful wrt networking. I know a > >reasonable amount about electronics and computer languages and older > >hardware, but what I know about connecting computers together you can > >fit on a pin head. Any help with literature references I can read would > >be appreciated. Also do you think or know if I could hook my and my > >son's computer to the same DSL line? > >Regards > >Barry > > > > > > >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with >the body of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: strainmeters/creepmeters From: "George Harris" gjharris@............. Date: Wed, 24 May 2000 20:38:27 -0700 > [Original Message] > From: S-T Morrissey > To: > Date: 5/20/00 7:43:15 PM > Subject: strainmeters/creepmeters > > Jim, > > The first task when considering strainmeters or tiltmeters is just > what range of strain or displacement is expected over what period of > time. > Among the best strainmeters are the 750 meter baseline laser interferometer > systems at Pinon Flat that operate in evacuated tubes and have massive > end monuments with "optical anchors" thru the decomposed granite of the > surface to virgin rock 20 meters down. They have achieved stability of > better than 10^-6 / year but at great expense and effort. > The above started me thinking about what type of an optical system might be easier. The follwing seems like it should work, and is not too difficult to try. It would use two laser pointers of the penlight size and a pair of receivers consisting of two solar cells each. The lasers woud be positioned on one side of the fault on a pier with their beams at 90 degrees to each other,and at 45 degrees with respect to the fault. On the other side of the fault would be the two receivers, one on each laser beam. The solar cells should be placed horizontally adjacent to each other so that the laser is half on each cell. The cells are connected so that the plus of one is connected to the minus of its adjacent cell. These two connections go directly to the plus and minus input of an opamp with suitable feedback resistor. When the beam is half on each cell, the output will be zero, and the sensitivity can be adjusted to microinch sensitivity by proper resistor choice and cell positioning. It must be assumed that there might be some rotary motion of the laser pier, so use of two beams would detect this and show similar signals on both beams. It would probably be necessary to put some heavy filtering in the system so that atmospheric effects due to wind or heat would be smoothed out. The system should measure both components of the motion. I'd be happy to work with someone who would wish to try this. I have one of the pointers, and all of the other components immediately available. In fact, a single laser with a beam splitter is probably even easier. I have that too. Anybody interested? --- George Harris (San Francisco area) --- gjhar __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: DSL From: macsmith macsmith@......... Date: Wed, 24 May 2000 19:56:47 -1000 Checkout http://www.zonealarm.com A superb and free software firewall. Everyone should have one who connects to the internet, even with a modem. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: DSL From: Karl Cunningham karlc@....... Date: Thu, 25 May 2000 10:40:15 -0700 Zonealarm is great (and I use it), but it doesn't work with a NAT system such as Win98SE's Internet Connection Sharing or Sygate unless you set its Internet security level to medium. But doing that doesn't protect you against incoming attacks from the Interent. On NAT systems, I use a combination of Zonealarm (to protect against trojans trying to talk out) and BlackIce (http://www.networkice.com) to protect against incoming attacks. I've done quite a bit of network setup at home and work, including DSL, hardware and software firewalls, using ICS, Sygate, and Wingate, hubs, routers, etc. I'm happy to share my experiences with anyone. Karl At 07:56 PM 5/24/2000 -1000, you wrote: >Checkout http://www.zonealarm.com A superb and free software firewall. Everyone >should have one who connects to the internet, even with a modem. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Impact detection system From: Larry Cochrane cochrane@.............. Date: Thu, 25 May 2000 20:23:45 -0700 Stephen, Sounds like an interesting project. Unfortunately I can't help you much. I would think three geophone would do the job if the sensors can pick up the impact offer the local ground noise. I'm CC'ing this message to the Public Seismic Network mailing list. Maybe someone on the list can help you. PSN'ers please send any info directly to Stephen Hertig at shertig@........... and CC the list, since he is not on this mailing list. Regards, Larry Cochrane Redwood City, PSN At 10:02 AM 5/25/00 -0500, Stephen Hertig wrote: > >Dear Mr. Cochrane > >I am researching how to calculate low-mass (like baseballs), impact surface >locations on a grass field (2D only, X & Y's) in a relatively small area (100 x >300 m) using vibration sensors or geophones and PC-based, real-time data >recording. > >The software and programming is very much in the public domain and I'm assuming >it can be worked out, but it's the general hardware parameters that have me >perplexed (out of my field) at this stage. > >I'm not sure how many geophones I'll need or what fequency response would best >be suited for these measurements. As the area is small the low-mass, hense low >energy impacts may not be a problem, but the signal to noise ratio is a concern. >However, I've got no feel if this is assumption is close to reality or >equivalent to the energy (db) distance ratios of earthquakes, but that is the >current analog I'm using to try to build a prototype system to record these xy, >impact locations. Although I suspect as all I need are s-wave, first arrivals I >may be able to detect and calculate the "epicenter" (+/- about 1/m???) from at >least 3 senors and hopefully be well above any noise. If more than 3 senors are >needed to record the events in this area (e.g., sensor has to be closer to the >impact than about 100 yds to see signal above noise) then I suspect things get >really complicated/expensive in terms of the A/D device and new modified >multi-channel (3+) software needed. > >Do you think this can be done with only 3 sensors (i.e. Channels)? > >If so what type/parameters of senors would you suggest? (i.e. geophone frequency >response, vertical or horizontal spring orientations. Is horizontal better for >just s waves?) > >If not any comments on a alternate system setup? or others to ask these >questions? > > >You can blame your great web page(s) for this request, and thank you very much >for taking time >for any consideration or comments. > >Sincerely, >Steve Hertig, geologist >shertig@.......... > > > > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Impact detection system From: The Lahrs JohnJan@........ Date: Fri, 26 May 2000 06:44:34 -0600 Stephen, Sounds like an interesting project. My first suggestion would be to join the PSN mailing list so there can be a full discussion. See: http://psn.quake.net/maillist.html to subscribe. Some needed details of your project include: purpose time available to complete rough budget limit size of field what other activity is going on in the field at the same time Cheers, John At 09:23 PM 5/25/00 , Larry Cochrane wrote: >Stephen, > >Sounds like an interesting project. Unfortunately I can't help you much. I >would think three geophone would do the job if the sensors can pick up the >impact offer the local ground noise. > >I'm CC'ing this message to the Public Seismic Network mailing list. Maybe >someone on the list can help you. > >PSN'ers please send any info directly to Stephen Hertig at >shertig@........... and CC the list, since he is not on this mailing list. > >Regards, >Larry Cochrane >Redwood City, PSN > >At 10:02 AM 5/25/00 -0500, Stephen Hertig wrote: > > > >Dear Mr. Cochrane > > > >I am researching how to calculate low-mass (like baseballs), impact surface > >locations on a grass field (2D only, X & Y's) in a relatively small area >(100 x > >300 m) using vibration sensors or geophones and PC-based, real-time data > >recording. > > > >The software and programming is very much in the public domain and I'm >assuming > >it can be worked out, but it's the general hardware parameters that have me > >perplexed (out of my field) at this stage. > > > >I'm not sure how many geophones I'll need or what fequency response would >best > >be suited for these measurements. As the area is small the low-mass, >hense low > >energy impacts may not be a problem, but the signal to noise ratio is a >concern. > >However, I've got no feel if this is assumption is close to reality or > >equivalent to the energy (db) distance ratios of earthquakes, but that > is the > >current analog I'm using to try to build a prototype system to record >these xy, > >impact locations. Although I suspect as all I need are s-wave, first >arrivals I > >may be able to detect and calculate the "epicenter" (+/- about 1/m???) >from at > >least 3 senors and hopefully be well above any noise. If more than 3 >senors are > >needed to record the events in this area (e.g., sensor has to be closer to >the > >impact than about 100 yds to see signal above noise) then I suspect things >get > >really complicated/expensive in terms of the A/D device and new modified > >multi-channel (3+) software needed. > > > >Do you think this can be done with only 3 sensors (i.e. Channels)? > > > >If so what type/parameters of senors would you suggest? (i.e. geophone >frequency > >response, vertical or horizontal spring orientations. Is horizontal better >for > >just s waves?) > > > >If not any comments on a alternate system setup? or others to ask these > >questions? > > > > > >You can blame your great web page(s) for this request, and thank you very >much > >for taking time > >for any consideration or comments. > > > >Sincerely, > >Steve Hertig, geologist > >shertig@.......... > > > > > > > > > > >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with >the body of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. John C. Lahr 1925 Foothills Road Golden, CO 80402 (303) 215-9913 http://lahr.org/john-jan/science.html __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: list your web list From: BOB BARNS roybar@........ Date: Fri, 26 May 2000 16:05:00 -0400 Hi gang, what's shakin'? The PSN mail has contianed reference to many members' personal web sites. Many of these sites contain info of interest to other members especially beginners. There is no way to get these URLs except to look thru all the old e-mail--a lot of work! I pointed this out to Larry that we need a list of these on the PSN web site. He said, "Fine, you collect the info and I will post it on the site." Rather than just a list of sites, I think that is desireable to include a brief mention of that info on the site which is of interest to the group. Here's an example (my site): ---- members.home.net/roybar contains photos and a brief description of my Lehman and photos of Nick Caporossi's first Lehman. ---- This is brief because there is not much there and I suppose that others will have quite a bit more. However, try to keep it to a reasonable size. I would like to avoid sites which do not contain seismological info. Just send your info to roybar@........ As these dribble in, I will send them along to Larry. If you abandon your web site, let me know so that dead links can be kept to a minimum. Bob Barns __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Worlds deepest rocks surface in Pacific From: John Hernlund hernlund@....... Date: Fri, 26 May 2000 14:45:30 -0700 (MST) On Sun, 21 May 2000, meredith lamb wrote: > Noted a interesting article on the web: > http://www.discovery.com/news/briefs/20000518/geology_deeprock.html The original Science paper was in the May 19 issue (Collerson et al.) at www.sciencemag.org. > >From my point of view....I can't really understand how they > could have gotten to the surface from the between the upper > and lower mantle intact, and, from the Pacific basin itself? > Meredith Lamb This is great stuff! For many years now people have been trying to defend the idea that mantle plumes, which may be responsible for many "hot spots" such as the Hawaiian islands, come from the lower mantle. Some people have even proposed the base of these plumes to be at or right above the core-mantle boundary. The evidence for this specific case is very solid, with crystals of MgSiO3 type perovskite contained in them. Perovskite is thought to be the dominant crystalline MgSiO3 phase in the lower mantle, making it probably the single most abundant material in the Earth. The other metal oxides present suggest a depth even deeper than 670 km which is where the famous discontinuity is present presumably due to the transformation of ringwoodite, clino pyroxene, majorite garnet and a few other minerals into perovskite and magnesiowustite. Only problem is that it is terribly difficult to get it up to the surface, hence its rare appearance on the surface of the Earth. The challenge is exactly as Meredith stated: how did it get up? Perhaps there are bursts of intense activity at some hot spots and the plumes eject material faster than usual. Everything rises as a deforming plastic mass until it reaches the crust and there melts form and rise to the surface as a lava. If this is the case, as this paper suggests, then there are probably no intense activities currently occurring at volcanoes because this stuff would likely be found. John Hernlund E-mail: hernlund@....... WWW: http://www.public.asu.edu/~hernlund/ ****************************************************************************** __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Re: Worlds deepest rocks surface in Pacific From: ABdikjse@....... Date: Fri, 26 May 2000 18:03:52 EDT John, I mostly lurk on psn-1 because I'm not an electronics whiz, nor geological expert (ie: nothing to add, but stuff to learn) --- I JUST read something about a Samoan volcano coming to life -- this is allegedly in (or near) the area where the mantle material was found. Maybe that is a clue as to why the emergence of this deep material at this time -- something is happening DEEP and is slowly coming to life? Just a thought. Fascinating group of people here.... Adrienne __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Re: Worlds deepest rocks surface in Pacific From: John Hernlund hernlund@....... Date: Fri, 26 May 2000 15:26:03 -0700 (MST) On Fri, 26 May 2000 ABdikjse@....... wrote: > John, I mostly lurk on psn-1 because I'm not an electronics whiz, nor > geological expert (ie: nothing to add, but stuff to learn) --- I JUST read > something about a Samoan volcano coming to life -- this is allegedly in (or > near) the area where the mantle material was found. Maybe that is a clue as > to why the emergence of this deep material at this time -- something is > happening DEEP and is slowly coming to life? Just a thought. > > Fascinating group of people here.... > Adrienne Adrienne, The deep rocks found in the region are dated at around 34 million years old. Because the tectonic plates are moving fairly fast in the Pacific, this stuff was injected when this island was far from its current location. This is where it would have been under the influence of mantle plumes. In its current location however, it is being dotted by volcanos that have a different origin. In modern times, most of the activity there is due to arc magmatism. John Hernlund E-mail: hernlund@....... WWW: http://www.public.asu.edu/~hernlund/ ****************************************************************************** __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Fw: New eruption-Kavachi volcano,Solomon Islands From: "Erich Kern" ekern@......... Date: Fri, 26 May 2000 17:14:28 -0700 Speaking of volcanoes, here's a forward of an item on the volcano mail list. Cheers, Erich Kern *************************************************** New eruption at Kavachi volcano, Solomon Islands *************************************************** From: Dan Shackelford Observations in late May 2000 by NZ geologists showed that the famous Kavachi submarine volcano in the Solomon Islands is once again erupting, with spectacular bomb ejections and possible island formation. From: http://www.gns.cri.nz/news/release/volcisland.htm NEWS RELEASE, 25 MAY 2000 NZ SCIENTISTS WATCH FIERY BIRTH OF NEW PACIFIC ISLAND Two New Zealand scientists were part of an international team who this week witnessed the dramatic birth of a new volcanic island near the Solomon Islands. The rare observation was made during an investigation of seafloor volcanic activity and associated mineral formation in the Bismark and Solomon seas north of Australia. Marine geochemist Gary Massoth and mineral geologist Cornel de Ronde, both of the Institute of Geological & Nuclear Sciences Limited (GNS), were part of an international team on the CSIRO research ship Franklin who made a comprehensive study of the island-building eruptive activity. The scientists found the shallow Kavachi seamount, which had been dormant for nine years, had started a new phase of eruptive activity. Kavachi, in the Solomon Island chain of volcanoes, is only 30km from the boundary of the Indian and Australian tectonic plates. A roughly conical feature rising from a seafloor depth of 1100m, Kavachi is about eight kilometres in diameter at its base and has produced ephemeral islands at least twice in the past century. " When we arrived at Kavachi, we found violent eruptions taking place every five minutes,’’ Mr Massoth said from Darwin today. " The eruptions were ejecting molten lava up to 70 metres above sea level, and sulphurous steam plumes rose to about 500 metres. At night we were treated to a spectacular fireworks display with the red glow of eruptions continuing." The peak of the volcano was forming a sandy ashen beach two metres below sea level with regular violent bomb-like eruptions. The ship approached to within 750 metres of the eruption centre and found that the volcano had grown substantially since it was last surveyed in 1984. The scientists were able to sample freshly formed volcanic rocks from the flanks of the erupting volcano. " This was an unprecedented opportunity and has given us valuable geological information. We also systematically sampled gases and seawater at various depths around the perimeter of the volcano – something that has not been achieved before with an erupting submarine volcano. " We detected particle and chemical plumes from the eruption at least 5 kilometres from the centre of the volcano. This has provided valuable information about the impact of active volcanoes on ocean chemistry." Mr Massoth said Kavachi differed from Brothers volcano, the largest and most active submarine volcano north east of White Island, in that Brothers was deeper and hydrothermally active while Kavachi was shallow and volcanically active. " Hot rock, or lava, predominates at Kavachi while hot water predominates at Brothers." Hydrothermal fluids were venting from Brothers volcano at about 300oC against 100oC at Kavachi. Hotter fluids react with the volcano host rocks more efficiently and are more heavily laden with dissolved minerals." Observations at Kavachi showed that lava being quickly quenched in seawater did not produce a strong chemical plume in the ocean, unlike the active volcanoes northeast of White Island which vent large volumes of hydrothermal fluids and heat into the ocean. " Kavachi has confirmed our observations that forearc volcano chains, such as the Kermadec chain north east of White Island, contribute significantly to the global inventory of heat and chemical emissions entering the oceans. " The work we have been doing in New Zealand waters is effectively re-writing the textbook on submarine volcanism." About 80 percent of the world’s volcanism occurred in the ocean and only a small proportion of all submarine volcanoes had been systematically surveyed with scientific equipment, Mr Massoth said. At another location, the scientists dredged up what they believe is a world-record size "black smoker" – a 2.7m-high chimney prised from an active volcanic vent at a depth of 1700m. Black smoker chimneys are packed with minerals – typically 1000 to 10,000 more concentrated than background levels in seawater. The chimney was expected to be rich in silver, zinc and gold, Mr Massoth said. John Callan Communications Co-ordinator Institute of Geological & Nuclear Sciences Limited Ph: 04-570-1444 (reception), 04-570-4732 (direct) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Is the Permian extinction tied to a nearby Pulsar star? From: meredith lamb mlamb1@.......... Date: Sat, 27 May 2000 10:58:33 -0700 Hi all, I suppose this is somewhat off topic, but being as the earth is a part of us, along with its history; the topic isn't too remote. Its seems that the southwest Pacific and Australia are having a "good go", what with the deep rocks, erupting volcanoe, huge undersea smokers found, and now it seems that another topic has popped up (it may have been expounded on in other media areas?). It seems that a newly discovered pulsar (August 1999), with a very slow period (~8 seconds), is only some 600 light years from earth. Pulsars originally explode (like the Crab Nebula did), and then form and age. This particular pulsar formed some 280 million years ago. Trouble is....the Permian extinction occurred roughly in the same time frame of 286-248 million years ago. According to what I've vaguely read, such a nearby explosion would surely have been devastating to life on earth then. See on the web about the pulsar at: http://www.csiro.au/page.asp?type=mediaRelease&id=UndeadStarTorpedoes The above web site also has storys on the volcanoe and big black smokers, explored by the ship the Franklin. Other web sites, to only crudely tie in this thought are at: http://members.tripod.com/pulsarz/chanlimit.htm http://hannover.park.org/Canada/Museum/extinction/permass.html Appreciate any notes or references from anyone in the know on this topic, if available. I haven't seen any tie in to the Permian extinction and this specific pulsar? Take care, Meredith Lamb __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Worlds deepest rocks surface in Pacific From: meredith lamb mlamb1@.......... Date: Sat, 27 May 2000 11:44:56 -0700 John Hernlund wrote: > This is great stuff! For many years now people have been trying to defend the > idea that mantle plumes, which may be responsible for many "hot spots" such as > the Hawaiian islands, come from the lower mantle. Some people have even > proposed the base of these plumes to be at or right above the core-mantle > boundary. The evidence for this specific case is very solid, with crystals of > MgSiO3 type perovskite contained in them. Perovskite is thought to be the > dominant crystalline MgSiO3 phase in the lower mantle, making it probably the > single most abundant material in the Earth. The other metal oxides > present suggest a depth even deeper than 670 km which is where the famous > discontinuity is present presumably due to the transformation of > ringwoodite, clino pyroxene, majorite garnet and a few other minerals into > perovskite and magnesiowustite. Only problem is that it is terribly difficult > to get it up to the surface, hence its rare appearance on the surface of the > Earth. > John, Think you're absolutely right on with the rising plume answer. Theres really no other way it could have made this mass transition otherwise. Speculate it must have been a extra large plume to have made the trip up, without the interaction of other lava mixing it up into less recognizable components chemically and its resulting minerology composition. Time and erosion likely presented it in its present state. The article also mentioned possible diamond mining possiblities. What struck me was the size of the garnet crystal mentioned. Thanks, Meredith Lamb __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Is the Permian extinction tied to a nearby Pulsar star? From: "Tom Schmitt" tschmitt@.............. Date: Sat, 27 May 2000 15:47:05 -0400 Question At one or more of the mass extinctions Iridium spikes are found in the sediments. I think it was Walter Alverez who first found this but I can not remeber where it was. I think in one of the limestones in Italy, well anyway. If there is a large Iridium spike associated with the Permian mass extection (which I think there is) then it would suggest the comet hypotheseis. Yes a pulsar produces alot of energy but with 1/(r^2) r being 600x365x1440x60x300000 km, there is lot of attenuation. Interesting idea I will look at the web sites. Back in the late 70's Karl Felessa looked at the fossil record in terms of plate tectonics and showed that many major faunal changes correlated with tectonics. Tom Schmitt tschmitt@.............. ----- Original Message ----- From: meredith lamb To: Sent: Saturday, May 27, 2000 1:58 PM Subject: Is the Permian extinction tied to a nearby Pulsar star? > Hi all, > > I suppose this is somewhat off topic, but being as the earth is > a part of us, along with its history; the topic isn't too remote. > > Its seems that the southwest Pacific and Australia are having > a "good go", what with the deep rocks, erupting volcanoe, huge > undersea smokers found, and now it seems that another topic has > popped up (it may have been expounded on in other media areas?). > > It seems that a newly discovered pulsar (August 1999), with a > very slow period (~8 seconds), is only some 600 light years from > earth. Pulsars originally explode (like the Crab Nebula did), and > then form and age. This particular pulsar formed some 280 > million years ago. Trouble is....the Permian extinction occurred > roughly in the same time frame of 286-248 million years ago. > According to what I've vaguely read, such a nearby explosion > would surely have been devastating to life on earth then. > > See on the web about the pulsar at: > > http://www.csiro.au/page.asp?type=mediaRelease&id=UndeadStarTorpedoes > > The above web site also has storys on the volcanoe and big > black smokers, explored by the ship the Franklin. > > Other web sites, to only crudely tie in this thought are at: > > http://members.tripod.com/pulsarz/chanlimit.htm > http://hannover.park.org/Canada/Museum/extinction/permass.html > > Appreciate any notes or references from anyone in the know on > this topic, if available. I haven't seen any tie in to the Permian > extinction and this specific pulsar? > > Take care, > > Meredith Lamb > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: amplifier noise and filter design From: S-T Morrissey sean@........... Date: Sat, 27 May 2000 14:56:04 -0500 (CDT) Recently I have been asked to look at a few designs of seismic amplifiers and filters used by PSN members. Two points that I have not previously noticed are worth considering. re: not amplifying all the noise: The first point is that even when an amplifier is not specifically being used as a low pass filter, but only for signal gain, the frequency response should still be limited to the low frequencies generally used in seismic work. There is no point amplifying all the noise, especially 60 hz noise. This may be strong enough that after a gain of 1000 it might even saturate a later amplifier stage. The solution is to always use a capacitor in parallel with the high value feedback resistor that sets the amplifier gain. For example, for a gain of 40 db or x 100, the feedback R would be 990k ohm to the inverting input, with 10k ohm to ground. If the 990k is paralleled with a 0.005 uf capacitor, the frequency response would begin to decrease by 6 db per octave at f=/2*pi*R*C or 32 hz. Otherwise it would only be limited by the gain-bandwidth figure of the amplifier. This frequency is usually selected to be well away from the response shaping multi-pole filters that are used, so it could be ignored in the circuit analysis. In the seismic amplifier I have posted, the first stage has a 0.001uf, which when in parallel with the highest gain resistor of 1.4 megohms (where less noise amplification is needed most), has a frequency of 114 hz. Only three gains are selectable for the second stage, so a capacitor is used for each, with a corner at about 25 hz. The following four-pole unity-gain filter has an effective corner at 19.5 hz. This consideration of "by passing" high value resistors should be used in variable gain stages as well as any offset adjustment arrangements (although I prefer to use the relatively low power LM308 amplifiers because they have little appreciable offset problems and produce little heat). Every effort is needed to eliminate any gain at 60 hz and above, especially where such noise will be amplified by later gain stages. If radio telemetry is used, further care in by-passing any vestige of it from the power supply rails, the input circuitry, etc, is needed. For RF suppression, low inductance ceramic capacitors should be used. Often low value (100 ohm) wire-wound (= inductive) resistors are used in series with the DC supplies at the inputs to a circuit card, which are then by-passed to common with both ceramic AND large electrolytic capacitors. Re: multi-pole filters The other observation is that simply cascading identical 2-pole filters is not the way to achieve multi-pole performance. The individual response curves don't stack up as one would expect because of interaction between the stages. In fact, different effective frequencies and/or damping are selected for each stage, depending on the total number of poles, to achieve the overall result of total attenuation and the shape of the rolloff (Buttworth, Chebyshev. Bessel, etc). "Stacking" identical filters with any appreciable gain often results in oscillation. Even multi-pole Butterworth filters have the same frequency but radically different damping (and gain) per stage. But Bessel filters are preferred in seismic amplifiers because of their uniform phase delay. For an example of the range of values, a 6-pole low pass Bessel filter will have three second-order sections with frequencies of 1.609f, 1.694f, 1.910f, and damping per section of 1.96, 1.64, 0.98, where "f" is the overall cutoff (-3db down) frequency. The "compromise" filter, also called a Thompson-Butterworth, has frequencies of 1.268f, 1.301f, 1.382f, and damping of 1.95, 1.52, 0.71. Even the flattest response Butterworth filter, where the frequencies are all 1.000f, has damping values of 1.93, 1.41, and 0.52 per section. Among the references I use, two give very workable designs and tables for multi-pole filters. The NASA publication, "An RC Active Filter Design Handbook", NASA SP-5104, 1977, gives standard designs for up to 8 poles, and uses a constant resistance algorithm for unity gain 1 khz filters that unfortunately results in very uncommon capacitor values. The designs are impedance and frequency scaled by multiplying/ dividing the R and C values. I have found that the odd capacitor values can usually be made up with two common values. The unity gain design is stable and simplifies inclusion in precision amplifier designs. The other reference is the Sams publication "Active-Filter Cookbook" by Don Lancster; Howard W. Sams & co, 1975, Indianapolis; ISBN 0-672-21168-8; Library of Congress 74-33839. He uses an algorithm that gives equal values for all the capacitors, with the frequency and damping changed by the filter and feedback resistors. The designs are also scaleable from 1 khz. Since the damping of each stage is controlled by the feedback resistance, this results in gain variability depending on the response selected and number of poles. There are excellent tables for filters of 7 different characteristics and up through sixth order (or poles) with all the resistance values, gains, and component tolerances calculated and graphs for frequency scaling the capacitor values. I prefer the NASA filters because they are all unity gain and often use a constant resistance for all the stages, which helps quantity buying of 1% values. The capacitor values are usually made up with a larger value, like 0.47, which can be purchased in quantity, and smaller parallel values, which cost much less and can be selected for value with a meter. So if your filter design involves several identical stages but doesn't realize the multi-pole performance you want, or even oscillates, you might want to look at these references. Regards, Sean-Thomas __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Is the Permian extinction tied to a nearby Pulsar star? From: meredith lamb mlamb1@.......... Date: Sat, 27 May 2000 14:49:00 -0700 Tom Schmitt wrote: > Question > > At one or more of the mass extinctions Iridium spikes are found in the > sediments. I think it was > Walter Alverez who first found this but I can not remeber where it was. I > think in one of the > limestones in Italy, well anyway. > > If there is a large Iridium spike associated with the Permian mass extection > (which I think there is) then it would suggest > the comet hypotheseis. > > Yes a pulsar produces alot of energy but with 1/(r^2) r being > 600x365x1440x60x300000 km, there is > lot of attenuation. > > Interesting idea I will look at the web sites. Back in the late 70's Karl > Felessa looked at the fossil > record in terms of plate tectonics and showed that many major faunal > changes correlated with tectonics. > > Tom Schmitt > > tschmitt@.............. > Thanks Tom, A big part of this explosion (or implosion), would be a massive amount of gamma rays radiation. I've read where (no immediate reference) this could cause alot of devastation, even for the distance. Another web site says that the plant life went on unattenuated, during this event. In a way...this doesn't make sense either, if radiation was there in massive amounts. One theory casts some speculation on climate change. Arriving much later than any radiation, would probably be a shock wave/s from such an explosion. Whether such a impact/s would do in conjunction with it is somewhat speculation. Could visualize a disruption of some geo-magnetic earth fields, for some time. To add to the complexity...its possible this shock front/s, could have disrupted the Ort cloud comets toward earth. Interesting stuff. Total arm chair/web speculation on my part. Meredith Lamb __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: amplifier noise and filter design From: ChrisAtUpw@....... Date: Mon, 29 May 2000 21:50:44 EDT In a message dated 27/05/00 20:57:35 GMT Daylight Time, sean@........... writes: > The first point is that even when an amplifier is not specifically being > used as a low pass filter, but only for signal gain, the frequency > response should still be limited to the low frequencies generally > used in seismic work. There is no point amplifying all the noise, > especially 60 Hz noise. This may be strong enough that after a > gain of 1000 it might even saturate a later amplifier stage. > This consideration of "by passing" high value resistors should be used > in variable gain stages as well as any offset adjustment arrangements > Every effort is needed to eliminate any gain at 60 Hz and above, > especially where such noise will be amplified by later gain stages. Large signals that you do not want are also liable to produce some intermodulation products / distortion / drift. Ordinary low noise OP-AMPs still produce excess noise at the low frequencies that we are interested in - called 1/f noise because the amplitude increases as the frequency decreases. The CAZ or commutating auto zero OP-AMPS (MAX422, MAX430, LTC1050, ICL7650, etc.) check and reset the zero continuously. They are still wide bandwidth devices, but the 1/f noise is greatly reduced. They do produce excess noise at the 'chopping frequency' which may be several hundred to several thousand Hz. You select the chopping frequency by your choice of device. It is particularly important for seismograph applications that the gain setting resistor should have a capacitor in parallel to give a roll off well below this frequency. Chopper amplifiers have a chopping frequency well above the roll off frequency and the total bandwidth is limited by this roll off. They are a bit more complicated to build, but may give noise levels 1/100 that of CAZ amplifiers. 0.1 to 10 Hz noise may be < 40 nV pk / pk. Two are described in AN-45 'Measurement and Control Circuit Collection' by Jim Williams, Linear Applications Handbook, Vol. II by Linear Technology Inc. http://www.linear-tech.com/ . This is an interesting collection of circuits. > Re: multi-pole filters > The other observation is that simply cascading identical 2-pole filters > is not the way to achieve multi-pole performance. The individual response > curves don't stack up as one would expect because of interaction between > the stages. This is particularly important if a correct roll off is to be achieved. Filters are normally designed to give a 3 dB reduction at the roll off frequency Fc. If you cascade 6 single stage sections, you will get 18 dB roll off at Fc. If you cascade three two pole filters you will get 9 dB roll off at Fc. Another good book is 'Electronic Filter Design' + Disk by Arthur B. Williams, McGraw Hill 1995, ISBN 0070704414, but at $90, it is definitely 'borrow from your library'. > For an example of the range of values, a 6-pole low pass Bessel filter > will have three second-order sections with frequencies of 1.609f, 1.694f, > 1.910f, and damping per section of 1.96, 1.64, 0.98, where "f" is the > overall cut-off (-3db down) frequency. Since Bessel Filters are often not even mentioned in Filter Handbooks, it would be very helpful if you could give the constants for low pass Bessel Filters up to 6th order please? I have been trying to get details through my library, so far without success. Regards, Chris Chapman __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: more filters From: S-T Morrissey sean@........... Date: Tue, 30 May 2000 02:30:15 -0500 (CDT) Barry, Chris, and Co, Good question about the availability of the NASA active RC filter book. I bought my copy of the NASA book in 1978; I have no idea about its current availability. I think it has a library of congress number: N78 18312 is stamped on the cover. Maybe someone can wade through some web sites and locate a source. They probably printed a NASA size quantity of this rather droll book, so there might be crates of them somewhere. Regarding other source info about equal-value, unity gain filters: Lancaster does show the configuration for a standard two pole, unity gain filter on page 125. Here, for the low pass design, for the first capacitor (the feedback to the center of the two Rs) the standard value is multiplied by 2/d, and the second capacitor (at the non-inverting input) is multiplied by d/2, where d is the damping. So you can use the tables for frequency and damping per desired rolloff response, but you have to calculate the Cs. The feedback to the inverting input is preferably a resistor of value 2R to minimize offsets, although a wire will do. I calculated values for a standard (1khz, 10k, 0.016uf) 4-pole Butterworth, and got C values of: for the first section: (d = 1.848): C1 = 0.173, and C2 = 0.01478; for the second section: (d = 0.765): C1 = 0.0418, and C2 = 0.00612 The NASA book gives 0.01723, 0.01470, 0.04159, and 0.006091 for the standard z = 10k, fc = 1khz Butterworth filter. This book only gives the capacitance values for Butterworth, Chebyshev (1db ripple), and Bessel filters through 8 poles, as well as alternate ripple (0.25db and 3.0db) for the Chebyshev filters.. There are no damping values. Lancaster doesn't use the standard names, but explains them on page 72; like "best delay" is the Bessel. There are 4 Chebychev or "slight dips" variations. All are described through 6 poles, but use equal Cs so the damping is controlled by the gain, which varies from 1 to less t than 3. Tables give both the frequency and damping per pole as well as listings of the actual values. The 1978 printing cost $15. Chris: I hope you find one of these books for the Bessel info. If I should try to list all the values, there are serious chances for error. Your comments about very low noise amplifiers reminded me of another point about seismic amplifiers: the first one is the most important. All the following gain amplifies the noise of the input amplifier. And unity gain multi-pole (=multi-amplifier) filters should follow all gain stages so that their cumulative noise is not amplified. So special considerations for the input amp (expense, power, etc.,) are much less important for later stages. I have found that an OP-27 is a good choice for the input for most seismometer Rs, and LM308A or similar for filters. For a micro-power amplifier, the LM4250 works well if they are screened for noise and the quietest used for the input; (ps if one solders these in, their noise often goes up by an order of magnitude). BUT these are my preferences, and I don't want to get into a major discussion about others' reading of amplifier specifications. Regards, Sean-Thomas __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Worlds deepest rocks surface in Pacific From: John Hernlund hernlund@....... Date: Tue, 30 May 2000 11:49:51 -0700 (MST) On Sat, 27 May 2000, meredith lamb wrote: > Think you're absolutely right on with the rising plume answer. Theres really > no other way it could have made this mass transition otherwise. Speculate > it must have been a extra large plume to have made the trip up, without the > interaction of other lava mixing it up into less recognizable components > chemically > and its resulting minerology composition. Time and erosion likely > presented it > in its present state. Yes, they used stream gravels which were the eroded remnants of the pipes. They also said that: "many of the macrocrysts exhibit a distinctive surficial polish that is interpreted to have been caused by abrasion during turbulent magmatic emplacement." This implies an awfully fast moving magma. > The article also mentioned possible diamond mining possiblities. What > struck me was the size of the garnet crystal mentioned. Yes, 1 cm X 0.5 cm X 0.5 cm...all the way from hundreds of kilometers beneath our feet. John Hernlund E-mail: hernlund@....... WWW: http://www.public.asu.edu/~hernlund/ ****************************************************************************** __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: A Diamagnetic horizontal seismometer From: meredith lamb mlamb1@.......... Date: Tue, 30 May 2000 14:49:55 -0700 Hi all, I finally constructed a horizontal diamagnetic seismometer with eddy current damping. It uses a levitated magnet mass, with attached plastic spacers on each end. On one end is a attached Radio Shack "pill" neodymium magnet; which is centered over a Hall sensor for output. Its been fun messing with, but I wouldn't recommend this approach....other than pure experimental tinkering. Realistically, one could roughly classify it as a Shackleford/Gunderson type seismometer/pendulum, as the levitated mass simply hangs with reference to the overhead ferrite magnets and other forces. For the moment there is no magnetic shielding, nor any temperature maintenance circuitry, and it only is inclosed in my normal "vault". The Hall circuit is the same as used with other S/G horizontal seismometers, less the 10K output attenuation resister, on the same web page, and for the moment, it maybe capable of 30 second response. See: http://www.geocities.com/meredithlamb/index.html and go to the "A Diamagnetic seismometer experiment", (it can take afew minutes to load, and/or the "Diamagnetic comparison graphs to other sensors" boxes, which for the moment only contain acouple nearby quake records. The graphs are GIF images from Larry's Winquake program. The results mostly show more response to LQ or LR seismic disturbances. Naturally it shows the larger bus and motor vehicle magnetic influences. It doesn't seem to show the same short period responses as the other comparison seismometers...but on the other hand, some of the 5-10 second phases remain perplexing as too reason/source. Credits for this experiment go to, Robert Lamb, John Lahr, Dann Bartmann, Charles Patton and Martin Simon, for their information and material assistance efforts. Thanks guys! Thanks, Meredith Lamb __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: more filters From: Karl Cunningham karlc@....... Date: Tue, 30 May 2000 14:14:28 -0700 Hi All -- Here is some info on active filters, especially Bessel: Bessel filters are preferred for seismic and other data-gathering work where the signals come in at various frequencies and where time correlation of the data is important. Bessel filters have linear-phase response, which means the phase shift varies approximately linearly with frequency. Since phase shift through the filter varies linearly with frequency, phase delay and group delay are constant. Other filter types don't maintain this time correlation and can distort the waveform since the various frequency components get delayed by differing amounts. This is bad for something like seismic waveforms where the shape of the waveform is of major importance. A note about cutoff frequency... Two ways to define cutoff frequency are in common use: The -3db point, and the intersection of asymptotes. The former is really the point where the amplitude attenuation through the filter is the square root of two, and the latter is the intersection of the tangents to the response curve at zero freqeuncy and infinite frequency. As I remember, these two are the same for Butterworth filters, but differ for other types. Try the filter mathematically before buying parts. Over the years I have saved various articles on filters from electronic journals. The following are some pertinent to the topic, in no particular order: 1. Kincaid, Russel, "RC Filter Design by the Numbers" The Electronic Engineer Oct 1968. p57-63 2. Al-Nasser, Farouk "Tables Speed Design of Low-Pass Active Filters" EDN Magazine, March 15, 1971. p23-32 3. Al-Nasser, Farouk "Tables Shorten Design Time for Active Filters" Electronics Magazine October 23, 1972 p113-118 4. Shepard, Robert R., "Active Filters: part 12 Short Cuts to Network Design" Electronics Magazine August 18, 1969 p82-91 5. Warren, George H., "Computer-aided-design Program Supplies Low-pass-filter Data" EDN Magazine August 20, 1980. p148-150 6. Keith, Timothy, "Design Active Low-Pass Filters" Electronic Design Magazine September 1, 1977 p144-145 7. Geffe, Philip R. "How to Build High-quality Filters out of Low-Quality Parts" Electronics Magazine November 11, 1976 p111- For notch filters: 8. Darilek, Glenn and Tranbarger, Oren "Try a Wien-Bridge Network Instead of a Twin-T..." Electronic Design Magazine February 1, 1978. p80-81 In addition, there is a good chart comparing the characteristics of Butterworth, Transitional Butterworth-Thompson, and Bessel filters in Electronic Design Magazine April 12, 1967 p81. I don't have the article reference. Reference 4 is probably the best for cookbook-type Bessel filter construction. References 2 is also good, but the capacitor values in the tables contain some errors. When designing a filter, it's best to check the response mathematically if you can before you build the filter. These articles are written around filters built using second- and third-order stages, cascaded if necessary for higher-order filters. Each stage uses a unity-gain amplifier (Shown as a box below) to isolate the filter output from its load and from the feedback component. The unity-gain amplifier is usually an op-amp with its output connected to its inverting input. The reference designators for the capacitors differ in the various articles, so be sure you understand what the author means. The second-order stage is this: C1 +-------------------||--------+ | | | +------+ | R1 | R2 | Amp | | Input O---\/\/\/\--+--\/\/\/\--+----| X1 |-----+------0 Output | | | --- +------+ C2 --- | | --- \ / V The third-order stage is this: C2 +-------------------||--------+ | | | +------+ | R1 R2 | R3 | Amp | | Input O---\/\/\/\---+--\/\/\/\--+--\/\/\/\--+----| X1 |-----+------0 Output | | | | --- --- +------+ C1 --- C3 --- | | | | --- --- \ / \ / V V For modeling purposes, the following are freqeuncy response equations for the second- and third-order stages above. Note that s is a complex value and must be treated as such. Once the real and imaginary components of the equations are are determined, amplitude response and phase shift are easily computed. The pitfalls I have found with modeling filters are 1) make sure references to the capacitors are the same (they are easy to get mixed up), 2) make sure of the frequency and resistor scaling, and 3) make sure frequency is multiplied by 2*pi. The frequency response of the second-order stage is given by: Eo/Ei = 1/(A*s^2 + B*s + 1) where A = R1*R2*C1*C2 B = C2*(R1 + R2) s = sqrt(-1) * 2 * pi * frequency The frequency response of the third-order stage is given by: Eo/Ei = 1/(A*s^3 + B*s^2 + C*s + 1) where A = R1*R2*R3*C1*C2*C3 B = C2*C3*R2*R3 + C2*C3*R1*R3 + C1*C3*R1*R3 + C1*C3*R1*R2 C = R3*C3 + R2*C3 + R1*C3 + R1*C1 s = sqrt(-1) * 2 * pi * frequency Now for the data: The following are tables of capacitor values in Farads for a 1Hz Bessel filter of various orders. Each filter is constructed from combinations of cascaded 2- and 3-pole sections. The values scale linearly with frequency and resistor value. To increase cutoff freqeuncy, reduce the capacitor values. To increase resistor values, reduce capacitor values. First order filters are trivial ones. These are single R-C's. C1 = 0.1591 2nd Order C1 = 0.1442 C2 = 0.1082 3rd Order C1 = 0.1572 C2 = 0.2264 C3 = 0.0403 4th Order C1 = 0.1169 C2 = 0.1073 C1 = 0.1610 C2 = 0.0620 5th Order C1 = 0.1656 C2 = 0.0493 C1 = 0.1386 C2 = 0.1605 C3 = 0.0492 6th Order C1 = 0.1010 C2 = 0.0970 C1 = 0.1149 C2 = 0.0769 C1 = 0.1707 C2 = 0.0407 7th Order C1 = 0.1153 C2 = 0.0660 C1 = 0.1747 C2 = 0.0344 C1 = 0.1240 C2 = 0.1357 C3 = 0.0481 8th Order C1 = 0.0902 C2 = 0.0881 C1 = 0.0969 C2 = 0.0773 C1 = 0.1154 C2 = 0.0571 C1 = 0.1776 C2 = 0.0295 9th Order C1 = 0.0962 C2 = 0.0692 C1 = 0.1162 C2 = 0.0502 C1 = 0.1809 C2 = 0.0259 C1 = 0.1125 C2 = 0.1203 C3 = 0.0453 10th Order C1 = 0.0823 C2 = 0.0810 C1 = 0.0861 C2 = 0.0745 C1 = 0.0954 C2 = 0.0620 C1 = 0.1165 C2 = 0.0444 C1 = 0.1831 C2 = 0.0228 -- Karl __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Web-based seismic monitoring of volcanoes (fwd) From: John Hernlund hernlund@....... Date: Tue, 30 May 2000 17:24:56 -0700 (MST) ---------- Forwarded message ---------- Date: Thu, 25 May 2000 09:11:08 +0001 From: Lisa Koenig Reply-To: VOLCANO To: VOLCANO@....... Subject: Web-based seismic monitoring of volcanoes Please respond to Glenn Thompson (glenn@............ directly; do not reply to the volcano list. ****************************************** Web-based seismic monitoring of volcanoes - request for information ****************************************** From: Glenn Thompson With a single PC workstation it is now possible to compute plots (e.g. spectrograms) of continuous seismic data for dozens of stations and display these on the World-Wide Web within minutes. Web-based seismic monitoring of volcanoes offers several advantages, perhaps the main one being that a person on beeper duty can respond to an alarm without having to leave home in the middle of the night. It also makes it easy to share data with other scientists and schools. I spent the last two years developing a Web-based system to monitor the seismicity at Alaskan volcanoes. I am curious to learn what other systems exist out there. I would be very grateful if the creators of such systems would get in touch with me and give me a short (a paragraph would be fine) description of your system (would be helpful if you included URL and related publications if any). I would also be happy to hear from anyone who is currently developing (or thinking about developing) such a system, or anyone's views on the future of Web-based monitoring of volcanoes (including web-cams, satellite data etc.). Many thanks, Glenn Thompson (glenn@............ Seismologist Montserrat Volcano Observatory ------------------------------------------------------------------- __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Mail Server - Many thanks.... From: Larry Cochrane cochrane@.............. Date: Tue, 30 May 2000 21:23:31 -0700 All, I would like to thank the following people who sent in money to help pay for the new mail server. They are: Ted Blank Steve Hammond Erich Kern John Lahr Bob Laney Michael Ziebell James O'Donnell So far I received $258.00. Many thanks guys! Regards, Larry Cochrane Redwood City, PSN __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Web Ring From: Larry Cochrane cochrane@.............. Date: Wed, 31 May 2000 17:13:25 -0700 Hi Wayne, The problem is I don't like these "free" services. They need to make money some how and that means advertising on their web site or selling info about their users too others. I already get enough spam email....I don't know if WebRing does this or not but I don't want to take a chance. It seem to me that if we had a page like Bob Barns was suggesting we could all place links to it and the need for something like WebRing goes away. -Larry At 09:31 PM 5/28/00 -0400, you wrote: >Hello Larry >You may have seen my message to the list concerning the PSN Web Ring. >The purpose of this ring is to bring all PSN resources together and >provide an avenue for getting each other's website more exposure to both >the general public and professionals. > >How does it work? Each member's web page has some special html code >which links users to the ring and to each other's website. Presently >there are two sites listed on the ring. Visit it at >http://nav.webring.org/cgi-bin/navcgi?ring=psn;list to see how it works. >I would be very happy if you can join the ring. You are invited to do so >at http://www.freeyellow.com/members6/dominicapsn/joinring.html .Your >html code for inclusion at the bottom of your webpage will be >automatically emailed to you. > >Do take care and all the best, > >Wayne > >-- >Wayne Abraham >1430 Rodney Street >Portsmouth, Dominica > >abrahamw@........ >http://www.freeyellow.com/members6/dominicapsn/ > > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: more filters From: ACole65464@....... Date: Wed, 31 May 2000 21:41:05 EDT To all, To add some more to the discussion, I would like to point out a couple of good on-line filter design tools. FilterPro: An old DOS program that is very helpfull for low pass filter design. It is down-loadable from Burr-Brown at: www.burr-brown.com/applications/ Application Bulletin #34 gives the instructions as to how to use it (make plots and component selection etc). FilterCAD: Available as a free CD from Analog Devices. CD also contains all of their Apllications bulletins, a very good resource in itself. Does plots etc, but a little light with help for the amateur hacker. Hope these will be a help to someone. Allan Coleman __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Mail Server - Many thanks.... From: Danie Overbeek danieo@............ Date: Thu, 01 Jun 2000 19:05:57 +0000 Very public spirited of you Larry. I hope you will forgive some of us in other parts of the world where the US$ is prohibitively expensive, when we do not contribute Cheers Danie Overbeek. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Mail Server - Many thanks.... From: Larry Cochrane cochrane@.............. Date: Thu, 01 Jun 2000 11:33:23 -0700 No problem Danie... -Larry At 07:05 PM 6/1/00 +0000, you wrote: >Very public spirited of you Larry. >I hope you will forgive some of us in other parts >of the world where the US$ is prohibitively expensive, >when we do not contribute >Cheers >Danie Overbeek. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: NASA technology used to reveal hidden faults From: meredith lamb mlamb1@.......... Date: Fri, 02 Jun 2000 21:20:46 -0700 Go too: ftp://pao.gsfc.nasa.gov/pub/PAO/Releases/2000/00-55.htm For the moment most of this is concentrated around the state of Washington. Meredith Lamb __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: present big quake From: meredith lamb mlamb1@.......... Date: Sun, 04 Jun 2000 11:34:26 -0700 Have watched this quake for some 40 minutes. Could be in the asian part of the world. Very long period waves now. Possible Tsunami? Meredith Lamb __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: present big quake From: Canie canie@........... Date: Sun, 04 Jun 2000 10:38:09 -0700 At 11:34 AM 6/4/00 -0700, meredith lamb wrote: >Have watched this quake for some 40 minutes. Could be >in the asian part of the world. Very long period waves now. >Possible Tsunami? > >Meredith Lamb Looks like a big one - TSUNAMI BULLETIN NUMBER 1 WEST COAST AND ALASKA TSUNAMI WARNING CENTER/NOAA/NWS ISSUED JUN 4 AT 1711 UTC ....THIS IS A TSUNAMI INFORMATION BULLETIN FOR ALASKA, BRITISH COLUMBIA, WASHINGTON, OREGON, AND CALIFORNIA ONLY... NO, REPEAT NO, WATCH OR WARNING IS IN EFFECT. AN EARTHQUAKE, PRELIMINARY MAGNITUDE 7.4, OCCURRED AT 0829 ADT ON JUN 4, OR 0929 PDT ON JUN 4, OR 1629 UTC ON JUN 4. THE EARTHQUAKE WAS LOCATED IN THE GENERAL AREA OF: SOUTHERN SUMATERA, INDONESIA NEAR 4.0S, 102.7E. THE PACIFIC TSUNAMI WARNING CENTER WILL ISSUE A TSUNAMI INFORMATION BULLETIN FOR HAWAII AND OTHER AREAS OF THE PACIFIC. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: present big quake From: Karl Cunningham karlc@....... Date: Sun, 04 Jun 2000 10:46:56 -0700 Meredeth -- Red Puma lists it as: 04Jun2000 16:28:13.4 9.9S 99.5E 33 mb=7.7 A*NOR SOUTHWEST OF SUMATERA, IND Karl At 11:34 6/4/2000 -0700, you wrote: >Have watched this quake for some 40 minutes. Could be >in the asian part of the world. Very long period waves now. >Possible Tsunami? > >Meredith Lamb __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: present big quake From: meredith lamb mlamb1@.......... Date: Sun, 04 Jun 2000 12:05:16 -0700 Canie wrote: > > > Looks like a big one - > > TSUNAMI BULLETIN NUMBER 1 > WEST COAST AND ALASKA TSUNAMI WARNING CENTER/NOAA/NWS > ISSUED JUN 4 AT 1711 UTC > > ...THIS IS A TSUNAMI INFORMATION BULLETIN FOR ALASKA, BRITISH > COLUMBIA, WASHINGTON, OREGON, AND CALIFORNIA ONLY... > > NO, REPEAT NO, WATCH OR WARNING IS IN EFFECT. > > AN EARTHQUAKE, PRELIMINARY MAGNITUDE 7.4, OCCURRED AT > 0829 ADT ON JUN 4, OR 0929 PDT ON JUN 4, OR 1629 UTC ON JUN 4. > THE EARTHQUAKE WAS LOCATED IN THE GENERAL AREA OF: > SOUTHERN SUMATERA, INDONESIA NEAR 4.0S, 102.7E. > > THE PACIFIC TSUNAMI WARNING CENTER WILL ISSUE A TSUNAMI > INFORMATION BULLETIN FOR HAWAII AND OTHER AREAS OF THE PACIFIC. > Canie and Karl, It almost looks like a "big hole" for tsunami's early warning in that region. NEIC only seems to cover the general Pacific area. The Russian center seems to have little or no update for the area either. I'd imagine some damage has already occurred, but its in a "no man's land" area. Unfortunately for the people in the area, about all they can do is seek higher ground....if....they felt the quake? Meredith Lamb __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Geomagnetism and its instruments From: meredith lamb mlamb1@.......... Date: Mon, 05 Jun 2000 16:16:00 -0700 Hi all, Bob Lamb let me know of this web site today, so I'll pass it on. http://www.XTRsystems.com/magnetometer/cgi/lister.pl It seems the site also shows other references. The Scientific American web sites do deliver some of the more recent (but no older articles; i.e. ~ 1996 and forward). The latest Amateur Scientist article is from March 2000. See: http://www.sciam.com/2000/0300issue/0300amsci.html For myself, part of this could be enlightening as mention is made of geomagnetic micropulsations "trains" on Roger Bakers web site. I've noticed some unusally rhythmic sine wave trains of the 4 to 10 second periods on my diamagnetic seismometer occurring sporadically, usually for some short period of time; but which do not show on my other normal seismometers. See: http://www.eden.com/~rcbaker/magnetometer.htm Meredith Lamb __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: SDR Question From: "Rex Klopfenstein, Jr." rklopfen@......... Date: Mon, 05 Jun 2000 19:12:31 -0400 Larry or anybody else-- I have just re-installed Win95 and SDR Rv2.7 (had a hard drive crash!). I am now running OK except I seem to experiencing a pause about every 30 seconds for about 7-9 seconds. After the 7-9 second pause, the graph 'catches up' along with the time readout. I don't remember this behavior before! I am running a 486/66 using your instructions to invoke DOS. I am sampling at 25/s. I am connected to my server via a network card. Actually my SDR computer is connected to the server via dedicated network card. I ran this setup prior to the disk crash. Any ideas!!! -- Rex Klopfenstein, Jr. Bowling Green, OH rklopfen@......... http://www.wcnet.org/~rklopfen __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: SDR Question From: Karl Cunningham karlc@....... Date: Mon, 05 Jun 2000 16:32:55 -0700 A couple of thoughts: I don't know how much changed during the reconfiguration, but it sounds like you may have a driver loaded in the computer that shouldn't be there. Check to see if there is anything in your config.sys or autoexec.bat files that wasn't there before. Sometimes, in the process loading software, drivers get inserted in these files without your knowledge. Also, make sure the network is operating properly. And try disabling network support. If the network isn't responding, there may be a delay until something times out. Karl At 07:12 PM 6/5/2000 -0400, you wrote: >Larry or anybody else-- > >I have just re-installed Win95 and SDR Rv2.7 (had a hard drive crash!). >I am now running OK except I seem to experiencing a pause about every 30 >seconds for about 7-9 seconds. After the 7-9 second pause, the graph >'catches up' along with the time readout. I don't remember this >behavior before! > >I am running a 486/66 using your instructions to invoke DOS. I am >sampling at 25/s. I am connected to my server via a network card. >Actually my SDR computer is connected to the server via dedicated >network card. I ran this setup prior to the disk crash. > >Any ideas!!! >-- >Rex Klopfenstein, Jr. >Bowling Green, OH >rklopfen@......... >http://www.wcnet.org/~rklopfen > > >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with >the body of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Geomagnetism and its instruments From: GeE777@....... Date: Tue, 6 Jun 2000 12:28:03 EDT I wasin a hurry at my mail and deleted somthing that said some funds are needed for a web site?? I'll help if you let me know again. Merideth Lamb. George Erich __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Voluntary Contributions From: meredith lamb mlamb1@.......... Date: Tue, 06 Jun 2000 10:51:40 -0700 GeE777@....... wrote: > I wasin a hurry at my mail and deleted somthing that said some funds are > needed for a web site?? I'll help if you let me know again. Merideth Lamb. > > George Erich Hi George, Apparently the email was not meant for the PSN email system. But it brings up a point of any voluntary contributions. Thats mighty generious of you to offer...but, the only current voluntary contributions that would be appreciated for, but not personally sought for, that I know of for the moment, are for: 1. Larry Cochrane 24 Garden St. Redwood City, CA. 94063 This is for a new email server, which we are all reaping the benefits for. He has made other contributions to others of equipment over time, that also came out of his pocket. Indeed the web site (and email server) is "our" main communication system. 2. Sean-Thomas Morrissey Saint Louis University Department of Earth and Atmospheric Sciences 3507 Laclede Ave. St. Louis, MO 63103 Sean-Thomas has extensively personally paid for materials in relation to the development of the STM-8 VBB seismometer. He has also became our main teacher and educator in regard to instrumention subjects, and has spent alot of time with all manner of email subjects and guidance. This is not to slight the contributions of time, money and effort by a large number of others over time, both past and present, for a variety of equipment to/for whomever, and a big variety of other items. Actually; its been a pnenomonal group I think. Take care all, Meredith Lamb __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Electrical Diagrams for the Lehman From: "John Finke" FINKEJE@............ Date: Tue, 06 Jun 2000 13:19:55 -0500 All, I would like to know if anyone has available schematic diagrams for the = Lehman seismograph construction. I understand a great deal of the = mechanics for such an instrument however my knowledge of electrical = systems and components is limited to the benefits of light switches and = the like! I have CAD capabilities (microstation or AutoCAD) so if electronic files = are available I would appreciate it if they could be forwarded. If hard = copies are available I will send a SASE and gladly pay for any reproduction= cost.=20 Thank you. Regards, John Finke, P.E., S.E. finkeje@............ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Electronic Drawings for Lehman From: "John Finke" FINKEJE@............ Date: Tue, 06 Jun 2000 13:23:31 -0500 All, I would like to know if anyone has available schematic diagrams for the = Lehman seismograph construction. I understand a great deal of the = mechanics for such an instrument however my knowledge of electrical = systems and components is limited to the benefits of light switches and = the like! I have CAD capabilities (microstation or AutoCAD) so if electronic files = are available I would appreciate it if they could be forwarded. If hard = copies are available I will send a SASE and gladly pay for any reproduction= cost.=20 Thank you. Regards, John Finke, P.E., S.E. finkeje@............ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Electronic Drawings for Lehman From: meredith lamb mlamb1@.......... Date: Tue, 06 Jun 2000 11:41:13 -0700 John Finke wrote: > All, > > I would like to know if anyone has available schematic diagrams for the Lehman seismograph construction. I understand a grea t deal of the mechanics for such an instrument however my knowledge of electrical systems and components is limited to the bene fits of light switches and the like! > > I have CAD capabilities (microstation or AutoCAD) so if electronic files are available I would appreciate it if they could be forwarded. If hard copies are available I will send a SASE and gladly pay for any reproduction cost. > > Thank you. > > Regards, > John Finke, P.E., S.E. > finkeje@............ > Hi John, A number of "Lehman" seismometer related articles and drawings is already available on the PSN web site, you can download and review. See: http://psn.quake.net/infoequip.html "Often", individually one has to adapt whatever material they "can" obtain or convert for use in relation to this type of instrument. There is other approaches that seem to be better (or more complicated), but they may yield better results. Personally, I'd suggest a more simplified version of the Shackleford-Gunderson horizontal seismometer as a better approach for a "first seismometer", and then if you're up to it; perhaps trying the more complicated versons later. Of course, this is only a suggestion. Meredith Lamb __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Electronic Drawings for Lehman From: Larry Cochrane cochrane@.............. Date: Tue, 06 Jun 2000 12:21:00 -0700 John, The electronics need for a Lehman is pretty straight forward. After the pickup coil, I use a 220 volt AC relay coil, you will need an amplifier, maybe a low-pass filter and some way too display the information. This can be a chart recorder or a computer with an A/D card and software. If you use a chart recorder the low-pass filter probably isn't needed. If you use a computer and A/D card you should have a low-pass filter between the Amp and the A/D card. For a schematic of an Amp / Filter board see http://www.seismicnet.com/eqampd.gif. If you don't want to make your own, check out http://www.seismicnet.com/eqamp.html. I also have an A/D card and software if you want to go that route. See http://www.seismicnet.com/atod.html for more info. Regards, Larry Cochrane Redwood City, PSN At 01:23 PM 6/6/00 -0500, you wrote: >All, > >I would like to know if anyone has available schematic diagrams for the Lehman seismograph construction. I understand a great deal of the mechanics for such an instrument however my knowledge of electrical systems and components is limited to the benefits of light switches and the like! > >I have CAD capabilities (microstation or AutoCAD) so if electronic files are available I would appreciate it if they could be forwarded. If hard copies are available I will send a SASE and gladly pay for any reproduction cost. > >Thank you. > >Regards, >John Finke, P.E., S.E. >finkeje@............ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Newbie questions... From: "Steve Olney" ollaneg@........... Date: Wed, 7 Jun 2000 06:12:54 +1000 G'day All, While hunting around for something else (can't remember what it was now) a couple of days ago, I found the PSN websites etc. I am interested in experimenting with a home-made seismograph and found the information available to be very useful. However, I have a few questions:- 1. All the seismograms I have seen on the sites show the P wave as being smaller than the S wave. As I understand it the P wave is longitudinal and the S wave is traverse, i.e. they are orthogonal. Question: Wouldn't the relative amplitudes then depend on the orientation of a horizontal seismograph (i.e. a Lehman)? I think I can understand that a vertical seismograph would show the higher S wave close to an event, but the situation for a horizontal one has me puzzled. 2. I would like to try and build a vertical seismograph using some Aura shaker transducers I have. I have tested the resonance frequency and they appear to be around 40Hz. I intend to try and make a vertical force-balance type which I understand is really an accelerometer. Question: What is the relative sensitivities and relative amplitudes of events of horizontal versus vertical seismographs? What are the relative pros and cons of vertical versus horizontal seismographs? Is there any disadvantage in using accelerometer (force-balance?) types versus displacement or velocity types of seismographs? 3. If I wanted to send a contribution to the supporters of this email reflector, who, where and how could I send it from here in Australia? Best regards Steve Olney QF56IK : Lat -33 34 07, Long +150 44 40) ============================================= HomePage URLs: http://www.zeta.org.au/~ollaneg Containing:- Laser Comms DX LF Experimentation Amateur Radio Astronomy ============================================= __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Newbie questions... From: John Hernlund hernlund@....... Date: Tue, 06 Jun 2000 13:37:50 -0700 (MST) On Wed, 7 Jun 2000, Steve Olney wrote: > 1. All the seismograms I have seen on the sites show the P wave as being > smaller than the S wave. As I understand it the P wave is longitudinal and > the S wave is traverse, i.e. they are orthogonal. > > Question: Wouldn't the relative amplitudes then depend on the orientation of > a horizontal seismograph (i.e. a Lehman)? I think I can understand that a > vertical seismograph would show the higher S wave close to an event, but the > situation for a horizontal one has me puzzled. Absolutely. Same with the P waves too. I have a horizontal seismograph oriented to swing NW-SE in Tempe, AZ and last week there was a quake down near Yuma, almost directly SW of here. So the seismogram I recorded had almost no P wave, since the P component would have been moving NE-SW relative to my station, and had a large shear component which was moving NW-SE at my location. If I had a seismometer which was oriented at right angles so that it swung NE-SW then that would have picked up a good P and a weak S. With all three components of motion I could have used this information, along with the P and S arrival times, to try and estimate the exact location of the quake using only one station. Unfortunately this is not always so accurate and many stations used at once greatly improve the estimate. Steve, I'll leave the rest of your questions to other members of the group who can probably provide better answers... Good luck! John Hernlund E-mail: hernlund@....... WWW: http://www.public.asu.edu/~hernlund/ ****************************************************************************** __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: [Fwd: another twist on State initiative to support eq monitoring] From: Edward Cranswick cranswick@........ Date: Tue, 06 Jun 2000 14:43:16 -0600 Subject: Great leap forward in ground motion Date: Tue, 06 Jun 2000 10:56:45 -0600 From: Edward Cranswick To: zoback@........ Mary Lou- Your excellent presentation yesterday about new approaches to ground motion data acquisition -- particularly the idea of a 3-d accelerometer on every PC CPU chip -- contained the most innovative and pro-active notions about the ways the community can sense the Earth that I have heard in the last decade. I am interested to see where you go with this enthusiasm. -Edward -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 PO Box 25046, Federal Center cranswick@........ Denver, CO 80225-0046 USA E.M. Forster said, "Only connect". -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 PO Box 25046, Federal Center cranswick@........ Denver, CO 80225-0046 USA E.M. Forster said, "Only connect". Hi all, Thought I would pass along the following info I sent to Jim Davis (CA State Geologist) and Dick McCarthy (Exec Director, CA State Seismic Safety Commission). As most of you know, we have been working with these guys (and others) to push through a CA state bill to support earthquake studies to the tune of $15-20M/year. Part of these $$ would go to monitoring and could respresent a significant CA cost-share for ANSS (~$6M/yr). In trying to sell this bill, there has always been the question of what is the state paying for, or why does the state need to pay if the feds will do it? As explained below, I think we may have a hook that would represent clear benefit to the state and which they might be interested in funding--one could easily imagine all sorts of colateral educational benefits. What do you think? cheers, Mary Lou Hi Jim and Dick, At Assemblywoman Ellen Corbett's invitation, I spoke last Friday at a public hearing she held in Hayward on Eq Safety and Preparedness in CA schools. I was asked to speak about eq probabilities on the Hayward, but I broadened my talk to the entire Bay area with a focus on Hayward--to make the point that no place is safe and that eqs on other faults could profoundly affect the East Bay. The night before a thought occurred to me--that this would be a good group to float a proposal to. As it turned out, only Ellen Corbett came and a staffer for Assemblyman Dutra--so I did not get the attention of the full committee. The audience was primarily composed of Emergency Respnse coordinators and Risk Managers for various East Bay school districts. I wanted to let both of you know about the state "initiative" I proposed. It may sound like something competing with our current eq monitoring request, or it may be a clever way to sell monitoring $$ to the state legislature. I began by planting the idea that with dramatic increases in digital technology and telecommunications over the past 10 years, not to mention the Internet, we have an opportunity to raise a whole generation of Californians who are aware of earthquakes and earthquake hazards by harnessing the power of the web (SHakeMap, Community Internet Intensity Map, etc). I ended the talk with the following proposal with bulleted benefits (simply one transparency): CA Schools Seismic Station Initiative- a real-time, Internet-connected strong motion station in every school * Educate kids and parents about eq hazards-- I explained that the kids could take "ownership" of their station, they could use the internet to view the data recorded by their station, learn how their station contributes to making a "ShakeMap" after any felt earthquake, and learn that not all earthquakes are large and destructive, some are small and not even felt). This could create many "teachable moments" in the schools and fundamentally integrate earth science as part of the core science curriculum. * Determine sensitivity of school site to shaking-- I briefly tried to explain how scientists could use numerous small earthquakes as proxies for larger ones and learn about the sites susceptibility to shaking. This could help promote the role of geology in determining shaking levels and lead to discussions about how different rocks form. * Provide real-time notification of potential damage for parents-- I suggested that based on the recorded level of shaking at the school, an asssesment of likely damage could be made immediately and posted on the web, this way parents could logon to their schools' site and get the information. With structural engineers we could establish a red, yellow, green system for each school. Another value of such monitoring is that in many communities schools are designated as emergency sites and temporary shelters *****************NOTE: I didn't mention with this group that this would be a way to greatly densify our coverage in urban areas and would go a long way toward getting a station in every zip code--that would not have sold to this audience. It occurs to me that maybe this may be a way to sell the state on eq monitoring. A station in every school would certainly address OES' needs, it would make it clear what the state was buying and getting, and all the collateral education benefits could be really played up. For example, maybe the Cal State system schools could adopt nearby schools and have students visit the schools to educate teachers and students about their seismograph station and eqs in general. Another potential twist would be to get the local communities involved in cost-share, corporations could sponsor schools' stations, Kiwanis Club could help raise funds, etc. Seems like CDMG would be the ideal group to adminster such a program. What do you think? cheers, Mary Lou ___________________________________________________________________________ Dr. Mary Lou Zoback, Chief Scientist OFFICE: 650-329-4760 Western Region Earthquake Hazards Team FAX: 650-329-5163 U.S. Geological Survey CELL: 650-868-2332 345 Middlefield Rd. MS 977 e-mail: zoback@................... Menlo Park, CA 94025 EHZ Team Secretary: Christine Jorgensen OFFICE: 650-329-5626 ------------------------------------------------------------- Earthquake & related info on the web: http://quake.usgs.gov ------------------------------------------------------------- for access to the World Stress Map database published in 1992, see README.worldstress in: ftp://andreas.wr.usgs.gov/pub/outgoing/zoback ____________________________________________________________________________ Subject: Re: [Fwd: another twist on State initiative to support eq monitoring] From: ddiffenderfer@........ Date: Tue, 6 Jun 2000 14:02:32 -0700 The idea of a 3-d accelerometer in a PC sure sounds interesting to me. I was not privileged to hear the speech would like to here more on this subject. David W. Diffenderfer P. O. Box 427 Palo Verde, CA 92266 760-854-2140 ddiffenderfer@........ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Test of the backup mail server From: Larry Cochrane cochrane@.............. Date: Wed, 07 Jun 2000 13:58:41 -0700 All, This is a test of the PSN-L backup server. Please read my email entitled "Backup mail server for PSN-L" for more info. Please do not respond to this message, Thanks, Larry Cochrane Redwood City, PSN ------------- Public Seismic Network Mailing List (PSN-L) Backup Server To leave this list email majordomo@........... with the body of the message: unsubscribe psn-l (first line only). You will also need to email: psn-l-request@.............. with the body of the message: unsubscribe Subject: Backup mail server for PSN-L and more thanks... From: Larry Cochrane cochrane@.............. Date: Wed, 07 Jun 2000 14:29:20 -0700 All, Last week one of our members, Bruce Cartwright, contacted me about helping out with the mail server. Since he has a system on the Internet, he ask if I wanted to move the list over to his system rather then buy a new mail server for my system. Since I already purchased the server, I ask if he would be willing to run a backup for this list in case my system goes down for a long period of time do to an earthquake, long term DSL outage or other disaster. He agreed, so we now have a backup for this list. His server is located in Seattle WA so a large event around here won't hopefully effect his system. This weekend Bruce and I set up a process so that the membership file for this list is automatically transferred to his system once a day. If my system goes down we can move over to his system until my system comes back online. The address for the backup list is PSN-L@............ It should only be used if my system goes down for a day or more. If you send out a message to the PSN-L and don't get back an acknowledgment please don't immediately start using the backup list. First check to see if my system is working. If its down for more then a day then you can move over to the backup list. One way of checking to see if my system is alive is to access my web server at www.seismicnet.com. The mail and web servers are on the same system so if you can't access my system with a web browser my system is offline. Thanks Bruce for allowing us to use your mail server! I recently received a few more donations for the new mail server. I would like to thank: Bob Barns Nick Caporossi Robert Fryer Charles Patton Dick Webb Thanks everyone! Regards, Larry Cochrane Redwood City, PSN __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Voluntary Contributions From: Larry Cochrane cochrane@.............. Date: Wed, 07 Jun 2000 14:47:00 -0700 At 10:51 AM 6/6/00 -0700, meredith lamb wrote: > >GeE777@....... wrote: > >> I wasin a hurry at my mail and deleted somthing that said some funds are >> needed for a web site?? I'll help if you let me know again. Merideth Lamb. >> >> George Erich > >Hi George, > >Apparently the email was not meant for the PSN email system. Actually the donations are for the new mail server I purchased two months ago... -Larry __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Newbie questions... From: Larry Cochrane cochrane@.............. Date: Thu, 08 Jun 2000 00:26:25 -0700 Hi Steve, At 06:12 AM 6/7/00 +1000, Steve Olney wrote: >2. I would like to try and build a vertical seismograph using some Aura >shaker transducers I have. I have tested the resonance frequency and they >appear to be around 40Hz. I intend to try and make a vertical force-balance >type which I understand is really an accelerometer. Yes, I believe that is correct. > >Question: What is the relative sensitivities and relative amplitudes of >events of horizontal versus vertical seismographs? What are the relative >pros and cons of vertical versus horizontal seismographs? Is there any >disadvantage in using accelerometer (force-balance?) types versus >displacement or velocity types of seismographs? I like running horizontals, if the sensor is in an area like mine with a lot of local ground noise from car trucks etc. Since most of the energy of the noise is in the vertical direction, a horizontal sensor will not pick up as much signal from cars and trucks going by. You can see the difference by looking at my *.LCZ (vertical), *.LCN (N-S horizontal) and *.LCE (E-W) event files. A good example is a M2.6 event 26km from me that happened last month. The event files are 000530A.LCZ, 000530A.LCN and 000530A.LCE. As you can see the event is hard to see in the vertical direction. The horizontal channels show the event very clearly. The sensor used to record this event is a three channel forced-balanced accelerometer with all channels having the same sensitivity. >3. If I wanted to send a contribution to the supporters of this email >reflector, who, where and how could I send it from here in Australia? Thanks, but given the extra cost to transfer money don't worry about it. Regards, Larry Cochrane Redwood City, PSN __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Is the Permian extinction tied to a nearby Pulsar star? From: "Robert W. Avakian" ravakian@............ Date: Thu, 08 Jun 2000 22:13:14 -0500 Was on vacation so is a bit late. Lost in the media hype is a book entitled "The Great Dinosaur Extinction Controversy" by Chas. Officer and Jake Page. Copyright 1996 it takes issue with the bollide impact theory and calls on some very interesting research and observations to counter Alverez and Alverez. I however, detect some personal anamosity towards the Alverezes so maybe it needs to be read with a grain of salt? One thing, though, if the collision theroy is correct, wouldn't you like to get hold of a copy of the event records? Bob Avakian > > Hi all, > > I suppose this is somewhat off topic, but being as the earth is > a part of us, along with its history; the topic isn't too remote. > > Its seems that the southwest Pacific and Australia are having > a "good go", what with the deep rocks, erupting volcanoe, huge > undersea smokers found, and now it seems that another topic has > popped up (it may have been expounded on in other media areas?). > > It seems that a newly discovered pulsar (August 1999), with a > very slow period (~8 seconds), is only some 600 light years from > earth. Pulsars originally explode (like the Crab Nebula did), and > then form and age. This particular pulsar formed some 280 > million years ago. Trouble is....the Permian extinction occurred > roughly in the same time frame of 286-248 million years ago. > According to what I've vaguely read, such a nearby explosion > would surely have been devastating to life on earth then. > > See on the web about the pulsar at: > > http://www.csiro.au/page.asp?type=mediaRelease&id=UndeadStarTorpedoes > > The above web site also has storys on the volcanoe and big > black smokers, explored by the ship the Franklin. > > Other web sites, to only crudely tie in this thought are at: > > http://members.tripod.com/pulsarz/chanlimit.htm > http://hannover.park.org/Canada/Museum/extinction/permass.html > > Appreciate any notes or references from anyone in the know on > this topic, if available. I haven't seen any tie in to the Permian > extinction and this specific pulsar? > > Take care, > > Meredith Lamb > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Passing solar flare geomagnetic shock wave? From: meredith lamb mlamb1@.......... Date: Fri, 09 Jun 2000 12:10:18 -0700 Hi all, A speculative time period comparison to the solar flare geomagnetic disturbance "around" 09:30 on June 8, 2000 UTC, is on: http://www.geocities.com/meredithlamb/page054.html The SOHO satellite out in space, transmits passing fronts and it arrives on earth "around" a hour later. The diamagnetic horizontal seismometer here is orientated N-S, with a natural period of .9 seconds, but with a amplifier capacitiance period of some 30 seconds. The possible but speculation wave front seemed to have produced a main sine wave of 3 minutes, but with other sequence sine waves of more/less frequency. No natural or otherwise vehicle disturbance has been known to create this extended effect previously. Passing bus's are known to create a much shorter "spike", as on the far right of the 3 views shown. This instrument is unshielded and of course subject to seismic and other magnetic influence. Another geomagnetic front may pass on June 10th, but with a lesser amplitude. See Space Science News at: http://www.spaceweather.com Meredith Lamb __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Is the Permian extinction tied to a nearby Pulsar star? From: meredith lamb mlamb1@.......... Date: Fri, 09 Jun 2000 15:13:32 -0700 "Robert W. Avakian" wrote: > Was on vacation so is a bit late. Lost in the media hype is a book > entitled "The Great Dinosaur Extinction Controversy" by Chas. Officer > and Jake Page. Copyright 1996 it takes issue with the bollide impact > theory and calls on some very interesting research and observations to > counter Alverez and Alverez. I however, detect some personal anamosity > towards the Alverezes so maybe it needs to be read with a grain of salt? > > One thing, though, if the collision theroy is correct, wouldn't you like > to get hold of a copy of the event records? > > Bob Avakian Hi Bob, All this stuff is fascinating for sure. Personally I wouldn't doubt that the Cretaceous extinction of some 65 million years ago is mostly tied up with the asteroid and its earth seismic anti-pod volcanic reaction. I couldn't even hazard to guess what magnitude shock wave that could be? The permian extinction for the moment really seems rather unique, as no definitive crater exists. Seems like years ago someone was saying that a crater exists off of the southeast land mass of South America in the Atlantic, but I've no followup. Recently a small 25km crater was found off Norway, but its not believed to be sufficient. (Believe that is a BBC reference) According to another British web site: http://www.bbc.co.uk/education/darwin/exfiles/permain.htm The present guess speculate on fluctuations in sea-level, a change in salinity of the ocean, and volcanic activity; with climate change being regarded as the most important factor. I find it rather odd that the aspect of cosmic radiation is not even considered to any real degree, much of anywhere with any extinction as a prospective culprit. Of course in the professional sciences, its a career risk to present anything out of the mainstream of acceptable long term science. Meredith Lamb __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Passing solar flare geomagnetic shock wave? From: ChrisAtUpw@....... Date: Fri, 9 Jun 2000 18:52:55 EDT Dear Meredith, If you go to http://www.geo.fmi.fi/image/gif/ click on 'on line magnetograms' and then on Kiruna, you will find FFT magnetic pulsation measurements as well as X, Y, Z and total field plots. You can also get sky camera images. Samnet has the current and yesterdays' magnetograms http://samsun.york.ac.uk/samnet/rt_mgram.html There is also extensive coverage on http://www.ips.gov.au/asfc/current/geomagnetic.html#geofor and a 'tutorial' on http://plasma.newcastle.edu.au/spwg/ Regards, Chris Chapman __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Passing solar flare geomagnetic shock wave? From: meredith lamb mlamb1@.......... Date: Fri, 09 Jun 2000 22:24:59 -0700 ChrisAtUpw@....... wrote: > Dear Meredith, > > If you go to http://www.geo.fmi.fi/image/gif/ click on 'on line > magnetograms' and then on Kiruna, you will find FFT magnetic pulsation > measurements as well as X, Y, Z and total field plots. You can also get sky > camera images. > > Samnet has the current and yesterdays' magnetograms > http://samsun.york.ac.uk/samnet/rt_mgram.html > > There is also extensive coverage on > http://www.ips.gov.au/asfc/current/geomagnetic.html#geofor > and a 'tutorial' on http://plasma.newcastle.edu.au/spwg/ > > Regards, > > Chris Chapman Thanks Chris, I checked right away, and think I have to withdraw any geo-magnetic conclusions; there just isn't any realistic match comparison. Nice of you to forward the web sites to explore, and answer the question. Take care, Meredith Lamb __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: A injection well and its consequences From: meredith lamb mlamb1@.......... Date: Sat, 10 Jun 2000 00:25:11 -0700 Hi all, The Denver Post newspaper ran a article on June 8th, 2000, of a injection well to dispose of brine water 14,000 feet into the earth. Seems there has been some 1500 mostly very small associated quakes since 1991. The recent 4.3 quake has brought with it changes in operation. See: http://www.denverpost.com/news/news0608a.htm If you run into problems with the above, go to: http://www.denverpost.com/news/news.htm and add on the "0608a" to the location and hit the enter button. Mention is made of Dave Wolny at Mesa State College in Grand Junction, Colorado. Dave is often approached by the local news media there for notes in his regional area. Its a interesting article on the attempt to reduce salt in the Colorado River Basin. Not mentioned, but historically, other injection wells in Colorado, have also created quakes. Take care, Meredith Lamb __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: A injection well and its consequences From: david wolny dwolny@............. Date: Sat, 10 Jun 2000 06:47:06 -0600 (MDT) On Sat, 10 Jun 2000, meredith lamb wrote: > Hi all, > > The Denver Post newspaper ran a article on June 8th, 2000, > of a injection well to dispose of brine water 14,000 feet into > the earth. Seems there has been some 1500 mostly very > small associated quakes since 1991. The recent 4.3 quake > has brought with it changes in operation. See: snip Meredith, The interesting thing about all this was that last year there were two 3.7 earthquakes in the Paradox Valley associated with deep well injection. In an article published at that time (Grand Junction Daily Sentinel), a representative for the Bureau of Reclamation said they weren't going to get worried about the earthquakes until they went over 4.0. Well, they just went over 4.0. The project has worthy goals, the desalinization of the Dolores (ultimately the Colorado) River. The concern? Once you start the process of deep well injection, how much control do you actually have over the magnitude of the earthquakes? We have seen a steady, yet slow increase in magnitudes. This would follow the pattern established in the deep well injection project at the Rocky Mountain Arsenal, near Denver, in the 1960s. While the frequency of the earthquakes at RMA somewhat matched the frequency of pumping, the magnitude of the associated earhtquakes did not. The project, started in 1962, produced magnitudes 5.3 and 5.1 by late 1967 (see Kirkham & Rogers, Colorado Geological Survey Bulletin 43). As was the case in Denver, the tectonic stresses in the Paradox Valley existed prior to the deep well injection project. The control of those stresses may now be out of the hands of the BOR. But, perhaps not. From a seismology point of view, I have a seismic experiment in my own backyard. Can't wait to see what happens next. Dave Wolny Mesa State College Grand Junction, Colorado dwolny@............. station MSCO __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Home Made PCBs From: Karl Cunningham karlc@....... Date: Sat, 10 Jun 2000 08:54:00 -0700 For those who want to put their favorite circuits on a PCB, see http://www.clarc.org/Articles/laserpcb.html Using high-quality printer paper from an office supply superstore and ferric chloride etchant from an electronics store, a friend of mine recently made a double-sided board with traces on 0.025" centers. Karl Cunningham La Mesa, CA. PSN Station #40 karlc@....... __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Passing solar flare geomagnetic shock wave? From: CapAAVSO@....... Date: Sat, 10 Jun 2000 12:25:00 EDT In a message dated 6/10/00 12:26:39 AM Eastern Daylight Time, mlamb1@.......... writes: << Thanks Chris, I checked right away, and think I have to withdraw any geo-magnetic conclusions; there just isn't any realistic match comparison. Nice of you to forward the web sites to explore, and answer the question. Take care, Meredith Lamb >> ------------------------------------------------------------------------------ ------------- Hi Meredith, That big pulse you recorded on 8 June was REAL despite your not being able to find it on those high-latitude European magnetic station's recordings. Here's how Jim Mandaville, an amateur in Tuscan, AZ described it: "It hit my magnetometer around 1100 UTC Thursday. The positive jump was so abrupt and strong that when I saw it in the morning I thought (1) my electronics had gone berserk or (2) a prowler had come and parked his getaway car beside my house! But when I checked the USGS Tucson magnetogram, it was identical. This unusual storm remained strongly positive for several hours, then fell back into the negative region (but not strongly so), then slowly recovered through the day. I got a good recording of it all. Here's how Alex McWilliams saw it at his amateur magnetic observatory in Minnesota: "A VERY unusual spike happened at close to 1230 UTC when the pen shot up very rapidly a very large amount and then recovered to original level - all in a matter of perhaps less than a minute. I do not recall moving anything in the house at that time." So you see, Meredith, your recording was no an artifact after all. It was an accurate recording of a real event. By the way, What is a diamagnetic horizontal seismograph and why does it record magnetic storms in addition to earthquakes? Best regards, Cap __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Passing solar flare geomagnetic shock wave? From: meredith lamb mlamb1@.......... Date: Sat, 10 Jun 2000 13:33:37 -0700 CapAAVSO@....... wrote: > In a message dated 6/10/00 12:26:39 AM Eastern Daylight Time, > mlamb1@.......... writes: > > << Thanks Chris, > > I checked right away, and think I have to withdraw any > geo-magnetic conclusions; there just isn't any realistic match > comparison. Nice of you to forward the web sites to explore, > and answer the question. > > Take care, > > Meredith Lamb >> > > ------------------------------------------------------------------------------ > ------------- > Hi Meredith, > That big pulse you recorded on 8 June was REAL despite your not being > able to find it on those high-latitude European magnetic station's > recordings. Here's how Jim Mandaville, an amateur in Tuscan, AZ described > it: "It hit my magnetometer around 1100 UTC Thursday. The positive jump was > so abrupt and strong that when I saw it in the morning I thought (1) my > electronics had gone berserk or (2) a prowler had come and parked his getaway > car beside my house! But when I checked the USGS Tucson magnetogram, it was > identical. This unusual storm remained strongly > positive for several hours, then fell back into the negative region (but > not strongly so), then slowly recovered through the day. I got a good > recording of it all. > Here's how Alex McWilliams saw it at his amateur magnetic observatory in > Minnesota: "A VERY unusual spike happened at close to 1230 UTC when the pen > shot up very rapidly a very large amount and then recovered to original level > - all in a matter of perhaps less than a minute. I do not recall > moving anything in the house at that time." > So you see, Meredith, your recording was no an artifact after all. It was > an accurate recording of a real event. By the way, What is a diamagnetic > horizontal seismograph and why does it record magnetic storms in addition to > earthquakes? A diamagnetic seismometer, is for all purposes, simply a levitated neodymium magnet in a diamagnetic graphite "sandwich" (magnetically repelling), with a overhead ferrite magnet for vertical adjustment. The magnet is balanced between the overhead magnet and the earths gravity. Naturally, being a magnet its not desireable as a seismometer "mass", especially with no present magnetic shielding (yet). Any magnetic environmental variations will have an effect on it and the output. The levitated magnet acts like a (non-physically attached) hanging pendulum from the magnetic centering influence of the overhead magnet. It hasn't been too sensitive to seismic P-S waves unless the quake is larger or relatively nearby of sufficient magntitude. I'am hoping permalloy shielding will alleviate some of the magnetic influences, and allow better views of seismic variations....but I'am not to sure it will be any better. It is simply a toy at the present. > Best regards, > Cap > Hi Cap, Some more web browsing/searching seemed to have come up with a bull's eye for the diamagnetic seismometer here. A USGS geomagnetic Boulder (BOU) geomagnetic plot on their horizontal showed a big and rapid (110 nt) change at the same time (+ or - 30 seconds) as shown on my graph recording. Boulder is closest at only ~ 30 miles away. Big difference in instrumentation here of course, as the seismometer is over damped, and the magnetometer uses vastly different electronics. Interesting, as it shows a influence of geomagnetic changes; but perhaps only of the big and rapid variety of such. The USGS web site is at: http://geomag.usgs.gov/wwwplots/plots.html I think the site only shows the BOU plots for 7 days, and then is no longer available on the web. The "H", or horizontal plot is the logical comparison to the diamagnetic seismometer. Per your message above, it seems that the spike is like a storm hitting areas at different times. Here it hit at 9:10 UTC. Have to admit strongly I'am a fish out of water with this geomagnetic stuff. Thanks to Cap, Chris Chapman and Edward Cranswick of USGS, for their assistances with this topic! I've since re-done the web site "show and tell" on this geomagnetic disturbance. See: http://www.geocities.com/meredithlamb/page054.html Thanks, Meredith Lamb __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Passing solar flare geomagnetic shock wave? From: ChrisAtUpw@....... Date: Sat, 10 Jun 2000 18:27:23 EDT In a message dated 10/06/00 17:26:09 GMT Daylight Time, CapAAVSO@....... writes: > That big pulse you recorded on 8 June was REAL despite your not being > able to find it on those high-latitude European magnetic station's > recordings. The peak spikes were > 50 nT on the Oulu and Nurmijarvi Magnetograms. The outputs of the recording stations depend on latitude and time. York and Hella only show small peaks and the sun would have been more nearly overhead. Chris __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Home Made PCBs From: "Al Allworth" allworth@.............. Date: Sat, 10 Jun 2000 17:02:06 -0700 Hi Karl, There is very little advantage in making double sided boards unless you can make them through-hole plated. It is impossible to get some devices properly connected to the runs under them. What is important about your information is the resolution achieved. With good resolution you can use the process perfected by the Japanese where you use a high resolution layout on one side and wire jumpers on the other. There are board fab houses that will make double sided through-hole plated boards in lots of 10 for under $5.00 each. Some have a tooling charge but many do not charge for the setup if your boards are a standard size. You can also save by laying out several circuits on one board and cutting them apart later yourself. The places to look at are the ones who offer prototype service. One place I talked to which was a production house wanted $500.00 tooling fee and $30.00 each for a minimum of 100 boards. This was their prototype rate. Where I worked, 10 boards was a production run !!! There are some that will take your information in the form of a "Gerber File". Most of the board design software programs provide this format. You can then send it to them by modem. There is one in Kentucky (I think) that does it that way and has a 5 day delivery. The design programs (Minimum versions) go for under $200.00 Some of the more professional ones offer a FREE trial cd that has a limitted number of holes. I am somewhat out of touch since retiring but have maintained a few sources for my future use. An internet search should provide plenty of possibilities. _______________________________ Al Allworth On the Beautiful Southern Oregon Coast ________________________________ ----- Original Message ----- From: "Karl Cunningham" To: Sent: Saturday, June 10, 2000 8:54 AM Subject: Home Made PCBs > For those who want to put their favorite circuits on a PCB, see > http://www.clarc.org/Articles/laserpcb.html > > Using high-quality printer paper from an office supply superstore and > ferric chloride etchant from an electronics store, a friend of mine > recently made a double-sided board with traces on 0.025" centers. > > > Karl Cunningham > La Mesa, CA. > PSN Station #40 > karlc@....... > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Home Made PCBs From: "Charles R. Patton" charles.r.patton@........ Date: Sat, 10 Jun 2000 22:16:13 -0700 Two places for PCB fab that you might check out are: 1) FAR circuits at: http://www.cl.ais.net/farcir/ look at the ARTICLE REPRINT, ORDER INFO, PAYMENT & SHIPPING second from the bottom. $0.50/sq.in for single sided and $0.75 for double sided (non-thru hole plated) which is pretty cheap. 2) Alberta Printed Circuits (AP Circuits) at: http://www.apcircuits.com/ This name was mentioned in some discussions as having reasonably priced boards. I never used either one, but stored the information for the future. FAR circuits is particulary interesting as they have a whole catalog of boards from various projects, primarily HAM related. So it's worth a look just for that. Additionally I kept several posts from the electronics discussion groups and put them together in a 33KB ZIP file which you can download from: http://www.pe.net/~crpatton/PCINFO.ZIP There is no index or other HTML pages at that address -- so use the URL exactly as shown and you should be able to pull it down. This includes discussion on several versions of iron on Xerox techniques, information on etching solutions, and sources of PCB design software -- both freeware and limited demo versions. Regards, Charles R. Patton __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: wobbly lines From: macsmith macsmith@......... Date: Sat, 10 Jun 2000 19:43:22 -1000 I've been getting wobbly traces from my geophone since I put it outside in the ground. The period is about 40 secs, see http://macsmith.net/quakes . The first geophone I put outside was "sealed" in a plastic length of pipe. I didn't fill the pipe with anything. The pipe actually has 2 geophones in it, and they both generate wobbly lines. I put another one out, this time covered by a plastic box. It was fine for a few days, but it too is now wobbly - and is the one generating the current graphs. I'm using a 4.5 Hz geophone from last year's group buy. All the connections are sealed with self amalgamating tape. Obviously the effect is caused by moisture, but I'm wondering where it is getting in. The group buy geophones seem to be sealed in rubber. Any suggestions? __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: PSN-L: Passing solar flare geomagnetic shock wave? From: walt_williams@........ Date: Sun, 11 Jun 2000 01:40:34 -0800 Hi Merideth, Cap, and All, See the HLMS array database for June 8, 10 - 11 UT: http://www.pfrr.alaska.edu/cgi-bin/hlmsmrmap/00?262,129 The bottom line is a RIOmeter graph, "Relative Ionospheric Opacity METER". Instrument measures the Cosmic noise absorption (CNA) of the ionosphere with relation to the Solar proton flux density charging it.. for visual index: http://www.pfrr.alaska.edu/~pfrr/DATA/MR-2000.HTM and database catalog page: http://www.pfrr.alaska.edu/~pfrr/DATA/HLMS-MR.HTM The lab presents a nice 'web-tour' of the PFRR lab, a miniature JPL with local launch capability in the high latitudes, lots of interesting reading and pictures. Best Wishes, Walt Williams ================================== Organization for SETV Research (OSR) Northridge California, USA walt_williams@........ http://www.setv.org =================================== ==================================================== ------- Forwarded Message Follows ------- From: CapAAVSO@....... Date: Sat, 10 Jun 2000 12:25:00 EDT Subject: Re: Passing solar flare geomagnetic shock wave? To: psn-l@.............. Reply-to: psn-l@.............. In a message dated 6/10/00 12:26:39 AM Eastern Daylight Time, mlamb1@.......... writes: << Thanks Chris, I checked right away, and think I have to withdraw any geo-magnetic conclusions; there just isn't any realistic match comparison. Nice of you to forward the web sites to explore, and answer the question. Take care, Meredith Lamb >> ------------------------------------------------------------------------ ------ ------------- Hi Meredith, That big pulse you recorded on 8 June was REAL despite your not being able to find it on those high-latitude European magnetic station's recordings. Here's how Jim Mandaville, an amateur in Tuscan, AZ described it: "It hit my magnetometer around 1100 UTC Thursday. The positive jump was so abrupt and strong that when I saw it in the morning I thought (1) my electronics had gone berserk or (2) a prowler had come and parked his getaway car beside my house! But when I checked the USGS Tucson magnetogram, it was identical. This unusual storm remained strongly positive for several hours, then fell back into the negative region (but not strongly so), then slowly recovered through the day. I got a good recording of it all. Here's how Alex McWilliams saw it at his amateur magnetic observatory in Minnesota: "A VERY unusual spike happened at close to 1230 UTC when the pen shot up very rapidly a very large amount and then recovered to original level - all in a matter of perhaps less than a minute. I do not recall moving anything in the house at that time." So you see, Meredith, your recording was no an artifact after all. It was an accurate recording of a real event. By the way, What is a diamagnetic horizontal seismograph and why does it record magnetic storms in addition to earthquakes? Best regards, Cap __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Passing solar flare geomagnetic shock wave? From: CapAAVSO@....... Date: Sun, 11 Jun 2000 10:50:19 EDT In a message dated 6/10/00 3:39:21 PM Eastern Daylight Time, mlamb1@.......... writes: << The levitated magnet acts like a (non-physically attached) hanging pendulum from the magnetic centering influence of the overhead magnet. >> ------------------------------------------------------------------------------ ------------- Hi Meredith, Thanks for the explanation of how your diamagnetic horizontal seismograph works and for updating your website with the solar wind-speed recording. The sudden jump in wind speed and the big spike on the Boulder magnetogram both coincide with the big spike on your seismogram. Your seismograph is a pretty good magnetometer with sensitivity comparable to the Geological Survey flux gate magnetometer in Boulder provided the change in the Earth's magnetic field is SUDDEN. This is confirmed by the signature of the bus passing by. It is a big hunk of iron that swings the magnetically levitated pendulum putting a big spike on the trace but quickly returns to its normal position due to damping I assume you provided for it as a seismograph. How far is this pendulum from the street where the bus passes by? I see what looks like many small spikes, mostly pointing downward, that are probably cars passing by. You could check this by watching out the window to see if a big van puts a spike on your trace. Have fun, Cap __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: A injection well and its consequences From: meredith lamb mlamb1@.......... Date: Sun, 11 Jun 2000 10:34:16 -0700 david wolny wrote: > >From a seismology point of view, I have a seismic experiment in my own > backyard. Can't wait to see what happens next. > > Dave Wolny > Mesa State College > Grand Junction, Colorado > dwolny@............. > station MSCO > Hi David, OK, you've aroused my curiosity......any details on the seismic experiment, going on there? I'am probably being too premature to ask.....ha. Meredith Lamb __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Home Made PCBs From: Karl Cunningham karlc@....... Date: Sun, 11 Jun 2000 10:22:07 -0700 Hi Al -- The resolution is impressive. It was made using a 600dpi printer. He used mostly surface-mount parts with a few through-hole parts. But his layout planned that the holes weren't going to be plated through and used "z-wires" to connect traces top-to-bottom where needed. Using wire-wrap sockets for ICs allowed the sockets to be spaced up off the board for top-side soldering. Also impressive is the ease with which a board can be made. If something doesn't work out right, you can just change it and make a new board with a turn-around time of a couple of hours. Karl At 17:02 6/10/2000 -0700, you wrote: >Hi Karl, > >There is very little advantage in making double sided boards unless you can >make them through-hole plated. It is impossible to get some devices properly >connected to the runs under them. What is important about your information >is the resolution achieved. With good resolution you can use the process >perfected by the Japanese where you use a high resolution layout on one side >and wire jumpers on the other. There are board fab houses that will make >double __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Passing solar flare geomagnetic shock wave? From: meredith lamb mlamb1@.......... Date: Sun, 11 Jun 2000 11:31:36 -0700 CapAAVSO@....... wrote: > > > > Hi Meredith, > Thanks for the explanation of how your diamagnetic horizontal seismograph > works and for updating your website with the solar wind-speed recording. The > sudden jump in wind speed and the big spike on the Boulder magnetogram both > coincide with the big spike on your seismogram. Your seismograph is a pretty > good magnetometer with sensitivity comparable to the Geological Survey flux > gate magnetometer in Boulder provided the change in the Earth's magnetic > field is SUDDEN. This is confirmed by the signature of the bus passing by. It > is a big hunk of iron that swings the magnetically levitated pendulum putting > a big spike on the trace but quickly returns to its normal position due to > damping I assume you provided for it as a seismograph. How far is this > pendulum from the street where the bus passes by? About 70-80 foot, to the street curb. > I see what looks like many > small spikes, mostly pointing downward, that are probably cars passing by. Yes, the cars also deflect the mass, but nothing like the larger iron/steel bus's and vans. Cars usually don't do much noteworthy in any amplitude scale. I use copper plates, or close in eddy current damping, which is alittle too much for its normal planned seismic use. > > You could check this by watching out the window to see if a big van puts a > spike on your trace. > Have fun, > Cap Although it won't happen here, I really wonder what the results would be if this device were situated out in the country, away from the local magnetic noise (vehicles)? Of course it would be a scramble of both magnetic and seismic signals. With enough shielding, then it may show somewhat more seismic signals, both here or in the country. Another source of noise is electric motors, I've noticed some time back, that it horizontally oscillated (with proper alignment), to a refrigerator motor some 4 foot away. Electromagnetic. Have to confess my ignorance....what does the AAVSO stand for in your email address? Your full name? Any web site? Curiosity of course. Take care, Meredith Lamb __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: PC Boards From: "Erich Kern" ekern@......... Date: Sun, 11 Jun 2000 13:34:20 -0700 One of the PC board makers Charles Patton mentioned in his PSN post yesterday has been giving us good service for 4 years now. We buy about 90 custom, single sided boards a year from FAR circuits. The URL is the same as in Charles' post at http://www.cl.ais.net/farcir/ All boards are on epoxy glass stock with solder plated foil traces and cleanly drilled holes. If you want a component layout silk screened, they do that too. Regards, Erich Kern ********************************************************* Please visit our web site at: http://fqs.dconn.com ********************************************************* __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: PSN and SDR on the web and in the media From: Doug Sutherland doug@............. Date: Sun, 11 Jun 2000 16:38:19 -0700 Some time ago Larry's very cool seismic system was added to my "sensorium" network. Just wanted to mention that Larry and PSN are mentioned in this article: http://java.sun.com/features/2000/06/jeniuses.html Also, I had KRON TV at my home on monday and was filmed on my couch. Larry's SDR was running on a monitor in the background. Short clips were shown last week on KRON but most of the footage will be used in a future show called Next Step. Finally, I made it onto the CBS evening news with Dan Rather, talking about my "jacketized computer". I hope to one day figure out how to stream data from Larry's SDR system to my jacket sleeve display, so I can watch them squiggly lines while walking the streets of SF :) http://cbsnews.cbs.com/now/story/0,1597,203652-412,00.shtml http://java.sun.com/features/2000/06/jacket.html Keep up the good work Larry. Regards, Doug __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Home Made PCBs From: Jack Ivey ivey@.......... Date: Mon, 12 Jun 2000 18:19:14 -0400 I recently used AP Circuits for a run of 8 3"x5" double-sided boards. It worked flawlessly and cost about $120. ($46 + $.65/sq. in.) There is a schematic capture/layout/autoroute package called Eagle (www.cadsoft.de) that has a freeware version for non-commercial projects measuring less than about 3.5" x 4". It works quite well if you only need a small board. Jack Ivey KB8SPI "Charles R. Patton" wrote: > > Two places for PCB fab that you might check out are: > 1) FAR circuits at: > http://www.cl.ais.net/farcir/ > look at the > ARTICLE REPRINT, ORDER INFO, PAYMENT & SHIPPING > second from the bottom. $0.50/sq.in for single sided and $0.75 for > double sided (non-thru hole plated) which is pretty cheap. > > 2) Alberta Printed Circuits (AP Circuits) at: > http://www.apcircuits.com/ > This name was mentioned in some discussions as having reasonably priced > boards. > > I never used either one, but stored the information for the future. FAR > circuits is particulary interesting as they have a whole catalog of > boards from various projects, primarily HAM related. So it's worth a > look just for that. Additionally I kept several posts from the > electronics discussion groups and put them together in a 33KB ZIP file > which you can download from: > http://www.pe.net/~crpatton/PCINFO.ZIP > There is no index or other HTML pages at that address -- so use the URL > exactly as shown and you should be able to pull it down. > This includes discussion on several versions of iron on Xerox > techniques, information on etching solutions, and sources of PCB design > software -- both freeware and limited demo versions. > > Regards, > Charles R. Patton > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Passing solar flare geomagnetic shock wave? From: CapAAVSO@....... Date: Mon, 12 Jun 2000 18:39:20 EDT In a message dated 6/11/00 1:38:07 PM Eastern Daylight Time, mlamb1@.......... writes: << With enough shielding, then it may show somewhat more seismic signals, both here or in the country. >> ------------------------------------------------------------------------------ ----- Hi Meredith, I have a couple of square feet of 1/32 thick mu-metal. Tell me how much you need to shield your seismometer's magnets and I'll cut off a piece and send it to you. It will be interesting to see what shielding it can do. I'll need your postal mailing address though. << Have to confess my ignorance....what does the AAVSO stand for in your email address? Your full name? Any web site? Curiosity of course.>> AAVSO stands for American Association of Variable Star Observers. AAVSO has a solar division that publishes a monthly Solar Bulletin. The current May issue of the Bulletin has a recording of the big magnetic storm of 24 May. It was made with a homemade torsion-pendulum magnetometer. There are also complete instructions how to build a flux gate magnetometer for a little over $50. These include the schematic, a circuit board layout, parts list and two pages describing how the flux gate works. If you, or anyone else, would like a copy, just send me a self addressed envelope at my address below and I'll be glad to send a copy. Casper H. Hossfield PO Box 23 New Milford, NY 10959 __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Passing solar flare geomagnetic shock wave? From: ChrisAtUpw@....... Date: Mon, 12 Jun 2000 19:00:42 EDT In a message dated 12/06/00 23:40:40 GMT Daylight Time, CapAAVSO@....... writes: > I have a couple of square feet of 1/32 thick mu-metal. Tell me how much > you need to shield your seismometer's magnets and I'll cut off a piece and > send it to you. It will be interesting to see what shielding it can do. Dear Meredith, I use a Mu-Metal cylinder 3.5" dia by 8" long by 0.020" thick and it gives a measured axial field reduction of about x30 at the centre. In the Earth's field, I can't measure any transverse field effect. When you bend Mu-Metal, the permeability does decrease a bit. Regards, Chris Chapman __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Passing solar flare geomagnetic shock wave? From: CapAAVSO@....... Date: Mon, 12 Jun 2000 19:53:07 EDT In a message dated 6/12/00 7:01:55 PM Eastern Daylight Time, ChrisAtUpw@....... writes: << When you bend Mu-Metal, the permeability does decrease a bit. >> ------------------------------------------------------------------------------ ----------- High Chris, I want to cut and bend some mu-metal to make a core for a flux gate. I have been told the core will need to be annealed to restore its permeability or the flux gate won't work very well. Can anyone tell me how to anneal a toroidal core about 5 cm in diameter? Many thanks, Cap __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Passing solar flare geomagnetic shock wave? From: Ed Thelen ethelen@........ Date: Mon, 12 Jun 2000 17:12:54 -0700 I've heard tales of ovens filled with hydrogen (in part to exclude O2 which is reputed to be an enemy in the annealing process) "cooled" slowly down through the range of 700 degress C. Live a long and together life ;-) Cheers Ed Thelen CapAAVSO@....... wrote: > > In a message dated 6/12/00 7:01:55 PM Eastern Daylight Time, > ChrisAtUpw@....... writes: > > << When you bend > Mu-Metal, the permeability does decrease a bit. >> > > ------------------------------------------------------------------------------ > ----------- > High Chris, > I want to cut and bend some mu-metal to make a core for a flux gate. I > have been told the core will need to be annealed to restore its permeability > or the flux gate won't work very well. Can anyone tell me how to anneal a > toroidal core about 5 cm in diameter? > Many thanks, > Cap > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Passing solar flare geomagnetic shock wave? From: meredith lamb mlamb1@.......... Date: Mon, 12 Jun 2000 19:55:28 -0700 ChrisAtUpw@....... wrote: > Dear Meredith, > I use a Mu-Metal cylinder 3.5" dia by 8" long by 0.020" thick and it > gives a measured axial field reduction of about x30 at the centre. In the > Earth's field, I can't measure any transverse field effect. When you bend > Mu-Metal, the permeability does decrease a bit. > Regards, > Chris Chapman Hi Chris, Thanks for the info on the field reduction of your unit, it helps give me an appreciation of the effect of shielding thats possible. Of course, a Hall sensor can be made into a gauss meter, or, is the main part for such, which you likely used there. Its also possible to see some reduction effect, by using Robert Lambs Hall sensor circuit, and open and close (the) potential shield over it. He had a small ~ 4"L x 1.5" diameter open mu-metal cylinder that he shoved the Hall sensor in as a demonstration .....it roughly halved the circuit noise at that time. Of course this just reminds me that a similar shield around the S-G type Hall circuit seismos could also be beneficial in that aspect.....but; for that application, the shield could be alot smaller and close to the Hall sensor itself. Thats another undone project ......ha. Take care, Meredith Lamb __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Passing solar flare geomagnetic shock wave? From: meredith lamb mlamb1@.......... Date: Mon, 12 Jun 2000 20:12:57 -0700 CapAAVSO@....... wrote: > In a message dated 6/11/00 1:38:07 PM Eastern Daylight Time, > mlamb1@.......... writes: > > << With enough shielding, then it may > show somewhat more seismic signals, both here or in the country. >> > > ------------------------------------------------------------------------------ > ----- > Hi Meredith, > I have a couple of square feet of 1/32 thick mu-metal. Tell me how much > you need to shield your seismometer's magnets and I'll cut off a piece and > send it to you. It will be interesting to see what shielding it can do. I'll > need your postal mailing address though. Hi Casper, Wow....thats very generious of you on the mu-metal offer. I'am hesitant here simply because of the sheer tentative size of the shield I'am considering. I think its quite different than a magnetometers relatively close-in shielding in that, with the levitated magnet, the simple magnetic attraction between the shield material and the magnet will need more distance and hence a huge sized shield/container/cylinder, with both ends covered. Presently I'am considering using a simple thick cardboard 12" in diameter tube that will be cut to 15" in height (or length), and stood on end to cover the frame and sit on the base plate. Even with this over the frame the distance to the magnet will be roughly 5.5" at its closest, and it could be still a no go, but all I can do is try that for now. So....its no small amount of magnetic shielding material that will be needed overall. Am planning on going the salvage route on permalloy/mu-metal. This is going to be selected and specific "old" torroid foil coils made by Arnold Engineering, or other material which have been proven to range from "good" to "super" stuff. Bob Lamb, my brother has already donated a quanity of super type material, which I hope will at least cover one unit shield (I'd like 2....ha, for the other direction of E-W possibly). Although its thin tape like stuff, it should help or work to a unknown degree. Time will tell eventually of the success or failure in this approach. Additional layers are possible to apply in this approach, with whatever is available, with a 1/16" to 1/8" separation between layers. I do have a appreciation of the big cost of the mu-metal material, and in particular to the thickness you mentioned.....its about like buying gold ....very, very expensive stuff. << Have to confess my ignorance....what does the AAVSO stand > for in your email address? Your full name? Any web site? > Curiosity of course.>> > AAVSO stands for American Association of Variable Star Observers. AAVSO > has a solar division that publishes a monthly Solar Bulletin. The current May > issue of the Bulletin has a recording of the big magnetic storm of 24 May. It > was made with a homemade torsion-pendulum magnetometer. There are also > complete instructions how to build a flux gate magnetometer for a little over > $50. These include the schematic, a circuit board layout, parts list and two > pages describing how the flux gate works. If you, or anyone else, would like > a copy, just send me a self addressed envelope at my address below and I'll > be glad to send a copy. Actually there is quite a number of PSN email recipients that are also interested in astronomy and/or other sciences. The torsion-pendulum magnetometer almost....sounds like it could be along the line of Roger Bakers design article in the Amateur Scientist section of Scientific American, of (?) January 1999, not withstanding another model? As far a a neodymium magnet attached to a thread/string, I'd wonder whether a stronger gauss magnet like a grade R45 (~14.2K) would be of any added benefit over a "standard" neo magnet of some (R30)~ 12-13K (potential)gauss field magnet? Seems like it would boost the sensitivity somewhat. Just a thought to ponder. Actually; for anyone interested...Forcefield/Wondermagnet does have afew R45 magnets left (1/4" diameter by 1" long, with the poles on each half of the rod diameter,lengthwise), item #16. This is the same magnet I use in the diamagnetic seismometer/aka, "pulse magnetometer".....ha. See: http://www.wondermagnet.com/dev/magnets.html > > Casper H. Hossfield > PO Box 23 > New Milford, NY 10959 > Take care, Meredith Lamb __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Mu-Metal??? From: SW6079@....... Date: Mon, 12 Jun 2000 23:02:30 EDT I must confess, I have not a clue what this stuff is, but am intrigued. Would anyone be able to enlighten me? Thanks, also nice to see another astronomer here. Mike. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Mu-Metal??? From: twleiper@........ Date: Mon, 12 Jun 2000 23:30:59 -0400 On Mon, 12 Jun 2000 23:02:30 EDT SW6079@....... writes: > I must confess, I have not a clue what this stuff is, but am > intrigued. > Would anyone be able to enlighten me? Thanks, also nice to see > another > astronomer here. Mike. It is a metal that stops magnetic fields, like shielding. It is magnetic, in that magnets are drawn to it, but the field does not pass through it. If you were to try to pick up a sting of paper clips made from Mu-Metal, only the first one would be picked up, the rest would not follow. It was discovered quite accidentally by a (retired Colonel) immigrant German steelworker in Pittsburgh named Otto Von Sherberg, who hurled a sack of kittens into an open hearth furnace on a day that they were making high permiability magnet iron, hence the rather unusual name. "Mu" is the German for "mew" and is pronounced the same way. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Re: Passing solar flare geomagnetic shock wave? & Mu-Metal From: ChrisAtUpw@....... Date: Mon, 12 Jun 2000 23:38:08 EDT In a message dated 13/06/00 00:54:31 GMT Daylight Time, CapAAVSO@....... writes: > I want to cut and bend some mu-metal to make a core for a flux gate. I > have been told the core will need to be annealed to restore its permeability > or the flux gate won't work very well. Can anyone tell me how to anneal a > toroidal core about 5 cm in diameter? When we had some tubular Mu-Metal shields made to screen photo-multipliers, they were rolled from sheet, Argon arc welded and then heat treated in hydrogen. If I remember correctly, the hydrogen prevents oxidation and also reduces selective evaporation of the alloy. I don't remember the temperature. The heat treatment anneals the metal and allows crystal growth. The final product was definitely rather brittle. The straight fluxgate sensors used to be made from insulated wire to reduce eddy current problems. If you have really thin foil, you could probably just roll up a multi turn coil, but the metal probably wouldn't have it's optimal magnetic properties. This might not be too critical in a toroidal core so long as the whole length had the same properties. If you can get a used tubular welded shield, could you varnish it thoroughly, scribe it and then etch rings from it? Dud Geophones? CRT shields? (Mine cost 60 c) There are some 'new' ferrites on the market with 'square' characteristics. See FairRite, Arnolds, muRata, Ferroperm, Siemens (and Philips if you can get their * Website to work) Ferrites tend not to have serious eddy current problems, but may be more temperature sensitive. METGLAS alloys are also available with phenomenal properties. See Honeywell at http://www.electronicmaterials.com/businesses/sem/amorph/page5_1_2.htm Sorry not to be more encouraging. Hope that this is of some help. It rather depends on your application. I would just try making a core. You would probably need more drive field, but so what? 5 cm sounds like a Jumbo size. Several companies market fluxgate sensors, but that's not like making your own. Regards, Chris Chapman __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Mu-Metal??? From: david@............. (David Josephson) Date: Mon, 12 Jun 2000 21:40:18 -0700 (PDT) > > I must confess, I have not a clue what this stuff is, but am > > intrigued. .... > It is a metal that stops magnetic fields, like shielding. It is magnetic, > in that magnets are drawn to it, but the field does not pass through it. > If you were to try to pick up a sting of paper clips made from Mu-Metal, > only the first one would be picked up, the rest would not follow. > > It was discovered quite accidentally by a (retired Colonel) immigrant > German steelworker in Pittsburgh named Otto Von Sherberg, who hurled a > sack of kittens into an open hearth furnace on a day that they were > making high permiability magnet iron, hence the rather unusual name. "Mu" > is the German for "mew" and is pronounced the same way. .... Ummm, no, sorry. Mu-metal is a trade name for a nickel alloy (77% Ni, 14% Fe, 5% Cu, 4% Mo), also known as Permalloy-C and several other names as well. "Mu" refers to the Greek letter, which is used to indicate magnetic permeability. There is some good information on applications of this material at www.magnetic-shield.com. High permeability alloys do *not* stop magnetic fields in the way that opaque things stop light. People think that they can put a sheet of mu-metal in the "path" of a magnetic field, for instance from a magnet, but this does not work. They are surprised to find that the magnetic field intensity is even higher near the edges of the sheet of "magnetic shield." If you create a tight, *seamless* housing of mu-metal, it will conduct the ambient magnetic field around the outside so that all points on its surface will be at (nearly) the same magnetic potential. Variations in the external field are greatly attenuated inside such a shield. But, the earth's field, or that of a magnet, is effectively like DC, or static air pressure. You have to seal a box pretty tightly to keep the static pressure from leaking inside. Likewise, a mu-metal shield must be a continuous surface enclosing some volume, in order for there to be significant shielding effect for the volume enclosed. It's analogous to electrostatic shielding using highly conductive materials; the closer you are to the shield, the closer you are to an equipotential surface. Mu-metal is to magnetic fields as silver is (more or less) to electrostatic fields. I doubt that any cats were harmed in the creation of mu-metal, the macabre story notwithstanding. -- David Josephson / Josephson Engineering / San Jose CA / david@............. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Mu-Metal??? From: "Erich Kern" ekern@......... Date: Mon, 12 Jun 2000 23:12:26 -0700 David, Thanks for the explanation. Your post rings true, but I didn't say anything as I didn't have the facts at hand as you do. Several years ago, I attempted making a magnetically shielded enclosure to test our magnetic sensors using 1" I.D. steel pipe 18" long with pipe caps which turned out to be completely ineffective. When I mentioned this to the late Richard Noble of Speake & Co., he told me the only effective shielding to do zero field tests was to fabricate concentric Mu metal shields which had been annealed AFTER fabrication and separated by an inch or more. This is very expensive. The alternative is to simply orient the sensors east-west outdoors, away from the building and road traffic. The Mu metal does not "stop" the magnetic flux, it conducts it around the object within. It's curious that most people seek an analogy with nuclear and microwave radiation (very much higher in frequency) rather than an electrostatic field which it most resembles. I used to do shielding effectiveness tests on very large enclosures, and more voids in the shielding were evident with a loop antenna at 200 KHz than with an E field dipole at microwave frequencies. Regards, Erich Kern .... __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Mu-Metal??? From: david@............. (David Josephson) Date: Tue, 13 Jun 2000 00:27:24 -0700 (PDT) Erich Kern writes > Several years ago, I attempted > making a magnetically shielded enclosure to test our magnetic sensors using 1" > I.D. steel pipe 18" long with pipe caps which turned out to be completely > ineffective. When I mentioned this to the late Richard Noble of Speake & Co., > he told me the only effective shielding to do zero field tests was to fabricate > concentric Mu metal shields which had been annealed AFTER fabrication and > separated by an inch or more. This is very expensive. The alternative is to > simply orient the sensors east-west outdoors, away from the building and road > traffic. You got good advice, but there is a cheaper way to do it. Plain soft iron is also highly permeable, but hard to work. When I worked at Geometrics we spend a pile of money on a mu-metal shield can for working on cesium magnetometers, and it was three layers of about 0.060" mu-metal, separated from one another with stiff felt. Checking for noise outdoors oriented east-west might work for vector (single-axis) instruments of moderate sensitivity, but not for (a) total field magnetometers or (b) instruments of high sensitivity. The problem is that even with perfect alignment to the east-west null, any motion of the magnetometer in the earth's field translates into a change in flux, which becomes an output signal. In other words, you've made a seismograph. > The Mu metal does not "stop" the magnetic flux, it conducts it around the > object within. It's curious that most people seek an analogy with nuclear and > microwave radiation (very much higher in frequency) rather than an > electrostatic field which it most resembles. I used to do shielding > effectiveness tests on very large enclosures, and more voids in the shielding > were evident with a loop antenna at 200 KHz than with an E field dipole at > microwave frequencies. You got it. For the other readers, note that a loop antenna works by magnetic coupling, while a (resonant) E field dipole intercepts both the magnetic and the electrostatic field. An E field probe intercepts almost exclusively the electrostatic field. -- David Josephson / Josephson Engineering / San Jose CA / david@............. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: PSN and SDR on the web and in the media From: Edward Cranswick cranswick@........ Date: Tue, 13 Jun 2000 02:50:08 -0600 Doug- I read your email and referenced articles with interest. At the risk of repeating myself, I am sending you two abstracts of presentations about the Public Seismic Network (PSN) that we made in the last few years at the American Geophysical Union Fall Meetings in San Francisco and that address a vision of the PSN within the context of Internet/Gaia -- which constitutes the mind/body duality of the current state of consciousness. -Edward %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% [1998 December American Geophysical Union Meeting, San Francisco] Public Seismic Network (PSN): A Model for Science, Technology and Community in the Coming Age Edward Cranswick The Public Seismic Network (PSN) is a model for using technology to connect human awareness to, rather than shield it from, the environment. The PSN is a rapidly growing international group of amateur seismologists, concentrated in California, who record earthquakes with their own digital seismographs and exchange waveform time series and communicate with each other via the Internet. At present, the PSN consists of about 50 seismograph stations, about 250 subscribers to its email list server, and about 10 websites (e.g., http://psn.quake.net/). The World Wide Web is rapidly engulfing many aspects of human life in technological societies and beginning to constitute a virtual reality where many of us spend more and more of our time. At the same time, the physical reality of Earth is being environmentally and ecologically degraded at an ever-increasing rate. A critical issue is whether the Web will be used to enhance or to obscure our vision of Earth. Most of the Web traffic contains very little sense data, i.e., empirical information, about the Earth. Other than the Internet and other artificial electromagnetic media, seismic waves propagate more rapidly and, therefore, convey information about the state of the planet faster than any other means. Ground motions are disturbances of our rest position on the Earth’s surface and convey the message that change in life is ubiquitous and inevitable. Most of the energy of earthquake-produced ground motions is in the frequency band, several seconds to several Hertz, to which the human brain is most sensitive. If we cannot respond to earthquakes, it will be even more difficult to respond to other phenomena, such as global warming, with much longer time constants. The distribution of low-cost broadband seismometers in conjunction with Web access would allow people worldwide, i.e., the next human generation of Earth, to directly perceive and to share the concrete perception with each other that we all share the same ground. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% [1997 December American Geophysical Union Meeting, San Francisco] Public Seismic Network (PSN): a Model for Preparing People to use Real-time Information About Natural Hazards Edward Cranswick and Benjamin Gardner (U.S. Geological Survey, MS 966, Box 25046, Federal Center, Denver, CO 80225, USA; 303-273-8609; cranswick@......... Public Seismic Network (http://psn.quake.net/, psn-l@.............. When an earthquake occurs, unlike any other natural hazard, every individual in the population at risk is aware within seconds that a dangerous event has happened. Without the aid of any technology, the consciousness of everyone affected is almost instantaneously focused on the same subject. Instead of soliciting that information, authorities broadcast the redundant message that an earthquake has occurred. A program of monitoring natural hazards for the public requires public participation to effectively mitigate those hazards. The Public Seismic Network (PSN), rather than relegating them to the role of sitting ducks waiting to be devastated by the unexpected, enables people to become aware that earthquakes are part of normal, on-going Earth processes. The PSN is a rapidly growing international group of amateur seismologists, concentrated in California, who record earthquakes with their own digital seismographs and exchange waveform time series and communicate with each other via the Internet. At present, the PSN consists of about 50 seismograph stations, about 250 subscribers to its email list server, and about 10 websites. In urban areas of high seismic risk, a grassroots organization like the PSN -- equipped with low-cost, mass-produced, standardized strong-motion seismographs -- could vastly increase the spatial density of sampling ground motions. This organization would form a constituency of well-informed residents who not only know how to respond to catastrophic earthquakes but also support hazard mitigation programs in the community. Rather than just building faster ambulances to mitigate the impact of heart attacks, it is more effective to modify the public habits of exercise and diet. The PSN is a model for using technology to connect human awareness to, rather than shield it from, the environment. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% Doug Sutherland wrote: > Some time ago Larry's very cool seismic system was added > to my "sensorium" network. Just wanted to mention that > Larry and PSN are mentioned in this article: > > http://java.sun.com/features/2000/06/jeniuses.html > > Also, I had KRON TV at my home on monday and was filmed > on my couch. Larry's SDR was running on a monitor in the > background. Short clips were shown last week on KRON > but most of the footage will be used in a future show > called Next Step. > > Finally, I made it onto the CBS evening news with Dan > Rather, talking about my "jacketized computer". I hope > to one day figure out how to stream data from Larry's > SDR system to my jacket sleeve display, so I can watch > them squiggly lines while walking the streets of SF :) > > http://cbsnews.cbs.com/now/story/0,1597,203652-412,00.shtml > http://java.sun.com/features/2000/06/jacket.html > > Keep up the good work Larry. > > Regards, > Doug > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 PO Box 25046, Federal Center cranswick@........ Denver, CO 80225-0046 USA E.M. Forster said, "Only connect". __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: PSN and SDR on the web and in the media From: "Erich Kern" ekern@......... Date: Tue, 13 Jun 2000 02:45:06 -0700 Totally Whacko. -----Original Message----- From: Edward Cranswick To: Doug Sutherland ; psn-l@.............. ; NOVELTY mailing list Date: Tuesday, June 13, 2000 2:03 AM Subject: Re: PSN and SDR on the web and in the media Doug- I read your email and referenced articles with interest. At the risk of repeating myself, I am sending you two abstracts of presentations about the Public Seismic Network (PSN) that we made in the last few years at the American Geophysical Union Fall Meetings in San Francisco and that address a vision of the PSN within the context of Internet/Gaia -- which constitutes the mind/body duality of the current state of consciousness. -Edward %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% [1998 December American Geophysical Union Meeting, San Francisco] Public Seismic Network (PSN): A Model for Science, Technology and Community in the Coming Age Edward Cranswick The Public Seismic Network (PSN) is a model for using technology to connect human awareness to, rather than shield it from, the environment. The PSN is a rapidly growing international group of amateur seismologists, concentrated in California, who record earthquakes with their own digital seismographs and exchange waveform time series and communicate with each other via the Internet. At present, the PSN consists of about 50 seismograph stations, about 250 subscribers to its email list server, and about 10 websites (e.g., http://psn.quake.net/). The World Wide Web is rapidly engulfing many aspects of human life in technological societies and beginning to constitute a virtual reality where many of us spend more and more of our time. At the same time, the physical reality of Earth is being environmentally and ecologically degraded at an ever-increasing rate. A critical issue is whether the Web will be used to enhance or to obscure our vision of Earth. Most of the Web traffic contains very little sense data, i.e., empirical information, about the Earth. Other than the Internet and other artificial electromagnetic media, seismic waves propagate more rapidly and, therefore, convey information about the state of the planet faster than any other means. Ground motions are disturbances of our rest position on the Earth’s surface and convey the message that change in life is ubiquitous and inevitable. Most of the energy of earthquake-produced ground motions is in the frequency band, several seconds to several Hertz, to which the human brain is most sensitive. If we cannot respond to earthquakes, it will be even more difficult to respond to other phenomena, such as global warming, with much longer time constants. The distribution of low-cost broadband seismometers in conjunction with Web access would allow people worldwide, i.e., the next human generation of Earth, to directly perceive and to share the concrete perception with each other that we all share the same ground. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% [1997 December American Geophysical Union Meeting, San Francisco] Public Seismic Network (PSN): a Model for Preparing People to use Real-time Information About Natural Hazards Edward Cranswick and Benjamin Gardner (U.S. Geological Survey, MS 966, Box 25046, Federal Center, Denver, CO 80225, USA; 303-273-8609; cranswick@......... Public Seismic Network (http://psn.quake.net/, psn-l@.............. When an earthquake occurs, unlike any other natural hazard, every individual in the population at risk is aware within seconds that a dangerous event has happened. Without the aid of any technology, the consciousness of everyone affected is almost instantaneously focused on the same subject. Instead of soliciting that information, authorities broadcast the redundant message that an earthquake has occurred. A program of monitoring natural hazards for the public requires public participation to effectively mitigate those hazards. The Public Seismic Network (PSN), rather than relegating them to the role of sitting ducks waiting to be devastated by the unexpected, enables people to become aware that earthquakes are part of normal, on-going Earth processes. The PSN is a rapidly growing international group of amateur seismologists, concentrated in California, who record earthquakes with their own digital seismographs and exchange waveform time series and communicate with each other via the Internet. At present, the PSN consists of about 50 seismograph stations, about 250 subscribers to its email list server, and about 10 websites. In urban areas of high seismic risk, a grassroots organization like the PSN -- equipped with low-cost, mass-produced, standardized strong-motion seismographs -- could vastly increase the spatial density of sampling ground motions. This organization would form a constituency of well-informed residents who not only know how to respond to catastrophic earthquakes but also support hazard mitigation programs in the community. Rather than just building faster ambulances to mitigate the impact of heart attacks, it is more effective to modify the public habits of exercise and diet. The PSN is a model for using technology to connect human awareness to, rather than shield it from, the environment. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% Doug Sutherland wrote: > Some time ago Larry's very cool seismic system was added > to my "sensorium" network. Just wanted to mention that > Larry and PSN are mentioned in this article: > > http://java.sun.com/features/2000/06/jeniuses.html > > Also, I had KRON TV at my home on monday and was filmed > on my couch. Larry's SDR was running on a monitor in the > background. Short clips were shown last week on KRON > but most of the footage will be used in a future show > called Next Step. > > Finally, I made it onto the CBS evening news with Dan > Rather, talking about my "jacketized computer". I hope > to one day figure out how to stream data from Larry's > SDR system to my jacket sleeve display, so I can watch > them squiggly lines while walking the streets of SF :) > > http://cbsnews.cbs.com/now/story/0,1597,203652-412,00.shtml > http://java.sun.com/features/2000/06/jacket.html > > Keep up the good work Larry. > > Regards, > Doug > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 PO Box 25046, Federal Center cranswick@........ Denver, CO 80225-0046 USA E.M. Forster said, "Only connect". __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: PSN and SDR on the web and in the media From: Doug Sutherland doug@............. Date: Tue, 13 Jun 2000 06:00:15 -0700 Erich Kern wrote: > Totally Whacko. In the words of Cosmo Kramer ... "Is it? Or is it so sane that it just blew your mind." -- Doug __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: cheap geophones From: BOB BARNS roybar@........ Date: Tue, 13 Jun 2000 11:16:36 -0400 Hi gang, Ad in Nutz & Volts: Geophone, 1.6" hi, 1.2" dia., made by Geosource, $7.95. The resonant freq. is not mentioned. www.gatewayelex.com Their web site offers (in Gadgets) only a kit (which incls. the geophone) for $9.95. Maybe a 'phone call to 1-800-669-5810 will get the geophone by itself. Bob __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Mu-Metal??? From: CapAAVSO@....... Date: Tue, 13 Jun 2000 11:22:53 EDT In a message dated 6/13/00 12:41:31 AM Eastern Daylight Time, david@............. writes: << Mu-metal is a trade name for a nickel alloy (77% Ni, 14% Fe, 5% Cu, 4% Mo), also known as Permalloy-C and several other names as well. "Mu" refers to the Greek letter, which is used to indicate magnetic permeability. >> ------------------------------------------------------------------------------ ------------ Hi David, Many thanks for your interesting and valuable information telling us what mu-metal really is and how it excludes magnetic fields from an enclosed volume. Very interesting stuff. Sounds like an expensive alloy though, and the need to anneal it in a hydrogen atmosphere after fabrication puts it out of reach for amateur applications. There is a way around the problems for Meredith and others, however. Top of the line oscilloscopes have a mu-metal shield around their CRTs (cathode ray tubes). Old tube-type oscilloscopes go cheap and are plentiful at Hamfests (ham radio fleamarkets). To find a hamfest near you and the weekend it will happen see <>. Look for Tektronix, Hewlett Packard or any military scopes. They have mu-metal shields around their CRTs but most other brands do not. The shield as it is will be annealed and big enough to do a pretty good job of hiding your diamagnetic seismograph or other project from street traffic and the Earth's magnetic field with its magnetic storms. Look for old scopes not in operating condition and offer $5 to $10 and you will take home most of them. Have fun, Cap __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Possibly From: "Erich Kern" ekern@......... Date: Tue, 13 Jun 2000 09:02:59 -0700 Good point. My apologies for an intemperate post to this fine mail list. Erich -----Original Message----- From: Doug Sutherland To: psn-l@.............. Date: Tuesday, June 13, 2000 3:41 AM Subject: Re: PSN and SDR on the web and in the media Erich Kern wrote: > Totally Whacko. In the words of Cosmo Kramer ... "Is it? Or is it so sane that it just blew your mind." -- Doug __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Another mu-metal/permalloy question From: meredith lamb mlamb1@.......... Date: Tue, 13 Jun 2000 11:22:31 -0700 Hi all, Thanks for all the notes and tips on magnetic shielding. I don't have the experience to really delve into the subject at all.....but I do have another question, that kind of makes me wonder alot. For a shielded enclosure that contains a strong neodymium magnet (mass), would that internal magnetic field, enhance the overall shields ability to help attenuate the EXTERNAL magnetic fields influence? To me, it would seem to help attenuate the external fields influence...as it would somewhat create a polarized shield according to the orientation of the internal magnet. Any thoughts? Thanks, Meredith Lamb __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Passing solar flare geomagnetic shock wave? From: CapAAVSO@....... Date: Tue, 13 Jun 2000 13:34:15 EDT In a message dated 6/12/00 10:18:52 PM Eastern Daylight Time, mlamb1@.......... writes: << Actually there is quite a number of PSN email recipients that are also interested in astronomy and/or other sciences. The torsion-pendulum magnetometer almost....sounds like it could be along the line of Roger Bakers design article in the Amateur Scientist section of Scientific American, of (?) January 1999 >> ------------------------------------------------------------------------------ ----- Hi Meredith, Yes, it is similar but the McWilliams torsion-pendulum magnetometer has been around for 20 years and many have been built and are sensitive enough to easily produce excellent magnetograms comparable to those made at USGS magnetic observatories. It is also a simple device not requiring any laser beams or fancy amplifiers like Roger Baker's. This easy to build magnetometer is an 8-inch long compass needle suspended on a torsion wire, a 15-inch length of guitar string (.008" dia.) from your local music store. A shadow vane on one end of the needle shades two Radio Shack Cadmium Sulfate photocells from the light of a 12-volt automobile bulb. The torsion wire is twisted enough to provide enough torque to make the needle point east and west rather than the north and south direction it would rather point. The needle is therefore torsion balanced against the Earth's magnetic field. In this position the two photocells are placed side by side under the light so the shadow vane on the end of the needle shades half of each photocell. The photocells are variable resistors and there resistance depends on how much light falls on them. When they are equally shaded their resistance is equal. They are made half of a Wheatstone bridge and a strip chart recorder or computer is connected across the bridge. No current flows so long as the bridge is balanced by the photocells being equally illuminated. When a solar flare or coronal mass ejection bombards the Earth's magnetosphere with high speed particles they generate a current that produces a magnetic field that either adds or subtracts to the Earth's ambient field thus changing the total field strength. The magnetic needle feels the change and its balance against torsion rotates the shadow vane so the photocells are no longer equally shaded and their resistance is unequal. This generates a current in the bridge and moves the chart recorder which is zero centered. The direction it moves depends on the polarity of the bridge current and this depends on whether the solar particle flux generates a magnetic field that adds or subtracts to the Earth's, thus making a recording that is the familiar magnetogram like the ones that you can see at <>. If you or anyone else would like a copy a Solar Bulletin that describes the McWilliams magnetometer in detail with drawings and a schematic of the Wheatstone bridge, just send a self addressed envelope to me at my address below and I'll be glad to send you a copy. The photocell displacement transducer might also work quite well on a seismograph. Casper H. Hossfield PO Box 23 New Milford, NY 10959 __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: cheap geophones From: BOB BARNS roybar@........ Date: Tue, 13 Jun 2000 13:37:08 -0400 Hi gang, Ad in Nutz & Volts: Geophone, 1.6" hi, 1.2" dia., made by Geosource, $7.95. The resonant freq. is not mentioned. www.gatewayelex.com Their web site offers (in Gadgets) only a kit (which incls. the geophone) for $9.95. Maybe a 'phone call to 1-800-669-5810 will get the geophone by itself. Bob __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Another mu-metal/permalloy question From: ChrisAtUpw@....... Date: Tue, 13 Jun 2000 14:24:47 EDT Dear Meredith, > For a shielded enclosure that contains a strong neodymium > magnet (mass), would that internal magnetic field, enhance > the overall shields ability to help attenuate the EXTERNAL > magnetic fields influence? To me, it would seem to help > attenuate the external fields influence...as it would somewhat > create a polarised shield according to the orientation of the > internal magnet. Suppose you have a hollow sphere of Permalloy etc. with a magnetic field detector inside and then apply an external magnetic field. At low external fields, almost all the field passes through the Permalloy and the internal sensor sees practically nothing. As you increase the external field, the Permalloy gets towards magnetic saturation and some reduced field will penetrate the sphere. At high external fields, the Permalloy will be completely saturated and there will be a high field inside the sphere. If you had two concentric spheres, you would be able to apply a higher external magnetic field before it started to penetrate the inner sphere. For your apparatus, I think you need an outer shield of Permalloy etc. to reduce the effect of the low external fields and an internal shield to screen the Permalloy from the core magnets. This shield might be silicon iron or you might get away with mild steel. You might need two layers. Hope this qualitative description helps. Chris Chapman __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Another mu-metal/permalloy question From: "Al Allworth" allworth@.............. Date: Tue, 13 Jun 2000 11:49:44 -0700 Hello Meredith and all, Like any magnetic material mu-metal can only carry or conduct a limited flux density. At this point it is said to saturate. If the outside flux is strong enough to saturate the material it appears to "leak" through it. A given material will "leak" at different flux densities depending on the internal structure which is affected by the mechanical stresses that have been imposed upon it since it was manufactured. This is why it must be heat treated to get the greatest attenuation. The attenuation is measured by placing a sample sleave of the material between the coils of a set of Helmholtz coils with a pickup coil in the center of the test sleave. The setup we used had about 3 foot diameter coils about 2 feet apart. The coils have no magnetic material in their construction. The coils are connected in series with their flux polarity aiding. The pickup coil support is made of all nonmetalic material and places the pickup coil on the axis of the pair of Helmholtz coils. The system is calibrated with no magnetic material near-by and no metal within the coils. the exciting AC current (often 60 Hz) is adjusted to produce some reference level output from the pickup coil. The test sleave is then placed over the pickup coil with the pickup coil centered in the length of the sleave. The sleave length should be about 20 times the length of the pickup coil. Our pickup coil was about 1/2 inch long and about 1 1/2 inches in diameter.It is wound with many turns of fine wire. Any improvement in attenuation from making the sleave longer or closing the ends can't be measured. The radial position of the coil within the sleave has little effect on the accuracy. The attenuation is expressed as a linear ratio although I have seen dB used in some papers I have read. I think a direct ratio is easier to understand in this application. I thought this might help the understanding of how shields work and are tested. _______________________________ Al Allworth On the Beautiful Southern Oregon Coast ________________________________ ----- Original Message ----- From: "meredith lamb" To: Sent: Tuesday, June 13, 2000 11:22 AM Subject: Another mu-metal/permalloy question > Hi all, > > Thanks for all the notes and tips on magnetic shielding. > > I don't have the experience to really delve into the subject > at all.....but I do have another question, that kind of makes > me wonder alot. > > For a shielded enclosure that contains a strong neodymium > magnet (mass), would that internal magnetic field, enhance > the overall shields ability to help attenuate the EXTERNAL > magnetic fields influence? To me, it would seem to help > attenuate the external fields influence...as it would somewhat > create a polarized shield according to the orientation of the > internal magnet. Any thoughts? > > Thanks, Meredith Lamb > > > > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Another mu-metal/permalloy question From: david@............. (David Josephson) Date: Tue, 13 Jun 2000 12:10:48 -0700 (PDT) Meredith Lamb writes > For a shielded enclosure that contains a strong neodymium > magnet (mass), would that internal magnetic field, enhance > the overall shields ability to help attenuate the EXTERNAL > magnetic fields influence? To me, it would seem to help > attenuate the external fields influence...as it would somewhat > create a polarized shield according to the orientation of the > internal magnet. Any thoughts? I don't think so. The permeability of ferromagnetic materials is reduced when the applied field is increased, so the magnetic "conductivity" of the shield would be reduced. Best bet to reduce the effect of the earth's field (DC, therefore very hard to make an effective shield against) is to install magnets or electromagnets to produce a mirror image of the earth's field at the point where you want the field to be zero. -- David Josephson / Josephson Engineering / San Jose CA / david@............. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Passing solar flare geomagnetic shock wave? From: CapAAVSO@....... Date: Tue, 13 Jun 2000 16:27:16 EDT In a message dated 6/12/00 10:18:52 PM Eastern Daylight Time, mlamb1@.......... writes: << Actually; for anyone interested...Forcefield/Wondermagnet does have afew R45 magnets left (1/4" diameter by 1" long, with the poles on each half of the rod diameter,lengthwise), item #16. This is the same magnet I use in the diamagnetic seismometer/aka, "pulse magnetometer".....ha. See: http://www.wondermagnet.com/dev/magnets.html >> ------------------------------------------------------------------------------ ----- Hi Meredith, I used a row of Wondermagnet's # 13, 1/4 by 1/2"long Neodymium magnets to build a magnetometer. They make a very nice strong compass needle but I heard somewhere they are more temperature sensitive than Alnico magnets we used to use. Can anybody shed any light on this? Regards, Cap __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Passing solar flare geomagnetic shock wave? From: CapAAVSO@....... Date: Tue, 13 Jun 2000 17:32:05 EDT In a message dated 6/13/00 2:38:16 PM Eastern Daylight Time, ChrisAtUpw writes: << Was this the Fat Quarters Magnetometer, the one published in the Amateur Scientist or another one, please? Lundqvist also published a good moving magnet magnetometer using a compass and field coils. >> ------------------------------------------------------------------------------ --------- Hi Chris, No. This one is from "the Magnetic Measurements Handbook" by J. M. Janicke. See his web site at <>. Janicke lives nearby so I visited him to buy a copy of his book and get permission to publish the chapter on the flux gate magnetometer in our Solar Bulletin. He is a retired electrical engineer who spent a good part of his life designing magnetic instruments for a company that builds a lot of military and aerospace stuff. His book is written mostly for amateurs who want to build homemade magnetic devices. It is an excellent book with many interesting projects. I very much doubt you could find a better book on the subject. He also sells flux gates for $35. Their toroidal core has been correctly annealed in Hydrogen and I bought one just in case I couldn't build my own, as I would very much prefer to do. With the benefit of hindsight I can see this was a GOOD IDEA !!! Best regards, Cap __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Passing solar flare geomagnetic shock wave? From: ChrisAtUpw@....... Date: Tue, 13 Jun 2000 19:13:39 EDT Hi CapAAVSO@....... > I used a row of Wondermagnet's # 13, 1/4 by 1/2"long Neodymium > magnets to build a magnetometer. They make a very nice strong > compass needle but I heard somewhere they are more temperature > sensitive than Alnico magnets we used to use. Does anyone know.... Funny that you should ask about temperature coefficients of magnets. I looked last month :- Ceramic magnets have a temperature coefficient of -0.18 to -0.2% per degree C. Radio Shack claim that the temperature coefficient of their ceramic magnets is -0.16%/degree C. They also quote 2250 Gauss. Nd-Fe-B permanent magnets have a temperature coefficient of -.09% to -.13% per degree C. Samarium Cobalt magnets have a temperature coefficient of -.03% to -.04% per degree C. Alnico has the lowest temperature coefficient of commercial magnetic material. However there are various 'grades' of Alnico. Alnico 5 at has a temperature coefficient 0.023%. Alnico 8H has a temperature coefficient of 0.012%, but it may only be available in in large quantity. I haven't yet got a figure for Ticonal. Anyone ..? See :- Bunting Magnetics for ALNICO 8HE on their website www.buntingmagnetics.com Arnold Engineering Company on http://www.grouparnold.com/products/alnico/pdf/sacatrev.pdf Regards, Chris Chapman __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Janicke book From: BOB BARNS roybar@........ Date: Tue, 13 Jun 2000 20:31:21 -0400 I heartily second the reccommendation of Janicke's book on magnetism. It is easy to understand and gives a lot of good info. Bob __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Passing solar flare geomagnetic shock wave? From: CapAAVSO@....... Date: Tue, 13 Jun 2000 22:12:26 EDT In a message dated 6/13/00 7:15:36 PM Eastern Daylight Time, ChrisAtUpw@....... writes: << .Funny that you should ask about temperature coefficients of magnets. I looked last month :- Ceramic magnets have a temperature coefficient of -0.18 to -0.2% per degree C. Radio Shack claim that the temperature coefficient of their ceramic magnets is -0.16%/degree C. They also quote 2250 Gauss. Nd-Fe-B permanent magnets have a temperature coefficient of -.09% to -.13% per degree C. Samarium Cobalt magnets have a temperature coefficient of -.03% to -.04% per degree C. Alnico has the lowest temperature coefficient of commercial magnetic material. However there are various 'grades' of Alnico. Alnico 5 at has a temperature coefficient 0.023%. Alnico 8H has a temperature coefficient of 0.012%, but it may only be available in in large quantity. I haven't yet got a figure for Ticonal. Anyone ..? See :- Bunting Magnetics for ALNICO 8HE on their website www.buntingmagnetics.com Arnold Engineering Company on http://www.grouparnold.com/products/alnico/pdf/sacatrev.pdf Regards, Chris Chapman >> ------------------------------------------------------------------------------ ------------- Hi Chris, Thanks for the very useful information about the temperature sensitivity of various magnets. The spring constant of the torsion wire that suspends the magnets is also temperature sensitive like the magnets but I don't know how their magnitudes compare or if they add (it would be nice if they canceled !!). Can somebody figure this one out? A magnet 1/4 inch diameter and 4 inches long is suspended on a 15-inch length of high carbon steel music wire ..008 inches in diameter. The torsion wire is twisted so the magnet points east and west instead of north and south as the magnet would like to do. Which direction will a temperature change rotate the magnet and how much is due to the magnet and how much to the torsion wire? Regards, Cap __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Another mu-metal/permalloy question (and magnetometer note) From: meredith lamb mlamb1@.......... Date: Tue, 13 Jun 2000 21:54:03 -0700 ChrisAtUpw@....... wrote: > If you had two concentric spheres, you would be able to apply a higher > external magnetic field before it started to penetrate the inner sphere. > > For your apparatus, I think you need an outer shield of Permalloy etc. to > reduce the effect of the low external fields and an internal shield to screen > the Permalloy from the core magnets. This shield might be silicon iron or you > might get away with mild steel. You might need two layers. > > Hope this qualitative description helps. > > Chris Chapman Chris, David, Al and all, Many thanks for the email replys to my original question, I've picked up your thoughts on it, and think I have a sufficient understanding now. Lacking alot of lab equipment for all this, about all I can do is perhaps apply some ribbon permalloy material to a shield and observe over time. With time I hope to have a second diamagnetic machine on line, and with both pointed in the same direction, one could be unshielded, and then a more visual comparison could be made with the SDR recording and perhaps additionally to a regular coil/magnet as the prospective "ideal". The most practical approach is too add layers if needed. ***************************************************** MAGNETOMETER THOUGHTS With reference to a magnetometer which uses a "string" and a magnet, its possible to use acouple layers of diamagnetic graphite with the magnet simply levitating in between (a regular diamagnetic stand, with overhead magnets). Of course it might need a reflective first surface mirror on a end of the single or multiple cluster of magnets for output (or other transducer means). Providing the graphite is diamagnetic enough and their is a stable temperature environment, and its far enough away from metallic/magnetic influences, it might suffer less temperature effects than is found possibly with a support "string" in the type previously mentioned. If the east -west orientation is desired, than another magnet could be placed nearby. A normal diamagnetic "stand" or machine is sensitive to temperature; but its in the vertical plane. I never tried this with my material in the city environment, and of course the goal was make a seismometer, so I added diamagnetic side "wedges" of graphite to limit its normal North-South or magnetic attraction to household items. Thanks again for all the generious help, from you all. Meredith Lamb __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Mu-Metal??? From: "Robert W. Avakian" ravakian@............ Date: