Hello Cruel world;

It seems to me that may be possible for preceeding compression or rarification
to cause a change in the material itself ( earth ) that may change
the frequecies it is able to propagate. This quiet may be like
when the water receeds at the beach just before the tsunami hits
the beach. Possibly the noise is shifted in frequency to the
point that the hardware is filtering it out ??


(e.g. Modulating the general background noise in frequency.)

I have a very narrow range I am looking at.
Effectively, Like, 7 seconds to 2 Hz.

BTW ( by the way ) does any of you play in the news groups ?

I have been trying to post to a binary news group called
alt.binaries.schematics.electronics
what are called Yenc files. It is my preferred method of
dealing with the general internet. News groups i mean.
Do any of you play there also ?
(seismically I mean, not socially)

Sometimes on these groups it seems a mysterious entity
is destroying otherwise complete files. A removal of a single
file in a group is disasterous since all are needed
to rebuild a complete whole.
Can anyone tell me who would be killing from a server
these important fragments of a whole ?

Seems to me like some kind of CYBER VANDALISM.

KILL == DELETE when it comes to files.
KILL is a BASIC programming command word as well as delete.
Im not talking violence here, Im talking programming.

geoff


----- Original Message ----- 
From: "Brett Nordgren" 
To: 
Sent: Thursday, September 03, 2009 6:16 AM
Subject: RE: ARRIVAL TIMES: Quiet Before The Storm


> Hi Steve and Geoffry,
> 
> I have been wondering about your filtering.  I assume that you are looking 
> at filtered data.  There is a type of very effective digital filter 
> described as IIR, Infinite Impulse Response, which is in a class of filters 
> called non-causal.  If that is what Larry, or the writer of your filter 
> program is using, then it might be possible to get false precursors to a 
> large, sudden signal.
> 
> In effect these filters "look into the future", using as part of their 
> input, recorded data which is later in time than the output point being 
> calculated.  In that way it is possible for them to generate the 
> precursors, though how much earlier and how large those might be will 
> depend on the details of the filter routine.  Or then again, maybe it's 
> something real.
> 
> There is one wave that could be described as a pre-P wave, called the Pn, 
> which is only seen in the nearer quakes, in which part of the P wave takes 
> the fast lane along the top of the Moho, arriving before the regular P 
> phase would.  The USGS travel time program usually includes the Pn time 
> when the quake is close enough.  The Pn was quite clear from one quake in 
> Mexico as seen in Los Angeles, though I don't think is could precede the P 
> for one as close as 25km.
> 
> Regards,
> Brett
> 
> At 10:06 PM 9/2/2009 -0700, you wrote:
> 
>>I also noticed an anomaly in local events within 20-25km south of my old 
>>San Jose location when I lived in south San Jose. My house was located 
>>between the San Andreas and Calaveras faults and I had data from both 
>>faults that had something going on just before the P wave arrived. I 
>>showed John Lahr the data and asked if there was such a thing as  a  pre-P 
>>wave and he told me there was not. I finally figured that it was a just a 
>>flaw in the sensor.
>>
>>Regards, Steve Hammond
>>
>>From: psn-l-request@.............. [mailto:psn-l-request@............... 
>>On Behalf Of Barry Lotz
>>Sent: Wednesday, September 02, 2009 6:54 PM
>>To: psn-l@..............
>>Subject: Re: ARRIVAL TIMES: Quiet Before The Storm
>>
>>
>>
>>Geoffrey
>>I've also noticed this for quite some time. I thought it was my sensors. 
>>Maybe not.
>>Regards
>>Barry
>>
>>
>>--- On Wed, 9/2/09, Geoffrey  wrote:
>>
>>
>>From: Geoffrey 
>>Subject: ARRIVAL TIMES: Quiet Before The Storm
>>To: "PSN-LIST" 
>>Date: Wednesday, September 2, 2009, 5:50 PM
>>
>>I have noticed in some Earthquakes you seem to notice
>>a short increase in quietness just before the impulse arrives.
>>
>>Is this a real phenomena or simply a coincidence ?
>>
>>Does this mean the real arrival time is
>>the beginning of the noticeable quiet ?
>>
>>WHY THE QUIET ??
>>What physics would possibly muffle the noise ?
>>
>>arrival of Possibly eP instead of simply P ?
>>
>>Also,
>>
>>What is the preferred format for a PSN files data ?
>>FLOAT or INTEGER
>>16 bit or 32 ?
>>
>>My data is all 8 bit So should I expand it to
>>meet the new format ?
>>
>>Comments ?
>>
>>geoff
>>__________________________________________________________
> 
> Watch our wiggles
> http://bnordgren.org/seismo/gif_images.htm
> 
> or watch some very very good wiggles
> http://aslwww.cr.usgs.gov/Seismic_Data/telemetry_data/ANMO_24hr.html
> 
> 
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