PSN-L Email List Message

Subject: Re: Digital Inverse Filter
From: Bobhelenmcclure@.......
Date: Fri, 20 Jan 2006 22:50:58 EST


In my email of December 31, 2005, I was pessimistic about digitally =20
extending the low frequency response of a geophone to a value useful for  te=
leseisms.=20
However, I have been encouraged by my experiments  on data recorded by J=F3n=
=20
Fr=EDmann J=F3nsson of Iceland. Please inspect the  volume file=20
=20
"060117.015700.hvtzlp  Mb4.5 259km from Hvammstangi, Iceland  (Inverse=20
Filtered):  REYKJANES RIDGE"=20
=20
which I have submitted to the New PSN Earthquake Data Files list. This  is a=
=20
volume file consisting of two traces. The upper trace is the result of =20
applying "WQFilter.exe" to the data of the bottom trace. You will see that =20=
inverse=20
filtering has brought out microseisms and the longer period  components of t=
he=20
event. I set the Long Period filter to extend the  sensor period from 0.22=20
seconds to 4.0 seconds.
=20
Bob McClure





  In my email of December 31, 2005, I was pessimistic about digita= lly=20 extending the low frequency response of a geophone to a value useful for=20 teleseisms. However, I have been encouraged by my experiments=20 on data recorded by J=F3n Fr=EDmann J=F3nsson of Iceland. Please i= nspect the=20 volume file
 
"060117.015700.hvtzlp  Mb4.5 259km from Hvammstangi, Icelan= d=20 (Inverse Filtered):  REYKJANES RIDGE"
 
which I have submitted to the New PSN Earthquake Data Files list.=20= This=20 is a volume file consisting of two traces. The upper trace is the result of=20 applying "WQFilter.exe" to the data of the bottom trace. You will see that=20 inverse filtering has brought out microseisms and the longer period=20 components of the event. I set the Long Period filter to extend th= e=20 sensor period from 0.22 seconds to 4.0 seconds.
 
Bob McClure

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