PSN-L Email List Message

Subject: Re: Missing clear S wave from local event
From: Dave Nelson dave.nelson@...............
Date: Thu, 13 Dec 2012 17:40:47 +1100


Are you sure that is the P wave ??
it may be the S wave and the P is VERY small,
or more porobably, at only 22 km from you, you are seeing the P and the S
together as their arrival difference is only around 3 seconds apart

Dave

At 10:20 PM 12/12/2012 -0100, you wrote:
>Hi.
>
>Some months back i recorded a Ml1.8 event (epicenter at 22km), the P wave=
=20
>is perfectly noticed, but the S wave is somewhat lost.
>
>This is a picture of the earthquake (no filter applied)..i can get the sac=
=20
>file if anyone is interested. A IDA station located more near from the=20
>epicenter also have this "issue" in this earthquake, clear P wave, S wave=
=20
>bit lost.
>http://imageshack.us/a/img=
252/2303/12102012.png
>
>I=B4ve this video from another event (Ml2.9) near that area, also doesnt=20
>have a clear S wave.
>https://www.youtube.com/watc=
h?v=3Dj0P2y2ahDNg
>
>In the Ml1.8 event the lack of a clear S Wave is more evident, what=20
>happened to the S wave? This events occured near a volcanic region, but=20
>i=B4ve recorded earthquakes from other volcanic regions, and i have always=
 a=20
>clear P, S wave.
>
>I apreciate any thought on this.
>
>Regards,
>Tiago.

Are you sure that is the P wave ??
it may be the S wave and the P is VERY small,
or more porobably, at only 22 km from you, you are seeing the P and the S
together as their arrival difference is only around 3 seconds apart

Dave

At 10:20 PM 12/12/2012 -0100, you wrote:
Hi.

Some months back i recorded a Ml1.8 event (epicenter at 22km), the P wave is perfectly noticed, but the S wave is somewhat lost.

This is a picture of the earthquake (no filter applied)..i can get the sac file if anyone is interested. A IDA station located more near from the epicenter also have this "issue" in this earthquake, clear P wave, S wave bit lost.
http://imageshack.= us/a/img252/2303/12102012.png

I=B4ve this video from another event (Ml2.9) near that area, also doesnt have a clear S wave.
https://www.youtube.= com/watch?v=3Dj0P2y2ahDNg

In the Ml1.8 event the lack of a clear S Wave is more evident, what happened to the S wave? This events occured near a volcanic region, but i=B4ve recorded earthquakes from other volcanic regions, and i have always a clear P, S wave.

I apreciate any thought on this.

Regards,
Tiago.

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