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.