PSN-L Email List Message

Subject: RE: Honduras Quake 5/28/09
From: Brett Nordgren brett3nt@.............
Date: Thu, 28 May 2009 20:49:14 -0400


Kareem,

Here's a waveform of that quake from a good broadband vertical in Southern 
California.

http://bnordgren.org/seismo/090528.083000.bhz-ph.psn.gif

The surface waves are usually around 20 seconds from each peak to the next 
and they definitely show up nicely on the broadband, though I wouldn't 
expect an ordinary geophone to have much sensitivity down at 0.05 Hz.   As 
you can see, the S wave is fairly weak, as is usual with a vertical.

Regards,
Brett

At 02:48 PM 5/28/2009 -0700, you wrote:
>Question:
>
>Since Rayleigh waves are vertical but vertical geophones are more designed
>for vertical, higher frequency motions, would the geophone still pick up
>these Rayleigh waves very well?
>
>Also, in regard to the 20 second statement, does this mean that twenty
>seconds pass before the second wave crest passes the sensor's location? What
>does that look like on the seismogram? Seems like the record wouldn't
>display much of a dramatic signature would it? Or would it display smooth
>wavy lines?


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