PSN-L Email List Message

Subject: Re: Really low stuff
From: Bob Hancock icarus@.........
Date: Tue, 29 Sep 2009 19:16:14 -0700

Hi Brett -

I recorded similar signals on both the vertical and north channel;  
however, my unit is on a cement pier which sits on dirt..........not  
very quiet.  I looked at data from 2000 - 2400, and saw other  
occurrences that had similar wave patterns.   One possibility is that  
these are surface wave packets from small aftershocks.

I found one aftershock , 21:51:01,  M 4.9, which could be the source  
of possible surface waves.   One other possibility is that these are  
wave packets of dispersive waves generated in the trailing coda of the  
main event.  I am not certain how either of these theories would hold  
up with professional seismologists, but offer them as two possibilities.

Bob Hancock

On Sep 29, 2009, at 5:17 PM, Brett Nordgren wrote:

> Hi all,
> As the Samoa quake was winding down, at about 23:04 UCT on the 50  
> sec vertical we see a very clear ~180 second signal that lasts for  
> about half an hour.  On the Trillium 120 Z channel it's much  
> bigger.  What's going on?  Is that what I think it is?
> Brett
> Watch our wiggles
> or watch some very very good wiggles
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