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.
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?
> Watch our wiggles
> or watch some very very good wiggles
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