PSN-L Email List Message
Subject: Re: Instrument quality - microseisms
From: Larry Conklin lconklin@............
Date: Thu, 22 Oct 2009 10:11:31 -0400
My experience has been that around this time of year the microseisms
have a tendency to turn into "megaseisms". They can get so strong that
they pretty much obscure the P/S arrivals of all but the strongest
events. I live in central New York, so I customarily compare my data
with the Lamont-Doherty 24 hour helicorder at
When I am getting clobbered, they typically are too. Interestingly, and
I can't quantify it, the rise and fall of the strength of the noise
seems to be offset by an hour of two between their data an mine. I
can't think of a plausible explanation, other than I may be imagining it.
The other thing I would love to hear an explanation for is why the
microseism noise is so narrow band. When it is strong, it looks
virtually sinusoidal on the monitor, and an FFT of the data shows a very
narrow peak. Does anyone know why that is?
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