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?

Larry Conklin
Liverpool, NY

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