PSN-L Email List Message
Subject: Re: Instrument quality - microseisms
From: Thomas Dick dickthomas01@.............
Date: Thu, 22 Oct 2009 09:26:24 -0500
Barry Lotz wrote:
>
> To all
> Related to instrument quality- maybe. I have noticed a lot more
> microseismic activity the last few days. The background noise on my
> vertical is around +/- 300 counts @ 8.7 sec and 6.6 sec (two narrow
> peaks). I don't remember this magnitude in years past. I'm sure it is
> weather related. I live about 200 miles east of the west coast of
> northern California. Anyone else noticed an increase in background
> lately? Every time I look at the output I think I'm looking at surface
> waves after an event.
> Barry
>
From about the 9th of October until yesterday, I was getting very
strong peaks in the frequency range of .177Hz or period of 6 seconds
here in southern Indiana. Today that peak as disappeared and a lesser
peak exists at about .142 Hz or period of approximately 7 seconds. It
was so strong that I gave up posting earthquakes to the network because
they just weren't clear without strong filtering. I, too, looked for a
reason; Great Lakes, Gulf of Mexico and both the east and west coast. I
could find no real association. I had NO local winds and no serious
temperature changes.
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