PSN-L Email List Message
Subject: Strange geophone pattern
From: Steinar Midtskogen steinar@.............
Date: Thu, 11 Sep 2008 10:36:05 +0200
I have a Mark Products 4.5 Hz 3 component L15B geophone, and since the
two major earthquakes in Indonesia and Hokkaido happened during the
night here when the local noise is low, I thought it would be
interesting to see whether such quakes show up at all on a geophone.
Apparently, they didn't, but I found a strange pattern repeating every
25 minutes:
http://voksenlia.net/met/seismometer/geo.jpg
Does anyone have any ideas what could cause this?
Perhaps an airconditioner two floors above? Then it seems to run
through some kind of program that I wasn't aware of. Or perhaps a
neighbour runnings some kind of machinery going through cycles?
The datalogger is fanless and diskless, so it shouldn't cause any
vibrations.
--
Steinar
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