PSN-L Email List Message

Subject: Re: Lehman seismometer movement
From: Steinar Midtskogen steinar@.............
Date: Sun, 13 Mar 2011 14:16:08 +0100

"Jim and Connie Lehman"  writes:

> Steinar---I am not sure what arithmetic would come out at 2cm motion!!!

I don't know the math behind those graphs.  Theory and real life might
differ, though.

> If so you would be heading for open space rather than watching your
> pendulum.

Well, if the movement was 2 cm in two minutes, I'd say that there is
little need for panic.  And the movements that I saw of the boom were
also very slow.  It looked like it moved a couple of mm in half a
minute, then stopped, and then a minute later it seemed to have moved
perhaps 2 more mm in the same direction.  I wish I had thought of
setting up a video camera and then play it back at 100x speed.  The
seismometer saturated for nearly 2 hours, so it would have been plenty
of time to set this up.

My seismometer is N oriented.  My N geophone recorded the biggest
amplitude.  E slightly weaker, and Z barely visible without filtering.
The shortest path to Japan from here is roughly NNE.


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