PSN-L Email List Message

Subject: Re: Range of 4,5Hz geophone
From: ian ian@...........
Date: Sun, 08 Jan 2006 16:39:27 +0000


I wouldn't really expect to pick up a quake from Greece with a geophone 
at the distance you are at.  You really have to have a longer period 
device to detect it.  I'm not sure if the spike on my geophone was the P 
wave or just something local. 

Either way, the geophone spike was brief compared to the 90 minutes or 
so that the quake grumbled on for.  Maybe you should have a go at making 
something like a Lehman.  They're not too difficult and you probably 
have a spare channel on your amp and A/D.

I've spent the afternoon replacing the desk lamp in the enclosure with 3 
car lights.  I'm starting off by feeding them 5 volts from an old PC 
power supply.  If that isn't warm enough then I'll switch to 12 volts.  
Thanks to Chris Chapman for pointing this out, it's made a huge difference.



Jón Frímann wrote:

>Hi Ian and others.
>I didn't recored or see this earthquake on my geophone, something
>probaly shatters the wave before it reaches me or trims it down below
>the local noise. I know it was detected by the i.m.o siesmonitors. I
>have alot bigger amplitude on my geophone then before, so i hope to
>pickup earthquakes when they happen. I now record alot of noise, for
>instance i see alot more wind being picked up by my geophone, even if it
>is inside and well isolated.

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