PSN-L Email List Message

Subject: Vertical sensors
From: "Roger Sparks" rsparks@...........
Date: Mon, 23 Dec 2002 09:23:15 -0800

Hi Larry,

Regarding vertical seismometers, I built one and have been very happy with
it.  Mauro Mariotti has some pictures of it on his site at  The pictures of my sensor are at
the end of a very long page on vertical sensors.

I am using the amplifier board from Dave Saum and the Amaseis software from
Allen Jones.  I am picking up about one earthquake a day average from
distant parts of the world in addition to local quakes here in Washington

One big problem for me is the background noise that I am told results from
wave action along the pacific coast.  Living about 200 miles inland, I
notice that the signal from many quakes is hidden in the background noise.
I recently added a 1 Hz filter/resonator loop to the Amaseis program which
is very effective in bringing the quake out of the noise.

Comments that indicate that the vertical sensor is affected by local noise
and air pressure changes are correct.  All the bigger quakes have a much
different pattern from local noise so are easily distinguished.  I can see a
distinctive pattern resulting from walking to the mail box, walking into the
room where the seismometer is located (my office ), and kitchen activity.
Yes, local noise can cover a quake signal but you can still see lots of
seismic activity during local quiet periods.

This is my first seismic project, and I have only been active in seismology
for about a year so I have a lot  to learn.  Never-the-less, I am very happy
with my vertical sensor and have seen a lot of distant quakes with it.

Best wishes,


> .------ ------ ------ ------ ------ ------ ------ ------ ------ ------.
> | Message 1                                                           |
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> Subject: Vertical "SG" sensor?
> From:    "Larry Conklin" 
> Date:    Tue, 17 Dec 2002 14:10:30 -0500
> Hi all,
> I've been thinking about building a vertical sensor.  One design I've been
> considering would use a bowed leaf spring similar to the Sean-Thomas
> Morisssey design, combined with the differential capacitor sensor using
> Larry's SG electronics board.  I'd be interested in hearing whether anyone
> else has tried this or if anyone has any thoughts regarding the viability
> this approach.
> Larry Conklin
> Liverpool, NY
> lconklin@............



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