PSN-L Email List Message

Subject: Re: a possible seismometer?
From: George Bush ke6pxp@.......
Date: Tue, 09 Dec 2008 10:15:15 -0800

Hi all-

Since Chris has mentioned me (or at least my email address), I thought I
would share some of my experiences with trying to build an updated
Mercury Tiltmeter. These instruments detect quakes, but my interest was
in Earth tides and other low freq phemomena. I constructred a tiltmeter
following the design in the Scientific American article but with a
capacitance sensor as suggested by Chris. Please see for
construction details. Sorry the site is not current and doesn't have the
new circuit on it as I consider it a work in progress. So far I have been
defeated by the thermal problems. I have the unit mounted in a solid foam
insulating chamber with a heated plate at the top to stratify the air
currents. But even with all of that it is just a VERRY expensive
(especially in time spent) thermometer!!!

There are successful instruments based on this principle around the
world, especially in Europe where one unit has cups separated by 100m of
tubing and is installed in an old mine tunnel. My plans are to completely
rebuild my unit with the cups separated to the ends of my gargage to
increase the sensitivity and install a motor-driven compensator, as
suggested in the Gile article, to balance out the thermal expansion of
the Hg. 

I hope this helps- George 

At 07:21 AM 12/9/2008 EST, you wrote: 


In a message dated 09/12/2008, rlthomasson@......... writes:

I have that CD but dang if I can find the article with the
built-in search function.  Do you happen to recall about what month and
year it was?

Hi Bob,


    Try Stong, CL The Amateur Scientist, Sci. Am. mag., Nov. 1973 pp
124-129 "The mercury tiltmeter."

    The detector electronics needs a re-design. George Bush has a good
updated circuit <ke6pxp@.......


    A large professional Hg seismometer designed by Benoit is described
by Gile, WW, Geophys. J. Roy. Astro. Soc. vol 36 1974 pp 153-165 "A
Mercury Pendulum Seismometer"




    Chris Chapman



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