Hi Dick,

You can see traces from a number of them on:

http://psn.quake.net/currentseismicity.html

They seem to do particularly well with local=20
events as their velocity response peaks at 1Hz.

The advantage of verticals is that the local site=20
noise will be much smaller in the vertical=20
direction, perhaps by 10 or 20x, while the size=20
of the earth motions are similar in the vertical=20
and horizontal.  You can often see much smaller=20
quakes on a vertical compared with a=20
horizontal.  (Note that I am unashamedly partial to verticals).

To be fair, verticals are more complicated to=20
make and for any kind of performance they will=20
need to involve feedback electronics as=20
with=20
http://bnordgren.org/seismo/gif_images.htm=20
There are a few less expensive commercial=20
verticals being sold, but they probably still=20
cost at least a couple $thousand and probably 3x=20
that for 3-axis.  See http://www.guralp.com   and=20
look at their EDU series as one possible example.

Regards,
Brett


At 02:45 AM 3/29/2010, you wrote:
>Hi All,
>
>I am reading the specs for the VolksMeter=20
>instrument. There is a 2-channel or single channel instrument.
>Is this a good one to get? Which one?
>Is there a better instrument to purchase near=20
>this price, including software and USB output?
>My funds are limited, but I would enjoy the features of this type=
 instrument.
>I have been told that this is a horizontal=20
>movement device and I would need one that includes a vertical sensor. True?
>I am at a stage where I do not want to re-invent=20
>the wheel, or piece something together. I've done that!
>
>I have some NICOLET Digital Oscilloscopes that I=20
>am willing to trade. I am a former service rep for NICOLET.
>While there, Sandia used this model of scope to=20
>document Earth tides. I still have a sales ad, showing the results.
>If interested I can scan it and place it on my Web Site as a pdf file.
>
>I am located in the high desert of Southern=20
>California, near the San Andreas fault.
>I was a participant to the former Seismic=20
>Pre-Cursor Net (W6FXN) on the 2-Meter HAM Band.
>This was when "dog and cat" reports were=20
>experimental and others measured water well heights.
>There was one prediction that came true:=20
>Whittier Quake near Whittier Narrows. I was prepared for that one (in=
 Anaheim).
>
>I always enjoy reading the messages, especially=20
>from J=F3n in the cold North. The expertise is too much for me to comment.
>Thanks to all!
>
>Regards,
>
>Dick Habegger, N6MAS
>amej@.............
>Phelan, CA
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