Richard,

The problem with a 14hz sensor is that local earthquakes produce information
mostly in the 1 to 5 hz range. A 4.5 Hz sensor will just barely record local
events or the P wave of a very large teleseismic event. A 14Hz sensor will
produce very little voltage at 5 Hz, so I can't imagine it working very well to
record earthquakes.

What I would do is make a Lehman since it can be used to record local and
teleseismic events.

Regards,
Larry Cochrane
Redwood City, PSN

----- Original Message ----- 
From: "Richard Schwaninger" 
To: 
Sent: Tuesday, June 24, 2003 10:48 PM
Subject: Re: Geosource MD-100 geophones


> Jim,
>
> Thanks for the comments. About the frequency response. Are these
> geophones
> damped to such a large extent that even if I roll off the output at,
> say,
> 10 Hz, I still wouldn't have anything resembling a useful output? I only
> intend these to monitor local events. I've figured it easier to first
> look
> at local events with commercial sensors and work on the electronics and
> data gathering/recording. Later I do intend to construct some other
> sensors for teleseisms.
>
> Thanks again,
>
> Richard
>
> Jim ODonnell wrote:
> >
> > Hi Richard-  The Geosource is a good geophone, but not adequate for
> > earthquake recording, too high a frequency response at 14 Hz, you will
> > need the 4.5 Hz or 1 Hz response.  Your questions and many more you have,
> > can be anwsered by going to the Public Seismic Network web page-
> > http://psn.quake.net/geophone/index.html for geophones that can record
> > earthquakes.
> >
> > More general information is at:  http://psn.quake.net
> >
> > Yes Pleasanton is an active area...
> > Best Regards-
> > Jim O'Donnell
> > UNLV
> > On Mon, 23 Jun 2003 22:55:20 -0700 Richard Schwaninger
> >  writes:
> > > Hello group.
> > >
> > > I'm new here but have a couple of questions. Please excuse me if
> > > this
> > > has been answered before, I did do a quick search and didn't come
> > > up
> > > with anything. If so please point me to the right place - archive
> > > or
> > > google.
> > >
> > > I'm in Pleasanton, and so should have something to look at every
> > > once in
> > > a while. I'm starting to set something up at home. I thought I'd
> > > first
> > > look for local events and so purchased a few Geosource MD-100
> > > geophones.
> > > They are labeled 14Hz, 330 Ohms.
> > >
> > > Looking at pictures, I've seen similar units arranged in a cluster
> > > in a
> > > X-Y-Z configuration. The MD-100s I have only work in one axis, so I
> > > figure I will not be able to construct a 3 axis unit with these
> > > geophones? Is there a work-around? Are there other available (in the
> > > $20
> > > range) units which work on their sides?
> > >
> > > The second question, which really should of been first, is: are
> > > these
> > > geophones adequate or appropriate for monitoring local events?
> > >
> > > Thanks for any information.
> > >
> > > Richard
> > >
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