PSN-L Email List Message

Subject: Re: 2 items of seis interest on ebay
From: Doug Crice dcrice@............
Date: Thu, 07 Feb 2002 09:29:49 -0800

For hammer work, you use sample rates on the order of 100 microseconds
(10,000 sample/sec). The veolcities might run something like this:

Soil	1000-2000 ft/sec (300-600 m/s)
clays, weathered rock	2000-5000 ft/sec (600-1500 m/s)
groundwater	5000 ft/sec (1500 m/s)
bedrock	5000-15000 ft/sec (1500-7500 m/s)

So, even though the block diagram is similar, you scale the frequencies
about three orders of magnitude. Modern exploration seismographs can be
seen at my old company  Anybody who wants to
look at the solutions in more detail should go to and download the booklet "Seismic 
Refraction Exploration for Engineering Site Investigations"


Jack Ivey wrote:
> Doug,
> It sounds like most of the people on this list would have
> the equipment needed to reproduce the gadgets listed.
> Would it be practical to throw a geophone in the
> back yard and try this as a weekend project or is some
> magic done inside the box?  What kind of sample rate would
> they use?

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