Dear Stuart,

In order to determine the direction from a seismic station to 
an earthquake, three seismometers need to be run at the seismic 
station.  One for up/down (vertical) motion, one for east/west 
(horizontal) motion and one for north/south (horizontal) motion.  
This is a tall order indeed!

You might want to consider building the table-top seismology 
demonstration that is described here:
http://lahr.org/john-jan/TableTop/index.html
This setup uses a single vertical seismometer, so you will not
be able to investigate the direction the waves are traveling.  
However you could experiment with the effect of friction on the
size and frequency of earthquakes.

Hope this helps a bit.

Cheers,

JCLahr

################################## John C. Lahr
################################# Seismologist
################################ U.S. Geological Survey
############################### Geologic Hazards Team, MS966
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Denver, Colorado 80225-0046 ################################
    Phone: (303) 273-8596 ##################################
     Fax: (303) 273-8600 ###################################
         lahr@........ #####################################
                http://giseis.alaska.edu/lahr
               http://lahr.org/john-jan


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