Several references which are good beginning books in understanding earthquakes are:

Bruce Bolt, 1978, "Earthquakes: A primer", published by Freeman of San Francisco
and

Don DeNevi, 1977, "Earthquakes", published by Celestial Arts, Millbrae, California

We would also be happy to send you some material aimed at the average
citizen on earthquakes. If you would like some of this, please contact me at my
e-mail and send your postal mail address (do not post your mailing address on
this board for reasons of privacy):
low@luna.ngdc.noaa.gov