for National Geographic News Seismologists have detected non-
volcanic tremors deep along the San Andreas Fault in central
California, near the epicenter of a 7.8-magnitude earthquake
that struck Fort Tejon in 1857. Such tremors had previously only
been recorded in subduction zones, such as Japan and the Pacific
Northwest, where one tectonic plate dives beneath another. The
San Andreas fault, on the other hand, forms what is known as a
transform plate boundary zone, an area where two plates slide
past each other. - Coming Soon: Your Local Earthquake Forecasts?
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Prediction Remains a Moving Target - 15 Years After Quake, San
Francisco Still Vulnerable - California Quake Zones May Be More
Lethal Than We Thought, Studies Say - Newfound L.A. Fault
Threatens Major Quake Scientists identified 110 tremor events
lasting four minutes or more in the Parkfield area of central
California during a three-year search period that ended with the
6.5-magnitude San Simeon e