Earthquake Hazards in California

The first earthquake happend in Los Angeles 1796 by tha San Andreas Fault. In January 1857 neart Fort Tejon there was another earthquake that threw buildings down and large trees.

http://earthquake.usgs.gov/earthquakes/states/index.php?regionID=5

Seismic Waves

http://en.wikipedia.org/wiki/Seismic_wave

Seismic waves are the waves of enery caused by the sudden break of rock within in the earth. The waves are energy that travel through the earth and is recorded on seismographs.