California Earthquake Activity
California is one of the most tectonically active regions of the world. The North America plate and the Pacific plate border each other only a few miles from the west coast of California. As these plates move in a north and south direction, hundreds of quakes occur across California every year. The quakes occur because the plates do not move smoothly and stresses build. The stress on the plates is released in the form of earthquakes. Most of the quakes are small, but there is an occasional large quake. The main fault that runs along the state is called the San Andreas Fault and is described as a transform fault.
This live image displays the data recorded by hundreds of seismic detectors placed across the state. You may view the page sponsored by the USGS Earthquake Hazards Program of Southern California at http://pasadena.wr.usgs.gov/recenteqs/latest.htm.
Link: Recent Earthquakes in California (USGS)
Link: Southern California Earthquake Data Center (Caltech)