More than fifty earthquakes have shaken the US State of California in the 14-hour period up to 2:00 p.m. GMT (6:00 a.m. PDT) Friday, according to the United States Geological Survey (USGS).

The quakes occurred throughout the Pacific coastal state, including the Greater Los Angeles area, San Diego and the San Francisco Bay area. The majority of the earthquakes ranged between 2-4 magnitude. Other areas to experience earth tremors include Holtville, Pinnacles, Johnville, Valle Vista, La Jolla, Anderson Springs, Hawthorns, Anza, The Geysers, San Carlos, Hemet and Keene.
Earthquake swarms are events where a local area experiences sequences of many earthquakes striking in a relatively short period of time. The length of time used to define the swarm itself varies, but the United States Geological Survey (USGS) points out that an event may be on the order of days, weeks, or months. They are differentiated from earthquakes succeeded by a series of aftershocks by the observation that no single earthquake in the sequence is obviously the main shock. Earthquake swarms also are one of the events typically preceding eruptions of volcanoes.

The earthquake swarm ends a relatively quite period for the seismically active State, which lies on the San Andreas Fault.

The most famous and most visible transform fault in the world is the San Andreas Fault. The enormous fault stretches for over 1,000 miles from northern California, through western California, to the East Pacific Rise beneath the waters of the Gulf of California. The Pacific Plate lies to the west of the San Andreas Fault and the North American Plate lies to the east. The western half of California lies on the Pacific Plate while the eastern half of California lies on the North American Plate.

Most recent earthquakes.