The United States Geological Survey recorded a Magnitude 3.4 Earthquake at a depth of 3.4 km approximately 130 km north of San Francisco and 115 km west of Sacramento at 3.40 pm local time (10.40 pm GMT) on Sunday 14 July 2013. There are not likely to be any damage or casualties from this quake, and there are no reports of anybody having felt it, though it is likely that it was noticeable in the Geysers and Clearlake areas.
The location of the 14 July north California Earthquake. Google Maps.
California is extremely prone to Earthquakes due to the presence of the San Andreas Fault, a tectonic plate margin that effectively bisects the state. The west of California, including Santa Barbara and Los Angeles, is located on the Pacific Plate, and is moving to the northwest. The east of California, including Fresno and Bakersfield is on the North American Plate, and is moving to the southeast. The plates do not move smoothly past one-another, but constantly stick together then break apart as the pressure builds up. This has led to a network of smaller faults that criss-cross the state, so that Earthquakes can effectively occur anywhere.
Witness accounts of Earthquakes can help geologists to understand these events and the underlying structures that cause them. If you felt this quake (or if you were in the area but did not, which is also useful information) then you can report it to the United States Geological Survey here.
See also Magnitude 3.9 Earthquake in north California, Earthquake off the coast of Isla Vista, California, Northeast California shaken by Magnitude 5.7 Earthquake, Los Angeles shaken by Earthquake and Central California shaken by Earthquake.
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