The United States Geological Survey recorded a Magnitude 4.5 Earthquake at a depth of 2.6 km, 6 km to the north of The Geysers in Sonoma County, northern California, slightly before 12.25 pm local time (slightly before 8.25 pm GMT) on Sunday 12 January 2014. There are no reports of any damage or casualties associated with this event, though people in the area reported feeling strong shaking for 15-20 seconds.
The approximate location of the 12 January 2014 Sonoma County 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 3.0 Earthquake in Mendocino County, California, Magnitude 2.6 Earthquake in northeast Sonoma County, California, Magnitude 4.5 Earthquake off the coast of northern California, Magnitude 3.4 Earthquake in northern California and Northeast California shaken by Magnitude 5.7 Earthquake.
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