The United States Geological Survey
recorded a Magnitude 4.0 Earthquake at a depth of about 11.1 km roughly 14 km to the northeast of the town of Julian in San Diego County, California,
slightly after 4.30 pm local time on Wednesday 6 December 2017 (slightly after 0.30 am on Thursday 7 December GMT). There
are no reports of any damage or injuries relating to
this quake, but people have reported feeling it across much of southern California and parts of northeastern Baja California, Mexico.
The approximate location of the 6 December 2017 San Diego County Earthquake. USGS.
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...
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