Sciency Thoughts: Over 150 injured after Earthquake in Napa County, California.

The United States Geological Survey recorded a Magnitude 6.0 Earthquake at a depth of 11.3 km in southern Napa County, California, at about 3.20 am local time (bout 10.20 am GMT) on Sunday 24 August 2014. This was a fairly large event, and the Queen of the Valley Medical Center in Napa City has reported 172 people being treated for injuries, three of them serious, one of whom has been described as a child. A large amount of damage has also been reported, with six fire breaking out as a result of the event, and 33 buildings in Napa City declared unsafe to enter due to damage. The area has been hit by a number of aftershocks following the initial event.

A building in Napa City, California, damaged by the 24 August 2014 Earthquake. AFP.

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 in the state.

The approximate location of the 24 August 2014 Napa County Earthquake. Google Maps.

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.

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