Natural Hazards and Disasters: Earthquake strikes California

Sunday 24 August 2014

Earthquake strikes California

An earthquake measuring 6.0 struck Northern California on 24 August at 3:20 local time. The earthquake had a depth of 10.7 km (6.6 miles) and was located 6 km (4 miles) NW of American Canyon and 9 km (6 miles) SSW of Napa. Several smaller aftershocks have followed the main event. It is the largest earthquake to hit Bay Area since the magnitude 6.9 Loma Prieta earthquake in 1989.

In Napa, 89 people have been injured, of which 3 are serious. Fortunately no deaths have been reported so far. 69,000 people have also been left without power. The earthquake has caused significant damage in Napa and American Canyon. Bridges and roads have been damaged including a bridge in American Canyon which has been closed due to the damage sustained.

Several historical buildings in Napa have been severely damaged, which includes the City Hall and two commercial buildings. Fires caused by the earthquakes destroyed four mobile homes. According to reports there were approximately 50 gas main breaks and 60 leaks from damaged water mains.

The earthquake was caused by the San Andreas fault system which is where the Pacific is moving northwest in relation to the North American plate.This movement causes a right lateral slip across the faults. According to the USGS the location of the earthquake was near the West Napa Fault which is located between two major strike slip fault systems; the Hayward-Rodgers Creek Fault system on the west and the Concord-Green Valley Fault system on the east.

As assessments are carried out, the extent and severity of the damage will become clear over the next few hours or days.

A state of emergency has been declared by the California Governor Jerry Brown.