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Friday 19th September 2014
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Napa Valley Quake Due To Lesser-Known Fault

Tuesday, 2nd September 2014 13:58

An earthquake that shook Northern California this month was due to the lesser-known West Napa Fault, according to scientists studying images from a new satellite.

The magnitude 6.0 quake on August 24 injured three people and sent panicked residents out onto the streets of Napa and other cities.

It damaged homes and historic buildings, and sparked fires that caused further damage.

The wine-making region Napa Valley was among the hardest-hit areas.

The European Space Agency's satellite allowed scientists with the Centre for the Observation and Modelling of Earthquakes, Volcanoes and Tectonics (COMET) to map the earthquake and the surface rupture.

They determined that the West Napa Fault was responsible for the earthquake.

"This fault had not been identified as being particularly hazardous prior to the event," said a statement by University of Leeds, one of the institutions attached to COMET.

Faults are fractures between two blocks of rock that form the Earth's crust. 

There are several hundred known faults in California, including the San Andreas fault, which is extremely active and produces a major earthquake every 100 to 200 years.

The US Geological Survey said the Napa earthquake was the most powerful to hit the San Francisco Bay area since the Loma Prieta magnitude 6.9 earthquake in 1989.