A magnitude 6.0 earthquake has struck 6 km northwest of American Canyon, California. It took place at 03.20 local time at the shallow depth of 10.7 km. No fatalities have been reported but 87 people have been emitted to hospitals for injuries, only 3 of which are said to be serious.
Officials have said roughly 50 gas mains and about 30 water mains have broken. Approximately 10,000 homes are currently without power after what has been the strongest earthquake California has felt in almost 25years.
The quake occurred in a stretch of fault systems just off the San Andreas fault where the Pacific plate is moving northwestward relative to the North American plate. The epicenter lay between two major active fault systems: the Hayward-Rodgers Creek Fault system in the west and the Concord-Green Valley Fault system in the east. The area is historically know for intense and damaging earthquakes such as the M 7.8 1906 San Andreas Fault and M 6.8 1868 Hayward Fault earthquakes. This region finds earthquakes particularly destructive as they are underlain by landfill and bay muds so soil failure and amplified s-waves are common during earthquakes.The Earthquake Early Warning test system functioned as designed in Sunday’s earthquake. Within five seconds of the earthquake it produced a warning (estimated at magnitude 5.7 within three seconds of its occurrence), sufficient to provide warning to Berkeley, San Francisco, and areas farther south. The EEW prototype was developed by the USGS in partnership with the UC Berkeley, California Institute of Technology, University of Washington, and the Gordon and Betty Moore Foundation.
Luckily it is also one of the most studied fault systems in the world in a country wealthy enough to have in place the California Governor’s Office of Emergency Services, regular earth quake drills and strongly enforced building regulations all to minimize risk.