Survival Homestead

Source: Reuters

Southern Californians simultaneously dropped to the floor and huddled under tables and desks for two minutes of imagined seismic turmoil on Thursday in the biggest U.S. earthquake drill.

The Great Southern California ShakeOut was organized by scientists and emergency officials as part of a campaign to prepare the state’s 22 million inhabitants for a catastrophic quake that experts say is inevitable and long overdue.

The drill is based on the premise of a magnitude 7.8 quake striking the southern portion of the famed San Andreas Fault, a subterranean chasm between two massive plates of the Earth’s crust that extends hundreds of miles (km) across the state.

The hypothetical quake, similar in strength to the devastating tremor that hit China in May, also is the basis for this year’s annual Golden Guardian exercise — a days-long disaster simulation for emergency-response agencies statewide.

“This helps us hone our skills,” said Patricia Aidem, a spokeswoman for Providence Holy Cross Medical Center in suburban Los Angeles, whose trauma center is taking part in the larger mass-casualty drill.

“We live in earthquake country, so being prepared to help the public is just an amazing advantage for the community.”

Teaching people quake survival skills also “means fewer patients for us,” she added.

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Source: Hayward Fault Scenario Earthquakes

In 2008 the USGS led a collaborative effort with URS Corporation, Lawrence Livermore National Laboratory, Stanford University, and the University of California at Berkeley to create computer simulations of large, anticipated earthquakes on the Hayward and Rodgers Creek faults. The most recent large earthquake on the Hayward fault was in 1868, 140 years ago. Because the past five large earthquakes on the Hayward fault have been about 140 years apart, the Hayward and Rodgers Creek faults are the most likely faults to produce a large earthquake in the Bay Area. These computer simulations of scenario (or anticipated) earthquakes provide detailed pictures of what shaking we should expect in such earthquakes. These computer models capture the shaking at length scales larger than about 300 ft (100 m), so they do not include the effects of very thin, soft sediments, such as Bay Mud around the perimeter of San Francisco Bay. For areas with these thin, soft sediments the shaking would be stronger than what is shown in the animations.

The computer simulations include a total of seven earthquake scenarios: three magnitude 6.8 scenarios with different starting locations (epicenters), three magnitude 7.0 scenarios with different starting locations, and one magnitude 7.2 scenario. The next large earthquake on the Hayward fault will likely fall in the range of magnitude 6.8-7.0. The magnitude 6.8 and magnitude 7.0 scenario earthquakes provide detailed examples of the type of shaking we should expect in such an event. The magnitude 7.2 scenario earthquake, while possible, is a much less likely event involving simultaneous rupture of both the Hayward and Rodgers Creek faults.

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