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Great Shakeout: California Prepares For Powerful Earthquakes

Loma Prieta earthquake damages house
A house remains intact, though its porch collapsed, following the 1989 Loma Prieta earthquake in Northern California. Experts say it's safer to stay in place during an earthquake. (Image credit: H.G. Wilshire , U.S. Geological Survey)

Most people create their own earthquake hazards.

When a quake hits, the first instinct for many is to run outdoors or huddle in a doorway. But as hundreds of YouTube videos prove, powerful earthquakes send furniture and glass flying and fracture buildings, raining down debris.

Instead, experts say the safest place during a big earthquake is under a desk or table, where you can drop, cover and hold on.

"If you think back to big earthquakes around the world, the people who survived were those who were underneath something that protected them from debris falling down on them," said Steve Walter, a seismologist with the U.S. Geological Survey in Menlo Park, Calif. Tomorrow (Oct. 18) more than 9 million California residents plan to practice dropping and covering at 10:18 a.m. PDT, during the Great American Shakeout.

Golden State Shakeout

In all, more than 14 million people are expected to participate in the 60-second exercise, including along the Pacific coast of Alaska and British Columbia. This year marks the first time the Shakeout will be observed in parts of the eastern United States (where people also will drop and cover at 10:18 local time – a time of day picked to coincide with the date).

"This provides a once-a-year reminder that we live in areas that can be strongly shaken at any time," Walter told OurAmazingPlanet.

The event aims to raise awareness among residents with little firsthand experience of powerful quakes, and to correct misperceptions about what to do when the ground trembles.

Leading up to the Shakeout, local, state and federal agencies will practice responding to a magnitude 7.6 shaker on the San Andreas Fault today, the anniversary of the 1989 Loma Prieta quake, which killed dozens of people in the San Francisco area.

People underestimate the power of earthquakes, Shakeout organizers say. While earthquake intensity depends on myriad conditions, even a relatively small event of magnitude 6.3 can produce waves more powerful than the force of gravity. The waves can knock you off your feet and make it impossible to walk. The intense back-and-forth motions will cause the floor or the ground to jerk sideways out from under you, and every unsecured object could topple, fall or become airborne. [Video – What Does Earthquake 'Magnitude' Mean?]

Don't underestimate quake's power

But California's stringent building codes mean offices and homes are unlikely to collapse during a quake, said Cindy Pridmore, an engineering geologist with the California Geological Survey in Sacramento. That's why experts advise residents to stay in place and find cover there. Most quake-related injuries come from flying TVs, falling fridges, stepping in broken glass, and tripping and twisting or breaking bones, Pridmore told OurAmazingPlanet.

And contrary to what many have been told, those building codes also mean doorframes are no stronger than the rest of the building. In a doorframe, you're more likely to be slammed by swinging doors.

"A doorframe has no structural integrity, and it could even be a weak spot," said Pridmore, who remembers her mother yelling at her to get in a doorway during the 1971 Sylmar quake in Southern California.

"Protect your head and neck. It's been proven statistically to be the best thing to do, and it's the easiest," Pridmore said. [Natural Disasters: Top 10 US Threats]

A view of damage to a kitchen in a townhouse near the Northridge Fashion Center in Southern California. According to the U.S. Geological Survey, an occupant cut her foot on glass when she ran into the kitchen area in the predawn hours after the Jan. 17, 1994 earthquake. Electrical power to the area was out at the time following the magnitude 6.8 quake. (Image credit: J. Dewey. U.S. Geological Survey)

If it's night, stay in bed unless something heavy could fall on you. (And if you live in earthquake country, the Shakeout is a good reminder to evaluate your living space. Move anything that's heavy enough to crush you in bed.)

Another reason to stay inside: falling brick and glass. Pridmore cites online videos showing panicked shoppers trying to escape a grocery store through its sole exit, exposing them to falling brick and shattering glass.

"People should not panic in a building. Drop, cover and protect your neck and spine, and wait until the shaking stops," Pridmore said. If outdoors, move as far away as possible from buildings, trees and power lines.

The Great American Shakeout began in 2008, following the centennial of the 1906 San Francisco earthquake.

"When you realize that maybe 10 percent of people in the area have made any preparation at all, it just seems like the right thing to encourage them to think about it on an annual basis," said Walter, who uses the Shakeout as a reminder to restock his emergency food and water supplies and donate the old stash to a local food bank. "Every year, if people do a little more or do an additional step of preparation, we'll be that much better to withstand the next big earthquake here in the Bay Area."

West Coast risk

California coastal areas and inland along the San Andreas Fault are at risk of powerful shaking. Many faults are overdue for a quake. But even the Golden State's inland valleys aren't immune. Sacramento, the state capital, could still feel the effects of a major quake, Pridmore said. Sacramento is the same distance from the Hayward Fault as San Francisco was from the center of the Loma Prieta quake, she said.

The California Geological Survey publishes a seismic shaking hazard map for California.

Farther north, Oregon and Washington state potentially face the same one-two punch as Japan's devastating earthquake and tsunami.

To sign up for the Shakeout, visit http://www.shakeout.org. And remember these steps:

  • DROP down onto your hands and knees (before the earthquake knocks you down). This position protects you from falling while allowing you to  move if necessary.
  • COVER your head and neck (and the rest of your body if possible) under a sturdy table or desk. If there is no such shelter nearby, only then should you get down near an interior wall (or next to low-lying furniture that won't fall on you) and cover your head and neck with your arms and hands.
  • HOLD ON to your shelter (or to your head and neck) until the shaking stops. Be prepared to move with your shelter if it is shifted around by the shaking.

Reach Becky Oskin at boskin@techmedianetwork.com. Follow her on Twitter @beckyoskin. Follow OurAmazingPlanet on Twitter @OAPlanet. We're also on Facebook and Google+.

Becky Oskin
Contributing Writer
Becky Oskin covers Earth science, climate change and space, as well as general science topics. Becky was a science reporter at Live Science and The Pasadena Star-News; she has freelanced for New Scientist and the American Institute of Physics. She earned a master's degree in geology from Caltech, a bachelor's degree from Washington State University, and a graduate certificate in science writing from the University of California, Santa Cruz.