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.

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"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.

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?]

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.

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.

"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."

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.

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.