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Alaska stands on shaky ground

State prone to big and frequent quakes

Posted: Monday, April 03, 2006

ANCHORAGE - The perky "cock-a-doodle-doo" of a rooster sounds in Roger Smith's office every time an earthquake rumbles beneath Alaska.

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Temblors throughout the state trigger the computer-generated crow about 60 times a day - roughly 22,000 times a year - in the office of Smith, director of the Geophysical Institute on the University of Alaska Fairbanks campus.

"It's just part of the background," said Smith. "The rooster is a good reminder that the earth's surface in Alaska is very active."

Although California gets most of the attention when it comes to earthquakes, especially with the 100th anniversary of the Great San Francisco Earthquake on April 18, 1906, Alaska is America's true seismic hotspot.

Seven of the 10 largest earthquakes in the U.S. have occurred in Alaska, which vibrates with 11 percent of the world's temblors each year.

More earthquakes occur here each year than in any other U.S. state, although the recorded total of quake-related deaths is much greater in California. Of the largest quakes in U.S. history, the 1906 San Francisco quake ranks 18th in magnitude, but it was the deadliest, with estimates of fatalities ranging as high as 6,000.

"California is more highly populated and so earthquakes matter more to the population, but here we get many more earthquakes," Smith said. Census estimates from 2004 put California's population at almost 36 million people, while about 655,000 people live in Alaska.

Alaska's most devastating quake, on March 27, 1964, still darkens the collective memory of longtime residents. The magnitude 9.2 earthquake, focused in Prince William Sound, is the second-largest in the world, behind a magnitude 9.5 that struck Chile in 1960. The Indian Ocean earthquake in December 2004, whose ensuing tsunami killed tens of thousands of people, ranks third with a magnitude 9.0.

The 1964 quake started south-central Alaska shaking at 5:36 p.m., on Good Friday. The four-minute temblor cracked roads and buildings, bent railroad tracks, set off landslides in Anchorage and spawned a tsunami that killed 103 Alaskans, four people in Oregon and 12 in California. In addition, 12 Alaskans died in the earthquake itself.

Web links

For more on how to prepare for an earthquake, check out the FEMA disaster supplies worksheet at: http://www.fema.gov/library/diskit/shtm

For more on Alaska's status, visit the Alaska Earthquake Information Center at: http://www.aeic.alaska.edu/

The clay and sand-based soil beneath Anchorage undulated like liquid in the quake. About 75 homes in the affluent West Anchorage neighborhood of Turnagain were destroyed as the bluffs on which they were built crumbled into Cook Inlet.

Julia Person was 8 years old at the time. She remembers sitting on a blanket in the snow while her babysitter rushed back into her tilted home to gather warm clothes and bread and jam.

"The front yard was way up at the top of the cliff," said Person, of Homer, now an advocate for children in state custody. "We were sitting on that little blanket and crevices were opening and closing around us."

Buildings throughout downtown Anchorage cracked or toppled, including stores, apartments and schools. A wide crack carved its way down 4th Avenue, sucking in cars and debris.

The quake caused more than $300 million in damage and forced two communities - Valdez and Portage - to relocate to higher and sturdier ground.

Smaller communities in south-central Alaska suffered less structural damage than Anchorage, but bore the brunt of tsunami-related deaths.

Jennifer Austin remembered fleeing with her parents and sister to an orphanage at the base of the mountains backing the coastal town of Seward to escape the subsequent tsunami, which killed 12 people in the Kenai Peninsula fishing community.

Austin, who is now assistant chief in Seward's fire department, said she fears earthquakes more than any other natural disaster.

"Hurricanes, tornadoes, floods all have warnings, but with an earthquake, there's no warning," Austin said. "They are totally out of your control."

Earthquakes in Alaska are caused as the Pacific tectonic plate slides beneath the North American plate. A chain of volcanos spanning the tip of the Aleutian Island arc to southeast Alaska are the result of the same inexorable plate movement.

Scientists in Alaska monitor subterranean convulsions with about 400 seismometers spangling the state. Computers run seismic data through a series of calculations to determine whether a quake, or another disturbance, such as magma moving beneath a volcano, has occurred. A positive result, no matter how small, alerts scientists throughout the state and sets off the crowing in Smith's office.

Smith said swarms of little earthquakes are preferable, despite the constant rooster crows, because they relieve pressure that is building within the earth.

"That's good," Smith said. "It prevents the big earthquakes from coming."



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