Posted on Fri, Sep. 02, 2011
last updated: September 03, 2011 03:50:32 PM
WASHINGTON — When a 5.8 magnitude earthquake shook the East Coast last week, millions of people felt it. When a 6.8 magnitude quake struck in Alaska's remote Aleutian island chain early Friday, few noticed — though it was about 10 times more powerful.
While earthquakes make the news when they're felt on the East Coast, Alaska has 12,000 a year, more than any other state. Consequently, it's much better prepared.
"They experience a lot of earthquakes out there," said Jeremy Zidek, a spokesman for the Alaska Department of Homeland Security. "It's not unusual, and people are used to it."
In Alaska, the Pacific plate is being pushed under the Aleutians, and most of the state's seismic activity is concentrated in the chain of 300 islands, which stretches 1,200 miles.
"That's why they're there," said Paul Caruso, a geophysicist at the National Earthquake Information Center in Golden, Colo. "Every one of those is a volcanic island."
Four of the most powerful quakes ever recorded were in Alaska, Caruso said.
One of those struck Alaska in March 1964, a 9.2 magnitude disaster that killed 131 people, including 16 in Oregon and California. And it wasn't the quake itself that caused most of the fatalities. As in the Japan disaster earlier this year, it was the tsunami.
The earthquake and resulting tsunami were especially destructive to the town of Valdez, where 31 people died. A wave surged inland after a large section of land slid into the Valdez Inlet. The events destroyed dozens of boats and started fires that burned for two weeks. The town was relocated after the Army Corps of Engineers found a site with more stable ground.
"We've got nine different sirens," said George Keeney, the Valdez fire chief. "After more than 20 seconds of violent shaking, our dispatcher automatically hits the alarm button."
Zidek said the state stepped up its earthquake and tsunami preparedness after 1964.
"We've seen a number of tsunami warnings recently and have been responding to them in a pretty timely fashion," he said. "We build the systems with redundancies, so if one of those systems fails, we have backups in place."
He said there are multiple ways a tsunami warning is distributed in Alaska, including email lists, weather radios, text messages and sirens.
The West Coast and Alaska Tsunami Warning Center in Palmer, Alaska, alerted communities Friday morning. The center provides tsunami warnings for Alaska, California, Oregon, Washington, and British Columbia.
"The most important warning we'll receive is violent shaking of the ground," Zidek said. "Residents in coastal communities are well trained for it."
Since Alaska is such a far-flung state, he said, local emergency responders and city officials have the ultimate discretion about when to issue evacuation orders.
And because Alaska is so large, geographically diverse and remote, communities have to have a level of preparedness that makes most of the lower 48 states seem, well, not prepared.
"When you guys call for hurricanes down there, we call them winter storms," Keeney said. Valdez gets more than 300 inches of snow a year and rarely closes its schools.
But as the town's 4,000 residents know from the 1964 disaster, the biggest threat comes from the sea. Keeney said his dispatchers test the sirens weekly, and the community stages regular drills.
"I've got enough sirens in this community that people complain to me that they can hear them in their bathrooms," he said.
Keeney said he pushes preparedness for everyone, "from kindergarten to adults." Local schoolchildren have color-coded backpacks so they can be quickly identified. Everyone is urged to have a survival kit with enough food and water to last several days. Keeney said he keeps one in his truck.
"Even though we think we're prepared and got it all lined out, Mother Nature can make your day harder," he said.
Zidek said that various regions of Alaska experience earthquakes, tsunamis, wildfires, floods, avalanches and sea storms. Sometimes wind or water pushes sea ice hundreds of yards inland, where it can affect roads and buildings.
"We have events that don't happen anywhere in the country," he said. "We have to be ready for anything."
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