Pacific Northwest vulnerable to massive earthquake

SEATTLE -- Is the big one right around the corner?

A new study suggests the entire Pacific Northwest coast is vulnerable to a 9.0 earthquake that could level parts of Seattle. This comes on the heels of a study last year that said we had a 40 percent chance of a major earthquake in the next 50 years.

Western Washington has been through earthquakes before, from simple tremors to 2001's destructive Nisqually quake that put the viaduct in jeopardy.

The new study, which came from a Canadian university, says an even bigger quake is coming.

"It's a higher than average danger," said John Vidale, a local earthquake expert.

Vidale backs up the findings in the study, saying it has been 300 years since a magnitude 9 earthquake hit the northwest.

The researchers looked at oceanic sediments, treating them like tree rings.

"We know we're probably looking at a megathrust earthquake in the past," said researcher Audrey Dallimore.

Vidale said the next megathrust quake wouldn't be pinpointed in just one area. A 9.0 would be massive in scale, moving the ground 10 to 20 yards.

"The damage would be spread across the Puget Sound," Vidale said. "In fact, all across the coast, from Vancouver Island down to Cape Mendocino in California."

He said the shaking could last five minutes or more. For comparison, the Nisqually quake lasted 45 seconds.

Washiongton's main worry is the viaduct.

"Part of the viaduct's problem is that it's weak. And part of the problem with the viaduct is that the ground underneath it could liquify," Vidale said.

Vidale said large buildings in Seattle may not topple because the nature of the quake. The epicenter will likely be off our coast, as many as 600 miles away, but it will still cause excessive damage just about everywhere.
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