Southern Oregon coast at high risk of quake in 50 years

Southern Oregon coast at high risk of quake in 50 years

Credit: Coos Bay, OR

Coos Bay, OR

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by Keely Chalmers, KGW Staff

KREM.com

Posted on August 2, 2012 at 9:49 AM

The odds of a devastating earthquake hitting the Oregon Coast are looking more certain.

Oregon State University scientists have even pinpointed the area that's most vulnerable - the southern coast near Coos Bay.

For more than a decade Oregon State University professor Chris Goldfinger and a team of researchers have studied core samples taken from the ocean floor.

By analyzing the samples, the researchers were able to track the earthquake activity over the last 10,000 years. They soon discovered there have been a lot more quakes than originally thought. Most of them rumbled along the southern end of the Cascadia Subduction Zone, a massive fault roughly 70 miles off the coast.

“The probabilities for the southern part of Cascadia are double over what we thought before,” said Chris Goldfinger, a professor in OSU’s College of Earth, Ocean and Atmospheric Sciences.

Goldfinger's research shows that from Florence south, there's about a 40 percent chance a magnitude 8 or stronger quake will happen in the next 50 years.

Goldfinger says the last large quake to strike our coast was 300 years ago. We are now overdue.

“In the north the average repeat time is every 500 years but in the south the repeat time is half that, about 250 years,” explained Goldfinger.

Goldfinger’s research shows the probability for a quake decreases as you head north. The northern Oregon coast has about a 20 percent chance of an earthquake in the next 50 years.

And when the "big one" hits, Oregon State University engineering professor Scott Ashford says we should expect damage similar to what we saw in the Japan earthquake last year. Even Portland will see severe damage.

“Some structures will collapse… some will be damaged… some will be repairable, and it’s something we are now just getting a handle on here in Oregon,” said Ashford.

He expects extensive bridge damage in the quake as well as the loss of electric, water, and sewage systems and says everyone should prepare to be on their own for at least a week.

Goldfinger agrees that when it comes to earthquakes, knowledge is our best defense.

“With enough preparedness and retrofitting buildings, hopefully it will be just a really bad day instead of a disaster,” he said.

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