Earthquake and tsunami preparedness in Oregon

By Pat Kight, Oregon Sea Grant

When a New Yorker feature suggested that a major Cascadia Subduction Zone earthquake would make “toast” of everything in Oregon west of Interstate 5 hit social media recently, it certainly drew attention to the seismic reality of life in the Pacific Northwest. 

But Oregon Sea Grant’s Pat Corcoran says focusing only on extreme scenarios can lead to a fatalistic sense that nothing can be done. And that’s the challenge of earthquake and tsunami preparedness in the U.S., says Corcoran, who works to prepare coastal communities, residents and visitors for just such disasters. 

“The Cascadia Subduction Zone has shifted from a science project to a social studies project,” Corcoran said. “We need to find a sweet spo between fear and action. What I try to do is temper the tendency of people to toggle between the poles of ‘It won’t happen here’ and ‘It will be so bad that there’s no use worrying about it.’ Both responses are a form of denial. The fact is, they do happen here. And, there are lots of things we can do to prepare.” 

It’s been more than a quarter century since Oregon State University researchers – some working under Sea Grant funding – began warning that the Cascadia Subduction Zone, where a deep-sea tectonic plate is inexorably slipping under the North American continent, will likely trigger an earthquake ranging from magnitude 8.0 (comparable to the 2010 quake in Chile) to 9.0 or greater, like Japan’s 2011 Tohoku quake. The geologic record and current seismic research indicates a 37% chance such a quake will occur in the next 50 years. 

Ever since, Oregon Sea Grant has been working with state and local officials, scientists and engineers to increase the region’s resilience to a major offshore earthquake and the tsunami that will likely follow. 

Corcoran acknowledges that a magnitude 9.0 earthquake and tsunami – what he calls “the largest of the large” – could devastate coastal communities and destroy infrastructure throughout western Oregon and Washington, including roads, bridges, water and sewer lines, and the power grid. 

But he adds that a more probable scenario is an earthquake on “the average side of large” – and the best response isn’t to move away or pretend it’s not going to happen, but to prepare now for disaster. 

“The best approach is to do something,” he said. “Don’t let fear about the potential worst case scenario prevent you from taking action that will help you in the more likely scenario.”

Corcoran suggests that people start by preparing for the “most likely next event” – and that doesn’t necessarily mean the destruction of western Oregon as we know it. 

“We don’t insist on the worst-case scenario with driving vehicles,” Corcoran said. ” We don’t have a zero-tolerance for car fatalities. We try to do our best to identify and mitigate the risks, but we assume a great deal of risk. We don’t require that all cars be able to hit a brick wall at 100 miles per hour and have passengers unharmed. That’s impractical. We need to consider a similar approach with earthquakes.” 

Oregon Sea Grant has resources on earthquake and tsunami preparedness.