Major earthquakes in the Pacific Northwest are fairly uncommon, yet a significant threat looms: “The Big One” is an anticipated earthquake of magnitude 8 or higher.
And it could happen any day.
This projected earthquake — which would occur along the Cascadia Subduction Zone spanning from Southern British Columbia to Northern California — prompted the formation of the Cascadia Region Earthquake Science Center (CRESCENT) and $15 million in funding recently approved by the National Science Foundation.
Two Western Washington University geologists, Emily Roland and Colin Amos, will support CRESCENT’s mission to help the Pacific Northwest prepare for earthquakes by studying the Cascadia Subduction Zone.
“It’s very possible that we could have a magnitude 8 or 9 earthquake tomorrow, or in 10 years, or in three weeks from now,” said Roland, an assistant professor of geophysics at Western. “And so it’s an important goal, I think, for us to keep pursuing a better understanding of that.”
CRESCENT is heavily modeled after the Southern California Earthquake Center, but the key difference between the two boils down to geography. The San Andreas Fault in Southern California is a strike-slip fault, meaning two tectonic plates moving horizontally against each other. The offshore Cascadia Subduction Zone is a megathrust fault — a large tectonic plate pushing under another large plate.
Earthquakes at faults like San Andreas are common.
“(If) you’ve talked to any Southern Californian, many or most of them have experienced earthquakes,” said Amos, a Western Washington University geology professor. “It’s just part of the cultural awareness and knowledge.”
Subduction zone earthquakes are much more rare; a high-magnitude earthquake along a subduction zone is expected every 550 years, according to Whatcom County’s 2021 Natural Hazards Mitigation Plan. The last quake along the Cascadia Subduction Zone occurred in 1700.
For Amos, the reality of what an earthquake in the Cascadia Subduction Zone would look like set in after the 2011 Tohoku earthquake in Japan.
“I think people recognizing that sort of thing can happen here, coupled with the availability of media, is kind of what got us to people caring about this, like, ‘No, that’s gonna happen here,’” Amos said.
Because it has been more than 320 years since the last earthquake in the Cascadia Subduction Zone, the scientific community has taken a while to recognize the Pacific Northwest as a likely location for a high-magnitude earthquake, Roland said.
Roland and Amos are leading the creation of a 3D model of the subduction zone that could be used to model earthquake shaking, Amos said. The tool can help researchers prepare for the hazards that follow earthquakes, such as tsunamis and landslides.
The model will include the subduction zone and the surrounding crustal faults — smaller faults in the Cascadia region that can create shallow earthquakes. The well-known Seattle Fault is a crustal fault that runs under CenturyLink field.
“Understanding not just the orientation and geometry of the Cascadia Subduction Zone fault itself but also this network of crustal faults is really important for anticipating earthquake hazards,” Roland said.
CRESCENT will also connect researchers and stakeholders from around the country. In addition to Western, collaborating institutions include the University of Oregon, Central Washington University, Stanford University, Purdue University and others.