For the last few years, the Pacific Northwest has braced for the possibility of “The Big One,” an earthquake that could happen on the Cascadia Subduction Zone, a massive fault line that stretches from Northern California to Canada.
A new study, however, says there’s another possible earthquake Oregonians have to consider.
Researchers from Portland State and the Oregon Department of Geology and Mineral Industries found an “extensive network of active geological faults” near Mt. Hood that have the possibility of triggering an earthquake with a magnitude of up to 7.2, Portland State said in a release. For comparison’s sake, a spokesman for Portland State who announced the release said it could be larger than the one that hit the San Francisco Bay Area in 1989.
“This would be a crustal earthquake as opposed to the Cascadia subduction zone earthquake Portland has been bracing for,” Ashley Streig, an assistant professor of geology at Portland State, said in a press release. “Subduction zone quakes are deeper below the surface, they last longer – as long as seven minutes – but they are lower in amplitude. The kind of quake we would get from Mt. Hood would be shorter – 20 seconds to less than a minute – and would be strong enough to knock you off your feet.”
An earthquake on the active fault line, according to the release, would have an epicenter closer to Portland that the Loma Prieta earthquake had to San Francisco in 1989, “which means it could be even more damaging,” Streig said in a press release.
The faults are north, south and southwest of Mt. Hood. In the north, the netwrok extends to the Columbia River, according to the release. An earthquake “could have implications for infrastructure including rail lines in the Columbia Gorge and power generation at Bonneville Dam,” the release said.
On top of that, the release said, “the Mt. Hood faults pose a serious seismic hazard to the cities of Hood River, Odell, Parkdale, White Salmon, Stevenson, Cascade Locks, Government Camp and the Villages at Mount Hood … The Portland metro would experience strong ground motions and could suffer liquefaction damage along waterfront areas.”
The research is ongoing, according to the release.