Earthquakes
Portland, Eugene, Oregon Earthquake Awareness Through Oct. 17: M9 Cascadia Threat
PORTLAND, Ore. — A massive earthquake capable of reaching magnitude 9.0 could leave portions of Oregon without essential services for weeks, with Portland, Eugene and coastal communities facing differ
By Lauren Beckett · 2026-10-13T12:54:01.416Z
PORTLAND, Ore. — A massive earthquake capable of reaching magnitude 9.0 could leave portions of Oregon without essential services for weeks, with Portland, Eugene and coastal communities facing different but potentially devastating consequences from the Cascadia Subduction Zone.
The threat is taking center stage as earthquake awareness activities continue through Saturday, Oct. 17, highlighted by Thursday's Great Oregon ShakeOut and a statewide push for families to prepare for extended emergencies.
According to the Oregon Department of Emergency Management, the Cascadia Subduction Zone stretches approximately 700 miles from northern California to British Columbia, roughly 70 to 100 miles offshore.
The fault last ruptured on Jan. 26, 1700, producing an estimated magnitude 9.0 earthquake and a tsunami that traveled across the Pacific Ocean to Japan.
Scientists have identified evidence of 43 earthquakes along Cascadia during the past 10,000 years, confirming a long history of powerful seismic activity beneath the Pacific Northwest.
Oregon emergency officials estimate a 37% chance of a magnitude 7.1 or greater megathrust earthquake along Cascadia over the next 50 years.
That estimate does not mean an earthquake is imminent, nor does it represent the probability of a magnitude 9.0 event specifically.
For Portland, the danger includes older buildings, vulnerable transportation infrastructure and the potential loss of utilities. City officials have identified more than 1,600 older unreinforced masonry buildings that may be particularly vulnerable during severe shaking.
Farther south, Eugene and surrounding Lane County communities could experience significant ground shaking and disruptions to transportation, electricity and communications.
Along the Oregon coast, the consequences could be even more immediate.
State emergency officials warn that a major Cascadia earthquake could generate several minutes of intense shaking and a destructive tsunami. Coastal residents in tsunami hazard zones may have only minutes to move toward higher ground after the shaking stops.
The Great Oregon ShakeOut is scheduled for Thursday, Oct. 15, at 10:15 a.m. Pacific time.
During the exercise, participating schools, businesses and households will practice dropping to their hands and knees, taking cover beneath sturdy furniture and holding on until shaking ends.
The University of Oregon plans to issue a campuswide earthquake preparedness alert at 10:15 a.m., while National Weather Service offices across Oregon will participate through NOAA Weather Radio and Emergency Alert System testing.
Some coastal communities may also activate tsunami warning sirens as part of the scheduled drill.
Oregon's preparedness efforts will continue beyond Thursday.
The state's Great Oregon Camp In, scheduled for Oct. 16–18, encourages residents to practice living without normal utilities, review emergency supplies and test household disaster plans.
State officials recommend households become prepared to remain self sufficient for at least two weeks following a major disaster.
That guidance reflects the possibility that damaged roads, bridges and communications networks could delay emergency assistance following a major Cascadia earthquake.
For Portland, Eugene, Salem, Newport and communities throughout Oregon, this week's preparedness activities underscore a persistent geological reality: the state's next major earthquake cannot be predicted, but its potential consequences are serious enough to warrant planning now.