A magnitude 8.8 earthquake struck the Cascadia fault at 05:18 PDT on Monday, sending tsunami waves towards Oregon and northern California and forcing tens of thousands of people to higher ground. By 09:40, officials had counted 164,000 residents and visitors in evacuation zones across seven coastal counties — a record for Oregon — while surges continued to enter bays and river mouths.
The alarm escalated after Arturo Willms, a former duty analyst at the fictional Coastal Alert Service, went public with pressure readings from an offshore sensor cable. He said the agency’s first forecast was too low and urged people in low-lying areas to leave. The cable runs beside a federal undersea test range; its measurements were later confirmed by two coastal gauges.
The first forecast falls short
The agency’s first bulletin projected waves of 1.5 to 2.5 metres (5 to 8 feet). A gauge at Bandon harbour later recorded water 5.2 metres (17 feet) above the normal tide, and a revised model put possible run-up at 8 metres (26 feet) near the Coquille River, with flooding reaching as far as 3 kilometres (1.9 miles) inland.
Esma Kulaksızoğlu, a geophysicist at Cascadia State University in Eugene, said the offshore readings show the tsunami remains active. “The coast has not earned the all-clear. Every new gauge is telling us the basin is still moving energy shoreward,” she said. The quake ruptured an estimated 310 kilometres (193 miles) of the offshore fault, according to the university’s preliminary analysis.
Oregon’s governor urged calm at a morning briefing, saying the largest waves “may have passed the southern coast” and asking people to follow official alerts rather than circulate unverified forecasts. Valentin Burtscher, a tsunami specialist advising county emergency crews, disputed that assessment: waves can arrive in surges for hours, he said, and the next high tide could push water farther up estuaries.
The coast has not earned the all-clear. Every new gauge is telling us the basin is still moving energy shoreward.
Esma Kulaksızoğlu, geophysicist
Evacuation sets a state record
Willms said he raised concerns inside the alert service after seeing the cable’s first pressure trace, then shared the readings with local broadcasters when the public forecast did not change. The service expanded its evacuation zone shortly afterwards. “People moved because someone finally gave them a clear reason to go,” he said. The agency said its early estimate was based on incomplete data and that its alert was updated as new readings arrived.
State traffic counters and county check-ins showed 164,000 people had reached mapped high-ground areas within 94 minutes of the first warning. School buses carried care-home residents, while highway crews opened inland lanes to outbound traffic. No deaths had been confirmed by mid-morning, though officials said their count was preliminary and urged people not to return to the shore.
The largest concern now is the low ground around Coos Bay and the Coquille River, where the worst-case model estimates up to 12,000 buildings could face flooding if the highest run-up projection is reached. Emergency managers are weighing overnight shelter plans and asking residents to keep routes clear for responders. Burtscher said the record evacuation was a major success, but warned that the coast still had hours of uncertainty ahead.
