5.8 Quake Rattles Off South Oregon Coast Near Port Orford - No Tsunami Threat

Published 09/09/25 at 12:05 a.m.
By Oregon Coast Beach Connection Staff

(Port Orford, Oregon) – A sizable underwater quake struck off the south Oregon coast mid Monday evening, with a magnitude 5.8 rattling 102 miles south by southwest of Port Orford. It hit at 9:08 p.m. and was about 8 miles beneath the surface.

There are many quakes in the area off Coos Bay, Bandon and Port Orford during the year, but at M 5.8 it's a bit larger than the usual 3.0 to 4.5 that occur out there.

There was no tsunami threat: it takes at least a 7.0 quake to start a tsunami.

It's a far cry from the Russian quake earlier this summer that created a tsunami alert across the entire Oregon and Washington coast.

Several people told the United States Geological Survey (USGS) website they had felt it, including a few from Portland – which is well over 500 miles. More plausible claims came from Coos Bay and northern California.

Orford Heads Museum

The quake hit near the Gorda Ridge, where these smaller shakers happen often.

Washington Coast Weather - Oregon Coast Weather  - Inland Oregon Weather

The stretch from northern California up to just north of Coos Bay experiences frequent seismic activity, though these quakes are unrelated to the anticipated “big one” from the Cascadia Subduction Zone. That major event could strike tomorrow, next month, or perhaps not for several hundred years.

Humbug Mountain - Oregon State Parks

Earthquake magnitude scales can be misleadingly subtle. While a 7.0 may seem only marginally larger than a 4.0, the USGS notes that it’s actually 1,000 times greater in size - and releases over 31,000 times more energy.

Though this recent quake off the Oregon coast was larger than usual, scientists say it falls within the expected behavior of the Blanco Fracture Zone: the geologically active region marked by fault lines and structural weaknesses. It’s not directly tied to the Cascadia fault, but it serves as a stark reminder that the big one is inevitable.

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Importantly, this activity doesn’t indicate that tectonic pressure is being relieved.

Live Earthquake, Tsunami Updates from Oregon Coast, Washington. B.C., California, Alaska

Seaside-based geologist Tom Horning explains that there’s significant interaction occurring beneath the offshore portions of Oregon’s coastline, where complex movements within the Earth’s crust continue to shape the region.

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