Overview
- The U.S. Geological Survey recorded a magnitude 5.5 earthquake about 140 miles west of the Oregon coast on Monday, with the epicenter located under the Pacific Ocean near the Blanco Fracture Zone.
- No tsunami warning was issued and officials reported no immediate damage or injuries, with only a very small number of people telling the USGS they felt the shaking.
- Seismologists noted at least one smaller quake in the same area after the main event and the USGS gives measurable odds of additional aftershocks in the next week.
- The quake came during a short burst of seismic activity across the Pacific Ring of Fire that included stronger events elsewhere, a pattern the USGS says fits normal plate motion in that belt.
- Officials continue close monitoring because the Pacific Northwest lies near the Cascadia Subduction Zone, which a 2024 study warned could produce a rare but catastrophic magnitude-9 event with large tsunamis and heavy losses.