US EditionStudy Reveals Potential for Devastating West Coast Earthquakes to Strike Simultaneously
New research shows a magnitude 9 Cascadia quake could trigger a magnitude 7.9 northern San Andreas fault earthquake within days, raising concern for consecutive West Coast disasters.
- On Thursday, October 9, 2025, scientists announced new evidence showing the Cascadia subduction zone and San Andreas fault on the West Coast may be in sync.
- Researchers at Oregon State University examined ocean sediment and historical records, finding evidence that a major earthquake on one of two West Coast faults can set off seismic activity on the other within hours—a sequence believed to have occurred in 1700.
- The published study in Geosphere outlines how back-to-back large quakes, though rare, could happen, putting cities like San Francisco, Portland, Seattle, and Vancouver at high risk.
- Lead author Chris Goldfinger explained that if both faults ruptured at the same time, major cities such as San Francisco, Portland, Seattle, and Vancouver could all simultaneously face emergency conditions.
- These findings highlight a serious hazard, prompting experts to urge emergency planners and residents to prepare for possible consecutive earthquakes across the West Coast.
15 Articles
15 Articles
2 major West Coast fault lines could be in sync and trigger double earthquake, scientists say
Scientists at Oregon State University say there's new evidence that two of the best-known earthquake fault lines on the West Coast are in sync and that has the potential for a major disaster. One of the fault lines is the San Andreas Fault.
2 major West Coast earthquake faults may be linked, study shows
Scientists have discovered a new seismic link between two of the West Coast’s largest earthquake faults, and it could be the recipe for a major natural disaster. The study out of Oregon State University shows two major faults — the San Andreas and the Cascadia Subduction Zone — could be sychronized, meaning an earthquake on one of the faults could trigger a second temblor within hours or possibly minutes on the other fault. Bob Redell has more i…
Coos Bay World
Twin Threat: Cascadia and San Andreas faults may be seismically linked
Two fault systems on North America’s West Coast – the Cascadia subduction zone and the San Andreas fault – may be synchronized, with earthquakes on one fault potentially triggering seismic events on the other, a new study found
Study reveals potential for devastating West Coast earthquakes to strike simultaneously
PORTLAND, Ore. (KOIN) — Oregonians have long known that a major earthquake could devastate the region in the next 50 years, but a new study suggests the impact could have implications for the entire country. Researchers suspect that when the large Cascadia earthquake does occur, it could coincide with another quake along the northern San Andreas fault, according to a new study from Oregon State University. "We’re used to hearing the 'Big One' – …
The spokesman-Review
San Andreas, Cascadia faults could combine to produce back-to-back earthquake disasters, new research suggests
They are two of the West Coast’s most destructive generators of huge earthquakes: The San Andreas fault in California and the Cascadia subduction zone offshore of California’s North Coast, Oregon, Washington and British Columbia. The public has often thought of these danger zones as separate entities. But what if they were capable of back-to-back disasters? That’s the unsettling possibility ...
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