Oregon State scientists say Cascadia quake could trigger San Andreas
Scientists at Oregon State University say a quake in the Cascadia Subduction Zone could trigger the San Andreas Fault, causing two big earthquakes at almost the same time.
This "double earthquake" could hit major cities like San Francisco, Portland, Seattle, and Vancouver.
The findings were published in September 2025 by marine geologist Chris Goldfinger's team.
Goldfinger team finds linked quakes
Goldfinger's team studied sediment layers from California's coast and found patterns showing both faults have shaken together before, sometimes within hours.
He points out that just one of these quakes is a huge challenge for emergency services, but two back-to-back would be a multi-state and international emergency situation.
Basically: it's rare, but history shows it has happened before, so it's something worth paying attention to.