Home / Disasters and Accidents / Cascadia Quake Could Trigger Devastating San Andreas Fault Tremors
Cascadia Quake Could Trigger Devastating San Andreas Fault Tremors
13 Oct
Summary
- Recent study finds Cascadia Subduction Zone quakes may trigger San Andreas Fault quakes
- Potential for simultaneous disasters in major West Coast cities like San Francisco, Portland, Seattle
- Oregon governor orders earthquake-proofing of new buildings and retrofitting of existing state buildings
According to a recent study published on September 29th, 2025, a major earthquake in the Cascadia Subduction Zone off the West Coast could trigger devastating tremors in the nearby San Andreas Fault system. The study, led by marine geologist Chris Goldfinger of Oregon State University, found that past Cascadia quakes have coincided with seismic activity in the San Andreas Fault, indicating the two fault systems are linked.
The findings are particularly concerning given the potential for a catastrophic Cascadia earthquake, which scientists estimate has a 16-22% chance of occurring in the next 50 years. Such a quake, potentially reaching magnitude 8.7 or higher, could wreak havoc across the region. And if it sets off tremors in the San Andreas Fault as well, the combined impact on cities like San Francisco, Portland, Seattle, and Vancouver could be overwhelming.
In response to these heightened seismic risks, Oregon Governor Tina Kotek issued an executive order in early September 2025 to immediately earthquake-proof new buildings over 10,000 square feet and retrofit existing state agency buildings by 2060. Kotek emphasized the need for "seismically sound state buildings" to withstand the inevitable "M8-9 earthquake" in the Cascadia Subduction Zone.
