Magnitude 7 earthquake (June 1838) affecting California from the San Francisco Peninsula to the Santa Cruz Mountains
One of the largest known earthquakes in California history, rupturing ~100 km of the San Andreas Fault in 1838.
Key Facts
- Estimated Magnitude
- 6.8 to 7.2 (moment magnitude)
- Fault Rupture Length
- ~100 km (62 miles)
- Fault Slip
- ~1.5 meters (5.0 feet)
- Fault Segment
- Northern San Andreas Fault
- Areas with Structural Damage
- San Francisco, Oakland, Monterey
By the Numbers
Location
Cause → Event → Consequence
The northern segment of the San Andreas Fault accumulated tectonic stress over time. In June 1838, that stress released in a sudden rupture spanning the San Francisco Peninsula to the Santa Cruz Mountains, a stretch of approximately 100 km of fault line.
A strong earthquake, estimated at magnitude 6.8 to 7.2, struck California in June 1838. The rupture produced roughly 1.5 meters of slip along the fault. Structural damage was reported in San Francisco, Oakland, and Monterey, though the region was sparsely populated at the time.
Whether any fatalities occurred remains unknown. The event was historically confused with a supposed 1836 earthquake on the Hayward Fault, but modern geological evidence indicates no major earthquake struck the region in 1836, and references to it now point to this 1838 event.