An earthquake with a preliminary magnitude of 3.4 struck near San Ramon at 11:21 p.m. Sunday, with the tremor about 8.4 km in depth. USGS data showed that several smaller quakes occurred shortly after the initial tremor, with events of 2, 2.3, 1.5, 1.8 and 2.8 magnitude, and at least seven earthquakes recorded in the area as of around 5 a.m. Eastern time.
This is the latest quake in San Ramon, which has seen multiple strings of tremors in the past several months. Since Dec. 1, 2025, the USGS said there have been roughly 300 quakes in that same area. San Ramon sits along the Calaveras Fault, a source of the area's regular seismic activity, and the city is located about 25 miles east of San Francisco in Northern California.
No injuries have been reported from the recent activity. However, hundreds of San Ramon residents gathered for a town hall regarding a sequence of earthquake swarms that have shaken their community into action. Mayor Mark Armstrong, a former FEMA official, emphasized essential steps for residents including creating a contingency plan, assembling emergency kits, and having designated out-of-area contacts to avoid communication breakdowns post-quake. Officials are focusing on preparedness rather than prediction, recognizing that San Ramon sits along the Calaveras Fault, a creeping fault that moves slowly and releases stress through lots of small-to-moderate quakes.