San Francisco, CA – Earthquake activity increased across California on Saturday, with at least seven earthquakes recorded statewide and a notable swarm near the San Francisco Bay Area, according to data from the U.S. Geological Survey (USGS) and the California Integrated Seismic Network (CISN).
According to USGS records, the most concentrated activity occurred near San Ramon in Contra Costa County, where five earthquakes ranging from magnitude 2.5 to 4.0 struck late Friday night into early Saturday morning. The strongest quake, a magnitude 4.0, was recorded approximately 5 kilometers south-southeast of San Ramon at a depth of about 9.6 kilometers. Several smaller quakes followed within a short time window, meeting the definition of an earthquake swarm.
Residents across parts of the East Bay, including Dublin and Pleasanton, reported light shaking, though no injuries or damage were immediately reported.
Additional earthquakes were recorded elsewhere in the state Saturday, highlighting broader West Coast seismic activity. A magnitude 3.0 quake struck south of Ojai in Southern California, while a magnitude 3.4 was recorded northeast of San Lucas in Central California. Northern California also saw quakes near Lakeport, Petrolia, and offshore west of Ferndale, with magnitudes between 2.6 and 2.9.
Seismologists note that earthquake swarms are relatively common in California and do not necessarily indicate a larger earthquake is imminent. However, officials continue to encourage residents to review earthquake safety plans and ensure emergency kits are ready.
Anyone who felt shaking is encouraged to submit a report through the USGS “Did You Feel It?” system.
