San Ramon, CA – Residents in the East Bay reported light shaking Sunday afternoon after a series of small earthquakes struck near San Ramon, according to the California Integrated Seismic Network (CISN).
The swarm began around 10:18 a.m. local time (18:18 UTC), with a magnitude 2.5 quake about 3 km southeast of San Ramon. Just seconds later, a magnitude 2.8 tremor was recorded near Patterson, about 17 km southwest, followed by a magnitude 3.0 quake west of San Ramon and a magnitude 3.2 quake east-southeast of the city.
According to CISN data, all four quakes originated between 8 and 9 kilometers deep, consistent with movement along the Calaveras Fault Zone, one of the Bay Area’s most active fault systems. The strongest event — the M3.2 quake east of San Ramon — reached an intensity level of IV (light shaking), and was felt in nearby cities including Dublin, Danville, Pleasanton, and parts of Walnut Creek.
No damage or injuries were immediately reported, but the rapid sequence of events prompted dozens of “Did You Feel It?” submissions to the U.S. Geological Survey (USGS).
Experts say such clusters, often called earthquake swarms, can occur as stress redistributes along local fault lines. “These are small but noteworthy reminders that the East Bay remains seismically active,” a CISN analyst noted.
Residents are encouraged to review earthquake preparedness plans and secure heavy furniture.
This article was produced by a journalist and may include AI-assisted input. All content is reviewed for accuracy and fairness.
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