San Ramon, CA – Residents across parts of Contra Costa County felt renewed shaking Monday morning as a small earthquake swarm struck just east of San Ramon, marking continued seismic activity in an area that has already experienced a recent cluster of quakes.
According to the U.S. Geological Survey and the California Integrated Seismic Network, at least three earthquakes were recorded within roughly four minutes early Monday, February 2. The strongest was a magnitude 3.1 quake that hit about 4 kilometers east-southeast of San Ramon at 7:06 a.m. local time, followed closely by magnitude 2.7 and 2.8 events in nearly the same location.
All three earthquakes occurred at shallow depths ranging from 6.9 to 7.8 kilometers, which increases the likelihood they were felt by nearby residents. No injuries or damage have been reported.
Seismologists classify this sequence as an earthquake swarm, a pattern in which multiple quakes of similar size occur in a concentrated area without a single dominant mainshock. Notably, this activity follows an earlier swarm recorded in the same San Ramon area in recent days, suggesting ongoing stress adjustment along local fault structures.
The epicenters were located east of Interstate 680, near residential neighborhoods and business corridors that span San Ramon, Danville, and the broader eastern Bay Area. Some residents reported light shaking and brief rattling, though official “Did You Feel It?” reports were still limited as of publication.
Experts emphasize that small earthquake swarms are common in Northern California and do not necessarily indicate a larger quake is imminent. However, they serve as reminders for residents to review earthquake preparedness plans.
USGS continues to monitor the region for additional aftershocks or continued swarm activity.
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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