A series of small earthquakes struck the San Francisco Bay Area on Monday morning, with the most powerful registering a magnitude 4.2, according to the U.S. Geological Survey. The quake hit just south of San Ramon shortly after 7 a.m., following more than a dozen smaller tremors that began around 6:30 a.m. and continued for over an hour.
No major damage was reported, but Bay Area Rapid Transit warned of possible delays as trains briefly operated at reduced speeds for routine track safety inspections. Shaking was felt more than 30 miles away in San Francisco and across East Bay cities including Oakland and Richmond.
The area has experienced heightened seismic activity in recent months, with 87 earthquakes of magnitude 2 or above recorded in Contra Costa County during November and December, according to a San Francisco Chronicle analysis of USGS data. Experts note that the region has a history of earthquake swarms, where multiple quakes occur in a small area without a typical mainshock-aftershock sequence.
