A swarm of at least a dozen earthquakes reaching up to magnitude 3.9 rattled San Ramon near San Francisco, the U.S. Geological Survey reports. The other quakes in the Saturday, Dec. 21, swarm ranged from magnitude 1.3 to 3.0, according to the USGS.

No reports of major injuries or structural damage have emerged, and authorities have not issued a tsunami warning.

A shake alert went out over the U.S. Geological Survey's early warning system on Dec. 4, warning that a 5.9 earthquake near Carson City in western Nevada could produce heavy shaking in the region. But moments later,

Several small earthquakes struck in the East Bay near San Ramon on Friday evening, according to data from the U.S. Geological Survey. The largest measured as a magnitude 4.0 quake.

A swarm of earthquakes rattled the Bay Area on the evening of Friday, December 19. The earthquakes occurred over a 30-minute span, according to the U.S. Geological Survey. There have been no reports of damage or casualties, and no tsunami warnings have been issued as of reporting.

There were at least six separate earthquakes that measured above a magnitude of 2.5 in an earthquake swarm in the San Ramon area on Friday night. No damage was reported, but locals were somewhat rattled by the frequency.

“On December 4, 2025, the ShakeAlert EEW system released an incorrect alert for a magnitude 5.9 earthquake near Reno and Carson City, Nevada,” the statement read. “The event did not occur, and has been deleted from USGS websites and data feeds. The USGS is working to understand the cause of the false alert.”

USGS said, “The ShakeAlert EEW system released an incorrect alert for a magnitude 5.9 earthquake near Reno and Carson City, Nevada. The event did not occur, and has been deleted from USGS websites and data feeds. The USGS is working to understand the cause of the false alert.”

Several earthquakes, the largest measured at magnitude-3.3, were reported Thursday morning in Ventura County. The earthquakes were centered near Fillmore, about 25 miles northeast of Ventura. Shaking was reported in Fillmore, Moorpark, Ventura and Santa Paula.

In California's East Bay, a recent swarm of small earthquakes has pushed long-standing seismic risks back into public view. Since early November 2025, at least 90 minor quakes have been recorded around San Ramon,