Early on the morning of February 2, 2026, residents of San Ramon and the wider East Bay awoke to a familiar, if unsettling, sensation: the ground shaking beneath their feet. What began as a single tremor quickly revealed itself to be yet another in a series of persistent earthquake swarms that have gripped the region since November 2025, keeping locals on edge and scientists intrigued.
The latest burst of seismic activity kicked off just before dawn, with the U.S. Geological Survey (USGS) recording a 3.8 magnitude quake at 6:27 a.m. near San Ramon, just south of Bollinger Canyon Road between Alcosta Boulevard and Dougherty Road. Over the next several hours, the earth rumbled repeatedly, with at least 20 additional earthquakes of magnitude 2.5 or higher striking the same general area. The most powerful of these, a 4.2 magnitude shaker, hit at 7:01 a.m., its epicenter located at the southern end of the Canyon Lakes Golf Course, according to the USGS.
Residents as far away as San Francisco felt the 4.2 quake, with mild shaking reported in neighborhoods like Glen Park and NoPa. The San Francisco Chronicle recounted stories of rattling windows and startled commuters. Even in the Tri-Valley and Concord, people reported feeling the tremors, a testament to the reach of these mid-sized quakes.
For San Ramon, a city of about 85,000 perched atop the Calaveras Fault, this was hardly a new experience. Since November 9, 2025, the area has been the epicenter of a historic swarm, with 91 earthquakes of magnitude 2.0 and above recorded before this latest surge. The swarm had quieted somewhat after January 10, with no quakes above magnitude 2.0 for over two weeks, but the calm proved temporary. As of midday February 2, the USGS had logged 37 earthquakes of magnitude 2.0 or higher in less than 12 hours, with more than 50 small quakes in total since the previous night.
Monday’s activity was not isolated. In the week leading up to February 2, 16 tremors of magnitude 2.5 or higher had already been detected in the San Ramon region. The strongest, the 4.2 magnitude event, preceded a 2.5 magnitude quake at 7:41 a.m., centered roughly 2 miles east-southeast of San Ramon at a depth of 4 miles, as reported by the USGS and United Robots California.
Despite the flurry of shaking, officials reported no significant damage or injuries. Some residents and businesses did note items falling off shelves, but nothing more serious was observed. The Bay Area Rapid Transit (BART) system, however, did not emerge unscathed from the disruption. As a precaution, BART issued an alert warning riders to expect delays, with trains running at reduced speeds while crews conducted track safety inspections. The delays were significant, stretching to at least 20 minutes system-wide, as commuters scrambled to adjust their Monday routines.
Earthquake swarms like the one in San Ramon are a peculiar phenomenon, often involving dozens or even hundreds of small, usually harmless quakes over a period of days or weeks. According to Sarah Minson, a research geophysicist at the USGS Earthquake Science Center at Moffett Field, “We had a little quiet period and it’s picked up again.” She noted that scientists are still learning about the underlying causes of these swarms, and there are no strict parameters for when they start or end. “It’s a matter of semantics,” Minson remarked. “You could say it’s the same swarm or a new one. They have this problem with TV shows. Do you call a reboot or a sequel?”
Unlike the massive, singular earthquakes that dominate disaster movies, swarms rarely cause major destruction. Most of the recent San Ramon quakes were too small for residents to even feel. Earthquakes between 2.5 and 5.4 magnitude are often felt but rarely cause much damage, according to Michigan Tech. The Department of Homeland Security notes that while earthquakes can happen anywhere, they are most common in places like California, which experiences its fair share of seismic activity each year.
San Ramon’s unique geology plays a role in its seismic story. The valley sits within a complex mix of small faults, many unnamed, nestled between the Calaveras Fault and Mount Diablo. This intricate network occasionally triggers flurries of small quakes, as explained by experts cited in the Mercury News. The region has experienced at least five other significant earthquake swarms since 1970—in 1970, 1976, 2002, 2003, and 2015—each generating hundreds of quakes, nearly all below magnitude 4.0 and none resulting in major damage or injuries.
Scientists like Roland Bürgmann, a professor at the UC Berkeley Seismology Lab, urge calm but caution. “These are most likely harmless,” Bürgmann said. “But they are a good reminder that we should be ready for earthquakes.” Minson echoed this advice, emphasizing the importance of preparedness. “If you ever feel shaking you should drop over and hold on to protect yourself,” she advised. “When you are hosting your Super Bowl party, feel free to tell people that. And it’s OK to take your snacks with you under the table.”
Public safety officials recommend following simple steps during an earthquake: drop to your hands and knees, cover your head and neck, and hold on to something sturdy. If you’re in a car, pull over and stop; if you’re outdoors, stay away from buildings. Aftershocks are likely, so remain alert and be ready to drop, cover, and hold on again if necessary. These guidelines, as reiterated by the USGS and other agencies, are designed to minimize injuries and keep people safe when the earth moves unexpectedly.
While earthquake swarms can slightly increase the chance of a larger quake, the risk remains small. Importantly, none of the previous San Ramon swarms have triggered a major earthquake on the Calaveras Fault or other nearby faults. Still, the persistent shaking is a reminder of the Bay Area’s seismic reality and the need for ongoing vigilance.
As scientists continue to review historical records and analyze new data, the story of San Ramon’s restless ground is far from over. For now, residents can take comfort in their community’s resilience—and perhaps, as Minson suggests, keep their snacks handy, just in case the next tremor arrives during the big game.