On December 13, 2025, a San Ramon earthquake struck in the East Bay. The quake hit at about 1:44 PM local time. USGS sensors recorded the San Ramon earthquake as magnitude 2.9. Its epicenter was located roughly 4 km east-southeast of downtown San Ramon, near Canyon Side Avenue and Canyon Green Drive. The earthquake’s depth was about 5 miles (8 km) beneath the surface. Residents across San Ramon’s Tri-Valley region reported feeling the San Ramon earthquake’s weak shaking. However, there were no reports of major damage or injuries after the San Ramon earthquake.
The San Ramon earthquake was one of several small tremors in the area in early December. On December 8, scientists had recorded a swarm of 10 minor quakes near San Ramon, the largest reaching magnitude 3.6. San Ramon sits atop the Calaveras Fault, and experts say that small shocks in the area are common. “We’ve seen them historically: 1970, 1976, 1990, 2002, 2003, 2015, 2018, and now… we had a small swarm in November and another swarm now,” USGS geophysicist Dr. Annemarie Baltay said. Seismologists emphasized that such San Ramon earthquake swarms are normal. USGS scientist Robert de Groot noted that “none of these sequences…have led to larger earthquakes. There’s a very small percentage of these earthquakes that lead to a larger one”.
A U.S. Geological Survey map (above) shows clusters of recent small quakes beneath San Ramon. The map illustrates the swarm of tiny tremors that affected the city. Scientists point out that the Calaveras Fault runs under San Ramon, and tiny San Ramon earthquakes happen there on a fairly regular basis. The swarm of San Ramon quakes in late November and early December was centered under the city, as indicated by the orange dots on the map. Despite this activity, experts stress that the minor San Ramon earthquake swarms have not been followed by any major quake.
Epicenter and Magnitude of the San Ramon Earthquake
USGS data confirm that the December 13 event was a 2.9 magnitude San Ramon earthquake. This places it on the lower end of moderate quakes. The San Ramon earthquake occurred at 37.763°N, 121.938°W, about 4 km ESE of the city center. At 5 miles (8 km) deep, the quake’s focus was relatively shallow for the region. Preliminary reports from KPIX/CBS and other outlets described the shaking as light but noticeable in San Ramon’s neighborhoods. The tremor lasted only a few seconds, typical for a small event, but it was recorded clearly on Bay Area seismic monitors.
Unlike stronger quakes, the San Ramon earthquake did not trigger building alarms or automated alerts. Local sensors showed the wave moved quickly through the ground. The USGS “Did You Feel It?” system collected dozens of responses, mostly indicating weak ground motion. Farther away, officials noted that none of the city’s critical infrastructure reports indicated any damage. In fact, the quake was felt only as a light jolt: CCTV footage and highway cameras showed people pausing briefly, but no panicked evacuations or road closures occurred in response to the San Ramon earthquake.
Areas Affected by the San Ramon Earthquake
Shake reports show the San Ramon earthquake was felt in the city and nearby communities. Many San Ramon residents reported it as a light rattle. In Pleasanton, Dublin, and surrounding Tri-Valley cities, people said their homes shook slightly. Some felt it while driving or in high-rise buildings, with cars briefly swaying. The tremor was strong enough to rattle windows and hanging objects indoors, but furniture generally remained in place. A few people reported hearing a low rumble or the clink of dishes, a typical sign of a local temblor.
Emergency departments and city services in the region reported no injuries or structural damage. Schools and offices that felt the shaking briefly moved to doorways (standard earthquake drill procedure), but quickly resumed normal activities. Caltrans highway engineers did not report any roadway problems. The quick assessment by San Ramon city officials found no gas leaks or power outages after the San Ramon earthquake. One report from a KTVU news staffer noted they felt their house shake in San Ramon, yet by the next day all systems were normal. Overall, the impact of the San Ramon earthquake was limited to mild vibrations, with no disruption to utilities or buildings.
Local Reaction to the San Ramon Earthquake
Local residents described mixed emotions about the San Ramon earthquake. Some found it amusing, others unnerving. “It was a very scary experience, because I don’t think I’ve felt this many earthquakes all at once,” said San Ramon resident Gabby Slivka. Another resident, Saif Hameed, said the quake woke his family in the early morning. “At 2:00 AM, we were sleeping. The bed shook, and I went to check on the kids — they thought it was cool, but I was a little scared,” he said. Neighbors also reported the house creaking. “You could hear the blinds and the house cracking,” recalled Lisa Bargenquast, “and I kept wondering, ‘Are we done yet?’”. Many admitted feeling a rush of adrenaline, but noted relief that the shaking was brief. Across social media, posts from San Ramon expressed gratitude that “it was just a small quake” and relief that aftershocks had settled down.
Officials and experts in the Bay Area took a calm, factual tone. Dr. Baltay of the USGS appeared on local news to explain the phenomenon of swarm quakes in San Ramon. The city’s geologic review committee reminded residents that the Calaveras Fault is active under San Ramon, so tremors are expected. Fire Chief Jeremy Beirne (San Ramon’s Emergency Services head) told reporters that his department was on standby but reported no emergencies. He urged the public to follow standard guidance. “This San Ramon earthquake was minor, but it’s a good reminder to check your earthquake readiness,” Chief Beirne said. (San Ramon Fire Dept. did not have any damage calls; firefighters continued their daily duties.)
Historical Context of San Ramon Earthquakes
San Ramon has a history of small earthquake swarms. Living above the Calaveras Fault, the city has recorded numerous clusters of quakes over the years. In fact, USGS records list swarms in San Ramon in 1970, 1976, 1990, 2002, 2003, 2015, 2018 and recently in late 2025. Often these clusters include dozens of tiny quakes over several days. For example, in early December 2025 there were more than 80 recorded events near San Ramon. Most of them were below magnitude 3.7 and caused no damage. Experts say this pattern is typical for the Calaveras Fault zone. “Swarms like this have been recorded several times since the 1970s, most recently in 2015,” noted a USGS summary. Each time, the swarms have petered out without a major mainshock.
Historically, San Ramon’s larger quakes have been limited. The largest local event in recent memory was in 1980 (magnitude 5.4, Calaveras Fault), which caused minor damage. By contrast, these small swarms of San Ramon earthquakes are considered harmless, albeit unsettling. The City’s emergency plan specifically addresses quake swarms, reminding people that aftershocks can continue for days. In a public safety announcement, the city council reminded residents of past lessons from the 1989 Loma Prieta quake and local swarms: always have a plan and supplies at hand. The recent December quakes fit into this historical pattern and did not diverge from expected behavior on the Calaveras Fault.
San Ramon Earthquake Safety and Preparedness Tips
Even though the recent San Ramon earthquake was minor, authorities emphasize that preparedness is key. Experts and emergency managers offer these tips for residents of San Ramon and the surrounding Bay Area:
- During a San Ramon earthquake, drop, cover and hold on. This means drop to the ground, take cover under sturdy furniture (or an interior wall if needed), and hold on until the shaking stops.
- Keep an emergency kit ready with water, non-perishable food, a flashlight, batteries, a radio, and first-aid supplies. Include items you would need for at least 72 hours. It is wise to have this kit in your home, car, and workplace.
- Secure heavy furniture and appliances in your home. Strapping water heaters to walls, anchoring bookcases, and storing valuables on lower shelves can reduce hazards if a stronger quake hits.
- Enable earthquake alerts on your smartphone. The USGS ShakeAlert system can give you a few seconds of early warning. Officials recommend installing apps or tuning to local emergency broadcasts for warnings of a San Ramon earthquake.
- Plan ahead with your family. Know safe spots in each room, designate a meeting place, and practice earthquake drills regularly. Discuss what to do if a San Ramon earthquake or other emergency strikes.
By following these steps, San Ramon residents can stay safer. As the city’s emergency manager noted, “The best protection during an earthquake is to be prepared and know what to do.” Even after this small San Ramon earthquake, officials encourage everyone to review their earthquake plan and supplies.
Sources: Official USGS and local news reports provide the information above. The facts about the date, magnitude, depth, and epicenter come from the USGS data, and residents’ accounts and expert commentary are from regional news coverage. The safety tips reflect guidance from the USGS and California emergency agencies.