A 2.8-magnitude earthquake struck near San Ramon at 5:25 a.m. on March 13, 2026, according to the U.S. Geological Survey (USGS).
The epicenter was located 5 kilometers southeast of San Ramon, at a depth of around 7.5 kilometers.
A total of 66 responses from people experiencing the earthquake were submitted on USGS’s “Did You Feel It?” reporting tool. The tremor was felt in nearby communities, including Dublin, Danville, Diablo, and San Pablo.
The tremor was categorized as CDI (Community Decimal Intensity) IV, which indicates light shaking, according to USGS.
No damage or injuries were reported due to the quake.
Earthquakes above magnitude 3.0 are typically noticeable to people, according to the USGS.
Friday’s earthquake follows a 3.3-magnitude earthquake that shook San Ramon late night on March 1, 2026, followed by a series of smaller quakes. The epicenter was located just southwest of San Ramon, at a depth of 8.4 kilometers along the Calaveras Fault.
Earthquakes Due to the Calaveras Fault
The Calaveras Fault is a right-lateral strike-slip fault in California’s Bay Area, according to the USGS. Scientists divided the fault into three main segments.
The northern section of the fault is virtually locked and moves very slowly. It creeps at a rate of 2 to 3 mm per year.
At the southern end of the central stretch, it creeps at about 14 mm per year, dropping northward to around 6 mm per year of creep at its intersection with the Hayward Fault.
The northern section of the Calaveras Fault last produced a noticeable quake in October 2007, when the 5.4-magnitude earthquake struck and ruptured southward along the fault.
Historically, the southern half of the central segment of the Calaveras Fault has been the most seismically active. It produced the 6.2-magnitude Morgan Hill earthquake in 1984, another 6.2-magnitude earthquake in 1911, and the 5.9-magnitude tremor in 1979.
In contrast, the northern section shows little small-scale seismic activity.
Frequent Earthquakes in California
Minor earthquakes, such as the ones near San Ramon over the month, are common across California.
On March 11, 2026, a 2.2-magnitude earthquake struck near The Geysers at 9:07 p.m., while a 1.9-magnitude earthquake was recorded 17 kilometers north-northwest of Benton.
California experiences frequent earthquakes largely due to its location between the Pacific and North American Plates. The San Andreas Fault runs almost the entire length of the state.
The two plates grind past each other along the fault system, which builds up stress and is released as earthquakes. This 800-mile network of faults is one of the most active seismic zones in the world.
In addition to the San Andreas Fault, California has numerous other active faults, such as the Hayward and San Jacinto faults.
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