Minor Earthquake Rattles East Bay
A moderate 3.3 magnitude earthquake rattled the East Bay near San Ramon, with tremors felt across the region. While no immediate damage was reported, the event serves as a reminder of the Bay Area's seismic activity.
The earthquake struck at 11:21 p.m. local time and was centered about 2.5 miles southeast of San Ramon at a relatively shallow depth of about 5.2 miles. This quake was part of a series of smaller tremors in the same area, including a magnitude 2.8 that followed about an hour later. This seismic activity is linked to the Calaveras Fault, a major branch of the San Andreas Fault system that runs directly through the East Bay. The San Ramon area is known for experiencing earthquake swarms—a series of many small quakes in a localized area—with notable sequences occurring in 1990, 2015, and 2025. While this event was minor, the U.S. Geological Survey forecasts a 72% probability of at least one earthquake of magnitude 6.7 or greater striking the Bay Area before 2043. The Hayward Fault, which is nearby and runs through densely populated areas like Oakland and Berkeley, is considered the most likely source of a major regional earthquake. California's Earthquake Early Warning system, operated by Cal OES, can provide vital seconds of notice before shaking begins. The system uses a network of sensors and can send alerts to phones via the free MyShake App for quakes of magnitude 4.5 or higher.
