Swarm of 20+ Quakes Hits Near San Ramon

A swarm of more than 20 earthquakes, with the strongest reaching a magnitude of 3.8, struck near San Ramon in Northern California on Sunday, November 9, shaking the area southeast of San Francisco and prompting reports from over 1,300 residents who felt the tremors.

The U.S. Geological Survey reported that the series began at 9:38 a.m., with quakes ranging from 1.0 to 3.7 magnitude recorded as of 11 a.m. The epicenters were centered around San Ramon, located about 35 miles southeast of San Francisco. Many of the events occurred in quick succession, though preliminary data from the agency indicated no significant structural damage or injuries. Residents as far as Mill Valley and Half Moon Bay submitted "Did You Feel It?" reports to the USGS, highlighting the widespread sensation of the shaking despite its relatively low intensity.

Seismologists attribute such swarms to natural tectonic activity along California's active fault lines, particularly in the East Bay region, which lies near the Hayward Fault. The quakes occurred at shallow depths, estimated around 5 to 6 miles, which can amplify surface effects but typically results in minimal disruption for magnitudes in this range....