Overview
- USGS recorded a preliminary magnitude 3.8 at 9:38 a.m. Sunday near San Ramon, followed within minutes by quakes of 3.7, 3.0 and 2.9, plus later events including a 2.5 and a 3.2.
- More than 40 earthquakes ranging from about M0.6 to M3.8 occurred between November 9 and 10 along a roughly 3–4 km stretch of the northern Calaveras fault.
- Hypocenters clustered at shallow depths of roughly 5 to 10 km, contributing to widespread light shaking reports in San Ramon, Dublin, Danville, Pleasanton and nearby communities.
- No injuries or damage have been reported by local authorities or via USGS Did You Feel It submissions, and most subsequent tremors declined to M1–M2 through Monday.
- Experts note the swarm’s tight clustering and “staccato” pattern fit past San Ramon sequences; agencies continue monitoring even as long‑term studies show the Calaveras fault can produce larger quakes.