Overview
- At least 19 earthquakes struck within roughly two hours Monday morning, starting around 6:27 a.m., according to USGS data.
- The strongest event registered magnitude 4.2 at about 7:01 a.m., centered roughly 2.5 miles southeast of San Ramon at a depth near six miles.
- Shaking was reported across the Bay Area and into the Central Valley, with intensity maps showing waves toward Sacramento, Stockton and Modesto.
- No major injuries or structural damage were reported, and BART temporarily reduced train speeds for safety inspections, causing delays of up to about 20 minutes.
- Scientists cite months of elevated Tri‑Valley seismicity—including dozens of magnitude‑2‑plus quakes—and say this swarm may continue for months with only a small probability of a much larger event.