Thu Feb 05 19:50:00 UTC 2026: Headline: Earthquake Swarm Rattles San Ramon, Triggering BART Delays and Raising Preparedness Concerns
The Story:
The East Bay city of San Ramon experienced a significant earthquake swarm on Monday, February 5, 2026, with over 40 earthquakes recorded, ranging in magnitude from 1.3 to 4.2. The largest quake, a 4.2 magnitude temblor, struck just after 7 a.m. and was felt across the Bay Area, including Oakland, Richmond, San Leandro, and Hayward. While no widespread damage was reported, some stores experienced items falling off shelves, and BART experienced delays due to track safety inspections. This event follows a pattern of seismic activity in the area, with previous swarms occurring in recent months and decades.
Key Points:
* Over 40 earthquakes struck near San Ramon on February 5, 2026.
* The largest quake registered a magnitude of 4.2.
* The earthquake swarm is located in an area bisected by Alcosta Boulevard and bordered by the Calaveras Fault, the Mount Diablo Thrust Fault, and the Concord-Green Valley Fault system.
* BART trains ran at reduced speeds, causing delays of up to 20 minutes due to track safety inspections.
* San Ramon experienced 87 quakes at magnitude 2 or above in November and December.
* Past earthquake swarms have been recorded in the Tri-Valley area in 1970, 1976, 1990, 2002, 2003, 2015, and 2018.
Key Takeaways:
* The San Ramon area is prone to earthquake swarms due to its location over many small subfaults.
* While scientists do not fully understand the cause of earthquake swarms, fluid movement from deep within the earth is a possible explanation.
* Although the events are relatively small, residents of the Bay Area are reminded to maintain earthquake preparedness plans and assemble earthquake kits.
* The surrounding large faults seem to have made many small cracks in the San Ramon Valley crust instead of a single large throughgoing fault which limits the magnitude.
* The recent event is not necessarily a sign that a larger quake is coming.
First Piper 