A preliminary magnitude 3.5 quake struck east of Clayton, Contra Costa County, at 3 p.m. on Monday. Shaking was reported from Antioch to Sacramento, yet no damage or injuries have been confirmed. The shallow 4‑mile depth helped the tremor travel far while staying relatively mild. Residents took to social media to share the brief jolt. The event underscores the Bay Area’s constant seismic buzz.