M1.8 earthquake 5 km SW of Cobb, California

A magnitude 1.8 earthquake struck 5 km SW of Cobb, California on Thu, Mar 21, 1985, 4:07 AM PST (12:07 UTC), 4 km (3 mi) below the surface.

A larger quake followed: M2.5 6 km E of Santa Rosa, California. This one was a foreshock.

Map

Where this earthquake was located, with the others nearby. Select one for its page.

No one has reported feeling this quake to the USGS.

Reviewed by a seismologist.

Distance and direction from each place to the epicenter, with its forecast.

Within 100 km, magnitude 1.5 and up: 179 in the 60 days after this one and 0 in the 30 days before it.

The first 60 of 179.

From the USGS Earthquake Hazards Program and its partner networks, event nc44428. Read Tue, Sep 22, 2026, 10:41 AM UTC.