M2.3 earthquake 5 km SW of Cobb, California

A magnitude 2.3 earthquake struck 5 km SW of Cobb, California on Tue, Dec 31, 1985, 9:30 PM PST (05:30 UTC), 1 km (0 mi) below the surface.

A larger quake followed: M2.4 5 km NE of Rohnert Park, 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: 174 in the 60 days after this one and 0 in the 30 days before it.

The first 60 of 174.

From the USGS Earthquake Hazards Program and its partner networks, event nc62545. Read Tue, Sep 22, 2026, 8:26 PM UTC.