M2.1 earthquake 4 km S of Cobb, California

A magnitude 2.1 earthquake struck 4 km S of Cobb, California on Tue, Dec 15, 1987, 2:32 PM PST (22:32 UTC), 1 km (1 mi) below the surface.

A larger quake followed: M2.6 Northern 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: 170 in the 60 days after this one and 0 in the 30 days before it.

The first 60 of 170.

From the USGS Earthquake Hazards Program and its partner networks, event nc109960. Read Tue, Sep 22, 2026, 10:58 AM UTC.