M1.6 earthquake 4 km E of Penngrove, California

A magnitude 1.6 earthquake struck 4 km E of Penngrove, California on Wed, Dec 23, 1981, 11:49 PM PST (07:49 UTC), 0 km (0 mi) below the surface.

A larger quake followed: M3.5 16 km E of Lower Lake, 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: 159 in the 60 days after this one and 85 in the 30 days before it.

The first 60 of 159.

From the USGS Earthquake Hazards Program and its partner networks, event nc1070592. Read Fri, Oct 2, 2026, 10:25 AM UTC.