California earthquakes

M3.9 earthquake 16 km SW of Volta, California

A magnitude 3.9 earthquake struck 16 km SW of Volta, California on Wed, May 20, 1981, 10:21 AM PDT (17:21 UTC), 4 km (3 mi) below the surface.

A larger quake followed: M4.3 4 km SW of Tres Pinos, California. This one was a foreshock.

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

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The earthquake

Magnitude: 3.9 (ml), minor
Local time: Wed, May 20, 1981, 10:21 AM PDT
UTC: 1981-05-20 17:21:31 UTC
Depth: 4.1 km (2.6 mi), shallow
Epicenter: 36.984° N, 121.050° W
Region: California
Tsunami flag: No
Status: Reviewed by a seismologist

Did you feel it?

No one has reported feeling this quake to the USGS.

How well it is located

Reviewed by a seismologist.

Location uncertainty: About 0.2 km horizontally, 0.8 km in depth
Depth from: From location
Station coverage gap: 92°
Stations used: 66

Nearest places

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

Nearby

Within 100 km, magnitude 1.5 and up: 155 in the 60 days after this one and 63 in the 30 days before it.

After

The first 60 of 155.

Before

Earthquakes today California earthquakes Live radar here

Sources

From the USGS Earthquake Hazards Program and its partner networks, event nc1063832 (also filed as usp0001dsg, ci516330). Read Thu, Sep 24, 2026, 1:01 PM UTC.