California earthquakes

M1.9 earthquake 20 km NNE of Potter Valley, California

A magnitude 1.9 earthquake struck 20 km NNE of Potter Valley, California on Wed, Jan 23, 1985, 9:43 AM PST (17:43 UTC), 7 km (4 mi) below the surface.

A larger quake followed: M1.9 4 km W of Cobb, California. This one was a foreshock.

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Map

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

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The earthquake

Magnitude: 1.9 (md), micro
Local time: Wed, Jan 23, 1985, 9:43 AM PST
UTC: 1985-01-23 17:43:19 UTC
Depth: 6.9 km (4.3 mi), shallow
Epicenter: 39.491° N, 123.008° 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, 0.6 km in depth
Magnitude uncertainty: ±0.12
Depth from: From location
Station coverage gap: 79°
Stations used: 17

Nearest places

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

Nearby

Within 100 km, magnitude 1.5 and up: 190 in the 60 days after this one and 0 in the 30 days before it.

After

The first 60 of 190.

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Sources

From the USGS Earthquake Hazards Program and its partner networks, event nc38475. Read Tue, Sep 22, 2026, 10:33 PM UTC.