California earthquakes

M1.7 earthquake 6 km NNE of Blackhawk, California

A magnitude 1.7 earthquake struck 6 km NNE of Blackhawk, California on Thu, Nov 21, 1985, 3:20 PM PST (23:20 UTC), 16 km (10 mi) below the surface.

A larger quake followed: M3.4 6 km NNE of Interlaken, 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
1.7 (md), micro
Local time
UTC
1985-11-21 23:20:06 UTC
Depth
16.2 km (10.0 mi), shallow
Epicenter
37.878° N, 121.877° W
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 3.0 km horizontally, 2.7 km in depth
Magnitude uncertainty
±0.17
Depth from
From location
Station coverage gap
260°, poorly surrounded by stations
Stations used
4

Nearest places

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

Nearby

Within 100 km, magnitude 1.5 and up: 100 in the 60 days after this one and 36 in the 30 days before it.

After

The first 60 of 100.

Before

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Sources

From the USGS Earthquake Hazards Program and its partner networks, event nc61192. Read Wed, Sep 30, 2026, 11:56 PM UTC.