California earthquakes

M2.4 earthquake 4km NNE of Simi Valley, CA

A magnitude 2.4 earthquake struck 4km NNE of Simi Valley, CA on Sun, Sep 20, 1981, 10:27 PM PDT (05:27 UTC), 21 km (13 mi) below the surface.

A larger quake followed: M2.5 4km SSW of Valencia, CA. 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
2.4 (mc), micro
Local time
UTC
1981-09-21 05:27:26 UTC
Depth
21.4 km (13.3 mi), shallow
Epicenter
34.300° N, 118.719° 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 0.7 km horizontally, 1.4 km in depth
Depth from
From location
Station coverage gap
41°
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: 186 in the 60 days after this one and 0 in the 30 days before it.

After

The first 60 of 186.

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Sources

From the USGS Earthquake Hazards Program and its partner networks, event ci523296. Read Tue, Sep 22, 2026, 9:33 PM UTC.