California earthquakes

M2.5 earthquake 5 km W of Cobb, California

A magnitude 2.5 earthquake struck 5 km W of Cobb, California on Fri, Sep 25, 1987, 7:39 PM PDT (02:39 UTC), 3 km (2 mi) below the surface.

A larger quake followed: M3.2 5 km SW of Cobb, California. This one was a foreshock.

Cobb forecastMore in California

Map

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

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The earthquake

Magnitude
2.5 (Md, duration), micro
Magnitude from
Northern California Seismic System
Local time
UTC
1987-09-26 02:39:15 UTC
Depth
3.0 km (1.9 mi), shallow
Epicenter
38.823° N, 122.791° 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 0.3 km horizontally, 0.5 km in depth
Magnitude uncertainty
±0.08
Depth from
From location
Station coverage gap
108°
Stations used
18

Nearest places

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

Nearby

Within 100 km, magnitude 1.5 and up: 160 in the 60 days after this one and 105 in the 30 days before it.

After

The first 60 of 160.

Before

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Sources

From the USGS Earthquake Hazards Program and its partner networks, event nc106435. Read Fri, Oct 2, 2026, 11:03 AM UTC.