M2.3 earthquake 2 km SW of Blackhawk, California

A magnitude 2.3 earthquake struck 2 km SW of Blackhawk, California on Wed, Jul 29, 1981, 7:03 PM PDT (02:03 UTC), 15 km (9 mi) below the surface.

A larger quake followed: M3.0 11 km SW of Brentwood, California. This one was a foreshock.

Map

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

No one has reported feeling this quake to the USGS.

Reviewed by a seismologist.

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

Within 100 km, magnitude 1.5 and up: 71 in the 60 days after this one and 39 in the 30 days before it.

The first 60 of 71.

From the USGS Earthquake Hazards Program and its partner networks, event nc1066097. Read Thu, Oct 1, 2026, 10:13 AM UTC.