M1.7 earthquake 7 km WSW of Cobb, California

A magnitude 1.7 earthquake struck 7 km WSW of Cobb, California on Tue, Aug 1, 1978, 1:08 AM PDT (08:08 UTC), 2 km (1 mi) below the surface.

A larger quake followed: M4.2 4 km SSW of Monument Hills, 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: 80 in the 60 days after this one and 33 in the 30 days before it.

The first 60 of 80.

From the USGS Earthquake Hazards Program and its partner networks, event nc1041314. Read Sat, Oct 3, 2026, 5:22 PM UTC.