M3.3 earthquake 6 km W of Cobb, California

A magnitude 3.3 earthquake struck 6 km W of Cobb, California on Fri, Jul 11, 1986, 1:02 PM PDT (20:02 UTC), 1 km (1 mi) below the surface.

A larger quake followed: M4.7 5 km NNE of Brooktrails, California. This one was a foreshock.

Map

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

Different scales measure different things and differ by a few tenths. The USGS marks one as preferred, and it is the one this page uses.

Mag.	Scale	Computed by	Notes
3.27	Md, duration	Northern California Seismic System	Preferred · Final · ±0.21 · 37 stations
2.8	ML, local (Richter)	USGS National Earthquake Information Center	Reviewed

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: 174 in the 60 days after this one and 84 in the 30 days before it.

The first 60 of 174.

From the USGS Earthquake Hazards Program and its partner networks, event nc76266 (also filed as usp0002vy0). Read Sat, Oct 3, 2026, 8:40 AM UTC.