M3.6 earthquake 7 km W of Cobb, California

A magnitude 3.6 earthquake struck 7 km W of Cobb, California on Sat, Mar 22, 1986, 8:58 PM PST (04:58 UTC), 0 km (0 mi) below the surface.

A larger quake followed: M4.1 7 km W of Lodoga, 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
3.6	ML, local (Richter)	Northern California Seismic System	Preferred · Final · 6 stations
3.7	mb, body-wave	USGS National Earthquake Information Center	Reviewed · 1 stations

The USGS’s account of the effects of this earthquake.

Felt strongly at The Geysers. Felt (V) at Cobb, (IV) at Loch Lomond and Jenner, (III) at Boyes Hot Springs and Freestone.

From the USGS event page for nc68586. U.S. Geological Survey text and figures are in the public domain.

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: 173 in the 60 days after this one and 103 in the 30 days before it.

The first 60 of 173.

From the USGS Earthquake Hazards Program and its partner networks, event nc68586 (also filed as usp0002s50). Read Thu, Oct 1, 2026, 8:06 AM UTC.