M2.8 earthquake 8km W of Cobb, CA

A magnitude 2.8 earthquake struck 8km W of Cobb, CA on Thu, Nov 4, 2021, 11:59 PM PDT (06:59 UTC), 2 km (1 mi) below the surface.

A larger quake followed: M3.1 4km NW of Cobb, CA. 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
2.79	Md, duration	Northern California Seismic System	Preferred · Final · ±0.102 · 38 stations
2.5	ML, local (Richter)	USGS National Earthquake Information Center	Reviewed · ±0.044 · 68 stations

13 people reported to the USGS what they felt; the strongest reported shaking was IV, light shaking.

Reviewed by a seismologist.

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

Within 100 km, magnitude 1.5 and up: 154 in the 60 days after this one and 108 in the 30 days before it.

The first 60 of 154.

From the USGS Earthquake Hazards Program and its partner networks, event nc73648890 (also filed as us7000frmq). Read Sun, Oct 4, 2026, 6:47 PM UTC.