M3.1 earthquake 5km W of Cobb, CA

A magnitude 3.1 earthquake struck 5km W of Cobb, CA on Tue, Mar 30, 2021, 10:05 AM PDT (17:05 UTC), 1 km (1 mi) below the surface.

A larger quake followed: M4.0 3km SW of Anderson Springs, 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
3.13	ML, local (Richter)	Northern California Seismic System	Preferred · Final · ±0.189 · 53 stations
2.9	ML, local (Richter)	USGS National Earthquake Information Center	Reviewed · ±0.038 · 91 stations

12 people reported to the USGS what they felt; the strongest reported shaking was III, weak 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: 197 in the 60 days after this one and 83 in the 30 days before it.

The first 60 of 197.

From the USGS Earthquake Hazards Program and its partner networks, event nc73541836 (also filed as us6000dxnw). Read Sun, Oct 4, 2026, 1:54 AM UTC.