M2.5 earthquake 7km WNW of Cobb, CA

A magnitude 2.5 earthquake struck 7km WNW of Cobb, CA on Thu, May 6, 2021, 2:52 PM PDT (21:52 UTC), 2 km (2 mi) below the surface.

A larger quake followed: M4.0 7km WNW of The Geysers, 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
2.53	Md, duration	Northern California Seismic System	Preferred · Final · ±0.142 · 55 stations
2.0	ML, local (Richter)	USGS National Earthquake Information Center	Reviewed · ±0.05 · 53 stations

2 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: 179 in the 60 days after this one and 117 in the 30 days before it.

The first 60 of 179.

From the USGS Earthquake Hazards Program and its partner networks, event nc73559120 (also filed as us7000e0u7). Read Sat, Oct 3, 2026, 11:25 PM UTC.