California earthquakes

M2.8 earthquake 2km ENE of Prattville, CA

A magnitude 2.8 earthquake struck 2km ENE of Prattville, CA on Thu, Dec 9, 2021, 6:39 PM PST (02:39 UTC), 6 km (4 mi) below the surface.

A larger quake followed: M2.9 12km SE of Mineral, CA. This one was a foreshock.

Hamilton Branch forecast More in California

Map

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

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The earthquake

Magnitude: 2.8 (Md, duration), micro
Magnitude from: Northern California Seismic System
Local time: Thu, Dec 9, 2021, 6:39 PM PST
UTC: 2021-12-10 02:39:47 UTC
Depth: 5.7 km (3.6 mi), shallow
Epicenter: 40.219° N, 121.132° W
Region: California
Felt reports: 10
Tsunami flag: No
Status: Reviewed by a seismologist

Magnitude estimates

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
2.82	Md, duration	Northern California Seismic System	Preferred · Final · ±0.15 · 57 stations
2.5	ML, local (Richter)	USGS National Earthquake Information Center	Reviewed · ±0.046 · 63 stations
2.7	ML, local (Richter)	Nevada Seismological Laboratory	Reviewed · ±0.42 · 5 stations

Did you feel it?

10 people reported to the USGS what they felt; the strongest reported shaking was III, weak shaking.

How well it is located

Reviewed by a seismologist.

Location uncertainty: About 0.3 km horizontally, 0.4 km in depth
Magnitude uncertainty: ±0.15
Depth from: From location
Station coverage gap: 57°
Stations used: 40

Nearest places

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

Nearby

Within 100 km, magnitude 1.5 and up: 20 in the 60 days after this one and 15 in the 30 days before it.

After

Before

Earthquakes today California earthquakes Live radar here

Sources

From the USGS Earthquake Hazards Program and its partner networks, event nc73662016 (also filed as nn00829753, us6000gb1z). Read Sun, Oct 4, 2026, 3:41 PM UTC.