M3.3 earthquake 12km NNE of Morgan Hill, CA

A magnitude 3.3 earthquake struck 12km NNE of Morgan Hill, CA on Sun, Oct 3, 2021, 5:02 AM PDT (12:02 UTC), 4 km (2 mi) below the surface.

A larger quake followed: M3.9 1km NE of San Ramon, 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
3.29	ML, local (Richter)	Northern California Seismic System	Preferred · Final · ±0.166 · 96 stations
3.1	ML, local (Richter)	USGS National Earthquake Information Center	Reviewed · ±0.031 · 141 stations

103 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: 153 in the 60 days after this one and 65 in the 30 days before it.

The first 60 of 153.

From the USGS Earthquake Hazards Program and its partner networks, event nc73632846 (also filed as us6000frb3). Read Sun, Oct 4, 2026, 5:56 AM UTC.