M2.8 earthquake 8km NE of Ridgemark, CA

A magnitude 2.8 earthquake struck 8km NE of Ridgemark, CA on Wed, Mar 24, 2021, 4:29 PM PDT (23:29 UTC), 7 km (5 mi) below the surface.

A larger quake followed: M3.6 15km N of Morgan Hill, 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
2.81	Md, duration	Northern California Seismic System	Preferred · Final · ±0.123 · 134 stations
2.6	ML, local (Richter)	USGS National Earthquake Information Center	Reviewed · ±0.042 · 76 stations

15 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: 127 in the 60 days after this one and 80 in the 30 days before it.

The first 60 of 127.

From the USGS Earthquake Hazards Program and its partner networks, event nc73539561 (also filed as us6000dw72). Read Sun, Oct 4, 2026, 11:01 PM UTC.