M3.0 earthquake 2km S of Placentia, CA

A magnitude 3.0 earthquake struck 2km S of Placentia, CA on Mon, Jul 6, 1981, 12:53 PM PDT (19:53 UTC), 5 km (3 mi) below the surface.

A larger quake followed: M3.8 28km SSE of Malibu, 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
3.04	ML, local (Richter)	Southern California Seismic Network	Preferred · Final · ±0.14 · 8 stations
3.2	ML, local (Richter)	USGS National Earthquake Information Center	Reviewed

The USGS’s account of the effects of this earthquake.

FELT (IV) AT PLACENTIA AND YORBA LINDA, (III) AT GARDEN GROVE AND SANTA ANA.

From the USGS event page for ci518940. U.S. Geological Survey text and figures are in the public domain.

No one has reported feeling this quake to the USGS.

Reviewed by a seismologist.

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

Within 100 km, magnitude 1.5 and up: 79 in the 60 days after this one and 38 in the 30 days before it.

The first 60 of 79.

From the USGS Earthquake Hazards Program and its partner networks, event ci518940 (also filed as usp0001eje). Read Thu, Oct 1, 2026, 9:22 PM UTC.