M3.0 earthquake 12 km WSW of Byron, California

A magnitude 3.0 earthquake struck 12 km WSW of Byron, California on Mon, Oct 10, 1983, 2:12 PM PDT (21:12 UTC), 12 km (7 mi) below the surface.

A larger quake followed: M3.6 12 km ESE of East Foothills, California. 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
3.0	ML, local (Richter)	Northern California Seismic System	Preferred · Final · 0 stations
3.3	ML, local (Richter)	USGS National Earthquake Information Center	Reviewed

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: 60 in the 60 days after this one and 43 in the 30 days before it.

From the USGS Earthquake Hazards Program and its partner networks, event nc1104720 (also filed as usp0001ywm). Read Sat, Oct 3, 2026, 9:31 PM UTC.