M2.3 earthquake 4 km SW of Three Rocks, California

A magnitude 2.3 earthquake struck 4 km SW of Three Rocks, California on Fri, Aug 18, 1989, 4:45 PM PDT (23:45 UTC), 8 km (5 mi) below the surface.

A larger quake followed: M4.0 11 km W of Three Rocks, 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
2.25	Md, duration	Northern California Seismic System	Preferred · Final · ±0.13 · 24 stations
2.86	Mh	Southern California Seismic Network	Final · 4 stations

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: 105 in the 60 days after this one and 58 in the 30 days before it.

The first 60 of 105.

From the USGS Earthquake Hazards Program and its partner networks, event nc142505 (also filed as ci665780). Read Sun, Oct 4, 2026, 8:59 PM UTC.