M1.9 earthquake 9 km SW of Ridgemark, California

A magnitude 1.9 earthquake struck 9 km SW of Ridgemark, California on Wed, Jul 16, 1975, 9:35 AM PDT (16:35 UTC), 8 km (5 mi) below the surface.

A larger quake followed: M4.9 7 km SW of Three Rocks, California. This one was a foreshock.

Map

Where this earthquake was located, with the others nearby. Select one for its page.

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: 183 in the 60 days after this one and 129 in the 30 days before it.

The first 60 of 183.

From the USGS Earthquake Hazards Program and its partner networks, event nc1024804. Read Thu, Oct 1, 2026, 12:03 PM UTC.