M3.5 earthquake 9km WSW of Grapevine, CA

A magnitude 3.5 earthquake struck 9km WSW of Grapevine, CA on Mon, Mar 12, 1984, 2:17 AM PST (10:17 UTC), 12 km (7 mi) below the surface.

A larger quake followed: M4.3 11km ENE of Santa Ynez, 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
3.51	ML, local (Richter)	Southern California Seismic Network	Preferred · Final · 11 stations
3.5	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: 187 in the 60 days after this one and 32 in the 30 days before it.

The first 60 of 187.

From the USGS Earthquake Hazards Program and its partner networks, event ci33443 (also filed as usp00022kk). Read Sun, Oct 4, 2026, 11:45 PM UTC.