M3.4 earthquake 18km NW of Grapevine, CA

A magnitude 3.4 earthquake struck 18km NW of Grapevine, CA on Fri, Aug 6, 2021, 7:37 AM PDT (14:37 UTC), 8 km (5 mi) below the surface.

A larger quake followed: M4.0 13km SE of Bodfish, 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
3.39	Mw, moment	Southern California Seismic Network	Preferred · Final · 4 stations
3.4	Mwr, regional moment	USGS National Earthquake Information Center	Reviewed · 4 stations

The USGS ShakeMap: shaking estimated from seismic stations and the quake’s size, on the Modified Mercalli intensity scale.

22 people reported to the USGS what they felt; the strongest reported shaking was III, weak shaking.

How the rock slipped, from the moment tensor, and the USGS estimate of landslides and liquefaction.

Reviewed by a seismologist.

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

Within 100 km, magnitude 1.5 and up: 49 in the 60 days after this one and 9 in the 30 days before it.

From the USGS Earthquake Hazards Program and its partner networks, event ci39765679 (also filed as us6000f2uq). Read Sun, Oct 4, 2026, 11:01 PM UTC.