California earthquakes

M5.7 earthquake 11 km NE of Mesa, California

A magnitude 5.7 earthquake struck 11 km NE of Mesa, California on Mon, Jul 21, 1986, 7:51 AM PDT (14:51 UTC), 8 km (5 mi) below the surface.

A larger quake followed: M5.8 10 km NNE of Dixon Lane-Meadow Creek, California. This one was a foreshock.

Dixon Lane-Meadow Creek forecast More in California

Map

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

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The earthquake

Magnitude: 5.7 (ML, local (Richter)), moderate
Magnitude from: Northern California Seismic System
Local time: Mon, Jul 21, 1986, 7:51 AM PDT
UTC: 1986-07-21 14:51:09 UTC
Depth: 8.5 km (5.3 mi), shallow
Epicenter: 37.493° N, 118.454° W
Region: California
Strongest shaking: VI, strong shaking
Tsunami flag: No
Status: Reviewed by a seismologist

Magnitude estimates

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
5.7	ML, local (Richter)	Northern California Seismic System	Preferred · Final · 6 stations
5.1	mb, body-wave	USGS National Earthquake Information Center	Reviewed · 28 stations
5.42	ML, local (Richter)	Southern California Seismic Network	Final · 10 stations
5.05	Mw, moment	USGS historic United States catalog	Final

What happened

The USGS’s account of the effects of this earthquake.

Felt (V) at Benton and Big Pine, California.

Maximum observed Modified Mercalli Intensity (MMI) V

From the USGS event page for nc10085764. U.S. Geological Survey text and figures are in the public domain.

Shaking

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

Strongest estimated: VI, strong shaking
Peak ground acceleration: 23.0% of gravity
Peak ground velocity: 2.4 cm/s
Map: Automatic

USGS ShakeMap: estimated shaking intensity around the epicenter — Estimated shaking intensity. Map: USGS ShakeMap.

Did you feel it?

No one has reported feeling this quake to the USGS.

How well it is located

Reviewed by a seismologist.

Location uncertainty: About 0.7 km horizontally, 1.3 km in depth
Depth from: From location
Station coverage gap: 198°, poorly surrounded by stations
Stations used: 28

Nearest places

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

Nearby

Within 100 km, magnitude 2.7 and up: at least 200 in the 60 days after this one and 88 in the 30 days before it.

After

The first 60 of at least 200.

Before

Earthquakes today California earthquakes Live radar here

Sources

From the USGS Earthquake Hazards Program and its partner networks, event nc10085764 (also filed as ushis3971, usp0002w9p, atlas19860721145110, ci602780). Read Thu, Oct 1, 2026, 5:39 PM UTC.