M4.5 earthquake 13 km NNE of Mesa, California

A magnitude 4.5 earthquake struck 13 km NNE of Mesa, California on Mon, Jul 21, 1986, 10:05 AM PDT (17:05 UTC), 10 km (6 mi) below the surface.

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
4.5	ML, local (Richter)	Northern California Seismic System	Preferred · Final · 2 stations
4.19	Mw, moment	USGS historic United States catalog	Final

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

Maximum observed Modified Mercalli Intensity (MMI) I

From the USGS event page for nc97418. U.S. Geological Survey text and figures are in the public domain.

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: at least 202 in the 60 days after this one and at least 200 in the 30 days before it.

The first 60 of at least 202.

From the USGS Earthquake Hazards Program and its partner networks, event nc97418 (also filed as ushis3980). Read Thu, Oct 1, 2026, 5:51 AM UTC.