California earthquakes

M5.1 earthquake 100 km W of Ferndale, California

A magnitude 5.1 earthquake struck 100 km W of Ferndale, California on Sat, May 28, 1983, 11:55 PM PDT (06:55 UTC), 10 km (6 mi) below the surface.

Ferndale 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: 5.1 (Ms, surface-wave), moderate
Magnitude from: USGS National Earthquake Information Center
Local time: Sat, May 28, 1983, 11:55 PM PDT
UTC: 1983-05-29 06:55:33 UTC
Depth: 10.0 km (6.2 mi), shallow
Epicenter: 40.457° N, 125.444° W
Region: California
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
5.1	Ms, surface-wave	USGS National Earthquake Information Center	Preferred · Reviewed · 5 stations
5.4	ML, local (Richter)	Northern California Seismic System	Final · 0 stations
5.49	Mw, moment	ISC-GEM global catalog	Final · ±0.1
5.1	Ms, surface-wave	USGS historic United States catalog	Final
5.5	Mwc, centroid moment	Global CMT project	Preliminary

What happened

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

Felt (III) at Rio Dell. Also felt at Eureka and other parts of Humboldt County.

Maximum observed Modified Mercalli Intensity (MMI) III

From the USGS event page for usp0001vs3. U.S. Geological Survey text and figures are in the public domain.

Did you feel it?

No one has reported feeling this quake to the USGS.

How well it is located

Reviewed by a seismologist.

Depth from: OPERATOR_ASSIGNED

Nearest places

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

Nearby

Within 100 km, magnitude 2.1 and up: 33 in the 60 days after this one and 19 in the 30 days before it.

After

Before

Earthquakes today California earthquakes Live radar here

Sources

From the USGS Earthquake Hazards Program and its partner networks, event usp0001vs3 (also filed as gcmtb052983f, ushis3800, gcmt19830529065533, nc1095710, iscgem577446). Read Sat, Oct 3, 2026, 4:36 PM UTC.