California earthquakes

M4.2 earthquake 21 km NNE of Soledad, California

A magnitude 4.2 earthquake struck 21 km NNE of Soledad, California on Thu, Dec 15, 1977, 3:15 AM PST (11:15 UTC), 8 km (5 mi) below the surface.

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Map

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

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The earthquake

Magnitude: 4.2 (ML, local (Richter)), light
Magnitude from: Northern California Seismic System
Local time: Thu, Dec 15, 1977, 3:15 AM PST
UTC: 1977-12-15 11:15:28 UTC
Depth: 8.3 km (5.1 mi), shallow
Epicenter: 36.592° N, 121.198° W
Region: California
Strongest shaking: IV, light 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
4.2	ML, local (Richter)	Northern California Seismic System	Preferred · Final · 0 stations
3.6	mb, body-wave	USGS National Earthquake Information Center	Reviewed
4.03	ML, local (Richter)	Southern California Seismic Network	Final · ±0.161 · 6 stations

Shaking

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

Strongest estimated: IV, light shaking
Peak ground acceleration: 5.0% of gravity
Peak ground velocity: 0.7 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 0.2 km horizontally, 0.4 km in depth
Depth from: From location
Station coverage gap: 36°
Stations used: 54

Nearest places

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

Nearby

Within 100 km, magnitude 1.5 and up: 156 in the 60 days after this one and 90 in the 30 days before it.

After

The first 60 of 156.

Before

Earthquakes today California earthquakes Live radar here

Sources

From the USGS Earthquake Hazards Program and its partner networks, event nc1038147 (also filed as ci3336933, usp0000s32). Read Sat, Oct 3, 2026, 4:32 PM UTC.