M1.9 earthquake 4 km SSE of Copperopolis, California
A magnitude 1.9 earthquake struck 4 km SSE of Copperopolis, California on Wed, Dec 7, 1977, 4:15 PM PST (00:15 UTC), 28 km (17 mi) below the surface.
A larger quake followed: M2.0 6 km E of Copperopolis, California. This one was a foreshock.
Map
Where this earthquake was located, with the others nearby. Select one for its page.
The earthquake
- Magnitude
- 1.9 (ma), micro
- Local time
- UTC
- 1977-12-08 00:15:38 UTC
- Depth
- 27.6 km (17.1 mi), shallow
- Epicenter
- 37.942° N, 120.622° W
- Region
- California
- Tsunami flag
- No
- Status
- Reviewed by a seismologist
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 1.7 km horizontally, 0.9 km in depth
- Magnitude uncertainty
- ±0.49
- Depth from
- From location
- Station coverage gap
- 228°, poorly surrounded by stations
- Stations used
- 4
Nearest places
Distance and direction from each place to the epicenter, with its forecast.
Nearby
Within 100 km, magnitude 1.5 and up: 4 in the 60 days after this one and 1 in the 30 days before it.
After
- 1.57 km N of Ione, California · 17816 days ago · 20 km deep · 60 km away
- 2.06 km E of Copperopolis, California · 17807 days ago · 8 km deep · 5 km away
- 1.623 km WNW of Diablo Grande, California · 17804 days ago · 2 km deep · 97 km away
- 1.63 km WNW of Volcano, California · 17786 days ago · 5 km deep · 57 km away
Before
Earthquakes todayCalifornia earthquakesLive radar here
Sources
From the USGS Earthquake Hazards Program and its partner networks, event nc1038049. Read Wed, Sep 23, 2026, 2:37 AM UTC.