Earthquake · reviewed by a seismologist
M 3.1ml
Earthquake near Chester, CA
No earthquake was likely felt in Chester in the 24 hours to 8:41 am PST (16:41 UTC). The last one was M 2.1, 17 km (11 mi) SE, at 8:09 am PDT on 29 October 2026, estimated intensity II (weak) in town. Every earthquake near Chester
This page: a magnitude 3.1 earthquake was recorded 12 km (7 mi) southeast of Chester, CA, at 6:12 am PDT on 4 July 2020 (13:12 UTC), 5.0 km deep. 86 people have reported feeling it to USGS.
USGS: 2km NE of Prattville, CA
- When
- 6:12 am PDT on 4 July 2020 ()
- Where
- 12 km (7 mi) southeast of Chester, CA · earthquakes near Chester
- Magnitude
- M 3.1 (ml)
- Depth
- 5.0 km below the surface
- Felt
- 86 reports · strongest reported intensity IV
- Nearest
- Plumas County, 37 km SE
- Nearest mapped fault
- Almanor fault, 3 km from its surface trace — near is not the same as on
- Status
- Reviewed by a seismologist
USGS · last changed by USGS · we first saw it 1957 days ago
Earthquake alerts for Chester, CA
Get a notification in this browser when USGS records an earthquake near Chester, CA. No account or email needed.
Alerts are on for .
Not a warning. An alert comes after USGS publishes a quake, usually minutes after the shaking. For early warning use ShakeAlert, through your phone's Wireless Emergency Alerts or the MyShake app.
This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage.
At this magnitude and depth, people at rest would likely notice it out to about 41 km (25 mi) from the epicentre. In Chester, 12 km away, the estimate is intensity III (weak). Estimated from magnitude, depth and distance with the intensity equation USGS Did You Feel It? uses; felt reports, where there are any, are the measurement.
Likely felt in: Chester 12 km, intensity III · Westwood 15 km, intensity III · Greenville 19 km, intensity III · East Quincy 38 km, intensity II. Estimated for each town centre; each link is that town's own record.
How big was it?
This earthquake released about 1,300 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.1 would have released about 32 times as much.
- Northridge, California 1994 M 6.7 260,000× the energy of this one
- Mineral, Virginia 2011 M 5.8 12,000× the energy of this one
- Magna, Utah 2020 M 5.7 8,200× the energy of this one
- This earthquake M 3.1 about 1,300 lb of TNT
- Around the size people start to feel M 3.0 this one released 1.4× more
Energy from the Gutenberg–Richter relation (log10E = 1.5M + 4.8), rounded to two figures; bar length is magnitude, which is already a logarithm of energy. Magnitudes of past earthquakes from the USGS catalogue.
For this area
No earthquake of M4 or more has been recorded within 50 km since our catalogue begins in 2016.
Before 2016, the USGS record lists 2 earthquakes of M5 or more within 50 km:
- 5.7 2 km NNE of Canyondam, California · 8 km ESE of this epicentre
- 5.5 15 km NE of Mineral, California · 37 km NW of this epicentre
Since 2016: the QuakeIndex catalogue (US, M1.5+), built from the USGS FDSN event service. Before 2016: USGS ComCat, M5+ from 1900. Distances are between epicentres. This is the record, not a forecast.
Where
Epicentre 40.2212, -121.1438. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Plumas County, CA | 37 km (23 mi) | SE | earthquakes near Plumas County |
| Lassen County, CA | 71 km (44 mi) | NE | earthquakes near Lassen County |
| Butte County, CA | 73 km (45 mi) | SSW | earthquakes near Butte County |
| Sierra County, CA | 89 km (55 mi) | SE | earthquakes near Sierra County |
| Tehama County, CA | 93 km (58 mi) | W | earthquakes near Tehama County |
| Shasta County, CA | 97 km (60 mi) | NW | earthquakes near Shasta County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
52 earthquakes have been recorded within 50 km since this one.
- 2.2 14km NNE of Mineral, CA
- 1.8 14km NNE of Mineral, CA
- 1.7 2 km ENE of East Quincy, California
- 1.5 11km SW of Chester, CA
- 2.6 4km NNE of Almanor, CA
- 1.5 6km NNE of Almanor, CA
- 2.0 8km NNW of Chester, CA
- 1.5 7km ENE of Mineral, CA
- 1.6 3km S of Canyondam, CA
- 1.7 12km SE of Mineral, CA
- 2.0 6km N of Greenhorn, CA
- 1.8 3km N of Spring Garden, CA
- 1.8 9km W of Susanville, CA
- 1.9 8km NW of Chester, CA
- 2.2 9km NW of Chester, CA
Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of . QuakeIndex does not forecast aftershocks. When USGS issues an operational aftershock forecast it appears on the USGS event page.
On USGS
- The official USGS event page — the source of record for every value above
- Did you feel it? Report it to USGS — reports go to USGS, not to us
- ShakeMap for this event, when USGS has produced one
QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.