Earthquake · reviewed by a seismologist
M 5.2mw
Earthquake near Chester, CA
No earthquake was likely felt in Chester in the 24 hours to 9:20 am PST (17:20 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 5.2 earthquake was recorded 17 km (10 mi) southeast of Chester, CA, at 3:18 am PDT on 12 May 2023 (10:18 UTC), 6.1 km deep. 1,350 people have reported feeling it to USGS.
USGS: 4km NW of Canyondam, CA
- When
- 3:18 am PDT on 12 May 2023 ()
- Where
- 17 km (10 mi) southeast of Chester, CA · earthquakes near Chester
- Magnitude
- M 5.2 (mw)
- Depth
- 6.1 km below the surface
- Felt
- 1,350 reports · strongest reported intensity VI
- Measured shaking
- intensity VII (ShakeMap)
- USGS impact alert
- green
- Nearest
- Plumas County, 33 km SE
- Nearest mapped fault
- Almanor fault, 2 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 1209 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 moderate earthquake. Shaking at this size can damage poorly built structures close to the epicentre.
At this magnitude and depth, people at rest would likely notice it out to about 213 km (132 mi) from the epicentre. In Chester, 17 km away, the estimate is intensity V (moderate). 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: Greenville 14 km, intensity V · Westwood 15 km, intensity V · Chester 17 km, intensity V · East Quincy 34 km, intensity IV · Susanville 45 km, intensity IV. Estimated for each town centre; each link is that town's own record.
How big was it?
This earthquake released about 830 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 6.2 would have released about 32 times as much.
- Northridge, California 1994 M 6.7 200× the energy of this one
- Mineral, Virginia 2011 M 5.8 9.1× the energy of this one
- Magna, Utah 2020 M 5.7 6.5× the energy of this one
- This earthquake M 5.2 about 830 tons of TNT
- Around the size people start to feel M 3.0 this one released 1,700× 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
The largest earthquake within 50 km since 2016 was M 5.5 on 2023-05-11 — about 3 times the energy of this one.
Before 2016, the USGS record lists 2 earthquakes of M5 or more within 50 km:
- 5.7 2 km NNE of Canyondam, California · 3 km E of this epicentre
- 5.5 15 km NE of Mineral, California · 42 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 40.1960, -121.0998. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Plumas County, CA | 33 km (20 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) | SW | earthquakes near Butte County |
| Sierra County, CA | 85 km (53 mi) | SE | earthquakes near Sierra County |
| Tehama County, CA | 97 km (60 mi) | W | earthquakes near Tehama County |
| Shasta County, CA | 102 km (63 mi) | NW | earthquakes near Shasta County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
60 earthquakes have been recorded within 50 km since this one.
- 1.6 4km NE of Prattville, CA
- 2.2 1km NE of Prattville, CA
- 1.9 3km NE of Almanor, CA
- 1.9 4km ENE of Prattville, CA
- 2.3 3km ENE of Prattville, CA
- 2.3 2km NE of Almanor, CA
- 2.4 0km NW of Prattville, CA
- 3.2 2km NNE of Almanor, CA
- 1.9 1km NNE of Prattville, CA
- 2.6 3km NNE of Prattville, CA
- 1.8 2km NNE of Almanor, CA
- 2.5 3km NNE of Almanor, CA
- 2.0 4km NNW of Almanor, CA
- 1.8 4km ESE of Prattville, CA
- 2.6 2km NE of Almanor, 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.