Earthquake · reviewed by a seismologist
M 1.8md
Earthquake near Chester, CA
No earthquake was likely felt in Chester in the 24 hours to 5:08 am PST (13:08 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 1.8 earthquake was recorded 10 km (6 mi) east of Chester, CA, at 5:47 pm PDT on 9 July 2023 (00:47 UTC), 11 km deep.
USGS: 4 km NNW of Hamilton Branch, CA
- When
- 5:47 pm PDT on 9 July 2023 ()
- Where
- 10 km (6 mi) east of Chester, CA · earthquakes near Chester
- Magnitude
- M 1.8 (md)
- Depth
- 11 km below the surface
- Felt
- no reports yet
- Nearest
- Plumas County, 43 km SE
- Nearest mapped fault
- Almanor fault, 4 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 1172 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 minor earthquake. Quakes this small are rarely felt and do not cause damage.
At this magnitude and depth, people at rest would likely notice it out to about 9 km (6 mi) from the epicentre. In Chester, 10 km away, the estimate is intensity II (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.
Earthquakes near other towns within 30 km: Westwood, Greenville.
How big was it?
This earthquake released about 17 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.8 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 870,000× the energy of this one
- Magna, Utah 2020 M 5.7 620,000× the energy of this one
- Around the size people start to feel M 3.0 55× the energy of this one
- This earthquake M 1.8 about 17 lb of TNT
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 290,000 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 · 14 km SSE of this epicentre
- 5.5 15 km NE of Mineral, California · 34 km WNW 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 40.3093, -121.1165. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Plumas County, CA | 43 km (27 mi) | SE | earthquakes near Plumas County |
| Lassen County, CA | 62 km (38 mi) | NE | earthquakes near Lassen County |
| Butte County, CA | 83 km (51 mi) | SSW | earthquakes near Butte County |
| Shasta County, CA | 93 km (58 mi) | WNW | earthquakes near Shasta County |
| Sierra County, CA | 96 km (60 mi) | SSE | earthquakes near Sierra County |
| Tehama County, CA | 97 km (60 mi) | WSW | earthquakes near Tehama County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
57 earthquakes have been recorded within 50 km since this one.
- 1.9 3 km NE of Almanor, CA
- 1.8 2 km N of Prattville, CA
- 1.9 4 km NE of Almanor, CA
- 2.7 2 km NE of Almanor, CA
- 1.9 2 km SW of Chester, CA
- 2.4 1 km NW of Prattville, CA
- 1.9 4 km SSE of Prattville, CA
- 2.4 9 km SSE of Meadow Valley, CA
- 2.5 9 km SSE of Meadow Valley, CA
- 2.1 1 km NE of Almanor, CA
- 2.6 2 km NE of Almanor, CA
- 1.9 1 km ENE of Almanor, CA
- 1.9 2 km N of Prattville, CA
- 1.7 1 km NW of Prattville, CA
- 1.7 2 km ESE of Prattville, 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.