Earthquake · reviewed by a seismologist
M 1.6md
Earthquake near Chester, CA
No earthquake was likely felt in Chester in the 24 hours to 10:44 am PST (18:44 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 1.6 earthquake was recorded 22 km (14 mi) north-northeast of Chester, CA, at 7:47 pm PDT on 22 September 2023 (02:47 UTC), 8.3 km deep.
USGS: 22 km NNE of Chester, CA
- When
- 7:47 pm PDT on 22 September 2023 ()
- Where
- 22 km (14 mi) north-northeast of Chester, CA · earthquakes near Chester
- Magnitude
- M 1.6 (md)
- Depth
- 8.3 km below the surface
- Felt
- no reports yet
- Nearest
- Lassen County, 48 km ENE
- Nearest mapped fault
- Almanor fault, 11 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 1140 days ago
Earthquake alerts for Chester, CA
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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 7 km (4 mi) from the epicentre. In Chester, 22 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.
How big was it?
This earthquake released about 7.1 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.6 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 2,100,000× the energy of this one
- Magna, Utah 2020 M 5.7 1,500,000× the energy of this one
- Around the size people start to feel M 3.0 130× the energy of this one
- This earthquake M 1.6 about 7.1 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 710,000 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 · 32 km S of this epicentre
- 5.5 15 km NE of Mineral, California · 31 km W 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 40.4793, -121.1038. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Lassen County, CA | 48 km (30 mi) | ENE | earthquakes near Lassen County |
| Plumas County, CA | 59 km (37 mi) | SSE | earthquakes near Plumas County |
| Shasta County, CA | 85 km (53 mi) | WNW | earthquakes near Shasta County |
| Butte County, CA | 100 km (62 mi) | SSW | earthquakes near Butte County |
| Tehama County, CA | 103 km (64 mi) | WSW | earthquakes near Tehama County |
| Sierra County, CA | 112 km (70 mi) | SSE | earthquakes near Sierra County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
59 earthquakes have been recorded within 50 km since this one.
- 1.9 26 km SE of Fall River Mills, CA
- 2.3 2 km ESE of Canyondam, CA
- 3.5 2 km E of Canyondam, CA
- 1.9 25 km S of Nubieber, California
- 2.2 26 km ESE of Fall River Mills, CA
- 2.4 2 km ENE of Canyondam, CA
- 2.6 2 km E of Canyondam, CA
- 2.5 2 km ENE of Canyondam, CA
- 2.2 2 km NE of Almanor, CA
- 1.8 2 km N of Almanor, CA
- 1.8 14 km NNE of Mineral, CA
- 1.8 17 km NNE of Mineral, CA
- 1.6 13 km NE of Mineral, CA
- 1.7 3 km ENE of Canyondam, California
- 1.7 2 km E 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.