mining explosion · reviewed by a seismologist
M 3.1ml
Earthquake near Gillette, WY
No earthquake was likely felt in Gillette in the 24 hours to 10:20 pm MST (05:20 UTC). The last one was M 3.4, 45 km (28 mi) SSE, at 2:13 pm MDT on 6 July 2026, estimated intensity II (weak) in town. Every earthquake near Gillette
No: USGS classifies this as a mining explosion, not an earthquake. A magnitude 3.1 mining explosion was recorded 20 km (12 mi) west of Gillette, WY, at 3:12 pm MDT on 10 August 2021 (21:12 UTC), less than 1 km deep.
USGS: 19 km W of Gillette, Wyoming
- When
- 3:12 pm MDT on 10 August 2021 ()
- Where
- 20 km (12 mi) west of Gillette, WY · earthquakes near Gillette
- Magnitude
- M 3.1 (ml)
- Depth
- 0.0 km below the surface
- Felt
- no reports yet
- Nearest
- Campbell County, 23 km SE
- Status
- Reviewed by a seismologist
USGS · last changed by USGS · we first saw it 1846 days ago
Earthquake alerts for Gillette, WY
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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 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 42 km (26 mi) from the epicentre. In Gillette, 20 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.
Earthquakes near other towns within 30 km: Antelope Valley-Crestview, Sleepy Hollow.
USGS catalogues this as mining explosion, not an earthquake.
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 6.7 250,000× the energy of this one
- Mineral, Virginia 2011 M 5.8 11,000× the energy of this one
- Magna, Utah 2020 M 5.7 7,900× 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 one earthquake of M5 or more within 50 km:
- 5.0 37 km W of Gillette, Wyoming · 19 km WSW 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 44.3105, -105.7465. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Campbell County, WY | 23 km (14 mi) | SE | earthquakes near Campbell County |
| Johnson County, WY | 73 km (46 mi) | WSW | earthquakes near Johnson County |
| Crook County, WY | 99 km (61 mi) | ENE | earthquakes near Crook County |
| Sheridan County, WY | 104 km (65 mi) | WNW | earthquakes near Sheridan County |
| Weston County, WY | 107 km (67 mi) | ESE | earthquakes near Weston County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
47 earthquakes have been recorded within 50 km since this one.
- 3.3 22 km SSE of Antelope Valley-Crestview, Wyoming
- 3.0 16 km SSE of Sleepy Hollow, Wyoming
- 2.9 26 km NNE of Wright, Wyoming
- 2.9 20 km NNW of Gillette, Wyoming
- 3.0 Wyoming
- 2.7 5 km W of Gillette, Wyoming
- 2.9 16 km SSE of Antelope Valley-Crestview, Wyoming
- 2.8 6 km WNW of Gillette, Wyoming
- 3.0 6 km NW of Gillette, Wyoming
- 2.8 24 km S of Antelope Valley-Crestview, Wyoming
- 3.2 11 km NNE of Gillette, Wyoming
- 3.1 19 km SSE of Sleepy Hollow, Wyoming
- 2.9 18 km NNE of Wright, Wyoming
- 2.6 3 km NNE of Antelope Valley-Crestview, Wyoming
- 2.5 9 km NNW of Gillette, Wyoming
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.