mining explosion · reviewed by a seismologist
M 2.8ml
Earthquake near Sleepy Hollow, WY
No earthquake was likely felt in Sleepy Hollow in the 24 hours to 3:14 pm MST (22:14 UTC). The last one was M 3.4, 38 km (23 mi) S, at 2:13 pm MDT on 6 July 2026, estimated intensity II (weak) in town. Every earthquake near Sleepy Hollow
No: USGS classifies this as a mining explosion, not an earthquake. A magnitude 2.8 mining explosion was recorded 11 km (7 mi) east-northeast of Sleepy Hollow, WY, at 1:41 pm MST on 19 December 2021 (20:41 UTC), less than 1 km deep.
USGS: 9 km ENE of Sleepy Hollow, Wyoming
- When
- 1:41 pm MST on 19 December 2021 ()
- Where
- 11 km (7 mi) east-northeast of Sleepy Hollow, WY · earthquakes near Sleepy Hollow
- Magnitude
- M 2.8 (ml)
- Depth
- 0.0 km below the surface
- Felt
- no reports yet
- Nearest
- Campbell County, 19 km WSW
- Status
- Reviewed by a seismologist
USGS · last changed by USGS · we first saw it 1716 days ago
Earthquake alerts for Sleepy Hollow, WY
Get a notification in this browser when USGS records an earthquake near Sleepy Hollow, WY. 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 27 km (17 mi) from the epicentre. In Sleepy Hollow, 11 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, Gillette, Moorcroft.
USGS catalogues this as mining explosion, not an earthquake.
How big was it?
This earthquake released about 480 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.8 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 32,000× the energy of this one
- Magna, Utah 2020 M 5.7 22,000× the energy of this one
- Around the size people start to feel M 3.0 2× the energy of this one
- This earthquake M 2.8 about 480 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
No earthquake of M4 or more has been recorded within 50 km since our catalogue begins in 2016.
Before 2016, the USGS record since 1900 lists no earthquake of M5 or more within 50 km.
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 44.2860, -105.3143. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Campbell County, WY | 19 km (12 mi) | WSW | earthquakes near Campbell County |
| Crook County, WY | 68 km (42 mi) | ENE | earthquakes near Crook County |
| Weston County, WY | 77 km (48 mi) | SE | earthquakes near Weston County |
| Johnson County, WY | 105 km (65 mi) | WSW | earthquakes near Johnson County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
58 earthquakes have been recorded within 50 km since this one.
- 2.9 26 km NNE of Wright, Wyoming
- 3.1 22 km ENE of Wright, Wyoming
- 2.9 20 km NNW of Gillette, Wyoming
- 3.0 Wyoming
- 3.2 Wyoming
- 2.7 5 km W of Gillette, Wyoming
- 3.2 25 km ENE of Wright, Wyoming
- 3.2 17 km NE of Wright, Wyoming
- 2.9 16 km SSE of Antelope Valley-Crestview, Wyoming
- 2.8 6 km WNW of Gillette, Wyoming
- 3.2 21 km ENE of Wright, Wyoming
- 3.0 6 km NW of Gillette, Wyoming
- 2.8 24 km S of Antelope Valley-Crestview, Wyoming
- 2.8 18 km NE of Wright, Wyoming
- 3.2 11 km NNE 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.