QuakeIndex

mining explosion · reviewed by a seismologist

M 3.0ml

Earthquake near Sheridan, WY

No earthquake was likely felt in Sheridan in the 24 hours to 8:31 am MST (15:31 UTC). The last one was M 3.5, 40 km (25 mi) N, at 10:02 am MDT on 29 May 2026, estimated intensity II (weak) in town. Every earthquake near Sheridan

No: USGS classifies this as a mining explosion, not an earthquake. A magnitude 3.0 mining explosion was recorded 29 km (18 mi) north-northeast of Sheridan, WY, at 1:58 pm MDT on 6 July 2020 (19:58 UTC), less than 1 km deep.

USGS: 29 km NNE of Sheridan, Wyoming

1:58 pm MDT, Jul 6, 2020 · · 0.0 km deep · released about 950 lb of TNT

10 km30 km60 km120 km N Sheridan County 28 kmBig Horn County 73 kmPowder River County 104 kmJohnson County 109 kmBig Horn County 112 km
Distance rings around the epicentre, with the nearest towns at their true direction and later quakes as coloured dots. Not a shaking map — see the USGS ShakeMap for that.
When
1:58 pm MDT on 6 July 2020 ()
Where
29 km (18 mi) north-northeast of Sheridan, WY · earthquakes near Sheridan
Magnitude
M 3.0 (ml)
Depth
0.0 km below the surface
Felt
no reports yet
Nearest
Sheridan County, 28 km SSW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2252 days ago

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 37 km (23 mi) from the epicentre. In Sheridan, 29 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.

USGS catalogues this as mining explosion, not an earthquake.

How big was it?

This earthquake released about 950 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.0 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 350,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 16,000× the energy of this one
  3. Magna, Utah 2020 M 5.7 11,000× the energy of this one
  4. This earthquake M 3.0 about 950 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 45.0208, -106.7637. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Sheridan County, WY 28 km (18 mi) SSW earthquakes near Sheridan County
Big Horn County, MT 73 km (45 mi) NW earthquakes near Big Horn County
Powder River County, MT 104 km (65 mi) ENE earthquakes near Powder River County
Johnson County, WY 109 km (68 mi) S earthquakes near Johnson County
Big Horn County, WY 112 km (69 mi) WSW earthquakes near Big Horn County
Campbell County, WY 135 km (84 mi) SE earthquakes near Campbell 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. 3.2 31 km WSW of Birney, Montana
  2. 2.6 33 km WSW of Birney, Montana
  3. 3.4 33 km NE of Ranchester, Wyoming
  4. 2.8 35 km WSW of Birney, Montana
  5. 3.2 34 km WSW of Birney, Montana
  6. 2.6 Eastern Montana
  7. 2.5 24 km NNE of Sheridan, Wyoming
  8. 3.5 23 km NNE of Sheridan, Wyoming
  9. 3.1 26 km SW of Birney, Montana
  10. 3.3 Eastern Montana
  11. 3.1 33 km NE of Ranchester, Wyoming
  12. 2.8 24 km WSW of Birney, Montana
  13. 3.3 30 km WSW of Birney, Montana
  14. 2.8 26 km WSW of Birney, Montana
  15. 3.1 29 km NE of Ranchester, 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

QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.