QuakeIndex

Earthquake · reviewed by a seismologist

M 2.8ml

8 km NE of Alder, Montana

· 9.1 km deep · released about 480 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Madison County 11 kmGallatin County 69 kmBeaverhead County 73 kmSilver Bow County 75 kmJefferson County 83 kmBroadwater County 113 kmPark County 117 kmDeer Lodge County 117 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
Magnitude
M 2.8 (ml)
Depth
9.1 km below the surface
Felt
1 report · strongest reported intensity I
Nearest
Madison County, 11 km ESE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2922 days ago

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage. 1 person has reported feeling it to USGS.

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.

  1. Mineral, Virginia 2011 M 5.8 32,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 22,000× the energy of this one
  3. Around the size people start to feel M 3.0 2× the energy of this one
  4. 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.

Where

Epicentre 45.3800, -112.0309. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Madison County, MT 11 km (7 mi) WNW of here earthquakes near Madison County
Gallatin County, MT 69 km (43 mi) WSW of here earthquakes near Gallatin County
Beaverhead County, MT 73 km (45 mi) ENE of here earthquakes near Beaverhead County
Silver Bow County, MT 75 km (47 mi) SE of here earthquakes near Silver Bow County
Jefferson County, MT 83 km (51 mi) S of here earthquakes near Jefferson County
Broadwater County, MT 113 km (70 mi) SSW of here earthquakes near Broadwater County

Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.

Aftershocks so far

54 earthquakes have been recorded within 50 km since this one.

  1. 1.8 29 km SSE of Virginia City, Montana
  2. 2.3 31 km SSE of Virginia City, Montana
  3. 1.6 16 km S of Whitehall, Montana
  4. 2.1 26 km S of Virginia City, Montana
  5. 2.4 2 km WNW of Sheridan, Montana
  6. 2.3 18 km WNW of Pony, Montana
  7. 2.3 33 km SSE of Virginia City, Montana
  8. 1.6 9 km SSE of Harrison, Montana
  9. 2.5 11 km E of Harrison, Montana
  10. 2.4 14 km ESE of Harrison, Montana
  11. 2.0 30 km SSE of Virginia City, Montana
  12. 1.8 5 km W of Sheridan, Montana
  13. 1.6 30 km SSE of Virginia City, Montana
  14. 2.0 30 km SSE of Virginia City, Montana
  15. 1.5 34 km S of Virginia City, Montana

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.

For this area

The largest earthquake within 50 km in our catalogue was M 4.0 on 2016-09-03 — it released about 70 times the energy of this one.

From the QuakeIndex catalogue, built from the USGS FDSN event service.

On USGS

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