QuakeIndex

Earthquake · reviewed by a seismologist

M 2.5ml

13 km SSE of Harrison, Montana

· 4.8 km deep · released about 170 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Madison County 32 kmGallatin County 46 kmJefferson County 65 kmSilver Bow County 79 kmBroadwater County 85 kmPark County 95 kmBeaverhead County 103 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 2.5 (ml)
Depth
4.8 km below the surface
Felt
no reports yet
Nearest
Madison County, 32 km SSW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 718 days ago

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage.

How big was it?

This earthquake released about 170 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.5 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 89,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 63,000× the energy of this one
  3. Around the size people start to feel M 3.0 5.6× the energy of this one
  4. This earthquake M 2.5 about 170 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 45.5861, -111.7410. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Madison County, MT 32 km (20 mi) NNE of here earthquakes near Madison County
Gallatin County, MT 46 km (28 mi) W of here earthquakes near Gallatin County
Jefferson County, MT 65 km (40 mi) SSE of here earthquakes near Jefferson County
Silver Bow County, MT 79 km (49 mi) ESE of here earthquakes near Silver Bow County
Broadwater County, MT 85 km (53 mi) SSW of here earthquakes near Broadwater County
Park County, MT 95 km (59 mi) W of here earthquakes near Park County

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

Aftershocks so far

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

  1. 1.9 14 km ESE of Harrison, Montana
  2. 2.1 12 km NW of Ennis, Montana
  3. 1.5 13 km NNW of Ennis, Montana
  4. 1.7 17 km ESE of Harrison, Montana
  5. 2.0 2 km NNW of Pony, Montana
  6. 1.6 6 km NW of Logan, Montana
  7. 1.5 4 km NE of Three Forks, Montana
  8. 2.0 14 km ESE of Harrison, Montana
  9. 1.7 4 km SW of Churchill, Montana
  10. 2.3 14 km NNE of Twin Bridges, Montana
  11. 2.9 14 km NNE of Twin Bridges, Montana
  12. 1.8 14 km NNE of Twin Bridges, Montana
  13. 1.9 9 km SSE of Harrison, Montana
  14. 1.8 15 km ESE of Harrison, Montana
  15. 2.4 16 km ESE of Harrison, 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 4.2 on 2019-08-16 — it released about 350 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.