QuakeIndex

Earthquake · reviewed by a seismologist

M 3.3ml

17 km NNE of Ennis, Montana

· 5.0 km deep · released about 1.3 tons of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Madison County 27 kmGallatin County 40 kmJefferson County 75 kmSilver Bow County 88 kmPark County 89 kmBroadwater County 93 kmBeaverhead County 104 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 3.3 (ml)
Depth
5.0 km below the surface
Felt
no reports yet
Nearest
Madison County, 27 km SW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1295 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 1.3 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.3 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 130,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 5,600× the energy of this one
  3. Magna, Utah 2020 M 5.7 4,000× the energy of this one
  4. This earthquake M 3.3 about 1.3 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 2.8× 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.

Where

Epicentre 45.5056, -111.6732. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Madison County, MT 27 km (17 mi) NE of here earthquakes near Madison County
Gallatin County, MT 40 km (25 mi) W of here earthquakes near Gallatin County
Jefferson County, MT 75 km (47 mi) SSE of here earthquakes near Jefferson County
Silver Bow County, MT 88 km (55 mi) ESE of here earthquakes near Silver Bow County
Park County, MT 89 km (55 mi) W of here earthquakes near Park County
Broadwater County, MT 93 km (58 mi) S of here earthquakes near Broadwater County

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

Aftershocks so far

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

  1. 2.0 4 km ESE of Three Forks, Montana
  2. 2.4 7 km NW of Willow Creek, Montana
  3. 2.0 7 km SE of Pony, Montana
  4. 1.5 29 km SE of Virginia City, Montana
  5. 1.6 5 km NW of Logan, Montana
  6. 1.6 28 km S of Ennis, Montana
  7. 1.6 5 km NW of Logan, Montana
  8. 1.5 28 km SE of Virginia City, Montana
  9. 1.5 18 km W of Pony, Montana
  10. 2.5 13 km SSE of Harrison, Montana
  11. 2.8 0 km NW of Cardwell, Montana
  12. 2.4 2 km E of Three Forks, Montana
  13. 1.5 11 km N of Ennis, Montana
  14. 1.5 15 km SSE of Pony, Montana
  15. 2.0 3 km WNW of Pony, 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 22 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.