QuakeIndex

Earthquake · reviewed by a seismologist

M 1.8ml

33 km S of Ennis, Montana

· 6.6 km deep · released about 13 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Madison County 35 kmGallatin County 67 kmFremont County 94 kmBeaverhead County 94 kmClark County 99 kmPark County 102 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 1.8 (ml)
Depth
6.6 km below the surface
Felt
no reports yet
Nearest
Madison County, 35 km NNW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2192 days ago

This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.

How big was it?

This earthquake released about 13 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.8 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 1,100,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 810,000× the energy of this one
  3. Around the size people start to feel M 3.0 72× the energy of this one
  4. This earthquake M 1.8 about 13 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 45.0483, -111.6987. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Madison County, MT 35 km (22 mi) SSE of here earthquakes near Madison County
Gallatin County, MT 67 km (42 mi) SW of here earthquakes near Gallatin County
Fremont County, ID 94 km (58 mi) N of here earthquakes near Fremont County
Beaverhead County, MT 94 km (59 mi) E of here earthquakes near Beaverhead County
Clark County, ID 99 km (62 mi) NNE of here earthquakes near Clark County
Park County, MT 102 km (63 mi) WSW of here earthquakes near Park County

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

Aftershocks so far

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

  1. 1.7 42 km NNE of Spencer, Idaho
  2. 1.8 3 km WSW of Hebgen Lake Estates, Montana
  3. 2.1 32 km S of Virginia City, Montana
  4. 1.9 30 km WNW of Hebgen Lake Estates, Montana
  5. 2.1 47 km ENE of Lima, Montana
  6. 2.3 45 km NE of Spencer, Idaho
  7. 1.9 27 km WNW of Hebgen Lake Estates, Montana
  8. 1.8 42 km W of Hebgen Lake Estates, Montana
  9. 2.7 26 km SSE of Virginia City, Montana
  10. 1.7 28 km SE of Virginia City, Montana
  11. 1.6 17 km SSE of Big Sky, Montana
  12. 1.5 23 km W of Hebgen Lake Estates, Montana
  13. 1.5 26 km W of Hebgen Lake Estates, Montana
  14. 1.9 38 km WNW of Hebgen Lake Estates, Montana
  15. 1.8 21 km W of Hebgen Lake Estates, 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 4.3 on 2016-06-13 — it released about 7,400 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.