QuakeIndex

Earthquake · reviewed by a seismologist

M 2.4ml

Earthquake near Big Sky, MT

No earthquake was likely felt in Big Sky in the 24 hours to 10:35 am MST (17:35 UTC). The last one was M 3.7, 68 km (42 mi) SE, at 7:22 am MDT on 28 October 2025, estimated intensity II (weak) in town; 11 felt reports to USGS. Every earthquake near Big Sky

This page: a magnitude 2.4 earthquake was recorded 48 km (30 mi) northwest of Big Sky, MT, at 1:26 pm MST on 31 December 2016 (20:26 UTC), 2.1 km deep.

USGS: 12 km SSE of Pony, Montana

1:26 pm MST, Dec 31, 2016 · · 2.1 km deep · released about 100 lb of TNT

Every earthquake near Big Sky Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Madison County 25 kmGallatin County 54 kmJefferson County 66 kmSilver Bow County 73 kmBroadwater County 92 kmBeaverhead County 93 kmPark County 104 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
1:26 pm MST on 31 December 2016 ()
Where
48 km (30 mi) northwest of Big Sky, MT · earthquakes near Big Sky
Montana today
every earthquake in Montana in the last 24 hours
Magnitude
M 2.4 (ml)
Depth
2.1 km below the surface
Felt
no reports yet
Nearest
Madison County, 25 km S
Nearest mapped fault
Madison fault, 22 km from its surface trace — near is not the same as on
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 3602 days ago

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

At this magnitude and depth, people at rest would likely notice it out to about 20 km (12 mi) from the epicentre. In Big Sky, 48 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.

How big was it?

This earthquake released about 100 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.4 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 150,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 110,000× the energy of this one
  3. Around the size people start to feel M 3.0 9.4× the energy of this one
  4. This earthquake M 2.4 about 100 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

The largest earthquake within 50 km since 2016 was M 4.0 on 2016-09-03 — about 330 times the energy of this one.

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 45.5440, -111.8615. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Madison County, MT 25 km (15 mi) S earthquakes near Madison County
Gallatin County, MT 54 km (34 mi) E earthquakes near Gallatin County
Jefferson County, MT 66 km (41 mi) NNW earthquakes near Jefferson County
Silver Bow County, MT 73 km (46 mi) WNW earthquakes near Silver Bow County
Broadwater County, MT 92 km (57 mi) NNE earthquakes near Broadwater County
Beaverhead County, MT 93 km (58 mi) WSW earthquakes near Beaverhead 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. 2.0 16 km S of Whitehall, Montana
  2. 1.7 4 km WSW of Three Forks, Montana
  3. 1.7 17 km S of Whitehall, Montana
  4. 2.2 6 km W of Willow Creek, Montana
  5. 2.3 7 km W of Willow Creek, Montana
  6. 2.4 6 km W of Willow Creek, Montana
  7. 2.2 17 km S of Whitehall, Montana
  8. 1.6 17 km S of Whitehall, Montana
  9. 1.9 17 km S of Whitehall, Montana
  10. 2.4 16 km WNW of Pony, Montana
  11. 1.8 17 km S of Whitehall, Montana
  12. 2.9 15 km S of Whitehall, Montana
  13. 3.3 17 km S of Whitehall, Montana
  14. 2.8 8 km NE of Alder, Montana
  15. 1.8 17 km S of Whitehall, 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.

On USGS

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