QuakeIndex

Earthquake · reviewed by a seismologist

M 1.7ml

Earthquake near Butte, MT

No earthquake was likely felt in Butte in the 24 hours to 8:31 am MST (15:31 UTC). The last one was M 2.0, 5 km (3 mi) E, at 12:56 pm MST on 9 November 2026, estimated intensity II (weak) in town. Every earthquake near Butte

This page: a magnitude 1.7 earthquake was recorded 44 km (27 mi) south of Butte, MT, at 8:33 pm MST on 15 December 2017 (03:33 UTC), 4.6 km deep.

USGS: 17 km WNW of Twin Bridges, Montana

8:33 pm MST, Dec 15, 2017 · · 4.6 km deep · released about 12 lb of TNT

Every earthquake near Butte Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Silver Bow County 34 kmMadison County 58 kmBeaverhead County 60 kmJefferson County 68 kmDeer Lodge County 72 kmGallatin County 107 kmGranite County 111 kmBroadwater County 114 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
8:33 pm MST on 15 December 2017 ()
Where
44 km (27 mi) south of Butte, MT · earthquakes near Butte
Montana today
every earthquake in Montana in the last 24 hours
Magnitude
M 1.7 (ml)
Depth
4.6 km below the surface
Felt
no reports yet
Nearest
Silver Bow County, 34 km NNW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 3252 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 12 km (7 mi) from the epicentre. In Butte, 44 km away, the estimate is intensity I (not felt). 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 12 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.7 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 1,200,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 870,000× the energy of this one
  3. Around the size people start to feel M 3.0 78× the energy of this one
  4. This earthquake M 1.7 about 12 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 2,700 times the energy of this one.

Before 2016, the USGS record lists 2 earthquakes of M5 or more within 50 km:

  1. 5.6 16 km N of Dillon, Montana · 28 km SSW of this epicentre
  2. 5.4 Near Butte, Montana · 44 km N of this epicentre

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 45.6072, -112.5373. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Silver Bow County, MT 34 km (21 mi) NNW earthquakes near Silver Bow County
Madison County, MT 58 km (36 mi) ESE earthquakes near Madison County
Beaverhead County, MT 60 km (37 mi) SSW earthquakes near Beaverhead County
Jefferson County, MT 68 km (42 mi) NNE earthquakes near Jefferson County
Deer Lodge County, MT 72 km (45 mi) NW earthquakes near Deer Lodge County
Gallatin County, MT 107 km (67 mi) E earthquakes near Gallatin County

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

Aftershocks so far

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

  1. 1.6 4 km E of Butte, Montana
  2. 1.5 4 km ENE of Butte, Montana
  3. 1.7 5 km E of Butte, Montana
  4. 1.9 5 km E of Butte, Montana
  5. 1.6 5 km ENE of Butte, Montana
  6. 1.9 33 km WNW of Twin Bridges, Montana
  7. 1.7 17 km S of Whitehall, Montana
  8. 1.9 5 km ESE of Walkerville, Montana
  9. 1.6 5 km E of Butte, Montana
  10. 1.5 5 km ESE of Walkerville, Montana
  11. 1.7 5 km W of Butte, MT
  12. 1.6 13 km WNW of Whitehall, Montana
  13. 1.5 5 km ESE of Walkerville, Montana
  14. 1.7 8 km SSW of Dillon, MT
  15. 2.4 4 km E of Walkerville, 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.