QuakeIndex

Earthquake · reviewed by a seismologist

M 1.8ml

Earthquake near Butte, MT

No earthquake was likely felt in Butte in the 24 hours to 9:50 pm MST (04:50 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 1.8 earthquake was recorded 36 km (22 mi) south-southeast of Butte, MT, at 3:03 pm MDT on 31 October 2023 (21:03 UTC), 9.6 km deep.

USGS: 19 km N of Twin Bridges, Montana

3:03 pm MDT, Oct 31, 2023 · · 9.6 km deep · released about 15 lb of TNT

10 km30 km60 km120 km N Silver Bow County 32 kmJefferson County 50 kmMadison County 54 kmDeer Lodge County 75 kmBeaverhead County 78 kmGallatin County 94 kmBroadwater County 94 kmGranite County 113 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
3:03 pm MDT on 31 October 2023 ()
Where
36 km (22 mi) south-southeast of Butte, MT · earthquakes near Butte
Montana today
every earthquake in Montana in the last 24 hours
Magnitude
M 1.8 (ml)
Depth
9.6 km below the surface
Felt
no reports yet
Nearest
Silver Bow County, 32 km NW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1107 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 10 km (6 mi) from the epicentre. In Butte, 36 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.

Earthquakes near other towns within 30 km: Whitehall.

How big was it?

This earthquake released about 15 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 1,000,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 710,000× the energy of this one
  3. Around the size people start to feel M 3.0 63× the energy of this one
  4. This earthquake M 1.8 about 15 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 2,200 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 · 45 km SSW of this epicentre
  2. 5.4 Near Butte, Montana · 34 km NNW 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 45.7165, -112.3330. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Silver Bow County, MT 32 km (20 mi) NW earthquakes near Silver Bow County
Jefferson County, MT 50 km (31 mi) NNE earthquakes near Jefferson County
Madison County, MT 54 km (34 mi) SE earthquakes near Madison County
Deer Lodge County, MT 75 km (47 mi) NW earthquakes near Deer Lodge County
Beaverhead County, MT 78 km (49 mi) SW earthquakes near Beaverhead County
Gallatin County, MT 94 km (58 mi) ESE 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. 1.7 5 km ENE of Butte, Montana
  2. 2.0 3 km WNW of Pony, Montana
  3. 1.7 5 km ENE of Butte, Montana
  4. 2.3 3 km WNW of Pony, Montana
  5. 1.5 5 km E of Butte, Montana
  6. 1.8 5 km E of Butte, Montana
  7. 1.6 4 km E of Butte, Montana
  8. 1.5 5 km ESE of Walkerville, Montana
  9. 1.5 5 km E of Butte, Montana
  10. 1.9 5 km ENE of Butte, Montana
  11. 1.9 4 km E of Butte, Montana
  12. 1.6 5 km E of Butte, Montana
  13. 1.6 5 km ENE of Butte, Montana
  14. 1.5 5 km E of Butte, Montana
  15. 1.5 5 km E of Butte, 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.