QuakeIndex

Earthquake · reviewed by a seismologist

M 2.9ml

11 km SW of Winston, Montana

· 4.6 km deep · released about 680 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Broadwater County 21 kmJefferson County 38 kmMeagher County 67 kmSilver Bow County 89 kmLewis and Clark County 94 kmPowell County 103 kmCascade County 107 kmGallatin County 107 kmDeer Lodge County 112 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 2.9 (ml)
Depth
4.6 km below the surface
Felt
4 reports · strongest reported intensity II
Nearest
Broadwater County, 21 km ESE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1511 days ago

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage. 4 people have reported feeling it to USGS.

How big was it?

This earthquake released about 680 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.9 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 22,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 16,000× the energy of this one
  3. Around the size people start to feel M 3.0 1.4× the energy of this one
  4. This earthquake M 2.9 about 680 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 46.3945, -111.7493. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Broadwater County, MT 21 km (13 mi) WNW of here earthquakes near Broadwater County
Jefferson County, MT 38 km (24 mi) NE of here earthquakes near Jefferson County
Meagher County, MT 67 km (42 mi) WSW of here earthquakes near Meagher County
Silver Bow County, MT 89 km (56 mi) NE of here earthquakes near Silver Bow County
Lewis and Clark County, MT 94 km (59 mi) SSE of here earthquakes near Lewis and Clark County
Powell County, MT 103 km (64 mi) ESE of here earthquakes near Powell County

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

Aftershocks so far

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

  1. 2.4 3 km NE of Helena West Side, Montana
  2. 1.6 Western Montana
  3. 1.6 3 km WSW of Ponderosa Pines, Montana
  4. 1.6 8 km W of Townsend, Montana
  5. 1.7 6 km WSW of Townsend, Montana
  6. 1.5 2 km NW of Montana City, Montana
  7. 2.4 12 km E of Elkhorn, Montana
  8. 1.5 5 km W of Townsend, Montana
  9. 1.7 2 km NW of Montana City, Montana
  10. 1.5 18 km SSW of Radersburg, Montana
  11. 1.5 Western Montana
  12. 1.6 7 km WSW of Townsend, Montana
  13. 1.6 8 km WSW of Townsend, Montana
  14. 1.6 Western Montana
  15. 1.7 5 km W of Ponderosa Pines, 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.