QuakeIndex

quarry blast · reviewed by a seismologist

M 1.6ml

6 km NE of Three Forks, Montana

· -2.0 km deep · released about 7.6 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Broadwater County 45 kmJefferson County 50 kmGallatin County 52 kmMadison County 75 kmMeagher County 85 kmPark County 90 kmSilver Bow County 91 kmSweet Grass County 120 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 1.6 (ml)
Depth
-2.0 km below the surface
Felt
no reports yet
Nearest
Broadwater County, 45 km N
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 347 days ago

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

USGS catalogues this as quarry blast, not an earthquake.

How big was it?

This earthquake released about 7.6 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.6 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 2,000,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 1,400,000× the energy of this one
  3. Around the size people start to feel M 3.0 130× the energy of this one
  4. This earthquake M 1.6 about 7.6 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 45.9265, -111.4850. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Broadwater County, MT 45 km (28 mi) S of here earthquakes near Broadwater County
Jefferson County, MT 50 km (31 mi) ESE of here earthquakes near Jefferson County
Gallatin County, MT 52 km (32 mi) NNW of here earthquakes near Gallatin County
Madison County, MT 75 km (46 mi) NNE of here earthquakes near Madison County
Meagher County, MT 85 km (53 mi) SSW of here earthquakes near Meagher County
Park County, MT 90 km (56 mi) NW of here earthquakes near Park County

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

Aftershocks so far

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

  1. 1.7 8 km W of Townsend, Montana
  2. 1.9 14 km ESE of Harrison, Montana
  3. 2.1 4 km NW of Ponderosa Pines, Montana
  4. 1.7 17 km ESE of Harrison, Montana
  5. 2.0 2 km NNW of Pony, Montana
  6. 1.6 9 km W of Townsend, Montana
  7. 1.6 6 km NW of Logan, Montana
  8. 1.5 9 km WSW of Townsend, Montana
  9. 1.5 4 km NE of Three Forks, Montana
  10. 2.0 14 km ESE of Harrison, Montana
  11. 1.7 4 km SW of Churchill, Montana
  12. 1.9 9 km SSE of Harrison, Montana
  13. 1.8 15 km ESE of Harrison, Montana
  14. 1.9 9 km W of Townsend, Montana
  15. 2.4 16 km ESE of Harrison, 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 4.2 on 2019-08-16 — it released about 7,900 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.