QuakeIndex

quarry blast · reviewed by a seismologist

M 1.5ml

2 km NNW of Logan, Montana

· -2.0 km deep · released about 5.9 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Broadwater County 47 kmGallatin County 49 kmJefferson County 53 kmMadison County 74 kmMeagher County 86 kmPark County 86 kmSilver Bow County 94 kmSweet Grass 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
Magnitude
M 1.5 (ml)
Depth
-2.0 km below the surface
Felt
no reports yet
Nearest
Broadwater County, 47 km N
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1816 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 5.9 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.5 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 2,500,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 1,800,000× the energy of this one
  3. Around the size people start to feel M 3.0 160× the energy of this one
  4. This earthquake M 1.5 about 5.9 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 45.9070, -111.4482. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Broadwater County, MT 47 km (29 mi) S of here earthquakes near Broadwater County
Gallatin County, MT 49 km (30 mi) NNW of here earthquakes near Gallatin County
Jefferson County, MT 53 km (33 mi) ESE of here earthquakes near Jefferson County
Madison County, MT 74 km (46 mi) NNE of here earthquakes near Madison County
Meagher County, MT 86 km (53 mi) SSW of here earthquakes near Meagher County
Park County, MT 86 km (54 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

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

  1. 1.6 5 km SE of Three Forks, Montana
  2. 1.6 5 km WSW of Logan, Montana
  3. 2.0 4 km NNW of Logan, Montana
  4. 2.4 12 km E of Elkhorn, Montana
  5. 1.8 20 km WSW of Gallatin Gateway, Montana
  6. 1.6 5 km W of Three Forks, Montana
  7. 3.0 18 km NNE of Ennis, Montana
  8. 1.5 5 km W of Townsend, Montana
  9. 1.5 18 km SSW of Radersburg, Montana
  10. 1.6 Western Montana
  11. 1.6 7 km WSW of Townsend, Montana
  12. 1.6 8 km WSW of Townsend, Montana
  13. 1.6 Western Montana
  14. 1.6 6 km NNW of Logan, Montana
  15. 1.6 Western 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 10,000 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.