QuakeIndex

quarry blast · reviewed by a seismologist

M 1.5ml

1 km ESE of South Hills, Montana

· -2.0 km deep · released about 5.7 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Broadwater County 45 kmJefferson County 48 kmLewis and Clark County 70 kmPowell County 79 kmMeagher County 81 kmSilver Bow County 89 kmCascade County 98 kmDeer Lodge County 102 kmGranite 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 1.5 (ml)
Depth
-2.0 km below the surface
Felt
no reports yet
Nearest
Broadwater County, 45 km ESE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 3440 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 5.7 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 2,600,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 1,900,000× the energy of this one
  3. Around the size people start to feel M 3.0 170× the energy of this one
  4. This earthquake M 1.5 about 5.7 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 46.5510, -111.9847. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Broadwater County, MT 45 km (28 mi) WNW of here earthquakes near Broadwater County
Jefferson County, MT 48 km (30 mi) N of here earthquakes near Jefferson County
Lewis and Clark County, MT 70 km (44 mi) SSE of here earthquakes near Lewis and Clark County
Powell County, MT 79 km (49 mi) ESE of here earthquakes near Powell County
Meagher County, MT 81 km (51 mi) W of here earthquakes near Meagher County
Silver Bow County, MT 89 km (56 mi) NE of here earthquakes near Silver Bow County

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

Aftershocks so far

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

  1. 1.8 8 km N of Elliston, Montana
  2. 1.9 14 km NW of Marysville, Montana
  3. 2.5 13 km WNW of Marysville, Montana
  4. 3.4 14 km NW of Marysville, Montana
  5. 1.6 6 km W of Townsend, 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.