QuakeIndex

Earthquake · reviewed by a seismologist

M 4.2mwr

9 km N of Black Eagle, Montana

· 24 km deep · released about 30 tons of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Cascade County 33 kmChouteau County 69 kmTeton County 79 kmJudith Basin County 97 kmPondera County 99 kmLewis and Clark County 100 kmLiberty County 107 kmMeagher 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 4.2 (mwr)
Depth
24 km below the surface
Felt
938 reports · strongest reported intensity V
Measured shaking
intensity IV (ShakeMap)
USGS impact alert
green
Nearest
Cascade County, 33 km S
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 3 days ago

This was a light earthquake. It is usually felt clearly nearby and can rattle windows and dishes, but damage is uncommon. 938 people have reported feeling it to USGS.

How big was it?

This earthquake released about 30 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.2 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 5,600× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 250× the energy of this one
  3. Magna, Utah 2020 M 5.7 180× the energy of this one
  4. This earthquake M 4.2 about 30 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 63× more

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 47.6105, -111.2654. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Cascade County, MT 33 km (21 mi) N of here earthquakes near Cascade County
Chouteau County, MT 69 km (43 mi) WSW of here earthquakes near Chouteau County
Teton County, MT 79 km (49 mi) ESE of here earthquakes near Teton County
Judith Basin County, MT 97 km (60 mi) NW of here earthquakes near Judith Basin County
Pondera County, MT 99 km (61 mi) SE of here earthquakes near Pondera County
Lewis and Clark County, MT 100 km (62 mi) ENE of here earthquakes near Lewis and Clark County

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

Aftershocks so far

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

  1. 3.7 7 km NNW of Black Eagle, Montana
  2. 2.4 9 km NNE of Black Eagle, Montana
  3. 1.9 9 km N of Black Eagle, Montana
  4. 2.6 10 km NNE of Black Eagle, Montana
  5. 3.7 3 km SE of Black Eagle, Montana
  6. 3.2 3 km NW of Malmstrom Air Force Base, Montana
  7. 2.7 5 km NNW of Malmstrom Air Force Base, 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.