QuakeIndex

Earthquake · reviewed by a seismologist

M 1.6ml

30 km ENE of Helena Valley Northeast, Montana

· 11 km deep · released about 7.1 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Broadwater County 56 kmCascade County 57 kmMeagher County 59 kmLewis and Clark County 67 kmJefferson County 86 kmPowell County 101 kmJudith Basin County 101 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
11 km below the surface
Felt
no reports yet
Nearest
Broadwater County, 56 km S
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 3312 days ago

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

How big was it?

This earthquake released about 7.1 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 2,100,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 1,500,000× 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 7.1 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 46.8312, -111.6073. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Broadwater County, MT 56 km (35 mi) N of here earthquakes near Broadwater County
Cascade County, MT 57 km (36 mi) SSW of here earthquakes near Cascade County
Meagher County, MT 59 km (37 mi) WNW of here earthquakes near Meagher County
Lewis and Clark County, MT 67 km (42 mi) ESE of here earthquakes near Lewis and Clark County
Jefferson County, MT 86 km (53 mi) NNE of here earthquakes near Jefferson County
Powell County, MT 101 km (63 mi) E of here earthquakes near Powell 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 2 km E of South Hills, Montana
  2. 1.6 2 km E of South Hills, Montana
  3. 1.8 31 km ENE of Helena Valley Northeast, Montana
  4. 1.9 30 km ENE of Helena Valley Northeast, Montana
  5. 1.6 3 km SW of Helena Valley Northwest, Montana
  6. 1.6 1 km SSE of South Hills, Montana
  7. 1.6 1 km SSE of South Hills, Montana
  8. 2.2 36 km SSW of Stockett, Montana
  9. 1.7 2 km NNW of Montana City, Montana
  10. 1.5 21 km NE of Townsend, Montana
  11. 2.2 6 km W of Helena Valley West Central, Montana
  12. 2.4 8 km NNE of Helena Valley Northwest, Montana
  13. 2.9 11 km SW of Winston, Montana
  14. 2.3 2 km WNW of East Helena, Montana
  15. 1.6 2 km NW of Montana City, 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.