QuakeIndex

Earthquake · reviewed by a seismologist

M 2.3ml

14 km NNE of Helena Valley Northwest, Montana

· 5.0 km deep · released about 85 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Lewis and Clark County 44 kmBroadwater County 67 kmCascade County 70 kmPowell County 74 kmJefferson County 80 kmMeagher County 85 kmTeton County 111 kmSilver Bow County 118 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 2.3 (ml)
Depth
5.0 km below the surface
Felt
no reports yet
Nearest
Lewis and Clark County, 44 km NW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2271 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 85 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.3 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 180,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 130,000× the energy of this one
  3. Around the size people start to feel M 3.0 11× the energy of this one
  4. This earthquake M 2.3 about 85 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 46.8444, -111.9642. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Lewis and Clark County, MT 44 km (28 mi) SE of here earthquakes near Lewis and Clark County
Broadwater County, MT 67 km (42 mi) NNW of here earthquakes near Broadwater County
Cascade County, MT 70 km (44 mi) SW of here earthquakes near Cascade County
Powell County, MT 74 km (46 mi) E of here earthquakes near Powell County
Jefferson County, MT 80 km (50 mi) N of here earthquakes near Jefferson County
Meagher County, MT 85 km (53 mi) WNW of here earthquakes near Meagher County

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

Aftershocks so far

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

  1. 1.5 Western Montana
  2. 1.6 12 km E of Lincoln, Montana
  3. 1.8 16 km E of Lincoln, Montana
  4. 1.5 12 km E of Lincoln, Montana
  5. 2.4 15 km ESE of Lincoln, Montana
  6. 1.7 10 km N of Elliston, Montana
  7. 1.6 2 km E of South Hills, Montana
  8. 1.6 2 km E of South Hills, Montana
  9. 1.8 31 km ENE of Helena Valley Northeast, Montana
  10. 1.9 30 km ENE of Helena Valley Northeast, Montana
  11. 1.8 8 km SSE of Marysville, Montana
  12. 1.6 3 km SW of Helena Valley Northwest, Montana
  13. 1.6 1 km SSE of South Hills, Montana
  14. 1.6 1 km SSE of South Hills, Montana
  15. 1.5 15 km ESE of Lincoln, 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 4.3 on 2016-01-30 — it released about 1,100 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.