QuakeIndex

Earthquake · reviewed by a seismologist

M 1.5ml

3 km SE of Helena Valley West Central, Montana

· 9.0 km deep · released about 5.6 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Broadwater County 53 kmJefferson County 57 kmLewis and Clark County 60 kmPowell County 72 kmMeagher County 85 kmCascade County 92 kmSilver Bow County 95 kmDeer Lodge County 104 kmGranite County 110 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
9.0 km below the surface
Felt
no reports yet
Nearest
Broadwater County, 53 km SE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 496 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 5.6 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 2,700,000× 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 5.6 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 46.6348, -112.0310. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Broadwater County, MT 53 km (33 mi) NW of here earthquakes near Broadwater County
Jefferson County, MT 57 km (35 mi) N of here earthquakes near Jefferson County
Lewis and Clark County, MT 60 km (38 mi) SSE of here earthquakes near Lewis and Clark County
Powell County, MT 72 km (45 mi) ESE of here earthquakes near Powell County
Meagher County, MT 85 km (53 mi) W of here earthquakes near Meagher County
Cascade County, MT 92 km (57 mi) SW of here earthquakes near Cascade County

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

Aftershocks so far

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

  1. 1.5 16 km NE of Helena Valley Northwest, Montana
  2. 1.6 14 km SSE of Craig, Montana
  3. 1.7 8 km W of Townsend, Montana
  4. 2.4 21 km SSE of Craig, Montana
  5. 1.6 9 km W of Townsend, Montana
  6. 1.5 9 km WSW of Townsend, Montana
  7. 1.5 1 km SSE of South Hills, Montana
  8. 1.7 0 km NNW of South Hills, Montana
  9. 1.7 8 km S of Marysville, Montana
  10. 2.0 32 km ENE of Helena Valley Northeast, Montana
  11. 2.0 20 km NNE of Helena Valley Northeast, Montana
  12. 1.7 13 km SE of Lincoln, Montana
  13. 1.5 31 km ENE of Helena Valley Northeast, Montana
  14. 1.9 1 km SSE of South Hills, Montana
  15. 2.4 2 km ESE of Clancy, 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 5.8 on 2017-07-06 — it released about 2,700,000 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.