QuakeIndex

Earthquake · reviewed by a seismologist

M 1.5ml

10 km W of Helena West Side, Montana

· 5.0 km deep · released about 5.4 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Jefferson County 56 kmLewis and Clark County 58 kmPowell County 58 kmBroadwater County 66 kmSilver Bow County 86 kmDeer Lodge County 89 kmGranite County 93 kmMeagher County 102 kmCascade County 104 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
5.0 km below the surface
Felt
no reports yet
Nearest
Jefferson County, 56 km SSE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 3720 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 5.4 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 2,800,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 2,000,000× the energy of this one
  3. Around the size people start to feel M 3.0 180× the energy of this one
  4. This earthquake M 1.5 about 5.4 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 46.6125, -112.2538. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Jefferson County, MT 56 km (35 mi) NNW of here earthquakes near Jefferson County
Lewis and Clark County, MT 58 km (36 mi) S of here earthquakes near Lewis and Clark County
Powell County, MT 58 km (36 mi) ESE of here earthquakes near Powell County
Broadwater County, MT 66 km (41 mi) WNW of here earthquakes near Broadwater County
Silver Bow County, MT 86 km (53 mi) NNE of here earthquakes near Silver Bow County
Deer Lodge County, MT 89 km (55 mi) NE of here earthquakes near Deer Lodge County

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

Aftershocks so far

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

  1. 3.3 14 km SSE of Lincoln, Montana
  2. 2.5 14 km SE of Lincoln, Montana
  3. 2.2 13 km ESE of Lincoln, Montana
  4. 2.2 14 km ESE of Lincoln, Montana
  5. 2.4 13 km SE of Lincoln, Montana
  6. 2.3 14 km ESE of Lincoln, Montana
  7. 3.7 12 km ESE of Lincoln, Montana
  8. 2.3 12 km SE of Lincoln, Montana
  9. 2.5 13 km WNW of Marysville, Montana
  10. 3.3 12 km SE of Lincoln, Montana
  11. 2.3 13 km SE of Lincoln, Montana
  12. 2.6 11 km SSE of Lincoln, Montana
  13. 3.2 14 km ESE of Lincoln, Montana
  14. 2.7 Western Montana
  15. 3.3 9 km SE 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 18,000 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.