QuakeIndex

Earthquake · reviewed by a seismologist

M 1.8md

24 km SW of Augusta, Montana

· 6.6 km deep · released about 16 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Lewis and Clark County 32 kmTeton County 59 kmPowell County 60 kmCascade County 97 kmMissoula County 101 kmPondera County 103 kmLake County 113 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 1.8 (md)
Depth
6.6 km below the surface
Felt
no reports yet
Nearest
Lewis and Clark County, 32 km SE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2825 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 16 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.8 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 970,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 680,000× the energy of this one
  3. Around the size people start to feel M 3.0 61× the energy of this one
  4. This earthquake M 1.8 about 16 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 47.3455, -112.6420. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Lewis and Clark County, MT 32 km (20 mi) NW of here earthquakes near Lewis and Clark County
Teton County, MT 59 km (37 mi) SSW of here earthquakes near Teton County
Powell County, MT 60 km (37 mi) NNE of here earthquakes near Powell County
Cascade County, MT 97 km (61 mi) W of here earthquakes near Cascade County
Missoula County, MT 101 km (63 mi) ENE of here earthquakes near Missoula County
Pondera County, MT 103 km (64 mi) SSW of here earthquakes near Pondera County

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

Aftershocks so far

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

  1. 1.5 12 km ESE of Lincoln, Montana
  2. 2.6 10 km ESE of Lincoln, Montana
  3. 1.6 6 km SSE of Lincoln, Montana
  4. 1.6 Western Montana
  5. 2.5 19 km NW of Lincoln, Montana
  6. 2.3 16 km E of Ovando, Montana
  7. 2.8 13 km E of Lincoln, Montana
  8. 2.8 35 km WSW of Augusta, Montana
  9. 2.5 39 km NNE of Ovando, Montana
  10. 2.3 12 km ESE of Lincoln, Montana
  11. 3.3 40 km NE of Seeley Lake, Montana
  12. 2.0 12 km ESE of Lincoln, Montana
  13. 1.8 29 km ENE of Seeley Lake, Montana
  14. 1.9 11 km ESE of Lincoln, Montana
  15. 2.9 17 km E 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 6,000 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.