QuakeIndex

Earthquake · reviewed by a seismologist

M 1.8ml

8 km S of Ponderosa Pines, Montana

· 0.1 km deep · released about 15 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Broadwater County 43 kmGallatin County 51 kmJefferson County 56 kmMeagher County 78 kmMadison County 82 kmPark County 85 kmSilver Bow County 100 kmSweet Grass County 111 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 (ml)
Depth
0.1 km below the surface
Felt
no reports yet
Nearest
Broadwater County, 43 km NNW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 643 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 15 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 1,000,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 730,000× the energy of this one
  3. Around the size people start to feel M 3.0 65× the energy of this one
  4. This earthquake M 1.8 about 15 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 45.9562, -111.3695. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Broadwater County, MT 43 km (27 mi) SSE of here earthquakes near Broadwater County
Gallatin County, MT 51 km (32 mi) NNW of here earthquakes near Gallatin County
Jefferson County, MT 56 km (35 mi) ESE of here earthquakes near Jefferson County
Meagher County, MT 78 km (48 mi) SSW of here earthquakes near Meagher County
Madison County, MT 82 km (51 mi) NNE of here earthquakes near Madison County
Park County, MT 85 km (53 mi) NW of here earthquakes near Park 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. 1.6 6 km NW of Logan, Montana
  2. 1.5 9 km WSW of Townsend, Montana
  3. 1.5 4 km NE of Three Forks, Montana
  4. 2.0 14 km ESE of Harrison, Montana
  5. 1.7 4 km SW of Churchill, Montana
  6. 1.9 9 km SSE of Harrison, Montana
  7. 1.8 15 km ESE of Harrison, Montana
  8. 1.9 9 km W of Townsend, Montana
  9. 2.4 16 km ESE of Harrison, Montana
  10. 1.6 3 km NNW of Townsend, Montana
  11. 2.5 16 km ESE of Harrison, Montana
  12. 2.4 17 km ESE of Harrison, Montana
  13. 1.6 6 km NE of Three Forks, Montana
  14. 1.6 6 km W of Townsend, Montana
  15. 1.6 2 km E of Churchill, 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 4.2 on 2019-08-16 — it released about 4,100 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.