QuakeIndex

Earthquake · reviewed by a seismologist

M 2.7ml

9 km SSE of Pony, Montana

· 5.0 km deep · released about 340 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Madison County 30 kmGallatin County 53 kmJefferson County 62 kmSilver Bow County 72 kmBroadwater County 87 kmBeaverhead County 97 kmPark County 102 kmDeer Lodge County 116 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 2.7 (ml)
Depth
5.0 km below the surface
Felt
4 reports · strongest reported intensity III
Nearest
Madison County, 30 km SSW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1752 days ago

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage. 4 people have reported feeling it to USGS.

How big was it?

This earthquake released about 340 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.7 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 45,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 32,000× the energy of this one
  3. Around the size people start to feel M 3.0 2.8× the energy of this one
  4. This earthquake M 2.7 about 340 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 45.5882, -111.8371. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Madison County, MT 30 km (19 mi) NNE of here earthquakes near Madison County
Gallatin County, MT 53 km (33 mi) W of here earthquakes near Gallatin County
Jefferson County, MT 62 km (39 mi) SSE of here earthquakes near Jefferson County
Silver Bow County, MT 72 km (45 mi) ESE of here earthquakes near Silver Bow County
Broadwater County, MT 87 km (54 mi) SSW of here earthquakes near Broadwater County
Beaverhead County, MT 97 km (60 mi) ENE of here earthquakes near Beaverhead County

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

Aftershocks so far

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

  1. 1.8 18 km N of Ennis, Montana
  2. 2.5 3 km WNW of Pony, Montana
  3. 2.4 20 km N of Twin Bridges, Montana
  4. 1.8 19 km N of Twin Bridges, Montana
  5. 1.7 16 km N of Big Sky, Montana
  6. 1.6 14 km ESE of Harrison, Montana
  7. 2.1 17 km NNE of Ennis, Montana
  8. 1.5 17 km SSW of Whitehall, Montana
  9. 1.5 10 km WNW of Four Corners, Montana
  10. 1.6 5 km SE of Three Forks, Montana
  11. 1.6 5 km WSW of Logan, Montana
  12. 2.0 4 km NNW of Logan, Montana
  13. 1.6 18 km WNW of Pony, Montana
  14. 1.8 20 km WSW of Gallatin Gateway, Montana
  15. 1.6 5 km W of Three Forks, 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 180 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.