QuakeIndex

Earthquake · reviewed by a seismologist

M 1.8ml

17 km SSE of Swan Lake, Montana

· 5.3 km deep · released about 14 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Lake County 27 kmFlathead County 61 kmMissoula County 84 kmSanders County 104 kmTeton County 112 kmGlacier County 119 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
5.3 km below the surface
Felt
no reports yet
Nearest
Lake County, 27 km SW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 131 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 14 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 1,100,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 760,000× the energy of this one
  3. Around the size people start to feel M 3.0 68× the energy of this one
  4. This earthquake M 1.8 about 14 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 47.7790, -113.7837. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Lake County, MT 27 km (17 mi) NE of here earthquakes near Lake County
Flathead County, MT 61 km (38 mi) SSE of here earthquakes near Flathead County
Missoula County, MT 84 km (52 mi) N of here earthquakes near Missoula County
Sanders County, MT 104 km (65 mi) E of here earthquakes near Sanders County
Teton County, MT 112 km (70 mi) W of here earthquakes near Teton County
Glacier County, MT 119 km (74 mi) SSW of here earthquakes near Glacier County

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

Aftershocks so far

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

  1. 0.9 9 km WSW of Condon, Montana
  2. 1.9 18 km E of Saint Ignatius, Montana
  3. 2.4 9 km SSW of Bear Dance, Montana
  4. 1.6 1 km SSW of Dayton, 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.

On USGS

QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.