QuakeIndex

Earthquake · reviewed by a seismologist

M 1.9ml

32 km ESE of Swan Lake, Montana

· 5.1 km deep · released about 25 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Lake County 50 kmFlathead County 71 kmTeton County 88 kmMissoula County 91 kmPondera County 104 kmGlacier County 107 kmLewis and Clark County 110 kmPowell 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 1.9 (ml)
Depth
5.1 km below the surface
Felt
no reports yet
Nearest
Lake County, 50 km WSW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2583 days ago

A magnitude 1.9 earthquake was recorded 32 km ESE of Swan Lake, Montana at 15:08 UTC on 2019-09-06. This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.

How big was it?

This earthquake released about 25 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.0 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 600,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 420,000× the energy of this one
  3. Around the size people start to feel M 3.0 38× the energy of this one
  4. This earthquake M 1.9 about 25 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.

For this area

No earthquake of M4 or more has been recorded within 50 km since our catalogue begins in 2016.

Before 2016, the USGS record lists one earthquake of M5 or more within 50 km:

  1. 5.5 Western Montana · 34 km NW of this epicentre

Since 2016: the QuakeIndex catalogue (US, M1.5+), built from the USGS FDSN event service. Before 2016: USGS ComCat, M5+ from 1900. Distances are between epicentres. This is the record, not a forecast.

Where

Epicentre 47.7942, -113.4593. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Lake County, MT 50 km (31 mi) WSW earthquakes near Lake County
Flathead County, MT 71 km (44 mi) NW earthquakes near Flathead County
Teton County, MT 88 km (55 mi) E earthquakes near Teton County
Missoula County, MT 91 km (57 mi) SSW earthquakes near Missoula County
Pondera County, MT 104 km (65 mi) ENE earthquakes near Pondera County
Glacier County, MT 107 km (67 mi) NNE earthquakes near Glacier County

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

Aftershocks so far

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

  1. 2.1 18 km SSE of Swan Lake, Montana
  2. 1.5 11 km ENE of Ronan, Montana
  3. 2.0 8 km S of Condon, Montana
  4. 1.9 21 km NNW of Condon, Montana
  5. 2.3 26 km ESE of Condon, Montana
  6. 1.7 Western Montana
  7. 2.3 19 km SSE of Swan Lake, Montana
  8. 1.5 11 km WNW of Condon, Montana
  9. 2.1 16 km NNE of Swan Lake, Montana
  10. 1.9 4 km NE of Bear Dance, Montana
  11. 1.6 20 km E of Finley Point, Montana
  12. 2.2 47 km WNW of Augusta, Montana
  13. 1.5 10 km ENE of Condon, Montana
  14. 1.8 13 km E of Pablo, Montana
  15. 2.0 6 km ESE of Bear Dance, 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.