QuakeIndex

Earthquake · reviewed by a seismologist

M 1.9ml

Earthquake near Libby, MT

USGS: 2 km NNW of Happys Inn, Montana

4:26 am MDT, Sep 16, 2017 · · 7.5 km deep · released about 19 lb of TNT

Every earthquake near Libby Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Sanders County 38 kmLincoln County 55 kmFlathead County 84 kmLake County 95 kmShoshone County 100 kmMineral County 108 kmBonner County 112 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
4:26 am MDT on 16 September 2017 ()
Where
44 km (27 mi) SE of Libby, MT · earthquakes near Libby
Magnitude
M 1.9 (ml)
Depth
7.5 km below the surface
Felt
no reports yet
Nearest
Sanders County, 38 km S
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 3303 days ago

A magnitude 1.9 earthquake was recorded 44 km (27 mi) SE of Libby, MT, at 4:26 am MDT on 16 September 2017 (10:26 UTC). This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.

How big was it?

This earthquake released about 19 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.9 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 810,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 580,000× the energy of this one
  3. Around the size people start to feel M 3.0 51× the energy of this one
  4. This earthquake M 1.9 about 19 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 since 1900 lists no earthquake of M5 or more within 50 km.

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 48.1017, -115.1525. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Sanders County, MT 38 km (24 mi) S earthquakes near Sanders County
Lincoln County, MT 55 km (34 mi) NNW earthquakes near Lincoln County
Flathead County, MT 84 km (52 mi) ENE earthquakes near Flathead County
Lake County, MT 95 km (59 mi) ESE earthquakes near Lake County
Shoshone County, ID 100 km (62 mi) SSW earthquakes near Shoshone County
Mineral County, MT 108 km (67 mi) S earthquakes near Mineral County

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

Aftershocks so far

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

  1. 1.7 19 km SW of Marion, Montana
  2. 2.3 18 km SW of Marion, Montana
  3. 2.0 19 km SW of Marion, Montana
  4. 1.7 21 km SSE of Happys Inn, Montana
  5. 2.4 23 km ENE of Noxon, Montana
  6. 2.0 17 km W of Niarada, Montana
  7. 1.8 3 km NW of Happys Inn, Montana
  8. 1.6 4 km NW of Niarada, Montana
  9. 2.6 4 km NW of Happys Inn, Montana
  10. 1.8 17 km WNW of Niarada, Montana
  11. 2.2 16 km ENE of Happys Inn, Montana
  12. 2.2 8 km WNW of Niarada, Montana
  13. 1.6 13 km WNW of Marion, Montana
  14. 1.7 18 km NW of Marion, Montana
  15. 1.7 6 km S of Happys Inn, 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.