QuakeIndex

Earthquake · reviewed by a seismologist

M 1.8ml

Earthquake near Bigfork, MT

USGS: 4 km NE of Bear Dance, Montana

8:53 pm MDT, Sep 27, 2016 · · 6.3 km deep · released about 15 lb of TNT

Every earthquake near Bigfork Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Lake County 35 kmFlathead County 39 kmSanders County 92 kmMissoula County 102 kmGlacier 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
8:53 pm MDT on 27 September 2016 ()
Where
15 km (9 mi) SSE of Bigfork, MT · earthquakes near Bigfork
Magnitude
M 1.8 (ml)
Depth
6.3 km below the surface
Felt
no reports yet
Nearest
Lake County, 35 km SSW
Nearest mapped fault
Mission fault, 3 km from its surface trace — near is not the same as on
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 3655 days ago

A magnitude 1.8 earthquake was recorded 15 km (9 mi) SSE of Bigfork, MT, at 8:53 pm MDT on 27 September 2016 (02:53 UTC). This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.

Earthquakes near other towns within 30 km: Lakeside, Somers.

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 5.7 710,000× the energy of this one
  3. Around the size people start to feel M 3.0 63× 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.

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 · 15 km ENE 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 47.9462, -113.9843. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Lake County, MT 35 km (21 mi) SSW earthquakes near Lake County
Flathead County, MT 39 km (24 mi) N earthquakes near Flathead County
Sanders County, MT 92 km (57 mi) WSW earthquakes near Sanders County
Missoula County, MT 102 km (64 mi) S earthquakes near Missoula County
Glacier County, MT 112 km (70 mi) NE earthquakes near Glacier County
Mineral County, MT 123 km (76 mi) SW earthquakes near Mineral County

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

Aftershocks so far

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

  1. 2.0 21 km SSE of Swan Lake, Montana
  2. 1.9 12 km E of Finley Point, Montana
  3. 2.2 12 km ESE of Finley Point, Montana
  4. 1.6 12 km ESE of Finley Point, Montana
  5. 1.9 18 km E of Finley Point, Montana
  6. 2.0 2 km ESE of Bear Dance, Montana
  7. 2.3 14 km SSE of Swan Lake, Montana
  8. 3.3 16 km SSE of Swan Lake, Montana
  9. 1.7 8 km NE of Bigfork, Montana
  10. 1.9 10 km WNW of Condon, MT
  11. 2.7 13 km E of Ronan, Montana
  12. 1.5 10 km WNW of Condon, Montana
  13. 2.3 11 km WNW of Condon, Montana
  14. 2.2 10 km WNW of Condon, Montana
  15. 1.9 21 km SSE of Swan Lake, 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.