QuakeIndex

Earthquake · reviewed by a seismologist

M 2.4ml

Earthquake near Ronan, MT

USGS: 14 km ENE of Saint Ignatius, Montana

55 km (34 mi) N of Missoula, MT

2:24 pm MDT, Oct 2, 2017 · · 14 km deep · released about 100 lb of TNT

10 km30 km60 km120 km N Lake County 34 kmMissoula County 37 kmMineral County 93 kmPowell County 93 kmFlathead County 105 kmSanders County 105 kmGranite County 113 kmLewis and Clark County 118 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
2:24 pm MDT on 2 October 2017 ()
Where
24 km (15 mi) SE of Ronan, MT · earthquakes near Ronan
Magnitude
M 2.4 (ml)
Depth
14 km below the surface
Felt
no reports yet
Nearest
Lake County, 34 km NNW
Nearest mapped fault
Mission fault, 7 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 3286 days ago

A magnitude 2.4 earthquake was recorded 24 km (15 mi) SE of Ronan, MT, at 2:24 pm MDT on 2 October 2017 (20:24 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 100 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.4 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 140,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 100,000× the energy of this one
  3. Around the size people start to feel M 3.0 9.1× the energy of this one
  4. This earthquake M 2.4 about 100 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 47.3587, -113.9055. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Lake County, MT 34 km (21 mi) NNW earthquakes near Lake County
Missoula County, MT 37 km (23 mi) S earthquakes near Missoula County
Mineral County, MT 93 km (58 mi) WSW earthquakes near Mineral County
Powell County, MT 93 km (58 mi) SE earthquakes near Powell County
Flathead County, MT 105 km (65 mi) N earthquakes near Flathead County
Sanders County, MT 105 km (65 mi) WNW earthquakes near Sanders County

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

Aftershocks so far

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

  1. 3.2 2 km ESE of Ravalli, Montana
  2. 2.3 26 km ESE of Condon, Montana
  3. 2.1 14 km N of Seeley Lake, Montana
  4. 1.7 Western Montana
  5. 1.9 1 km W of Charlo, Montana
  6. 1.8 12 km SE of Seeley Lake, Montana
  7. 2.3 19 km SSE of Swan Lake, Montana
  8. 1.5 11 km WNW of Condon, Montana
  9. 1.6 20 km E of Finley Point, Montana
  10. 1.5 10 km ENE of Condon, Montana
  11. 1.8 13 km E of Pablo, Montana
  12. 1.5 18 km E of Finley Point, Montana
  13. 1.7 19 km SSE of Swan Lake, Montana
  14. 1.8 16 km NNE of Seeley Lake, Montana
  15. 1.9 5 km WSW of Condon, 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.