QuakeIndex

Earthquake · reviewed by a seismologist

M 1.9ml

Earthquake near Polson, MT

No earthquake was likely felt in Polson in the 24 hours to 5:36 pm MST (00:36 UTC). The last one was M 3.0, 32 km (20 mi) ENE, at 9:19 pm MDT on 14 March 2024, estimated intensity II (weak) in town; 1 felt report to USGS. Every earthquake near Polson

This page: a magnitude 1.9 earthquake was recorded 36 km (22 mi) southeast of Polson, MT, at 10:54 am MDT on 25 July 2020 (16:54 UTC), 14 km deep.

USGS: 5 km WSW of Condon, Montana

10:54 am MDT, Jul 25, 2020 · · 14 km deep · released about 22 lb of TNT

10 km30 km60 km120 km N Lake County 27 kmMissoula County 54 kmFlathead County 90 kmPowell County 98 kmMineral County 107 kmSanders County 108 kmLewis and Clark County 114 kmTeton 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
10:54 am MDT on 25 July 2020 ()
Where
36 km (22 mi) southeast of Polson, MT · earthquakes near Polson
Montana today
every earthquake in Montana in the last 24 hours
Magnitude
M 1.9 (ml)
Depth
14 km below the surface
Felt
no reports yet
Nearest
Lake County, 27 km NW
Nearest mapped fault
Mission fault, 17 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 2298 days ago

This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.

At this magnitude and depth, people at rest would likely notice it out to about 5 km (3 mi) from the epicentre. In Polson, 36 km away, the estimate is intensity II (weak). Estimated from magnitude, depth and distance with the intensity equation USGS Did You Feel It? uses; felt reports, where there are any, are the measurement.

Earthquakes near other towns within 30 km: Ronan, Pablo.

How big was it?

This earthquake released about 22 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 5.8 680,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 480,000× the energy of this one
  3. Around the size people start to feel M 3.0 43× the energy of this one
  4. This earthquake M 1.9 about 22 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 47.5042, -113.7817. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Lake County, MT 27 km (17 mi) NW earthquakes near Lake County
Missoula County, MT 54 km (33 mi) S earthquakes near Missoula County
Flathead County, MT 90 km (56 mi) NNW earthquakes near Flathead County
Powell County, MT 98 km (61 mi) SE earthquakes near Powell County
Mineral County, MT 107 km (66 mi) WSW earthquakes near Mineral County
Sanders County, MT 108 km (67 mi) WNW earthquakes near Sanders County

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

Aftershocks so far

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

  1. 2.4 9 km SSW of Bear Dance, Montana
  2. 1.8 17 km SSE of Swan Lake, Montana
  3. 2.6 13 km ESE of Kicking Horse, Montana
  4. 2.0 15 km ENE of Ronan, Montana
  5. 2.1 5 km WNW of Saint Ignatius, Montana
  6. 1.7 20 km E of Finley Point, Montana
  7. 1.6 20 km E of Finley Point, Montana
  8. 1.6 20 km E of Finley Point, Montana
  9. 2.1 20 km E of Finley Point, Montana
  10. 1.8 17 km E of Condon, Montana
  11. 1.7 19 km E of Finley Point, Montana
  12. 1.6 16 km NNE of Condon, Montana
  13. 2.4 16 km ENE of Seeley Lake, Montana
  14. 2.7 6 km SSE of Seeley Lake, Montana
  15. 1.9 6 km SSE of Seeley 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.