QuakeIndex

Earthquake · reviewed by a seismologist

M 1.5ml

Earthquake near Polson, MT

USGS: 9 km NNW of Old Agency, Montana

9:23 pm MDT, Jun 30, 2020 · · 0.8 km deep · released about 5.6 lb of TNT

Every earthquake near Polson Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Lake County 32 kmMissoula County 54 kmMineral County 64 kmSanders County 74 kmFlathead County 101 kmShoshone County 116 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
9:23 pm MDT on 30 June 2020 ()
Where
34 km (21 mi) SSW of Polson, MT · earthquakes near Polson
Magnitude
M 1.5 (ml)
Depth
0.8 km below the surface
Felt
no reports yet
Nearest
Lake County, 32 km NE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2284 days ago

A magnitude 1.5 earthquake was recorded 34 km (21 mi) SSW of Polson, MT, at 9:23 pm MDT on 30 June 2020 (03:23 UTC). This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.

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

How big was it?

This earthquake released about 5.6 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.5 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 2,700,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 1,900,000× the energy of this one
  3. Around the size people start to feel M 3.0 170× the energy of this one
  4. This earthquake M 1.5 about 5.6 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 47.4103, -114.3428. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Lake County, MT 32 km (20 mi) NE earthquakes near Lake County
Missoula County, MT 54 km (34 mi) SE earthquakes near Missoula County
Mineral County, MT 64 km (40 mi) WSW earthquakes near Mineral County
Sanders County, MT 74 km (46 mi) WNW earthquakes near Sanders County
Flathead County, MT 101 km (63 mi) NNE earthquakes near Flathead County
Shoshone County, ID 116 km (72 mi) W earthquakes near Shoshone County

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

Aftershocks so far

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

  1. 0.9 9 km WSW of Condon, Montana
  2. 1.9 2 km NNE of Alberton, Montana
  3. 1.9 18 km E of Saint Ignatius, Montana
  4. 1.9 6 km S of Huson, Montana
  5. 1.6 1 km SSW of Dayton, Montana
  6. 1.9 3 km SSW of Alberton, Montana
  7. 1.7 2 km ENE of Alberton, Montana
  8. 2.2 2 km NE of Alberton, Montana
  9. 2.6 13 km ESE of Kicking Horse, Montana
  10. 2.1 3 km S of Alberton, Montana
  11. 2.0 15 km ENE of Ronan, Montana
  12. 2.1 5 km WNW of Saint Ignatius, Montana
  13. 2.2 1 km SE of Alberton, Montana
  14. 1.8 14 km WNW of Condon, Montana
  15. 1.6 16 km WSW of Kerr, 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.