QuakeIndex

Earthquake · reviewed by a seismologist

M 2.2ml

Earthquake near Helena, MT

No earthquake was likely felt in Helena in the 24 hours to 12:21 pm MST (19:21 UTC). The last one was M 1.6, 7 km (4 mi) SE, at 11:34 am MDT on 14 October 2026, estimated intensity II (weak) in town. Every earthquake near Helena

This page: a magnitude 2.2 earthquake was recorded 45 km (28 mi) south-southeast of Helena, MT, at 1:46 am MST on 22 February 2024 (08:46 UTC), 5.2 km deep.

USGS: 10 km WNW of Radersburg, Montana

1:46 am MST, Feb 22, 2024 · · 5.2 km deep · released about 54 lb of TNT

Every earthquake near Helena Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Broadwater County 23 kmJefferson County 26 kmMeagher County 75 kmSilver Bow County 79 kmGallatin County 92 kmMadison County 102 kmDeer Lodge County 108 kmLewis and Clark County 109 kmPowell 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
1:46 am MST on 22 February 2024 ()
Where
45 km (28 mi) south-southeast of Helena, MT · earthquakes near Helena
Montana today
every earthquake in Montana in the last 24 hours
Magnitude
M 2.2 (ml)
Depth
5.2 km below the surface
Felt
no reports yet
Nearest
Broadwater County, 23 km ENE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 993 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 17 km (11 mi) from the epicentre. In Helena, 45 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: Townsend, Boulder.

How big was it?

This earthquake released about 54 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.2 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 280,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 200,000× the energy of this one
  3. Around the size people start to feel M 3.0 18× the energy of this one
  4. This earthquake M 2.2 about 54 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

The largest earthquake within 50 km since 2016 was M 4.2 on 2019-08-16 — about 1,100 times the energy of this one.

Before 2016, the USGS record lists 10 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.6 The 1925 Clarkston Valley, Montana Earthquake · 26 km SE of this epicentre
  2. 6.4 Clarkston Valley, Montana (Aftershock) · 26 km SE of this epicentre
  3. 6.1 The 1935 Helena, Montana Earthquakes (Mainshock) · 40 km NNE of this epicentre
  4. 5.9 2 km ENE of Helena, Montana · 44 km NNW of this epicentre
  5. 5.9 The 1935 Helena, Montana Earthquakes (Largest Aftershock) · 34 km NNW 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 46.2387, -111.7602. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Broadwater County, MT 23 km (14 mi) ENE earthquakes near Broadwater County
Jefferson County, MT 26 km (16 mi) WSW earthquakes near Jefferson County
Meagher County, MT 75 km (47 mi) ENE earthquakes near Meagher County
Silver Bow County, MT 79 km (49 mi) WSW earthquakes near Silver Bow County
Gallatin County, MT 92 km (57 mi) SSE earthquakes near Gallatin County
Madison County, MT 102 km (64 mi) S earthquakes near Madison County

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

Aftershocks so far

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

  1. 1.7 14 km NNW of Winston, Montana
  2. 1.6 7 km W of Townsend, Montana
  3. 1.9 5 km NNW of Logan, Montana
  4. 1.5 3 km SE of Helena Valley West Central, Montana
  5. 1.6 8 km W of Townsend, Montana
  6. 1.8 7 km NW of Logan, Montana
  7. 1.9 9 km W of Townsend, Montana
  8. 1.8 8 km W of Townsend, Montana
  9. 1.6 6 km SSW of The Silos, Montana
  10. 1.7 8 km W of Townsend, Montana
  11. 2.2 6 km NNW of Logan, Montana
  12. 1.7 7 km WSW of Townsend, Montana
  13. 1.7 4 km ESE of The Silos, Montana
  14. 1.9 7 km N of Manhattan, Montana
  15. 1.5 6 km NE of Three Forks, 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.