QuakeIndex

Earthquake · reviewed by a seismologist

M 2.1ml

Earthquake near Helena Valley Northeast, MT

No earthquake was likely felt in Helena Valley Northeast in the 24 hours to 10:02 am MST (17:02 UTC). The last one was M 2.7, 11 km (7 mi) SSW, at 3:38 pm MDT on 9 March 2025, estimated intensity III (weak) in town; 267 felt reports to USGS. Every earthquake near Helena Valley Northeast

This page: a magnitude 2.1 earthquake was recorded 30 km (18 mi) east-northeast of Helena Valley Northeast, MT, at 5:50 am MST on 1 January 2025 (12:50 UTC), 12 km deep.

USGS: 29 km ENE of Helena Valley Northeast, Montana

5:50 am MST, Jan 1, 2025 · · 12 km deep · released about 41 lb of TNT

10 km30 km60 km120 km N Broadwater County 53 kmMeagher County 57 kmCascade County 60 kmLewis and Clark County 69 kmJefferson County 84 kmJudith Basin County 101 kmPowell County 102 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
5:50 am MST on 1 January 2025 ()
Where
30 km (18 mi) east-northeast of Helena Valley Northeast, MT · earthquakes near Helena Valley Northeast
Montana today
every earthquake in Montana in the last 24 hours
Magnitude
M 2.1 (ml)
Depth
12 km below the surface
Felt
no reports yet
Nearest
Broadwater County, 53 km S
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 679 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 12 km (7 mi) from the epicentre. In Helena Valley Northeast, 30 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.

How big was it?

This earthquake released about 41 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.1 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 370,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 260,000× the energy of this one
  3. Around the size people start to feel M 3.0 23× the energy of this one
  4. This earthquake M 2.1 about 41 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 4 earthquakes of M5 or more within 50 km:

  1. 6.1 The 1935 Helena, Montana Earthquakes (Mainshock) · 24 km S of this epicentre
  2. 5.9 2 km ENE of Helena, Montana · 38 km SW of this epicentre
  3. 5.9 The 1935 Helena, Montana Earthquakes (Largest Aftershock) · 35 km SSW of this epicentre
  4. 5.0 2 km ENE of Helena, Montana · 38 km SW 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 46.8050, -111.5938. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Broadwater County, MT 53 km (33 mi) S earthquakes near Broadwater County
Meagher County, MT 57 km (35 mi) ESE earthquakes near Meagher County
Cascade County, MT 60 km (37 mi) NNE earthquakes near Cascade County
Lewis and Clark County, MT 69 km (43 mi) WNW earthquakes near Lewis and Clark County
Jefferson County, MT 84 km (52 mi) SSW earthquakes near Jefferson County
Judith Basin County, MT 101 km (63 mi) ENE earthquakes near Judith Basin County

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

Aftershocks so far

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

  1. 1.6 2 km SE of South Hills, Montana
  2. 1.5 16 km NE of Helena Valley Northwest, Montana
  3. 1.6 14 km SSE of Craig, Montana
  4. 2.4 21 km SSE of Craig, Montana
  5. 1.5 1 km SSE of South Hills, Montana
  6. 1.7 0 km NNW of South Hills, Montana
  7. 2.0 32 km ENE of Helena Valley Northeast, Montana
  8. 2.0 20 km NNE of Helena Valley Northeast, Montana
  9. 1.5 31 km ENE of Helena Valley Northeast, Montana
  10. 1.9 1 km SSE of South Hills, Montana
  11. 2.4 2 km ESE of Clancy, Montana
  12. 1.7 14 km NNW of Winston, Montana
  13. 1.5 3 km SE of Helena Valley West Central, Montana
  14. 1.6 6 km SE of Craig, Montana
  15. 1.7 4 km ESE of The Silos, 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.