QuakeIndex

Earthquake · reviewed by a seismologist

M 1.5ml

Earthquake near Townsend, MT

No earthquake was likely felt in Townsend in the 24 hours to 11:22 am MST (18:22 UTC). The last one was M 1.7, 9 km (5 mi) W, at 2:32 pm MDT on 15 October 2026, estimated intensity II (weak) in town. Every earthquake near Townsend

This page: a magnitude 1.5 earthquake was recorded 21 km (13 mi) northeast of Townsend, MT, at 6:10 am MST on 21 November 2021 (13:10 UTC), 3.6 km deep.

USGS: 21 km NE of Townsend, Montana

6:10 am MST, Nov 21, 2021 · · 3.6 km deep · released about 5.7 lb of TNT

Every earthquake near Townsend Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Broadwater County 19 kmMeagher County 34 kmJefferson County 68 kmCascade County 98 kmJudith Basin County 101 kmGallatin County 103 kmWheatland County 111 kmLewis and Clark 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
6:10 am MST on 21 November 2021 ()
Where
21 km (13 mi) northeast of Townsend, MT · earthquakes near Townsend
Montana today
every earthquake in Montana in the last 24 hours
Magnitude
M 1.5 (ml)
Depth
3.6 km below the surface
Felt
no reports yet
Nearest
Broadwater County, 19 km SW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1816 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 10 km (6 mi) from the epicentre. In Townsend, 21 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 5.7 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 2,600,000× 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 5.7 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 8 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.6 The 1925 Clarkston Valley, Montana Earthquake · 43 km SSW of this epicentre
  2. 6.4 Clarkston Valley, Montana (Aftershock) · 43 km SSW of this epicentre
  3. 6.1 The 1935 Helena, Montana Earthquakes (Mainshock) · 32 km WNW of this epicentre
  4. 5.9 The 1935 Helena, Montana Earthquakes (Largest Aftershock) · 43 km WNW of this epicentre
  5. 5.5 Clarkston Valley, Montana (Aftershock) · 43 km SSW 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 46.4360, -111.3053. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Broadwater County, MT 19 km (12 mi) SW earthquakes near Broadwater County
Meagher County, MT 34 km (21 mi) ENE earthquakes near Meagher County
Jefferson County, MT 68 km (42 mi) WSW earthquakes near Jefferson County
Cascade County, MT 98 km (61 mi) N earthquakes near Cascade County
Judith Basin County, MT 101 km (63 mi) NE earthquakes near Judith Basin County
Gallatin County, MT 103 km (64 mi) S earthquakes near Gallatin County

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

Aftershocks so far

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

  1. 1.7 7 km SSW of The Silos, Montana
  2. 1.9 8 km WSW of Townsend, Montana
  3. 1.8 4 km WNW of Ponderosa Pines, Montana
  4. 1.6 8 km W of Townsend, Montana
  5. 2.2 11 km S of Radersburg, Montana
  6. 1.5 6 km SSW of The Silos, Montana
  7. 1.5 7 km SSW of The Silos, Montana
  8. 1.9 7 km SSW of The Silos, Montana
  9. 1.7 6 km WSW of Townsend, Montana
  10. 2.2 30 km ENE of Helena Valley Northeast, Montana
  11. 2.3 30 km ENE of Helena Valley Northeast, Montana
  12. 1.6 6 km WSW of Townsend, Montana
  13. 1.9 7 km WSW of Radersburg, Montana
  14. 2.6 15 km E of Townsend, Montana
  15. 2.4 20 km NNW of Springhill, 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.