QuakeIndex

Earthquake · reviewed by a seismologist

M 1.6ml

Earthquake near Townsend, MT

No earthquake was likely felt in Townsend in the 24 hours to 2:24 pm MST (21:24 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 1.6 earthquake was recorded 26 km (16 mi) south-southwest of Townsend, MT, at 4:59 am MST on 27 February 2021 (11:59 UTC), 4.3 km deep.

USGS: 9 km SW of Radersburg, Montana

4:59 am MST, Feb 27, 2021 · · 4.3 km deep · released about 6.4 lb of TNT

Every earthquake near Townsend Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Jefferson County 27 kmBroadwater County 28 kmSilver Bow County 78 kmMeagher County 79 kmGallatin County 80 kmMadison County 91 kmDeer Lodge County 111 kmPark County 117 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
4:59 am MST on 27 February 2021 ()
Where
26 km (16 mi) south-southwest of Townsend, MT · earthquakes near Townsend
Montana today
every earthquake in Montana in the last 24 hours
Magnitude
M 1.6 (ml)
Depth
4.3 km below the surface
Felt
no reports yet
Nearest
Jefferson County, 27 km W
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2083 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, 26 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: Three Forks.

How big was it?

This earthquake released about 6.4 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 2,400,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 1,700,000× the energy of this one
  3. Around the size people start to feel M 3.0 150× the energy of this one
  4. This earthquake M 1.6 about 6.4 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 9,400 times the energy of this one.

Before 2016, the USGS record lists 7 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.6 The 1925 Clarkston Valley, Montana Earthquake · 16 km ESE of this epicentre
  2. 6.4 Clarkston Valley, Montana (Aftershock) · 16 km ESE of this epicentre
  3. 5.9 The 1935 Helena, Montana Earthquakes (Largest Aftershock) · 48 km NNW of this epicentre
  4. 5.5 Clarkston Valley, Montana (Aftershock) · 16 km ESE of this epicentre
  5. 5.5 Clarkston Valley, Montana (Aftershock) · 16 km ESE 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 46.1265, -111.7040. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Jefferson County, MT 27 km (17 mi) W earthquakes near Jefferson County
Broadwater County, MT 28 km (17 mi) NE earthquakes near Broadwater County
Silver Bow County, MT 78 km (49 mi) WSW earthquakes near Silver Bow County
Meagher County, MT 79 km (49 mi) NE earthquakes near Meagher County
Gallatin County, MT 80 km (49 mi) SSE earthquakes near Gallatin County
Madison County, MT 91 km (56 mi) S earthquakes near Madison County

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

Aftershocks so far

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

  1. 2.3 3 km NW of Three Forks, Montana
  2. 2.1 3 km NNW of Three Forks, Montana
  3. 2.0 3 km NNW of Three Forks, Montana
  4. 1.6 2 km WNW of Townsend, Montana
  5. 1.6 3 km S of Logan, Montana
  6. 1.6 6 km NW of Ponderosa Pines, Montana
  7. 1.9 8 km WSW of Townsend, Montana
  8. 1.5 21 km NE of Townsend, Montana
  9. 1.9 9 km WSW of Townsend, Montana
  10. 2.4 4 km NNW of Logan, Montana
  11. 1.8 7 km WSW of Townsend, Montana
  12. 1.7 20 km SSW of Boulder, Montana
  13. 3.4 17 km S of Boulder, Montana
  14. 1.9 8 km WSW of Townsend, Montana
  15. 1.6 4 km NNW of Logan, 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.