Earthquake · reviewed by a seismologist
M 2.1ml
Earthquake near Dillon, MT
No earthquake was likely felt in Dillon in the 24 hours to 8:36 pm MST (03:36 UTC). The last one was M 2.0, 14 km (9 mi) N, at 2:45 pm MDT on 7 May 2026, estimated intensity II (weak) in town. Every earthquake near Dillon
This page: a magnitude 2.1 earthquake was recorded 18 km (11 mi) north-northeast of Dillon, MT, at 1:27 pm MST on 28 December 2021 (20:27 UTC), 8.3 km deep.
USGS: 17 km NNE of Dillon, Montana
- When
- 1:27 pm MST on 28 December 2021 ()
- Where
- 18 km (11 mi) north-northeast of Dillon, MT · earthquakes near Dillon
- Montana today
- every earthquake in Montana in the last 24 hours
- Magnitude
- M 2.1 (ml)
- Depth
- 8.3 km below the surface
- Felt
- no reports yet
- Nearest
- Beaverhead County, 36 km SW
- Status
- Reviewed by a seismologist
USGS · last changed by USGS · we first saw it 1779 days ago
Earthquake alerts for Dillon, MT
Get a notification in this browser when USGS records an earthquake near Dillon, MT. No account or email needed.
Alerts are on for .
Not a warning. An alert comes after USGS publishes a quake, usually minutes after the shaking. For early warning use ShakeAlert, through your phone's Wireless Emergency Alerts or the MyShake app.
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 16 km (10 mi) from the epicentre. In Dillon, 18 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 51 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.
- Mineral, Virginia 2011 M 5.8 300,000× the energy of this one
- Magna, Utah 2020 M 5.7 210,000× the energy of this one
- Around the size people start to feel M 3.0 19× the energy of this one
- This earthquake M 2.1 about 51 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 one earthquake of M5 or more within 50 km:
- 5.6 16 km N of Dillon, Montana · 3 km WSW 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 45.3720, -112.5802. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Beaverhead County, MT | 36 km (22 mi) | SW | earthquakes near Beaverhead County |
| Madison County, MT | 52 km (33 mi) | E | earthquakes near Madison County |
| Silver Bow County, MT | 59 km (36 mi) | N | earthquakes near Silver Bow County |
| Deer Lodge County, MT | 91 km (57 mi) | NNW | earthquakes near Deer Lodge County |
| Jefferson County, MT | 93 km (58 mi) | NNE | earthquakes near Jefferson County |
| Gallatin County, MT | 112 km (69 mi) | E | earthquakes near Gallatin County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
38 earthquakes have been recorded within 50 km since this one.
- 2.4 13 km N of Dillon, Montana
- 1.6 23 km N of Dillon, Montana
- 1.6 4 km ESE of Twin Bridges, Montana
- 2.4 3 km SE of Twin Bridges, Montana
- 1.6 13 km E of Dillon, Montana
- 1.5 1 km NNE of Twin Bridges, Montana
- 1.6 12 km NNE of Dillon, Montana
- 1.6 12 km NNE of Dillon, Montana
- 1.5 14 km E of Dillon, Montana
- 2.7 12 km E of Dillon, Montana
- 2.5 13 km E of Dillon, Montana
- 4.1 11 km E of Dillon, Montana
- 2.4 18 km NNE of Twin Bridges, Montana
- 1.5 18 km W of Pony, Montana
- 2.2 11 km NNE of Dillon, 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
- The official USGS event page — the source of record for every value above
- Did you feel it? Report it to USGS — reports go to USGS, not to us
- ShakeMap for this event, when USGS has produced one
QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.