Earthquake · reviewed by a seismologist
M 1.6ml
Earthquake near Bozeman, MT
No earthquake was likely felt in Bozeman in the 24 hours to 8:32 am MST (15:32 UTC). The last one was M 3.0, 17 km (10 mi) NW, at 7:42 am MDT on 1 June 2024, estimated intensity II (weak) in town; 20 felt reports to USGS. Every earthquake near Bozeman
This page: a magnitude 1.6 earthquake was recorded 50 km (31 mi) northwest of Bozeman, MT, at 7:40 am MDT on 20 September 2021 (13:40 UTC), 8.2 km deep.
USGS: 3 km WNW of Ponderosa Pines, Montana
49 km (30 mi) NW of Bozeman, MT
- When
- 7:40 am MDT on 20 September 2021 ()
- Where
- 50 km (31 mi) northwest of Bozeman, MT · earthquakes near Bozeman
- Montana today
- every earthquake in Montana in the last 24 hours
- Magnitude
- M 1.6 (ml)
- Depth
- 8.2 km below the surface
- Felt
- no reports yet
- Nearest
- Broadwater County, 33 km N
- Status
- Reviewed by a seismologist
USGS · last changed by USGS · we first saw it 1875 days ago
Earthquake alerts for Bozeman, MT
Get a notification in this browser when USGS records an earthquake near Bozeman, 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 8 km (5 mi) from the epicentre. In Bozeman, 50 km away, the estimate is intensity I (not felt). 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, Manhattan.
How big was it?
This earthquake released about 7.8 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.6 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 1,900,000× the energy of this one
- Magna, Utah 2020 M 5.7 1,400,000× the energy of this one
- Around the size people start to feel M 3.0 120× the energy of this one
- This earthquake M 1.6 about 7.8 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 7,700 times the energy of this one.
Before 2016, the USGS record lists 6 earthquakes of M5 or more within 50 km; the five largest:
- 6.6 The 1925 Clarkston Valley, Montana Earthquake · 8 km WNW of this epicentre
- 6.4 Clarkston Valley, Montana (Aftershock) · 8 km WNW of this epicentre
- 5.5 Clarkston Valley, Montana (Aftershock) · 8 km WNW of this epicentre
- 5.5 Clarkston Valley, Montana (Aftershock) · 8 km WNW of this epicentre
- 5.5 Clarkston Valley, Montana (Aftershock) · 8 km WNW 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 46.0410, -111.4160. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Broadwater County, MT | 33 km (20 mi) | N | earthquakes near Broadwater County |
| Jefferson County, MT | 50 km (31 mi) | W | earthquakes near Jefferson County |
| Gallatin County, MT | 61 km (38 mi) | SSE | earthquakes near Gallatin County |
| Meagher County, MT | 71 km (44 mi) | NNE | earthquakes near Meagher County |
| Madison County, MT | 88 km (55 mi) | SSW | earthquakes near Madison County |
| Park County, MT | 94 km (58 mi) | SE | earthquakes near Park 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.
- 1.6 3 km WSW of Ponderosa Pines, Montana
- 1.6 8 km W of Townsend, Montana
- 1.7 6 km WSW of Townsend, Montana
- 1.6 14 km ESE of Harrison, Montana
- 1.5 10 km WNW of Four Corners, Montana
- 1.6 5 km SE of Three Forks, Montana
- 1.6 5 km WSW of Logan, Montana
- 2.0 4 km NNW of Logan, Montana
- 2.4 12 km E of Elkhorn, Montana
- 1.6 5 km W of Three Forks, Montana
- 1.5 5 km W of Townsend, Montana
- 1.5 18 km SSW of Radersburg, Montana
- 1.6 Western Montana
- 1.6 7 km WSW of Townsend, Montana
- 1.6 8 km WSW of Townsend, 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.