Earthquake · reviewed by a seismologist
M 1.9ml
Earthquake near Big Sky, MT
No earthquake was likely felt in Big Sky in the 24 hours to 7:48 am MST (14:48 UTC). The last one was M 3.7, 68 km (42 mi) SE, at 7:22 am MDT on 28 October 2025, estimated intensity II (weak) in town; 11 felt reports to USGS. Every earthquake near Big Sky
This page: a magnitude 1.9 earthquake was recorded 34 km (21 mi) south of Big Sky, MT, at 12:35 am MDT on 18 June 2025 (06:35 UTC), 5.0 km deep.
USGS: 26 km NNW of Hebgen Lake Estates, Montana
- When
- 12:35 am MDT on 18 June 2025 ()
- Where
- 34 km (21 mi) south of Big Sky, MT · earthquakes near Big Sky
- Montana today
- every earthquake in Montana in the last 24 hours
- Magnitude
- M 1.9 (ml)
- Depth
- 5.0 km below the surface
- Felt
- no reports yet
- Nearest
- Madison County, 58 km NW
- Nearest mapped fault
- Hebgen fault, 13 km from its surface trace — near is not the same as on
- Status
- Reviewed by a seismologist
USGS · last changed by USGS · we first saw it 511 days ago
Earthquake alerts for Big Sky, MT
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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 14 km (9 mi) from the epicentre. In Big Sky, 34 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 22 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.9 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 680,000× the energy of this one
- Magna, Utah 2020 M 5.7 480,000× the energy of this one
- Around the size people start to feel M 3.0 43× the energy of this one
- This earthquake M 1.9 about 22 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 4.4 on 2017-06-16 — about 4,700 times the energy of this one.
Before 2016, the USGS record lists 10 earthquakes of M5 or more within 50 km; the five largest:
- 7.2 The 1959 Hebgen Lake, Montana Earthquake · 24 km SSE of this epicentre
- 6.5 14 km N of Madison Junction, Wyoming · 44 km ESE of this epicentre
- 6.3 22 km SW of Mammoth, Wyoming · 43 km ESE of this epicentre
- 6.1 30 km SSW of Big Sky, Montana · 17 km WNW of this epicentre
- 5.7 13 km SSW of Mammoth, Wyoming · 50 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 44.9772, -111.3635. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Madison County, MT | 58 km (36 mi) | NW | earthquakes near Madison County |
| Gallatin County, MT | 62 km (39 mi) | NNE | earthquakes near Gallatin County |
| Park County, MT | 84 km (52 mi) | NE | earthquakes near Park County |
| Fremont County, ID | 85 km (53 mi) | S | earthquakes near Fremont County |
| Clark County, ID | 109 km (68 mi) | SW | earthquakes near Clark County |
| Teton County, WY | 127 km (79 mi) | SE | earthquakes near Teton County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
60 earthquakes have been recorded within 50 km since this one.
- 2.7 22 km SSW of Mammoth, Wyoming
- 1.8 22 km SSW of Mammoth, Wyoming
- 2.0 7 km ESE of Hebgen Lake Estates, Montana
- 1.8 47 km NE of Spencer, Idaho
- 1.6 6 km SE of Hebgen Lake Estates, Montana
- 2.7 23 km SSW of Mammoth, Wyoming
- 2.1 23 km SSW of Mammoth, Wyoming
- 1.7 23 km SSW of Mammoth, Wyoming
- 1.7 23 km SSW of Mammoth, Wyoming
- 1.6 23 km SSW of Mammoth, Wyoming
- 1.7 22 km SSW of Mammoth, Wyoming
- 2.2 23 km SSW of Mammoth, Wyoming
- 1.7 21 km ENE of West Yellowstone, Montana
- 1.5 23 km SSW of Mammoth, Wyoming
- 3.1 22 km SSW of Mammoth, Wyoming
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.