Earthquake · reviewed by a seismologist
M 2.7ml
5 km NNW of Malmstrom Air Force Base, Montana
- When
- Magnitude
- M 2.7 (ml)
- Depth
- 16 km below the surface
- Felt
- 19 reports · strongest reported intensity III
- Nearest
- Cascade County, 29 km SSW
- Status
- Reviewed by a seismologist
USGS · last changed by USGS · we first saw it 156 days ago
This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage. 19 people have reported feeling it to USGS.
How big was it?
This earthquake released about 340 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.7 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 45,000× the energy of this one
- Magna, Utah 2020 M 5.7 32,000× the energy of this one
- Around the size people start to feel M 3.0 2.8× the energy of this one
- This earthquake M 2.7 about 340 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.
Where
Epicentre 47.5537, -111.2020. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction | |
|---|---|---|---|
| Cascade County, MT | 29 km (18 mi) | NNE of here | earthquakes near Cascade County |
| Chouteau County, MT | 68 km (42 mi) | WSW of here | earthquakes near Chouteau County |
| Teton County, MT | 86 km (53 mi) | ESE of here | earthquakes near Teton County |
| Judith Basin County, MT | 89 km (55 mi) | NW of here | earthquakes near Judith Basin County |
| Lewis and Clark County, MT | 101 km (63 mi) | ENE of here | earthquakes near Lewis and Clark County |
| Pondera County, MT | 107 km (66 mi) | SE of here | earthquakes near Pondera County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
6 earthquakes have been recorded within 50 km since this one.
- 3.7 7 km NNW of Black Eagle, Montana
- 2.4 9 km NNE of Black Eagle, Montana
- 1.9 9 km N of Black Eagle, Montana
- 2.6 10 km NNE of Black Eagle, Montana
- 3.7 3 km SE of Black Eagle, Montana
- 3.2 3 km NW of Malmstrom Air Force Base, 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.
For this area
The largest earthquake within 50 km in our catalogue was M 4.2 on 2026-01-29 — it released about 180 times the energy of this one.
From the QuakeIndex catalogue, built from the USGS FDSN event service.
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.