Earthquake · reviewed by a seismologist
M 1.7ml
8 km SSW of Dillon, MT
Yes. A magnitude 1.7 earthquake was recorded 8 km SSW of Dillon, MT, at 7:04 pm MDT on 12 August 2018 (01:04 UTC), 6.8 km deep.
- When
- Magnitude
- M 1.7 (ml)
- Depth
- 6.8 km below the surface
- Felt
- no reports yet
- Nearest
- Beaverhead County, 28 km SW
- Status
- Reviewed by a seismologist
USGS · last changed by USGS · we first saw it 3012 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 11 km (7 mi) from the epicentre. 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.
Likely felt in: Dillon 8 km, intensity II. Estimated for each town centre; each link is that town's own record.
How big was it?
This earthquake released about 12 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.7 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 1,200,000× the energy of this one
- Magna, Utah 2020 M 5.7 870,000× the energy of this one
- Around the size people start to feel M 3.0 78× the energy of this one
- This earthquake M 1.7 about 12 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 45.2840, -112.6108. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Beaverhead County, MT | 28 km (17 mi) | SW | earthquakes near Beaverhead County |
| Madison County, MT | 55 km (34 mi) | E | earthquakes near Madison County |
| Silver Bow County, MT | 68 km (42 mi) | N | earthquakes near Silver Bow County |
| Deer Lodge County, MT | 99 km (62 mi) | NNW | earthquakes near Deer Lodge County |
| Jefferson County, MT | 103 km (64 mi) | NNE | earthquakes near Jefferson County |
| Lemhi County, ID | 108 km (67 mi) | WSW | earthquakes near Lemhi County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
52 earthquakes have been recorded within 50 km since this one.
- 2.3 17 km N of Dillon, Montana
- 1.6 17 km ESE of Dillon, Montana
- 1.7 10 km SW of Twin Bridges, Montana
- 1.7 17 km ESE of Dillon, Montana
- 1.6 17 km ESE of Dillon, Montana
- 1.5 2 km NW of Alder, Montana
- 1.7 3 km NW of Alder, Montana
- 2.1 4 km NNW of Alder, Montana
- 2.2 3 km NW of Alder, Montana
- 1.5 16 km ESE of Dillon, Montana
- 1.7 17 km ESE of Dillon, Montana
- 1.8 15 km NE of Dillon, Montana
- 1.7 17 km ESE of Dillon, Montana
- 1.8 7 km W of Sheridan, Montana
- 1.5 18 km ESE 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.