Earthquake · reviewed by a seismologist
M 1.8ml
Earthquake near Three Forks, MT
No earthquake was likely felt in Three Forks in the 24 hours to 9:12 am MST (16:12 UTC). The last one was M 1.6, 7 km (5 mi) NE, at 4:03 pm MDT on 11 August 2026, estimated intensity II (weak) in town. Every earthquake near Three Forks
This page: a magnitude 1.8 earthquake was recorded 45 km (28 mi) southwest of Three Forks, MT, at 1:36 pm MDT on 7 July 2019 (19:36 UTC), less than 1 km deep.
USGS: 10 km S of Pony, Montana
- When
- 1:36 pm MDT on 7 July 2019 ()
- Where
- 45 km (28 mi) southwest of Three Forks, MT · earthquakes near Three Forks
- Montana today
- every earthquake in Montana in the last 24 hours
- Magnitude
- M 1.8 (ml)
- Depth
- 1.0 km below the surface
- Felt
- no reports yet
- Nearest
- Madison County, 26 km S
- Nearest mapped fault
- Madison fault, 24 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 2683 days ago
Earthquake alerts for Three Forks, MT
Get a notification in this browser when USGS records an earthquake near Three Forks, 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 14 km (9 mi) from the epicentre. In Three Forks, 45 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.
How big was it?
This earthquake released about 16 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.8 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 930,000× the energy of this one
- Magna, Utah 2020 M 5.7 660,000× the energy of this one
- Around the size people start to feel M 3.0 59× the energy of this one
- This earthquake M 1.8 about 16 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 4.0 on 2016-09-03 — about 2,100 times the energy of this one.
Before 2016, the USGS record since 1900 lists no earthquake of M5 or more within 50 km.
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 45.5612, -111.8818. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Madison County, MT | 26 km (16 mi) | S | earthquakes near Madison County |
| Gallatin County, MT | 56 km (35 mi) | E | earthquakes near Gallatin County |
| Jefferson County, MT | 64 km (40 mi) | NNW | earthquakes near Jefferson County |
| Silver Bow County, MT | 71 km (44 mi) | WNW | earthquakes near Silver Bow County |
| Broadwater County, MT | 90 km (56 mi) | NNE | earthquakes near Broadwater County |
| Beaverhead County, MT | 92 km (57 mi) | WSW | earthquakes near Beaverhead County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
3 earthquakes have been recorded within 50 km since this one.
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.