Earthquake · reviewed by a seismologist
M 2.3ml
Earthquake near Butte, MT
No earthquake was likely felt in Butte in the 24 hours to 9:52 am MST (16:52 UTC). The last one was M 2.0, 5 km (3 mi) E, at 12:56 pm MST on 9 November 2026, estimated intensity II (weak) in town. Every earthquake near Butte
This page: a magnitude 2.3 earthquake was recorded 46 km (29 mi) southeast of Butte, MT, at 6:20 am MDT on 18 August 2020 (12:20 UTC), 5.0 km deep. 1 person has reported feeling it to USGS.
USGS: 18 km WNW of Pony, Montana
- When
- 6:20 am MDT on 18 August 2020 ()
- Where
- 46 km (29 mi) southeast of Butte, MT · earthquakes near Butte
- Montana today
- every earthquake in Montana in the last 24 hours
- Magnitude
- M 2.3 (ml)
- Depth
- 5.0 km below the surface
- Felt
- 1 report · strongest reported intensity II
- Nearest
- Madison County, 45 km SSE
- Status
- Reviewed by a seismologist
USGS · last changed by USGS · we first saw it 2209 days ago
Earthquake alerts for Butte, 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 19 km (12 mi) from the epicentre. In Butte, 46 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.
Earthquakes near other towns within 30 km: Whitehall.
How big was it?
This earthquake released about 85 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.3 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 180,000× the energy of this one
- Magna, Utah 2020 M 5.7 130,000× the energy of this one
- Around the size people start to feel M 3.0 11× the energy of this one
- This earthquake M 2.3 about 85 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 390 times the energy of this one.
Before 2016, the USGS record lists one earthquake of M5 or more within 50 km:
- 5.4 Near Butte, Montana · 44 km NW 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 45.6959, -112.1319. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Madison County, MT | 45 km (28 mi) | SSE | earthquakes near Madison County |
| Silver Bow County, MT | 47 km (29 mi) | WNW | earthquakes near Silver Bow County |
| Jefferson County, MT | 48 km (30 mi) | N | earthquakes near Jefferson County |
| Gallatin County, MT | 78 km (48 mi) | ESE | earthquakes near Gallatin County |
| Broadwater County, MT | 86 km (53 mi) | NE | earthquakes near Broadwater County |
| Beaverhead County, MT | 86 km (54 mi) | SW | earthquakes near Beaverhead County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
56 earthquakes have been recorded within 50 km since this one.
- 1.9 4 km E of Butte, Montana
- 1.9 6 km ENE of Butte, Montana
- 1.6 6 km ENE of Butte, Montana
- 1.7 6 km E of Butte, Montana
- 1.6 4 km E of Butte, Montana
- 1.6 5 km E of Butte, Montana
- 1.5 5 km ENE of Butte, Montana
- 1.8 6 km E of Butte, Montana
- 1.9 5 km ENE of Butte, Montana
- 1.8 4 km E of Butte, Montana
- 1.9 6 km ENE of Butte, Montana
- 1.7 5 km ENE of Butte, Montana
- 1.8 4 km E of Butte, Montana
- 1.7 5 km E of Butte, Montana
- 1.8 6 km ENE of Butte, 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.