Earthquake · reviewed by a seismologist
M 1.5ml
47 km SSE of Virginia City, Montana
Yes. A magnitude 1.5 earthquake was recorded 47 km SSE of Virginia City, Montana, at 6:36 pm MDT on 11 August 2020 (00:36 UTC), 6.3 km deep.
- When
- Montana today
- every earthquake in Montana in the last 24 hours
- Magnitude
- M 1.5 (ml)
- Depth
- 6.3 km below the surface
- Felt
- no reports yet
- Nearest
- Madison County, 50 km N
- Nearest mapped fault
- Madison fault, 21 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 2282 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 8 km (5 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.
How big was it?
This earthquake released about 5.9 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.5 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 2,500,000× the energy of this one
- Magna, Utah 2020 M 5.7 1,800,000× the energy of this one
- Around the size people start to feel M 3.0 160× the energy of this one
- This earthquake M 1.5 about 5.9 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 4.3 on 2016-06-13 — about 16,000 times the energy of this one.
Before 2016, the USGS record lists 6 earthquakes of M5 or more within 50 km; the five largest:
- 7.2 The 1959 Hebgen Lake, Montana Earthquake · 48 km ESE of this epicentre
- 6.1 30 km SSW of Big Sky, Montana · 26 km NE of this epicentre
- 5.2 32 km WNW of Hebgen Lake Estates, Montana · 18 km E of this epicentre
- 5.2 26 km WNW of Hebgen Lake Estates, Montana · 23 km E of this epicentre
- 5.0 31 km W of Hebgen Lake Estates, Montana · 18 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 44.8800, -111.7945. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Madison County, MT | 50 km (31 mi) | N | earthquakes near Madison County |
| Fremont County, ID | 78 km (48 mi) | SSE | earthquakes near Fremont County |
| Clark County, ID | 79 km (49 mi) | SW | earthquakes near Clark County |
| Gallatin County, MT | 86 km (54 mi) | NE | earthquakes near Gallatin County |
| Beaverhead County, MT | 91 km (56 mi) | WNW | earthquakes near Beaverhead County |
| Park County, MT | 118 km (73 mi) | ENE | earthquakes near Park 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.
- 2.1 25 km WNW of Hebgen Lake Estates, Montana
- 1.7 42 km NNE of Spencer, Idaho
- 1.9 32 km N of Spencer, Idaho
- 2.0 28 km N of Spencer, Idaho
- 2.1 32 km S of Virginia City, Montana
- 1.9 30 km WNW of Hebgen Lake Estates, Montana
- 2.1 47 km ENE of Lima, Montana
- 2.3 45 km NE of Spencer, Idaho
- 1.9 27 km WNW of Hebgen Lake Estates, Montana
- 1.8 42 km W of Hebgen Lake Estates, Montana
- 2.7 26 km SSE of Virginia City, Montana
- 1.7 28 km SE of Virginia City, Montana
- 1.6 17 km SSE of Big Sky, Montana
- 1.5 23 km W of Hebgen Lake Estates, Montana
- 1.5 26 km W of Hebgen Lake Estates, 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.