37 km SW of Big Sky, Montana

2023-10-25 17:15 UTC · 8.8 km deep · released about 18 lb of TNT

Distance rings around the epicentre, with the nearest towns at their true direction and later quakes as coloured dots. Not a shaking map — see the USGS ShakeMap for that.

When: 2023-10-25 17:15 UTC
Magnitude: M 1.9 (ml)
Depth: 8.8 km below the surface
Felt: no reports yet
Nearest: Madison County, 41 km NNW
Status: Reviewed by a seismologist

USGS · last changed by USGS 1068 days ago · we first saw it 1068 days ago

This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.

How big was it?

This earthquake released about 18 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.9 would have released about 32 times as much.

Mineral, Virginia 2011 M 5.8 840,000× the energy of this one
Magna, Utah 2020 M 5.7 600,000× the energy of this one
Around the size people start to feel M 3.0 53× the energy of this one
This earthquake M 1.9 about 18 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

Map loads when it scrolls into view

Epicentre 45.0058, -111.6450. Map © OpenStreetMap contributors.

Nearby places

Place	Distance	Direction
Madison County, MT	41 km (26 mi)	SSE of here	earthquakes near Madison County
Gallatin County, MT	68 km (42 mi)	SSW of here	earthquakes near Gallatin County
Fremont County, ID	89 km (55 mi)	N of here	earthquakes near Fremont County
Clark County, ID	97 km (61 mi)	NE of here	earthquakes near Clark County
Beaverhead County, MT	99 km (62 mi)	E of here	earthquakes near Beaverhead County
Park County, MT	101 km (63 mi)	WSW of here	earthquakes near Park County

Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.

Aftershocks so far

47 earthquakes have been recorded within 50 km since this one.

2.6 43 km WNW of Hebgen Lake Estates, Montana 16:47 UTC
1.9 43 km W of Hebgen Lake Estates, Montana 02:05 UTC
1.7 18 km WNW of Hebgen Lake Estates, Montana 20:14 UTC
2.3 18 km NW of Hebgen Lake Estates, Montana 20:14 UTC
2.0 26 km W of Hebgen Lake Estates, Montana 20:42 UTC
1.5 29 km SE of Virginia City, Montana 20:29 UTC
1.6 41 km NE of Spencer, Idaho 23:16 UTC
1.7 5 km ESE of Hebgen Lake Estates, Montana 21:51 UTC
1.7 4 km E of Hebgen Lake Estates, Montana 14:06 UTC
1.6 28 km S of Ennis, Montana 18:13 UTC
1.9 6 km E of Hebgen Lake Estates, Montana 01:10 UTC
1.6 5 km E of Hebgen Lake Estates, Montana 17:15 UTC
1.6 34 km S of Virginia City, Montana 23:22 UTC
2.3 34 km S of Virginia City, Montana 16:31 UTC
1.5 28 km SE of Virginia City, Montana 15:44 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 15:08 UTC. 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 4.3 on 2016-06-13 — it released about 5,400 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.