29 km E of West Yellowstone, Montana

2021-09-23 00:53 UTC · 7.1 km deep · released about 17 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: 2021-09-23 00:53 UTC
Magnitude: M 1.8 (ml)
Depth: 7.1 km below the surface
Felt: no reports yet
Nearest: Teton County, 70 km SSE
Status: Reviewed by a seismologist

USGS · last changed by USGS 1830 days ago · we first saw it 1830 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 17 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 5.8 900,000× the energy of this one
Magna, Utah 2020 M 5.7 640,000× the energy of this one
Around the size people start to feel M 3.0 57× the energy of this one
This earthquake M 1.8 about 17 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 44.6390, -110.7328. Map © OpenStreetMap contributors.

Nearby places

Place	Distance	Direction
Teton County, WY	70 km (44 mi)	NNW of here	earthquakes near Teton County
Fremont County, ID	76 km (47 mi)	NE of here	earthquakes near Fremont County
Park County, WY	92 km (57 mi)	W of here	earthquakes near Park County
Park County, MT	93 km (58 mi)	S of here	earthquakes near Park County
Gallatin County, MT	103 km (64 mi)	SSE of here	earthquakes near Gallatin County
Teton County, ID	105 km (65 mi)	NNE of here	earthquakes near Teton 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.

1.6 19 km ENE of West Yellowstone, Montana 23:01 UTC
1.9 22 km SSW of Mammoth, Wyoming 12:15 UTC
1.9 46 km ESE of West Yellowstone, Montana 23:13 UTC
2.4 19 km NE of West Yellowstone, Montana 00:00 UTC
1.9 39 km ESE of West Yellowstone, Montana 09:00 UTC
1.8 30 km ESE of West Yellowstone, Montana 15:00 UTC
1.8 29 km S of Mammoth, Wyoming 17:06 UTC
1.9 28 km S of Mammoth, Wyoming 08:23 UTC
1.9 50 km SSE of Mammoth, Wyoming 12:31 UTC
1.7 27 km S of Mammoth, Wyoming 13:45 UTC
1.6 Wyoming 04:09 UTC
1.5 40 km SSE of West Yellowstone, Montana 04:07 UTC
1.6 21 km ENE of Hebgen Lake Estates, Montana 18:51 UTC
2.3 21 km ENE of Hebgen Lake Estates, Montana 04:23 UTC
1.9 27 km S of Mammoth, Wyoming 16:38 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 13:13 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 4.4 on 2017-06-16 — it released about 6,200 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.