QuakeIndex

Earthquake · reviewed by a seismologist

M 1.9ml

Earthquake near West Yellowstone, MT

No earthquake was likely felt in West Yellowstone in the 24 hours to 10:56 am MST (17:56 UTC). The last one was M 2.8, 11 km (7 mi) NNW, at 1:21 am MDT on 8 September 2026, estimated intensity II (weak) in town. Every earthquake near West Yellowstone

This page: a magnitude 1.9 earthquake was recorded 49 km (30 mi) west-northwest of West Yellowstone, MT, at 9:32 pm MDT on 19 October 2021 (03:32 UTC), 10.0 km deep.

USGS: 38 km WNW of Hebgen Lake Estates, Montana

9:32 pm MDT, Oct 19, 2021 · · 10.0 km deep · released about 21 lb of TNT

Every earthquake near West Yellowstone Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Madison County 55 kmFremont County 73 kmGallatin County 83 kmClark County 84 kmBeaverhead County 102 kmPark County 110 kmMadison County 119 km
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
9:32 pm MDT on 19 October 2021 ()
Where
49 km (30 mi) west-northwest of West Yellowstone, MT · earthquakes near West Yellowstone
Montana today
every earthquake in Montana in the last 24 hours
Magnitude
M 1.9 (ml)
Depth
10.0 km below the surface
Felt
no reports yet
Nearest
Madison County, 55 km NNW
Nearest mapped fault
Madison fault, 11 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 1848 days ago

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 11 km (7 mi) from the epicentre. In West Yellowstone, 49 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 21 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.

  1. Mineral, Virginia 2011 M 5.8 730,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 520,000× the energy of this one
  3. Around the size people start to feel M 3.0 46× the energy of this one
  4. This earthquake M 1.9 about 21 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 4,700 times the energy of this one.

Before 2016, the USGS record lists 6 earthquakes of M5 or more within 50 km; the five largest:

  1. 7.2 The 1959 Hebgen Lake, Montana Earthquake · 37 km ESE of this epicentre
  2. 6.1 30 km SSW of Big Sky, Montana · 22 km NNE of this epicentre
  3. 5.2 32 km WNW of Hebgen Lake Estates, Montana · 7 km ENE of this epicentre
  4. 5.2 26 km WNW of Hebgen Lake Estates, Montana · 12 km E of this epicentre
  5. 5.0 31 km W of Hebgen Lake Estates, Montana · 7 km SE 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 44.8622, -111.6572. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Madison County, MT 55 km (34 mi) NNW earthquakes near Madison County
Fremont County, ID 73 km (45 mi) S earthquakes near Fremont County
Gallatin County, MT 83 km (51 mi) NNE earthquakes near Gallatin County
Clark County, ID 84 km (52 mi) SW earthquakes near Clark County
Beaverhead County, MT 102 km (63 mi) WNW earthquakes near Beaverhead County
Park County, MT 110 km (69 mi) NE earthquakes near Park County

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

Aftershocks so far

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

  1. 1.6 42 km S of Alder, Montana
  2. 2.0 16 km WSW of West Yellowstone, Montana
  3. 2.2 32 km S of Virginia City, Montana
  4. 1.5 29 km S of Ennis, Montana
  5. 1.6 23 km WNW of Hebgen Lake Estates, Montana
  6. 1.5 Idaho-Montana border region
  7. 1.9 4 km WNW of Hebgen Lake Estates, Montana
  8. 1.8 53 km NNE of Spencer, Idaho
  9. 1.7 36 km NE of Spencer, Idaho
  10. 1.9 37 km SW of Big Sky, Montana
  11. 1.8 7 km SW of West Yellowstone, Montana
  12. 2.5 46 km NW of Island Park, Idaho
  13. 1.6 28 km SE of Virginia City, Montana
  14. 1.8 41 km W of Hebgen Lake Estates, Montana
  15. 1.7 28 km S of Ennis, 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

QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.