QuakeIndex

Earthquake · reviewed by a seismologist

M 1.6ml

Earthquake near West Yellowstone, MT

No earthquake was likely felt in West Yellowstone in the 24 hours to 7:11 am MST (14:11 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 1.6 earthquake was recorded 39 km (24 mi) east-northeast of West Yellowstone, MT, at 5:54 pm MDT on 4 October 2021 (23:54 UTC), 4.1 km deep.

USGS: 25 km SSE of Mammoth, Wyoming

5:54 pm MDT, Oct 4, 2021 · · 4.1 km deep · released about 7.8 lb of TNT

Every earthquake near West Yellowstone Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Park County 79 kmTeton County 80 kmPark County 87 kmFremont County 90 kmGallatin County 94 kmMadison County 119 kmTeton County 120 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
5:54 pm MDT on 4 October 2021 ()
Where
39 km (24 mi) east-northeast of West Yellowstone, MT · earthquakes near West Yellowstone
Magnitude
M 1.6 (ml)
Depth
4.1 km below the surface
Felt
no reports yet
Nearest
Park County, 79 km N
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1863 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, 39 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 7.8 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.6 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 1,900,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 1,400,000× the energy of this one
  3. Around the size people start to feel M 3.0 120× the energy of this one
  4. This earthquake M 1.6 about 7.8 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 4.4 on 2017-06-16 — about 13,000 times the energy of this one.

Before 2016, the USGS record lists 13 earthquakes of M5 or more within 50 km; the five largest:

  1. 7.2 The 1959 Hebgen Lake, Montana Earthquake · 45 km W of this epicentre
  2. 6.5 14 km N of Madison Junction, Wyoming · 20 km W of this epicentre
  3. 6.3 22 km SW of Mammoth, Wyoming · 19 km WNW of this epicentre
  4. 6.0 21 km E of West Yellowstone, Montana · 20 km SW of this epicentre
  5. 5.9 26 km SSE of Mammoth, Wyoming · 3 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 44.7552, -110.6347. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Park County, MT 79 km (49 mi) N earthquakes near Park County
Teton County, WY 80 km (50 mi) SSE earthquakes near Teton County
Park County, WY 87 km (54 mi) ESE earthquakes near Park County
Fremont County, ID 90 km (56 mi) SW earthquakes near Fremont County
Gallatin County, MT 94 km (59 mi) NNW earthquakes near Gallatin County
Madison County, MT 119 km (74 mi) WNW earthquakes near Madison 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. 1.5 52 km SE of West Yellowstone, Montana
  2. 1.6 39 km SSE of Mammoth, Wyoming
  3. 2.0 39 km SSE of Mammoth, Wyoming
  4. 1.9 40 km SSE of Mammoth, Wyoming
  5. 2.4 51 km SE of Mammoth, Wyoming
  6. 1.8 49 km SE of Mammoth, Wyoming
  7. 1.9 32 km SE of West Yellowstone, Montana
  8. 1.7 33 km SE of West Yellowstone, Montana
  9. 1.8 33 km SE of West Yellowstone, Montana
  10. 1.8 46 km ESE of West Yellowstone, Montana
  11. 2.8 50 km SSE of Mammoth, Wyoming
  12. 2.1 51 km SSE of Mammoth, Wyoming
  13. 2.3 61 km SSE of Mammoth, Wyoming
  14. 2.0 41 km SSW of Silver Gate, Montana
  15. 2.1 22 km SSW of Mammoth, Wyoming

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.