QuakeIndex

Earthquake · reviewed by a seismologist

M 1.7ml

Earthquake near West Yellowstone, MT

No earthquake was likely felt in West Yellowstone in the 24 hours to 12:53 am MST (07:53 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 1.7 earthquake was recorded 29 km (18 mi) east of West Yellowstone, MT, at 12:19 am MDT on 19 September 2021 (06:19 UTC), 7.4 km deep.

USGS: 29 km E of West Yellowstone, Montana

12:19 am MDT, Sep 19, 2021 · · 7.4 km deep · released about 11 lb of TNT

Every earthquake near West Yellowstone Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Teton County 70 kmFremont County 75 kmPark County 92 kmPark County 94 kmGallatin County 104 kmTeton County 104 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
12:19 am MDT on 19 September 2021 ()
Where
29 km (18 mi) east of West Yellowstone, MT · earthquakes near West Yellowstone
Montana today
every earthquake in Montana in the last 24 hours
Magnitude
M 1.7 (ml)
Depth
7.4 km below the surface
Felt
no reports yet
Nearest
Teton County, 70 km SSE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1879 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 10 km (6 mi) from the epicentre. In West Yellowstone, 29 km away, the estimate is intensity II (weak). 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 11 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.7 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 1,400,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 1,000,000× the energy of this one
  3. Around the size people start to feel M 3.0 89× the energy of this one
  4. This earthquake M 1.7 about 11 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 9,800 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 · 41 km WNW of this epicentre
  2. 6.5 14 km N of Madison Junction, Wyoming · 19 km NW of this epicentre
  3. 6.3 22 km SW of Mammoth, Wyoming · 22 km NNW of this epicentre
  4. 6.0 21 km E of West Yellowstone, Montana · 8 km W of this epicentre
  5. 5.9 26 km SSE of Mammoth, Wyoming · 16 km NE 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 44.6343, -110.7363. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Teton County, WY 70 km (43 mi) SSE earthquakes near Teton County
Fremont County, ID 75 km (47 mi) SW earthquakes near Fremont County
Park County, WY 92 km (57 mi) E earthquakes near Park County
Park County, MT 94 km (58 mi) N earthquakes near Park County
Gallatin County, MT 104 km (65 mi) NNW earthquakes near Gallatin County
Teton County, ID 104 km (65 mi) SSW 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. 1.8 30 km ESE of West Yellowstone, Montana
  2. 1.8 29 km S of Mammoth, Wyoming
  3. 1.9 28 km S of Mammoth, Wyoming
  4. 1.9 50 km SSE of Mammoth, Wyoming
  5. 1.7 27 km S of Mammoth, Wyoming
  6. 1.6 Wyoming
  7. 1.5 40 km SSE of West Yellowstone, Montana
  8. 1.6 21 km ENE of Hebgen Lake Estates, Montana
  9. 2.3 21 km ENE of Hebgen Lake Estates, Montana
  10. 1.9 27 km S of Mammoth, Wyoming
  11. 1.5 44 km SE of West Yellowstone, Montana
  12. 1.7 28 km S of Mammoth, Wyoming
  13. 1.7 27 km S of Mammoth, Wyoming
  14. 2.0 28 km S of Mammoth, Wyoming
  15. 2.1 28 km S 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.