QuakeIndex

Earthquake · reviewed by a seismologist

M 2.8ml

Earthquake near West Yellowstone, MT

No earthquake was likely felt in West Yellowstone in the 24 hours to 9:50 am MST (16:50 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 2.8 earthquake was recorded 49 km (31 mi) east-southeast of West Yellowstone, MT, at 3:21 am MST on 31 December 2018 (10:21 UTC), 2.5 km deep. 1 person has reported feeling it to USGS.

USGS: 48 km SSE of Mammoth, Wyoming

3:21 am MST, Dec 31, 2018 · · 2.5 km deep · released about 400 lb of TNT

Every earthquake near West Yellowstone Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Teton County 58 kmPark County 72 kmFremont County 88 kmPark County 100 kmTeton County 107 kmGallatin County 118 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
3:21 am MST on 31 December 2018 ()
Where
49 km (31 mi) east-southeast of West Yellowstone, MT · earthquakes near West Yellowstone
Magnitude
M 2.8 (ml)
Depth
2.5 km below the surface
Felt
1 report · strongest reported intensity II
Nearest
Teton County, 58 km S
Nearest mapped fault
Eagle Bay fault, 9 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 2808 days ago

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage.

At this magnitude and depth, people at rest would likely notice it out to about 26 km (16 mi) from the epicentre. In West Yellowstone, 49 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 400 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.8 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 38,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 27,000× the energy of this one
  3. Around the size people start to feel M 3.0 2.4× the energy of this one
  4. This earthquake M 2.8 about 400 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 260 times the energy of this one.

Before 2016, the USGS record lists 12 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.5 14 km N of Madison Junction, Wyoming · 38 km NW of this epicentre
  2. 6.3 22 km SW of Mammoth, Wyoming · 40 km NW of this epicentre
  3. 6.0 21 km E of West Yellowstone, Montana · 29 km WNW of this epicentre
  4. 5.9 26 km SSE of Mammoth, Wyoming · 22 km NNW of this epicentre
  5. 5.7 13 km SSW of Mammoth, Wyoming · 39 km NNW 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 44.5685, -110.4932. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Teton County, WY 58 km (36 mi) S earthquakes near Teton County
Park County, WY 72 km (45 mi) E earthquakes near Park County
Fremont County, ID 88 km (55 mi) WSW earthquakes near Fremont County
Park County, MT 100 km (62 mi) N earthquakes near Park County
Teton County, ID 107 km (66 mi) SSW earthquakes near Teton County
Gallatin County, MT 118 km (73 mi) NNW earthquakes near Gallatin 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. 2.6 56 km SE of West Yellowstone, Montana
  2. 1.5 21 km SSW of Mammoth, Wyoming
  3. 1.6 23 km SSW of Mammoth, Wyoming
  4. 2.0 24 km SSE of West Yellowstone, Montana
  5. 1.8 25 km SSE of West Yellowstone, Montana
  6. 1.6 24 km SSE of West Yellowstone, Montana
  7. 1.6 25 km ENE of West Yellowstone, Montana
  8. 1.7 25 km ENE of West Yellowstone, Montana
  9. 1.8 25 km ENE of West Yellowstone, Montana
  10. 1.6 25 km ENE of West Yellowstone, Montana
  11. 1.9 25 km ENE of West Yellowstone, Montana
  12. 1.8 15 km NE of West Yellowstone, Montana
  13. 1.7 21 km SSE of Mammoth, Wyoming
  14. 1.6 49 km SSE of Mammoth, Wyoming
  15. 1.7 37 km S of Silver Gate, 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.