QuakeIndex

Earthquake · reviewed by a seismologist

M 1.8ml

57 km E of Warm River, Idaho

Yes. A magnitude 1.8 earthquake was recorded 57 km E of Warm River, Idaho, at 7:47 am MDT on 28 September 2026 (13:47 UTC), 12 km deep.

· 12 km deep · released about 14 lb of TNT

10 km30 km60 km120 km N Teton County 24 kmTeton County 69 kmFremont County 69 kmPark County 87 kmMadison County 96 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
Idaho today
every earthquake in Idaho in the last 24 hours
Magnitude
M 1.8 (ml)
Depth
12 km below the surface
Felt
no reports yet
Nearest
Teton County, 24 km SE
Nearest mapped fault
East Mount Sheridan faults, 7 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 27 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 6 km (4 mi) from the epicentre. 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 14 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.

  1. Mineral, Virginia 2011 M 5.8 1,100,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 790,000× the energy of this one
  3. Around the size people start to feel M 3.0 70× the energy of this one
  4. This earthquake M 1.8 about 14 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

No earthquake of M4 or more has been recorded within 50 km since our catalogue begins in 2016.

Before 2016, the USGS record lists 2 earthquakes of M5 or more within 50 km:

  1. 5.1 51 km ESE of West Yellowstone, Montana · 35 km NNE of this epicentre
  2. 5.0 62 km ESE of West Yellowstone, Montana · 30 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 44.2122, -110.6163. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Teton County, WY 24 km (15 mi) SE earthquakes near Teton County
Teton County, ID 69 km (43 mi) SW earthquakes near Teton County
Fremont County, ID 69 km (43 mi) W earthquakes near Fremont County
Park County, WY 87 km (54 mi) ENE earthquakes near Park County
Madison County, ID 96 km (59 mi) WSW earthquakes near Madison County
Bonneville County, ID 122 km (76 mi) SW earthquakes near Bonneville County

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

Aftershocks so far

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

  1. 1.4 68 km ESE of West Yellowstone, Montana
  2. 0.7 51 km SE of Mammoth, Wyoming
  3. 1.1 35 km ESE of West Yellowstone, Montana
  4. 0.8 33 km ESE of West Yellowstone, Montana
  5. 1.0 30 km ESE of West Yellowstone, Montana
  6. 0.8 29 km ESE of West Yellowstone, Montana
  7. 0.6 29 km ESE of West Yellowstone, Montana
  8. 0.6 29 km ESE of West Yellowstone, Montana
  9. 0.9 27 km SSE of West Yellowstone, Montana
  10. 0.6 27 km SSE of West Yellowstone, Montana
  11. 1.6 34 km E of West Yellowstone, Montana
  12. 1.1 35 km E of West Yellowstone, Montana
  13. 1.5 53 km SE of West Yellowstone, Montana
  14. 1.2 51 km NE of Alta, Wyoming
  15. 1.8 46 km ESE of West Yellowstone, 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.