QuakeIndex

Earthquake · reviewed by a seismologist

M 2.3ml

41 km NW of Island Park, Idaho

Yes. A magnitude 2.3 earthquake was recorded 41 km NW of Island Park, Idaho, at 9:36 pm MDT on 25 April 2021 (03:36 UTC), 15 km deep.

· 15 km deep · released about 85 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Fremont County 56 kmClark County 64 kmMadison County 73 kmMadison County 99 kmBeaverhead County 103 kmGallatin County 105 kmJefferson County 108 kmTeton County 111 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 2.3 (ml)
Depth
15 km below the surface
Felt
no reports yet
Nearest
Fremont County, 56 km SSE
Nearest mapped fault
Centennial fault, 10 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 1954 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 12 km (7 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 85 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.3 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 180,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 130,000× the energy of this one
  3. Around the size people start to feel M 3.0 11× the energy of this one
  4. This earthquake M 2.3 about 85 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 1,100 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 · 46 km ENE of this epicentre
  2. 6.1 30 km SSW of Big Sky, Montana · 44 km NNE of this epicentre
  3. 5.2 32 km WNW of Hebgen Lake Estates, Montana · 27 km NE of this epicentre
  4. 5.2 26 km WNW of Hebgen Lake Estates, Montana · 28 km NE of this epicentre
  5. 5.0 31 km W of Hebgen Lake Estates, Montana · 21 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 44.6776, -111.7597. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Fremont County, ID 56 km (35 mi) SSE earthquakes near Fremont County
Clark County, ID 64 km (40 mi) SW earthquakes near Clark County
Madison County, MT 73 km (45 mi) N earthquakes near Madison County
Madison County, ID 99 km (62 mi) S earthquakes near Madison County
Beaverhead County, MT 103 km (64 mi) WNW earthquakes near Beaverhead County
Gallatin County, MT 105 km (65 mi) NNE earthquakes near Gallatin 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. 2.4 30 km WNW of Hebgen Lake Estates, Montana
  2. 2.0 9 km WNW of Hebgen Lake Estates, Montana
  3. 1.5 29 km WNW of Hebgen Lake Estates, Montana
  4. 1.6 42 km S of Alder, Montana
  5. 2.0 16 km WSW of West Yellowstone, Montana
  6. 2.2 32 km S of Virginia City, Montana
  7. 1.5 29 km S of Ennis, Montana
  8. 1.6 23 km WNW of Hebgen Lake Estates, Montana
  9. 1.5 Idaho-Montana border region
  10. 1.9 4 km WNW of Hebgen Lake Estates, Montana
  11. 1.8 53 km NNE of Spencer, Idaho
  12. 1.7 36 km NE of Spencer, Idaho
  13. 1.9 37 km SW of Big Sky, Montana
  14. 2.5 46 km NW of Island Park, Idaho
  15. 1.6 28 km SE of Virginia City, 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.