QuakeIndex

Earthquake · reviewed by a seismologist

M 3.1ml

45 km NW of Island Park, Idaho

Yes. A magnitude 3.1 earthquake was recorded 45 km NW of Island Park, Idaho, at 2:48 pm MDT on 23 August 2023 (20:48 UTC), 7.3 km deep.

· 7.3 km deep · released about 1,300 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Fremont County 58 kmClark County 63 kmMadison County 71 kmBeaverhead County 99 kmMadison County 101 kmGallatin County 105 kmJefferson County 108 kmTeton County 113 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 3.1 (ml)
Depth
7.3 km below the surface
Felt
no reports yet
Nearest
Fremont County, 58 km SSE
Nearest mapped fault
Centennial fault, 11 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 1110 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 41 km (25 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 1,300 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.1 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 250,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 11,000× the energy of this one
  3. Magna, Utah 2020 M 5.7 7,900× the energy of this one
  4. This earthquake M 3.1 about 1,300 lb of TNT
  5. Around the size people start to feel M 3.0 this one released 1.4× more

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 72 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 · 49 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 · 28 km NE of this epicentre
  4. 5.2 26 km WNW of Hebgen Lake Estates, Montana · 29 km NE of this epicentre
  5. 5.0 31 km W of Hebgen Lake Estates, Montana · 22 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 44.6897, -111.7995. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Fremont County, ID 58 km (36 mi) SSE earthquakes near Fremont County
Clark County, ID 63 km (39 mi) SW earthquakes near Clark County
Madison County, MT 71 km (44 mi) N earthquakes near Madison County
Beaverhead County, MT 99 km (62 mi) WNW earthquakes near Beaverhead County
Madison County, ID 101 km (63 mi) S earthquakes near Madison 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

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

  1. 1.6 31 km SSE of Virginia City, Montana
  2. 1.8 40 km NNE of Spencer, Idaho
  3. 1.9 26 km NNW of Hebgen Lake Estates, Montana
  4. 1.7 22 km WNW of Hebgen Lake Estates, Montana
  5. 1.6 43 km W of Hebgen Lake Estates, Montana
  6. 1.5 28 km S of Ennis, Montana
  7. 1.6 31 km NNE of Spencer, Idaho
  8. 1.7 29 km WNW of Hebgen Lake Estates, Montana
  9. 1.5 21 km W of Hebgen Lake Estates, Montana
  10. 1.6 40 km NE of Spencer, Idaho
  11. 1.9 31 km SSE of Virginia City, Montana
  12. 1.6 29 km SSE of Virginia City, Montana
  13. 2.2 41 km NE of Spencer, Idaho
  14. 1.8 25 km WNW of Hebgen Lake Estates, Montana
  15. 2.1 29 km WNW of Hebgen Lake Estates, 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.