QuakeIndex

Earthquake · reviewed by a seismologist

M 2.2ml

45 km NNE of Spencer, Idaho

Yes. A magnitude 2.2 earthquake was recorded 45 km NNE of Spencer, Idaho, at 12:36 pm MDT on 4 October 2026 (18:36 UTC), 3.2 km deep.

· 3.2 km deep · released about 62 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Clark County 59 kmMadison County 65 kmFremont County 69 kmBeaverhead County 85 kmGallatin County 107 kmMadison County 108 kmJefferson County 108 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 2.2 (ml)
Depth
3.2 km below the surface
Felt
no reports yet
Nearest
Clark County, 59 km SSW
Nearest mapped fault
Centennial fault, 16 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 15 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 18 km (11 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 62 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.2 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 240,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 170,000× the energy of this one
  3. Around the size people start to feel M 3.0 15× the energy of this one
  4. This earthquake M 2.2 about 62 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 4.6 on 2019-04-09 — about 3,800 times the energy of this one.

Before 2016, the USGS record lists 5 earthquakes of M5 or more within 50 km:

  1. 6.1 30 km SSW of Big Sky, Montana · 47 km NE of this epicentre
  2. 5.2 32 km WNW of Hebgen Lake Estates, Montana · 35 km ENE of this epicentre
  3. 5.2 26 km WNW of Hebgen Lake Estates, Montana · 39 km ENE of this epicentre
  4. 5.0 31 km W of Hebgen Lake Estates, Montana · 31 km ENE of this epicentre
  5. 5.0 39 km W of Hebgen Lake Estates, Montana · 23 km E 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 44.7390, -111.9640. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Clark County, ID 59 km (36 mi) SSW earthquakes near Clark County
Madison County, MT 65 km (41 mi) N earthquakes near Madison County
Fremont County, ID 69 km (43 mi) SSE earthquakes near Fremont County
Beaverhead County, MT 85 km (53 mi) WNW earthquakes near Beaverhead County
Gallatin County, MT 107 km (66 mi) NE earthquakes near Gallatin County
Madison County, ID 108 km (67 mi) SSE earthquakes near Madison County

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

Aftershocks so far

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

  1. 1.1 46 km NW of Island Park, Idaho
  2. 0.8 24 km WNW of Hebgen Lake Estates, Montana
  3. 0.1 25 km WNW of Hebgen Lake Estates, Montana
  4. 0.6 25 km WNW of Hebgen Lake Estates, Montana
  5. 0.7 24 km WNW of Hebgen Lake Estates, Montana
  6. 0.9 24 km WNW of Hebgen Lake Estates, Montana
  7. -0.0 25 km WNW of Hebgen Lake Estates, Montana
  8. 0.2 24 km WNW of Hebgen Lake Estates, Montana
  9. 0.5 51 km W of Hebgen Lake Estates, Montana
  10. 0.3 20 km W of Hebgen Lake Estates, Montana
  11. 0.4 26 km WNW of Hebgen Lake Estates, Montana
  12. 0.4 24 km WNW of Hebgen Lake Estates, Montana
  13. 0.3 36 km S of Virginia City, Montana
  14. -0.5 26 km W of Hebgen Lake Estates, Montana
  15. -0.1 40 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.