QuakeIndex

Earthquake · reviewed by a seismologist

M 2.9ml

Earthquake near Challis, ID

No earthquake was likely felt in Challis in the 24 hours to 9:34 pm MST (04:34 UTC). The last one was M 2.0, 9 km (6 mi) SSW, at 1:32 am MDT on 17 August 2026, estimated intensity II (weak) in town. Every earthquake near Challis

This page: a magnitude 2.9 earthquake was recorded 28 km (17 mi) west-northwest of Challis, ID, at 9:19 pm MDT on 6 April 2023 (03:19 UTC), 10 km deep. 2 people have reported feeling it to USGS.

USGS: 27 km WNW of Challis, Idaho

9:19 pm MDT, Apr 6, 2023 · · 10 km deep · released about 680 lb of TNT

Every earthquake near Challis Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Custer County 43 kmLemhi County 65 kmValley County 88 kmBoise County 114 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
9:19 pm MDT on 6 April 2023 ()
Where
28 km (17 mi) west-northwest of Challis, ID · earthquakes near Challis
Idaho today
every earthquake in Idaho in the last 24 hours
Magnitude
M 2.9 (ml)
Depth
10 km below the surface
Felt
2 reports · strongest reported intensity II
Nearest
Custer County, 43 km SE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1028 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 30 km (19 mi) from the epicentre. In Challis, 28 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.

Likely felt in: Challis 28 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 680 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.9 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 22,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 16,000× the energy of this one
  3. Around the size people start to feel M 3.0 1.4× the energy of this one
  4. This earthquake M 2.9 about 680 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 4.1 on 2020-11-25 — about 63 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. 6.1 37 km N of Stanley, Idaho · 27 km W of this epicentre
  2. 6.0 44 km NNW of Stanley, Idaho · 42 km W of this epicentre
  3. 5.6 18 km ESE of Challis, Idaho · 46 km ESE of this epicentre
  4. 5.5 22 km E of Clayton, Idaho · 50 km SE of this epicentre
  5. 5.1 9 km SE of Challis, Idaho · 37 km ESE 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 44.5933, -114.5610. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Custer County, ID 43 km (27 mi) SE earthquakes near Custer County
Lemhi County, ID 65 km (40 mi) NE earthquakes near Lemhi County
Valley County, ID 88 km (55 mi) WNW earthquakes near Valley County
Boise County, ID 114 km (71 mi) SW earthquakes near Boise County
Butte County, ID 150 km (93 mi) SE earthquakes near Butte County

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

Aftershocks so far

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

  1. 2.2 20 km NNW of Challis, Idaho
  2. 2.0 13 km NNE of Challis, Idaho
  3. 2.2 21 km NNW of Challis, Idaho
  4. 1.6 23 km NNW of Challis, Idaho
  5. 1.9 11 km NE of Stanley, Idaho
  6. 2.2 9 km ENE of Stanley, Idaho
  7. 1.6 30 km NNW of Challis, Idaho
  8. 2.6 southern Idaho
  9. 2.0 33 km NNW of Challis, Idaho
  10. 2.2 southern Idaho
  11. 2.1 28 km WNW of Challis, Idaho
  12. 2.3 32 km NNW of Challis, Idaho
  13. 2.3 32 km NNW of Challis, Idaho
  14. 2.5 33 km NNW of Challis, Idaho
  15. 2.5 33 km NNW of Challis, Idaho

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.