QuakeIndex

Earthquake · reviewed by a seismologist

M 2.4ml

Earthquake near Challis, ID

No earthquake was likely felt in Challis in the 24 hours to 10:21 pm MST (05:21 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 2.4 earthquake was recorded 40 km (25 mi) south of Challis, ID, at 7:27 pm MDT on 23 April 2020 (01:27 UTC), 10 km deep.

USGS: 13 km SSE of Clayton, Idaho

7:27 pm MDT, Apr 23, 2020 · · 10 km deep · released about 120 lb of TNT

Every earthquake near Challis Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Custer County 15 kmCamas County 81 kmBlaine County 89 kmLemhi County 93 kmButte County 105 kmBoise 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
7:27 pm MDT on 23 April 2020 ()
Where
40 km (25 mi) south of Challis, ID · earthquakes near Challis
Idaho today
every earthquake in Idaho in the last 24 hours
Magnitude
M 2.4 (ml)
Depth
10 km below the surface
Felt
no reports yet
Nearest
Custer County, 15 km NNE
Nearest mapped fault
Lone Pine fault, 23 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 2314 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 19 km (12 mi) from the epicentre. In Challis, 40 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.

How big was it?

This earthquake released about 120 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.4 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 130,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 89,000× the energy of this one
  3. Around the size people start to feel M 3.0 7.9× the energy of this one
  4. This earthquake M 2.4 about 120 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 7 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.9 The 1983 Borah Peak Earthquake, Idaho · 38 km ESE of this epicentre
  2. 5.6 18 km ESE of Challis, Idaho · 43 km NE of this epicentre
  3. 5.5 22 km E of Clayton, Idaho · 22 km NE of this epicentre
  4. 5.4 29 km NW of Mackay, Idaho · 34 km ESE of this epicentre
  5. 5.4 23 km E of Clayton, Idaho · 19 km ENE 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 44.1487, -114.3189. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Custer County, ID 15 km (9 mi) NNE earthquakes near Custer County
Camas County, ID 81 km (50 mi) SSW earthquakes near Camas County
Blaine County, ID 89 km (55 mi) SSE earthquakes near Blaine County
Lemhi County, ID 93 km (58 mi) NNE earthquakes near Lemhi County
Butte County, ID 105 km (65 mi) ESE earthquakes near Butte County
Boise County, ID 113 km (70 mi) W earthquakes near Boise County

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

Aftershocks so far

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

  1. 2.1 10 km NE of Stanley, Idaho
  2. 1.8 9 km SE of Challis, Idaho
  3. 2.3 10 km NE of Stanley, Idaho
  4. 2.0 13 km NE of Stanley, Idaho
  5. 1.8 30 km ESE of Clayton, Idaho
  6. 2.8 southern Idaho
  7. 2.2 3 km ENE of Clayton, Idaho
  8. 2.7 19 km E of Stanley, Idaho
  9. 1.8 12 km NNE of Stanley, Idaho
  10. 2.1 23 km WNW of Mackay, Idaho
  11. 2.0 southern Idaho
  12. 2.0 18 km NNE of Stanley, Idaho
  13. 2.0 17 km WNW of Clayton, Idaho
  14. 1.7 16 km WNW of Clayton, Idaho
  15. 1.7 15 km WNW of Clayton, 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.