QuakeIndex

Earthquake · reviewed by a seismologist

M 1.9ml

Earthquake near Challis, ID

No earthquake was likely felt in Challis in the 24 hours to 4:04 pm MST (23:04 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 1.9 earthquake was recorded 28 km (17 mi) west-southwest of Challis, ID, at 8:05 am MDT on 29 May 2018 (14:05 UTC), 3.8 km deep.

USGS: 23 km NW of Clayton, Idaho

8:05 am MDT, May 29, 2018 · · 3.8 km deep · released about 23 lb of TNT

10 km30 km60 km120 km N Custer County 31 kmLemhi County 77 kmValley County 95 kmBoise County 104 kmCamas County 104 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
8:05 am MDT on 29 May 2018 ()
Where
28 km (17 mi) west-southwest of Challis, ID · earthquakes near Challis
Idaho today
every earthquake in Idaho in the last 24 hours
Magnitude
M 1.9 (ml)
Depth
3.8 km below the surface
Felt
no reports yet
Nearest
Custer County, 31 km SE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 3088 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 15 km (9 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.

How big was it?

This earthquake released about 23 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.9 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 660,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 470,000× the energy of this one
  3. Around the size people start to feel M 3.0 42× the energy of this one
  4. This earthquake M 1.9 about 23 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. 6.1 37 km N of Stanley, Idaho · 30 km WNW of this epicentre
  2. 6.0 44 km NNW of Stanley, Idaho · 45 km WNW of this epicentre
  3. 5.6 18 km ESE of Challis, Idaho · 45 km E of this epicentre
  4. 5.5 22 km E of Clayton, Idaho · 40 km ESE of this epicentre
  5. 5.4 23 km E of Clayton, Idaho · 43 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 44.4298, -114.5705. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Custer County, ID 31 km (19 mi) SE earthquakes near Custer County
Lemhi County, ID 77 km (48 mi) NE earthquakes near Lemhi County
Valley County, ID 95 km (59 mi) WNW earthquakes near Valley County
Boise County, ID 104 km (64 mi) WSW earthquakes near Boise County
Camas County, ID 104 km (65 mi) S earthquakes near Camas County
Blaine County, ID 125 km (78 mi) SSE earthquakes near Blaine County

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

Aftershocks so far

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

  1. 2.1 25 km SSW of Clayton, Idaho
  2. 1.7 2 km N of Challis, Idaho
  3. 2.2 6 km N of Stanley, Idaho
  4. 2.1 9 km NNW of Stanley, Idaho
  5. 1.7 6 km N of Stanley, Idaho
  6. 1.6 5 km N of Stanley, Idaho
  7. 1.6 33 km W of Challis, Idaho
  8. 2.4 9 km N of Stanley, Idaho
  9. 1.6 8 km N of Stanley, Idaho
  10. 1.6 16 km SE of Challis, Idaho
  11. 1.6 9 km N of Stanley, Idaho
  12. 1.6 7 km NNW of Stanley, Idaho
  13. 1.6 7 km NNW of Stanley, Idaho
  14. 2.5 12 km NNE of Stanley, Idaho
  15. 1.6 southern 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.