Earthquake · reviewed by a seismologist
M 2.3ml
Earthquake near Challis, ID
No earthquake was likely felt in Challis in the 24 hours to 4:09 pm MST (23:09 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 2.3 earthquake was recorded 36 km (22 mi) east-northeast of Challis, ID, at 12:30 am MDT on 18 September 2018 (06:30 UTC), 11 km deep.
USGS: 36 km ENE of Challis, Idaho
- When
- 12:30 am MDT on 18 September 2018 ()
- Where
- 36 km (22 mi) east-northeast of Challis, ID · earthquakes near Challis
- Idaho today
- every earthquake in Idaho in the last 24 hours
- Magnitude
- M 2.3 (ml)
- Depth
- 11 km below the surface
- Felt
- no reports yet
- Nearest
- Lemhi County, 31 km N
- Nearest mapped fault
- Lemhi fault, 4 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 2976 days ago
Earthquake alerts for Challis, ID
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Alerts are on for .
Not a warning. An alert comes after USGS publishes a quake, usually minutes after the shaking. For early warning use ShakeAlert, through your phone's Wireless Emergency Alerts or the MyShake app.
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 16 km (10 mi) from the epicentre. In Challis, 36 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 85 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.3 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 180,000× the energy of this one
- Magna, Utah 2020 M 5.7 130,000× the energy of this one
- Around the size people start to feel M 3.0 11× the energy of this one
- This earthquake M 2.3 about 85 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 4 earthquakes of M5 or more within 50 km:
- 5.6 18 km ESE of Challis, Idaho · 25 km SW of this epicentre
- 5.5 22 km E of Clayton, Idaho · 48 km SSW of this epicentre
- 5.1 9 km SE of Challis, Idaho · 35 km SW of this epicentre
- 5.0 9 km E of Challis, Idaho · 28 km SW 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 44.6555, -113.8270. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Lemhi County, ID | 31 km (19 mi) | N | earthquakes near Lemhi County |
| Custer County, ID | 54 km (34 mi) | SW | earthquakes near Custer County |
| Beaverhead County, MT | 91 km (56 mi) | NE | earthquakes near Beaverhead County |
| Butte County, ID | 120 km (74 mi) | SSE | earthquakes near Butte County |
| Clark County, ID | 124 km (77 mi) | ESE | earthquakes near Clark County |
| Jefferson County, ID | 153 km (95 mi) | SE | earthquakes near Jefferson 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.
- 1.6 15 km NE of Challis, Idaho
- 2.3 12 km SE of Challis, Idaho
- 1.7 25 km SE of Challis, Idaho
- 2.3 7 km NNW of Leadore, Idaho
- 1.7 38 km NE of Challis, Idaho
- 1.6 9 km NNW of Challis, Idaho
- 1.7 7 km NNW of Challis, Idaho
- 1.7 24 km E of Clayton, Idaho
- 2.3 8 km NNW of Challis, Idaho
- 2.2 7 km NNW of Challis, Idaho
- 1.6 8 km NW of Challis, Idaho
- 1.6 6 km NNW of Challis, Idaho
- 1.9 8 km NW of Challis, Idaho
- 1.9 42 km N of Challis, Idaho
- 1.6 7 km NW 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
- The official USGS event page — the source of record for every value above
- Did you feel it? Report it to USGS — reports go to USGS, not to us
- ShakeMap for this event, when USGS has produced one
QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.