Earthquake · reviewed by a seismologist
M 2.8ml
Earthquake near Challis, ID
No earthquake was likely felt in Challis in the 24 hours to 10:26 am MST (17:26 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 2.8 earthquake was recorded 13 km (8 mi) southeast of Challis, ID, at 9:34 am MDT on 16 September 2018 (15:34 UTC), 5.0 km deep. 3 people have reported feeling it to USGS.
USGS: 13 km SE of Challis, Idaho
- When
- 9:34 am MDT on 16 September 2018 ()
- Where
- 13 km (8 mi) southeast of Challis, ID · earthquakes near Challis
- Idaho today
- every earthquake in Idaho in the last 24 hours
- Magnitude
- M 2.8 (ml)
- Depth
- 5.0 km below the surface
- Felt
- 3 reports · strongest reported intensity II
- Nearest
- Custer County, 21 km SSW
- Nearest mapped fault
- Lost River fault, under 1 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 1557 days ago
Earthquake alerts for Challis, ID
Get a notification in this browser when USGS records an earthquake near Challis, ID. No account or email needed.
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 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 27 km (17 mi) from the epicentre. In Challis, 13 km away, the estimate is intensity III (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 13 km, intensity III. Estimated for each town centre; each link is that town's own record.
How big was it?
This earthquake released about 480 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.8 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 32,000× the energy of this one
- Magna, Utah 2020 M 5.7 22,000× the energy of this one
- Around the size people start to feel M 3.0 2× the energy of this one
- This earthquake M 2.8 about 480 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:
- 6.9 The 1983 Borah Peak Earthquake, Idaho · 46 km SSE of this epicentre
- 5.6 18 km ESE of Challis, Idaho · 9 km ENE of this epicentre
- 5.5 22 km E of Clayton, Idaho · 16 km S of this epicentre
- 5.4 29 km NW of Mackay, Idaho · 42 km SSE of this epicentre
- 5.4 23 km E of Clayton, Idaho · 22 km S 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 44.4278, -114.1085. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Custer County, ID | 21 km (13 mi) | SSW | earthquakes near Custer County |
| Lemhi County, ID | 58 km (36 mi) | NNE | earthquakes near Lemhi County |
| Butte County, ID | 111 km (69 mi) | SE | earthquakes near Butte County |
| Blaine County, ID | 116 km (72 mi) | S | earthquakes near Blaine County |
| Camas County, ID | 116 km (72 mi) | SSW | earthquakes near Camas County |
| Beaverhead County, MT | 124 km (77 mi) | NE | earthquakes near Beaverhead County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
59 earthquakes have been recorded within 50 km since this one.
- 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
- 1.6 7 km NW of Challis, Idaho
- 1.9 8 km NNW of Challis, Idaho
- 2.8 12 km NNW of Challis, Idaho
- 2.2 9 km NW of Challis, Idaho
- 2.6 11 km NNW of Challis, Idaho
- 3.0 11 km NW of Challis, Idaho
- 2.4 9 km NNW of Challis, Idaho
- 1.8 7 km NW of Challis, Idaho
- 2.1 8 km NW of Challis, Idaho
- 2.2 7 km NNW of Challis, Idaho
- 2.3 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.