Earthquakes in Custer County, Idaho
The most recent earthquake of M2.5 or more near Custer County was M 2.6, 25 km S of Clayton, Idaho, 32 km (20 mi) SSW of the centre of Custer County, at 8:43 am MST on 7 November 2026, 12 km deep. The estimated shaking at the centre of Custer County was intensity II (weak), felt by some people at rest indoors.
No earthquake of M1.5 or more was recorded within 50 km (31 mi) of the centre of Custer County in the last 24 hours.
- Last 24 hours
- 0
- Last 7 days
- 1
- Last 30 days
- 2 · an average 30 days here since 2016: 8.2
- Last 12 months
- 13 · largest M 2.6 on 7 November 2026
- Since 2016
- 1,087 earthquakes of M1.5 or more
- Largest since 2016
- M 4.3 on 8 June 2025, 24 km E of Clayton, Idaho
- Nearest mapped fault
- Lone Pine fault, 11 km from the centre to its surface trace
Latest quake, 24 hours and 7 days: the QuakeIndex database, which reads USGS every 30 seconds, read at ; 30 days and 12 months: the QuakeIndex catalogue, counted to · earthquakes of M1.5 or more within 50 km (31 mi) of the centre of Custer County · shaking is estimated for the centre with the intensity equation USGS Did You Feel It? uses
Every earthquake in Idaho in the last 24 hours →
Elevated QuakeIndex 82 / 100
1 quake of M1.5 or larger in the last 7 days within 50 km. Normal for here is 0 to 2 in a week.
Compared against Custer County, Idaho's own 10 years · USGS catalogue · updated
If you felt one
- Was that an earthquake? — checks what was recorded near you in the last hour
- Report what you felt to USGS — reports go to USGS, not to us, and they are what produces the intensity maps
- Expect aftershocks, and be ready to Drop, Cover, and Hold On if you feel one; if you are in a damaged building, go outside and move away from it (Ready.gov, FEMA; what to do during and after an earthquake)
QuakeIndex does not issue warnings or forecasts. For earthquake early warning see ShakeAlert and the MyShake app.
The last 30 days
Show these earthquakes on your own site: a free card with this strip and the latest quakes near Custer County, Idaho, for a local news site, school or neighborhood page.
Live · last 7 days
Latest earthquakes within 50 km
None within 50 km in the latest snapshot we hold; the full 7 days load from USGS as this page opens.
Source USGS · snapshot of
The last 7 days on the map
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The centre is 44.273, -114.252, the Census internal point of Custer County, Idaho from the US Census Bureau Gazetteer (2024). Activity on this page is measured within 50 km of it — the dashed circle.
Largest on record nearby
The strongest shaking this record implies at the centre of Custer County, Idaho is intensity IV (light), from the M 4.3 of 2025, 12 km away. At that level most people indoors notice it; dishes and windows rattle.
| Magnitude | When | Where | Shaking here (est.) |
|---|---|---|---|
| M 4.3 | 24 km E of Clayton, Idaho · felt by 27 | IV · Light | |
| M 4.2 | 26 km NW of Clayton, Idaho · felt by 328 | III · Weak | |
| M 3.8 | 18 km NE of Stanley, Idaho · felt by 14 | II · Weak | |
| M 3.8 | 10 km SE of Challis, Idaho · felt by 8 | III · Weak | |
| M 3.7 | 27 km NE of Stanley, Idaho · felt by 13 | II · Weak | |
| M 3.7 | 12 km N of Challis, Idaho · felt by 13 | II · Weak | |
| M 3.6 | 33 km W of Challis, Idaho | II · Weak | |
| M 3.6 | 15 km NE of Challis, Idaho · felt by 9 | II · Weak |
From the QuakeIndex catalogue, built from the USGS FDSN event service · within 50 km of the centre above. Shaking is an estimate for the centre from magnitude, depth and distance, with the intensity equation USGS Did You Feel It? uses (Atkinson & Wald, 2007), on the Modified Mercalli scale. Ground conditions change it locally; it is a description of the past, not a hazard rating.
Before 2016
The USGS record from 1900 to 2015 lists 7 earthquakes of M5 or more within 50 km of the centre of Custer County, Idaho:
- 6.9 The 1983 Borah Peak Earthquake, Idaho · 40 km SE of the centre
- 5.6 18 km ESE of Challis, Idaho · 29 km NE of the centre
- 5.5 22 km E of Clayton, Idaho · 11 km E of the centre
- 5.4 29 km NW of Mackay, Idaho · 35 km SE of the centre
- 5.4 23 km E of Clayton, Idaho · 13 km ESE of the centre
- 5.1 9 km SE of Challis, Idaho · 20 km NNE of the centre
- 5.0 9 km E of Challis, Idaho · 28 km NNE of the centre
USGS ComCat, M5+ from 1900 to 2015. Epicentres of early earthquakes are estimates. This is the record, not a forecast.
Nearest mapped faults
- Lone Pine fault, 11 km from the centre of Custer County, Idaho to its surface trace
- Lost River fault, 20 km from the centre of Custer County, Idaho to its surface trace
- Lemhi fault, 48 km from the centre of Custer County, Idaho to its surface trace
USGS Quaternary Fault and Fold Database, within 50 km. Near is not the same as on, and faults with no surface trace are not in it.
Town pages near Custer County, Idaho
Challis 26 km · 105 M2.5+ named after it
Each town page lists every M1.5+ earthquake within 30 km since 2016 and the ones USGS named after it. Town names: GeoNames (CC BY 4.0).
Be ready
Earthquakes cannot be predicted, here or anywhere, so the useful step is the one taken beforehand. The advice below is from the agencies responsible for it.
- Ready.gov: earthquakes (FEMA) — what to do before, during and after, including Drop, Cover, and Hold On
- Build a kit (FEMA) — water, food and supplies for several days; our summary
- USGS: preparedness — the hazard behind the advice, from the agency that records every quake on this page
- The Great ShakeOut — the yearly earthquake drill, with material for homes, schools and workplaces