QuakeIndex

Fault · Idaho

Lost River fault

127 kmlong (79 mi), as mapped
0.2–1 mm/yrhow fast it slips
last 150 yearssince it last broke the surface
25quakes of M2.5+ within 10 km since 2016

In plain English

The two sides move 0.2 to 1 mm a year — 2 to 10 cm every century.

It has broken the ground surface within the last 150 years.

USGS maps it as 7 sections: Arco section, Challis section, Mackay section, Pass Creek section, Thousand Springs section, Warm Springs section, Willow Creek hills section.

This week vs. its last ten years

0/100

quiet

0 quakes of M1.5+ within 5 km of the trace in the last 7 days — busier than 0% of weeks since 2016. A normal week: 0–0.

Computed from the USGS catalogue · a description of the past, not a forecast · method

Lemhi faultBeaverhead faultRed Rock faultLone Pine fault
The Lost River fault as mapped at the surface (glowing), with the other mapped faults nearby, 25 of the M2.5+ earthquakes within 10 km of it since 2016 (dots), . Traces: USGS Quaternary Fault and Fold Database. Historic epicentres are estimates.

Every year since 2016

Earthquakes of M2.5+ with an epicentre within 10 km of the mapped trace. Near is not the same as on: some will have slipped on neighbouring faults.

Most recent near it

  1. M 2.6 4 km NW of Challis, Idaho
    2026-05-20 · 7 km from the trace
  2. M 3.2 25 km E of Clayton, Idaho
    2025-06-08 · 8 km from the trace
  3. M 3.0 7 km NW of Challis, Idaho
    2025-05-15 · 8 km from the trace
  4. M 2.7 10 km NNW of Challis, Idaho
    2024-02-14 · 7 km from the trace
  5. M 3.7 12 km N of Challis, Idaho
    2023-06-12 · 6 km from the trace
  6. M 2.7 11 km WNW of Mackay, Idaho
    2020-09-06 · 9 km from the trace

Neighbouring faults

Fault trace, slip rate and age: USGS Quaternary Fault and Fold Database (public domain), simplified for the web. Earthquakes: USGS ComCat. QuakeIndex does not forecast earthquakes; a fault's history describes the past. For early warning use ShakeAlert.