QuakeIndex

Fault · Idaho, Montana

Centennial fault

62 kmlong (39 mi), as mapped
0.2–1 mm/yrhow fast it slips
< 15,000 yearssince it last broke the surface
18quakes 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.

Its most recent surface rupture is younger than 15,000 years.

The largest earthquake recorded near it was M 7.2 in 1959 (The 1959 Hebgen Lake, Montana Earthquake) — about 2,000,000 times the energy of an M3.0, the size people start to feel. It released about 950 kilotons of TNT.

USGS maps it as 4 sections: Henrys Lake section, Red Rock Lakes section, Red Rock Pass section, western Centennial Valley section.

This week vs. its last ten years

Too quiet to rank: fewer than half a year's worth of weeks with any M1.5+ quake within 5 km, in ten years. A single quake here would read as "unusual", so we do not score it.

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

Madison faultEmigrant faultRed Rock faultRed Canyon faultHebgen fault M 7.2 · 1959 · The 1959 Hebgen Lake, Montana Earthquake
The Centennial fault as mapped at the surface (glowing), with the other mapped faults nearby, 18 of the M2.5+ earthquakes within 10 km of it since 2016 (dots), and the epicentres of the large historic earthquakes recorded near it (rings). 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.

The big ones recorded near it

  1. M 7.2 The 1959 Hebgen Lake, Montana Earthquake
    August 18, 1959 · epicentre 22 km from the trace

Before 1973 from the USGS ComCat historical catalogue (within 25 km; epicentres of old earthquakes are estimates). Since 2016, M4+ within 10 km.

Most recent near it

  1. M 2.6 24 km N of Spencer, Idaho
    2025-11-05 · 5 km from the trace
  2. M 2.9 23 km N of Spencer, Idaho
    2025-10-05 · 5 km from the trace
  3. M 2.6 26 km N of Spencer, Idaho
    2025-10-04 · 3 km from the trace
  4. M 2.7 23 km N of Spencer, Idaho
    2025-10-04 · 5 km from the trace
  5. M 2.5 23 km N of Spencer, Idaho
    2025-10-03 · 4 km from the trace
  6. M 3.8 22 km NNW of Spencer, Idaho
    2025-10-03 · 7 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.