QuakeIndex

Fault · Montana

Hebgen fault

13 kmlong (8 mi), as mapped
0.2–1 mm/yrhow fast it slips
last 150 yearssince it last broke the surface
15quakes 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.

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.

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 faultCentennial faultEmigrant faultEagle Bay faultRed Canyon faultEast Mount Sheridan faults M 7.2 · 1959 · The 1959 Hebgen Lake, Montana Earthquake
The Hebgen fault as mapped at the surface (glowing), with the other mapped faults nearby, 15 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 2 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 2.8 3 km ESE of Hebgen Lake Estates, Montana
    2026-09-08 · 7 km from the trace
  2. M 2.6 10 km W of Hebgen Lake Estates, Montana
    2026-01-10 · 9 km from the trace
  3. M 2.7 3 km ENE of Hebgen Lake Estates, Montana
    2025-06-04 · 6 km from the trace
  4. M 2.7 5 km E of Hebgen Lake Estates, Montana
    2024-03-10 · 8 km from the trace
  5. M 2.8 6 km ESE of Hebgen Lake Estates, Montana
    2022-10-01 · 10 km from the trace
  6. M 3.1 5 km ESE of Hebgen Lake Estates, Montana
    2020-03-31 · 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.