QuakeIndex

Fault · Alaska

Malaspina fault (Chugach-St. Elias fold and thrust belt)

62 kmlong (39 mi), as mapped
> 5 mm/yrhow fast it slips
< 130,000 yearssince it last broke the surface
129quakes of M2.5+ within 10 km since 2016

In plain English

The two sides grind past each other faster than 5 mm a year — more than half a metre (20 inches) every century.

Its most recent surface rupture is younger than 130,000 years.

The largest earthquake recorded near it was M 4.8 in 2023 (98 km NW of Yakutat, Alaska) — about 500 times the energy of an M3.0, the size people start to feel. It released about 240 tons of TNT.

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: 0–2.

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

Denali faultPamplona faultYakutat fault (also known as Foothills fault)Chaix Hills fault (Chugach-St. Elias fold and thrust belt)Coal Glacier fault (Chugach-St. Elias fold and thrust belt)White River syncline (Chugach-St. Elias fold and thrust belt)Yakataga anticline (Chugach-St. Elias fold and thrust belt)Bancas Point faultOtmeloi fault
The Malaspina fault (Chugach-St. Elias fold and thrust belt) as mapped at the surface (glowing), with the other mapped faults nearby, 129 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.

The big ones recorded near it

  1. M 4.8 98 km NW of Yakutat, Alaska
    January 11, 2023 · epicentre 10 km from the trace
  2. M 4.5 76 km NW of Yakutat, Alaska
    September 8, 2019 · epicentre 2 km from the trace
  3. M 4.1 51 km NNW of Yakutat, Alaska
    September 6, 2021 · epicentre 2 km from the trace
  4. M 4.0 50 km NNW of Yakutat, Alaska
    September 5, 2021 · epicentre 7 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 2.9 90 km NW of Yakutat, Alaska
    2026-05-27 · 5 km from the trace
  2. M 2.5 48 km NNW of Yakutat, Alaska
    2026-03-01 · 4 km from the trace
  3. M 2.6 83 km NW of Yakutat, Alaska
    2025-12-25 · 1 km from the trace
  4. M 2.5 87 km NW of Yakutat, Alaska
    2025-11-21 · 8 km from the trace
  5. M 2.9 106 km WNW of Yakutat, Alaska
    2025-09-22 · 9 km from the trace
  6. M 3.2 86 km WNW of Yakutat, Alaska
    2025-08-26 · 8 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.