QuakeIndex

Fault · Alaska

Fairweather fault system

713 kmlong (443 mi), as mapped
> 5 mm/yrhow fast it slips
last 150 yearssince it last broke the surface
373quakes 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.

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

The largest earthquake recorded near it was M 7.8 in 1958 (22 km W of Elfin Cove, Alaska) — about 16,000,000 times the energy of an M3.0, the size people start to feel. It released about 7.6 megatons of TNT.

USGS maps it as 2 sections: Art Lewis Glacier fault, Fairweather fault.

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: 1–3.

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

Alaska-Aleutian subduction zoneDenali faultTransition faultPamplona faultTotschunda faultYakutat fault (also known as Foothills fault)Chaix Hills fault (Chugach-St. Elias fold and thrust belt)Kosakuts fault (Chugach-St. Elias fold and thrust belt)Hope Creek fault (Chugach-St. Elias fold and thrust belt)Coal Glacier fault (Chugach-St. Elias fold and thrust belt)Malaspina 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)Boundary faultMiller Creek fault (Chugach-St. Elias fold and thrust belt)Sullivan fault (Chugach-St. Elias fold and thrust belt)Bancas Point faultYaga syncline (Chugach-St. Elias fold and thrust belt)Otmeloi fault M 7.8 · 1958 · 22 km W of Elfin Cove, Alaska M 7.6 · 1972 · 55 km SW of Sitka, Alaska M 7.2 · 1927 · 31 km SSW of Pelican, Alaska M 6.2 · 1956 · 96 km SW of Hydaburg, Alaska M 6.1 · 1972 · 53 km WSW of Port Alexander, Alaska
The Fairweather fault system as mapped at the surface (glowing), with the other mapped faults nearby, 373 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 7.8 22 km W of Elfin Cove, Alaska
    July 10, 1958 · epicentre 7 km from the trace
  2. M 7.6 55 km SW of Sitka, Alaska
    July 30, 1972 · epicentre 6 km from the trace
  3. M 7.2 31 km SSW of Pelican, Alaska
    October 24, 1927 · epicentre 2 km from the trace
  4. M 7.0 2025 Hubbard Glacier Earthquake
    December 6, 2025 · epicentre 9 km from the trace
  5. M 6.2 96 km SW of Hydaburg, Alaska
    November 17, 1956 · epicentre 14 km from the trace
  6. M 6.1 53 km WSW of Port Alexander, Alaska
    August 4, 1972 · epicentre 4 km from the trace
  7. M 5.9 69 km WNW of Port Alexander, Alaska
    January 12, 2024 · epicentre 4 km from the trace
  8. M 5.2 93 km NNE of Yakutat, Alaska
    December 6, 2025 · epicentre 3 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 50 km E of Yakutat, Alaska
    2026-09-24 · 9 km from the trace
  2. M 2.6 94 km NW of Elfin Cove, Alaska
    2026-06-24 · 4 km from the trace
  3. M 2.6 47 km ENE of Yakutat, Alaska
    2026-06-21 · 7 km from the trace
  4. M 2.6 95 km N of Yakutat, Alaska
    2026-06-11 · 10 km from the trace
  5. M 2.5 93 km N of Yakutat, Alaska
    2026-06-08 · 7 km from the trace
  6. M 2.6 59 km NNE of Yakutat, Alaska
    2026-06-04 · 4 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.