Earthquakes in Alaska

Alaska records approximately 40,000-50,000 earthquakes per year of all magnitudes, of which about 1,000 are M2.5+. This accounts for approximately 11% of all earthquakes on Earth. A damaging earthquake (M6.0+) occurs roughly every 1-2 years near populated areas.

The March 27, 1964 Good Friday earthquake (M9.2) in Prince William Sound is the largest earthquake in North American recorded history and the second largest globally. It caused massive tsunamis that swept Alaskan coastal towns and sent waves to California, Oregon, and Hawaii. Geologically, it uplifted some areas by over 10 meters.

Yes, significantly. Alaska's Aleutian Trench generates Pacific-wide tsunamis that threaten Hawaii, Japan, and the US West Coast. Local tsunamis from submarine landslides can strike Alaska coastal communities within minutes. All Alaskan coastal residents should know their tsunami evacuation zones.

Anchorage has strengthened earthquake preparedness significantly since the 1964 event and after the 2018 M7.1 earthquake. The city has modern seismic building codes, ShakeAlert early warning coverage, and designated evacuation sites. However, a repeat of the 1964 M9.2 would be catastrophic for modern infrastructure including the Ted Stevens Anchorage International Airport.

The Aleutian Trench extends 3,400 km from Alaska to Kamchatka and marks where the Pacific Plate subducts beneath the North American Plate at 5-7 cm per year. This subduction has generated some of the largest earthquakes and tsunamis in the instrumental record, including the 1964 M9.2, 1957 M9.1, and 2021 M8.2 events.