Which 1965 earthquake in Alaska was one of the largest earthquakes ever recorded?

The Rat Islands earthquake was the giant Alaska earthquake of 4 February 1965, measured at magnitude 8.7.

It ruptured along the Aleutian subduction zone, where the Pacific Plate descends beneath the North American Plate. The event generated a tsunami that affected parts of the Aleutian Islands and reached Hawaii, although its impacts were far smaller than those of several other Pacific megathrust earthquakes.

The earthquake occurred in the remote Rat Islands, which helped limit direct casualties and structural damage. Its great magnitude reflects the enormous area of fault that slipped, not simply the amount of shaking at one town.

The event is sometimes mixed up with Alaska’s 1964 Prince William Sound earthquake, which was larger and measured magnitude 9.2. It is also distinct from the 2002 Denali earthquake, a major strike-slip event on an inland Alaskan fault.