The 524-metre tsunami recorded in 1958 occurred in Lituya Bay, Alaska.
The event began on July 9, 1958, when a magnitude 7.8–8.3 earthquake struck the Fairweather Fault near southeastern Alaska. The shaking destabilized a mountainside, sending roughly 30 million cubic metres of rock into Gilbert Inlet, a narrow section of Lituya Bay. The sudden impact displaced water and produced a localized megatsunami.
The water surged up the surrounding slopes, stripping trees and vegetation to an elevation of about 524 metres. This measurement is best described as run-up—the highest elevation reached by the water—not the height of a free-standing wave traveling across the open ocean. The bay’s steep, confined geography greatly amplified the result.
Three fishing boats were in the bay during the disaster. Two were carried over a wave and survived, while two people aboard another boat died. The event remains the highest known tsunami run-up, although its extreme height was confined to the immediate inlet rather than representing a normal ocean-wide tsunami.