The 1958 Lituya Bay Megatsunami: The Tallest Wave Ever Recorded

On the evening of July 9, 1958, three fishing boats were anchored in Lituya Bay, a remote glacial fjord on the Gulf of Alaska coast. At 10:15 PM local time, a magnitude 7.8 earthquake struck the Fairweather Fault, triggering a chain of events that would produce the tallest wave ever recorded in modern history and permanently change how scientists understand tsunamis.

A Wave That Rewrote the Record Books

The earthquake dislodged a massive section of the mountainside above Gilbert Inlet at the head of the bay. Roughly 30 million cubic meters of rock, approximately 90 million tons, broke loose and plummeted several hundred meters into the inlet below, striking the water with a force that displaced the bay on a geologic scale. The resulting megatsunami sent water surging up the opposite slope to a height of 524 meters, or 1,719 feet, stripping trees and soil from the hillside up to the elevation of a modern 170-story building. That runup remains the highest ever reliably documented.

The tremors were felt across more than 400,000 square miles of Alaska and Canada, reaching as far as Seattle and Whitehorse, Yukon. The sound of the initial rockfall impact was heard 80 kilometers away. According to NASA Earth Observatory, the damage scar carved into the hillside by the wave remains visible from space to this day.