On July 9, 1958, at 10:15 p.m. Pacific time, the earth fractured beneath Lituya Bay in southeast Alaska. A magnitude 7.8 to 8.3 earthquake ruptured the Fairweather Fault, a geological weak point running through the region. The violent shaking triggered something far more catastrophic than the earthquake itself: a massive rockslide tumbled 30 million cubic meters of rock and ice, roughly 90 million tons, into the narrow inlet below. The impact was deafening, audible from 50 miles away. When that enormous mass of stone crashed into the confined waters, it created a wave of terrifying proportions.

The megatsunami that surged from the bay reached an elevation of 1,720 feet (524 meters) at the entrance of Gilbert Inlet. To visualize this: imagine water tall enough to dwarf a 150-story building, stripped bare of its bark and branches by the force of the surge. The wave obliterated every tree in its path, shaving the forest back to bare rock and soil along a scar that scientists could later measure precisely. The three fishing boats anchored in the bay became witnesses and victims. Two sank, taking their crews down; a third, the *Edgewateb*, rode the crest and was deposited on the opposite shore, miraculously with its two occupants alive.

This event fundamentally changed how scientists understood natural disasters. Before 1958, the largest tsunamis on record had been generated by underwater earthquakes displacing vast volumes of seawater. Lituya Bay demonstrated that a sudden rockfall or landslide into a confined body of water could produce waves dwarfing anything previously documented. The wave forced a complete re-evaluation of hazard modeling and the recognition that impact events, not just seismic displacement, posed catastrophic risk. Coastal communities worldwide had to reconsider which geological processes could spawn killer waves. Modern tsunami science owes a debt to Lituya Bay, where nature performed an inadvertent experiment in the mechanics of megawaves.