Alaska megatsunami reaches 482 meters, second highest ever recorded

In August 2025 a massive landslide of roughly 64 million cubic metres of rock fell into Tracy Arm fjord on Alaska’s southeast coast, generating a wave almost 482 metres high. The wave, the second‑largest ever measured, struck the remote fjord in the early morning, sparing tourists and vessels that normally cruise the area.

Scientists attribute the slide to the rapid retreat of a nearby glacier, which had previously buttressed the rock mass. Dr. Stephen Hicks explained, “the glacier used to hold the rock in place; its melt allowed the huge volume of material to collapse into the water.” Researchers warn that continued glacial melt and the region’s steep terrain could increase the frequency of such megatsunamis, urging expanded monitoring of vulnerable Alaskan fjords. Several tour operators have already suspended trips to Tracy Arm for safety reasons.