Alaska megatsunami of 481 m hits Tracy Arm Fjord, second‑largest ever recorded
On 10 August 2025, a massive landslide of about 64 million m³ of rock fell 1 km into Tracy Arm Fjord in southeast Alaska. The rapid retreat of the South Sawyer Glacier, driven by climate‑change‑induced warming, removed the support that had held the rock face, triggering the collapse.
The impact generated a megatsunami that surged up the fjord walls to a run‑up height of roughly 481 m (1,578 ft), taller than the Empire State Building and the second‑largest wave ever documented after the 1958 Lituya Bay event. The wave travelled at over 70 m s⁻¹, created a 36‑hour seiche, and was recorded by seismic stations worldwide. Because the tsunami struck at 5:26 a.m. local time, no cruise ships were in the narrow head of the fjord; the one vessel present avoided the worst of the surge.
Researchers published the analysis in Science, linking the event to accelerating glacier retreat and warning that expanding cruise‑ship traffic and infrastructure in fjord regions—from Alaska to British Columbia—could face similar hazards. The study urges systematic monitoring and early‑warning systems to protect tourists, local communities, and marine traffic.
No injuries or fatalities were reported, but the incident prompted several cruise lines to suspend visits to Tracy Arm and highlighted growing climate‑related risks for coastal slopes worldwide.