Huge tsunami in popular area for Alaskan cruises provides lessons in steep, mountainous terrain

Calgary, AB - A massive tsunami that ran 481 meters - two-and-a-half times the height of the Calgary Tower - up the wall of a fjord in a popular spot for Alaskan cruises provides valuable lessons for anyone who spends time in steep, mountainous terrain, new research shows.

The 'near-miss' tsunami in Tracy Arm fjord, 80 kilometres south of Juneau, Alaska, was the second highest one ever recorded. Despite its size, no one was caught in the wave that hit around 5:30 a.m. on Aug. 10, 2025.

The study, which will be published on May 6 in the prestigious journal Science, was conducted by a team of international researchers at multiple institutions - including two scientists from the University of Calgary.

"We reconstructed the event from a suite of perspectives, including eyewitness accounts from a variety of ship passengers and kayakers."

Dr. Dan Shugar, PhD, associate professor in the Department of Earth, Energy, and Environment

A group of kayakers reported waking at 5:45 a.m. to see water flowing past their tent, carrying away one of their kayaks and much of their gear. Another observer described a two-metre wave coming along the beach, while those on a cruise ship anchored near the mouth of the fjord saw currents and white water, but no obvious wave.

The researchers, including a UCalgary postdoctoral scholar, also studied satellite data before and after the event, seismic data, and did numerical modelling to understand exactly what happened.

"Climate change is not just warming the air. It is physically moving mountains."

Dr. Aram Fathian, PhD, postdoctoral researcher in Earth, Energy, and Environment

Shugar, lead author of the study, adds there wasn't much warning before the landslide hit.

"They often give some sort of warning signs in the weeks, months, years prior when the slope is slowly moving down the mountain," he said. "It's sagging and then it catastrophically gives way in a rock avalanche. In this case, that didn't happen."

Shugar says the unexpected event presents some challenges when it comes to disaster reduction in high-risk areas.
He adds that it's important for the cruise ship industry and other stakeholders to pay close attention, particularly in areas on the West Coast and in polar regions where glaciers are thinning due to the changing climate.

Media inquiries
Colette Derworiz
Lead, Media and Communications, Faculty of Science
403-815-1556
[email protected]

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