May 6 - Tracy Arm Fjord, in southeastern Alaska within the Tongass National Forest, presents a majestic vista, with a narrow sea inlet surrounded by towering granite cliffs, waterfalls and glaciers. One morning last year it also was the site of a powerful landslide that triggered a huge localized tsunami.

Researchers have now determined that the tsunami on August 10, 2025, was the second-highest ever recorded, with a wave reaching up to 1,578 feet (481 meters) tall - higher than New York City's Empire State Building. The tsunami surged through the fjord, violently stripping vegetation from the steep rock walls.

The fjord has been a popular sightseeing destination, but because the tsunami occurred at 5:30 a.m., there were no cruise ships or other boats in the waterway and no one was hurt.

The researchers said the landslide was driven by climate change. The glacier buttressing the mountain had retreated amid warming temperatures, eventually leaving the rock unsupported.

"The fact that the landslide occurred this early in the morning was unbelievably lucky. Next time - and there will be a next time - we may not be so lucky," said University of Calgary geomorphologist Dan Shugar, lead author of the study published on Wednesday in the journal Science.

Such locations have been at the forefront of climate change impacts.

There were no photographs or video recordings of the tsunami, so the scientists reconstructed the events using aerial photos taken afterward, satellite and seismic data, fieldwork at the site and accounts of people who were nearby at the time.

Tracy Arm, about 50 miles (80 km) south of Alaska's capital Juneau, is roughly 25 miles (40 km) long and six-tenths of a mile (1 km) wide, with surrounding cliffs more than 3,280 feet (1,000 meters) high. The researchers determined the wave height by measuring where the stripping of vegetation had occurred, leaving dramatic scars on the rock walls. The wave rose so high because the immense volume of water displaced by rock from the landslide was squeezed through a confined space.

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