A tsunami that struck an Alaskan fjord in 2025 splashed higher than the top floor of One World Trade Center, new research confirms.
Published May 6 in the journal Science, the study found the wave reached 1,578 feet up the slopes of Tracy Arm fjord, south of Juneau. That makes it one of the tallest tsunamis ever recorded-only surpassed by a 1958 wave in Lituya Bay, Alaska.
The event began on August 10, 2025, when a massive landslide dumped 2.1 billion cubic feet of rock into the water. The fjord serves as the outlet for the rapidly retreating South Sawyer Glacier. Scientists are still debating whether glacial retreat or recent rains destabilized the slope.
No one was killed. Cruise ships had not been in the area that day. Kayakers miles away at the fjord's mouth reported strong waves washing away their equipment.
Researchers used satellite imagery and seismic data to reconstruct the tsunami. Thomas Monahan, a senior research associate at the University of Oxford, led the team. They observed long-lasting reverberations, indicating the wave sloshed back and forth as a seiche-a phenomenon previously documented in Greenland in 2023.
"This study shows that enclosed basins like fjords can effectively act as giant tuning forks," Monahan said. The satellite observations also revealed the wave was more energetic than computer models predicted.
As a result, cruise lines have canceled all trips into the fjord this year due to the risk of another slide. Study co-author Stephen Hicks, an Earth scientist at University College London, said tiny earthquakes increased in frequency hours before the landslide, raising hopes for a future early warning system.