A wave taller than London’s The Shard or the Empire State Building devastating everything in its path sounds like the plot of a scientifically-questionable Hollywood disaster film. But this happened last summer, in a real fjord visited by thousands of tourists.
The second highest tsunami ever struck Tracy Arm Fjord, Alaska, in August 2025 with a runup as high as 481-metres. This wave, triggered by a major landslide preconditioned by glacier retreat, is explored in a new research paper co-authored by Dr Maximillian Van Wyk De Vries, Assistant Professor at Cambridge’s Departments of Earth Sciences and Geography.
Dr Van Wyk de Vries said: “The fact that this did not become a major disaster was largely a matter of luck and timing. The landslide happened early in the morning, before most vessels had travelled far into the fjord. Had the same event occurred later in the day, the consequences could have been substantially worse.”
The paper, published in Science, focuses on a fjord visited by three cruise ships and scores of smaller vessels daily over the summer season. The landslide struck at 5:26am on 10 August 2025, when that traffic had yet to enter the fjord. Kayakers camped 55km away woke 20 minutes later to water rushing through their camp, carrying away a kayak and much of their gear. The wave quickly dissipated as it left the fjord, leaving a major scar on the surrounding landscape but fortunately very little damage and no deaths.
“This is the type of event that sounds almost unreal, but it happened in a real fjord that people visit every day in summer,” Van Wyk de Vries said. “The difficult question is how to manage exposure in places where rare but extreme events can happen with very little warning.”
The study found that the landslide was preceded by several days of small seismic events, identified retrospectively. However, the authors stress that short-term prediction remains extremely challenging.
“’Predictable’ is a difficult concept,” Van Wyk de Vries said. “We may be able to identify some slopes or fjords where the risk is higher, but knowing exactly when a large landslide will occur is much harder. That matters because these cascades can unfold in minutes.”
The paper highlights the importance of monitoring unstable slopes, modelling realistic tsunami scenarios, and considering how tourism and vessel traffic should operate in fjords where landslide-tsunamis are possible.
Van Wyk de Vries said: “We cannot remove all risk from these environments, and we cannot engineer our way out of a landslide this large. But we can improve how we identify unstable slopes, understand possible tsunami impacts, and make decisions about access and exposure.”
The event also raises wider questions about the role of climate change in altering hazard landscapes. In Tracy Arm, rapid glacier retreat helped expose and debuttress the slope before failure.
“Climate warming is changing glacierised mountain and polar environments,” Dr Van Wyk de Vries said. “In places like Tracy Arm, glacier retreat can change whether a landslide falls onto ice or into water. That can be the difference between a landslide and a landslide-generated tsunami.”
He added: “A core part of my research is understanding multi-hazards, where one process triggers or amplifies another. If we study landslides, floods and tsunamis separately, we can miss large parts of the risk.”
Similar cascading hazards have caused major disasters elsewhere. In north-east India in 2023, a landslide into a glacial lake generated a flood that travelled more than 200 km downstream, killing 55 people and destroying major infrastructure, including a hydropower dam. In this earlier study, Van Wyk de Vries, PhD student Louie Bell and colleagues were able to identify clear movement on the slope preceding the collapse, something which was not possible at Tracy Arm.
The Tracy Arm event did not cause fatalities, but researchers argue that it should be treated as a warning.
“Historically, many lessons have been learned only after disasters,” said Van Wyk de Vries (pictured below). “This was different: it was a near-miss and studying it now can help make the risk visible before a future event causes loss of life.”
A number of cruise companies have stopped travelling into Tracy Arm and are using other fjords instead. But Van Wyk de Vries said this does not necessarily mean the risk has been removed.
“Moving vessels to another fjord may reduce overall risk, but we don’t currently have a comprehensive understanding of which areas are safe,” he said. “That is why studies like this matter. They help us ask not just what happened here, but where similar risks might exist elsewhere.”
Dr Maximillian Van Wyk De Vries is a Gonville & Caius College Fellow and director of the Cambridge Complex and Multihazard Research Group (CoMHaz). Read the original story, published by Gonville & Caius College here.
The full paper, A 481 m-high landslide-tsunami in a cruise ship-frequented Alaska fjord, is available at: https://www.science.org/doi/10.1126/science.aec3187
Main image, credit: Bill Billmeier