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A staggering geological event last summer has recently come to light, revealing that a colossal ‘megatsunami’ in Alaska was the second largest ever documented. This monumental wave, triggered by a catastrophic landslide into a remote fjord, serves as a stark reminder of the dangers associated with rapidly melting glaciers as climate change accelerates.
A Cataclysmic Landslide
In August 2025, a massive section of rock—approximately 64 million cubic metres, equivalent to 24 Great Pyramids—plunged into the frigid waters of Southeast Alaska’s Tracy Arm Fjord. The impact resulted in an extraordinary wave that reached nearly 500 metres in height, creating devastation in the serene landscape. Although the event occurred in the early hours of the morning, sparing tourist vessels from potential catastrophe, it left behind a landscape marred by destruction.
Dr Bretwood Higman, a geologist based in Alaska, conducted an on-site assessment of the damage and described it as a “close call.” He noted, “We know that there were people that were very nearly in the wrong place. I’m quite terrified that we’re not going to be so lucky in the future.”
Understanding Megatsunamis
Megatsunamis are distinct from their oceanic counterparts, typically generated by underwater earthquakes or volcanic activity. They are primarily localised phenomena, resulting from landslides into water bodies. The largest recorded megatsunami occurred in the 1950s, exceeding 500 metres, making this recent event the second most significant on record.
Dr Higman, who examined the aftermath in Tracy Arm, reported scenes of devastation: uprooted trees flung into the water and extensive areas of rock stripped bare. These geological features make Alaska particularly susceptible to such events, with its steep mountains and narrow fjords creating ideal conditions for megatsunamis.
Climate Change and Glacier Melting
Recent research published in *Science* sheds light on the role of climate change in exacerbating the risks posed by such landslides. As glaciers recede, they lose their stabilising effect on rocky cliffs, increasing the likelihood of catastrophic collapses. Dr Stephen Hicks from University College London, part of the research team, explained that the retreat of glaciers has exposed cliff faces, allowing loose rock to fall into the fjord.
Hicks and his colleagues have been studying tsunamis for years and express deep concern over the increasing frequency of these events. “More people are now going to remote areas—often these tourist cruises are aimed at experiencing the natural beauty of the region and learning about climate change—but these are also dangerous places to be,” he cautioned.
A Call for Action
Dr Higman believes the risk of megatsunamis is on the rise, potentially increasing by tenfold compared to previous decades. The need for enhanced monitoring and hazard assessment in Alaska has never been more urgent. Some cruise companies have already made the decision to cease operations in Tracy Arm, reflecting growing safety concerns among operators and tourists alike.
Why it Matters
The occurrence of this megatsunami is not merely a geological curiosity; it illustrates the profound impacts of climate change on our planet’s stability. As melting glaciers reshape our landscapes, they reveal a precarious future where natural beauty coexists with increased geological hazards. The implications for local communities and tourism are immense, urging us to confront the environmental challenges head-on and adapt to a rapidly changing world.
