A powerful megatsunami that struck Southeast Alaska in August 2025 has been identified as the second largest ever recorded, highlighting critical dangers associated with melting glaciers. The event, caused by a massive landslide, unleashed a wave reaching nearly 500 metres in height, devastating a remote fjord and serving as a stark reminder of the threats posed by climate change.
The Catastrophic Event
In the early hours of a summer morning, the tranquil beauty of Tracy Arm Fjord was shattered when 64 million cubic metres of rock—equivalent to 24 Great Pyramids—plunged into the sea. This catastrophic landslide generated a colossal wave that surged through the fjord, leaving a trail of destruction that went largely unnoticed at the time.
Dr. Bretwood Higman, a geologist who surveyed the aftermath, described the scene: “Broken trees littered the mountainside, and vast areas of rock were stripped bare of soil and vegetation. It was a close call; we know that there were people who were very nearly in the wrong place.” The timing of the incident, occurring in the dark of night, spared potential tourist cruise ships from being swept into the chaos.
Understanding Megatsunamis
Megatsunamis differ from traditional tsunamis, which are typically triggered by underwater earthquakes or volcanic activity. Instead, these massive waves are generated by landslides, often in steep, narrow fjords like those found in Alaska. The last recorded megatsunami, which occurred in the 1950s, surpassed 500 metres in height, making this recent event the second highest on record.
Dr. Higman expressed his concern about the frequency of such events increasing significantly. “I’m pretty confident that these are increasing not just a little bit, but a lot—maybe ten times as frequent as they were just a few decades ago,” he stated.
Climate Change and Glacier Melting
Recent research published in the journal *Science* indicates that climate change is exacerbating the risks associated with these catastrophic landslides. The study found that melting glaciers, which previously stabilised rock formations, are now retreating, leaving cliffs vulnerable to collapse. Dr. Stephen Hicks of University College London, a co-author of the study, explained, “When the ice retreated, it exposed the bottom of the cliff face, allowing that rock material to suddenly collapse into the fjord.”
As the climate continues to warm, the implications of these findings are alarming. The growing number of tourists visiting Alaska’s breathtaking landscapes poses additional risks, as more people venture into these hazardous environments. Dr. Higman warned that despite the allure of nature, these areas can be perilous.
Industry Response and Future Monitoring
In light of the increased risk of megatsunamis, some cruise companies have begun to reconsider their routes, with announcements to halt operations in Tracy Arm due to safety concerns. This precaution underlines the urgent need for enhanced monitoring of potential hazards in Alaska, particularly as more visitors flock to witness the dramatic effects of climate change firsthand.
The scientific community is calling for a comprehensive assessment of vulnerable areas to better prepare for future megatsunamis and mitigate potential disasters.
Why it Matters
The Alaskan megatsunami serves as a potent reminder of the growing dangers posed by climate change and the urgent need for awareness and preparedness. As glaciers continue to melt and landscapes evolve, the potential for catastrophic events threatens both natural ecosystems and human safety. Understanding these risks is crucial, not only for those who seek to explore the beauty of Alaska but also for the broader global community grappling with the impacts of a changing climate.
