A recent geological event in Alaska has revealed the staggering power of nature and the urgent realities of climate change. A megatsunami, triggered by a significant landslide, has been classified as the second tallest ever recorded. This catastrophic wave, which surged through a remote fjord last summer, serves as a poignant reminder of the dangers posed by melting glaciers and increasingly unstable landscapes.
The Catastrophic Event Unfolded
In August 2025, a massive section of a mountain collapsed into the sea near South Sawyer Glacier, unleashing a torrent of 64 million cubic metres of rock—equivalent to the weight of 24 Great Pyramids. This immense volume of rock plummeted into the water in less than a minute, generating a wave that reached nearly 500 metres in height. Remarkably, the disaster occurred in the early hours, sparing potential casualties among tourist cruise ships that frequent the area, as highlighted by Alaskan geologist Dr Bretwood Higman.
Dr Higman, who surveyed the aftermath at Tracy Arm Fjord, described the destruction with a sense of urgency. “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,” he stated. The fjord, renowned for its dramatic cliffs and icy vistas, has now been transformed into a landscape marked by chaos and devastation.
Understanding Megatsunamis and Their Triggers
Megatsunamis are distinct from the more commonly known tsunamis that are spawned by seismic activities. These colossal waves arise from sudden, large-scale landslides—often triggered by earthquakes or the destabilisation of rock formations. Typically, megatsunamis are localised events, dissipating rapidly, unlike their oceanic counterparts that can travel vast distances, such as the 2011 tsunami in Japan.
The largest recorded megatsunami occurred in the 1950s, exceeding 500 metres in height. This latest event now stands as the second highest on record.
The Role of Climate Change
Recent research published in the journal *Science* has established a link between climate change and the heightened risk of such geological disasters. The study, led by Dr Stephen Hicks from University College London, used a combination of fieldwork, seismic data, and satellite imagery to illustrate how glacial retreat has exacerbated the instability of rock formations.
Dr Hicks explained that glaciers previously helped to anchor the rock face, and with their retreat, the underlying cliff has become increasingly vulnerable to collapse. “When the ice retreated, it exposed the bottom of the cliff face, allowing that rock material to suddenly collapse into the fjord,” he noted. As tourism in these pristine yet perilous areas grows, the risks to visitors increase substantially.
Increasing Risks and Calls for Action
The scientists involved in this research have expressed alarm at the rising frequency of such events. Dr Higman stated, “At this point, I’m pretty confident that these are increasing not just a little bit, but increasing a lot—maybe in the order of ten times as frequent as they were just a few decades ago.”
In response to the growing dangers, some cruise companies have opted to halt their operations in Tracy Arm, recognising the need for enhanced safety measures. The researchers are advocating for comprehensive monitoring systems to better understand and mitigate the risks associated with megatsunamis in Alaska.
Why it Matters
The Alaska megatsunami serves as a critical alarm bell about the increasing instability of our planet’s ecosystems as climate change accelerates. As glaciers melt, the potential for catastrophic events like this rises, posing significant threats not only to natural landscapes but also to human lives. The intersection of tourism, climate awareness, and geological hazards highlights an urgent need for proactive measures. Understanding and addressing these risks is essential for protecting both the environment and the communities that cherish these breathtaking yet treacherous locales.