A recent analysis has revealed that an extraordinary megatsunami triggered by a landslide in Alaska is the second tallest ever documented, underscoring the escalating risks associated with climate change and melting glaciers. This event, which occurred in August 2025, unleashed a colossal wave that left devastation in a remote fjord, highlighting the urgent need for enhanced monitoring and awareness in vulnerable regions.
The Cataclysmic Event
In August 2025, a substantial section of a mountain in southeast Alaska collapsed into the sea, generating a wave that reached nearly 500 metres in height. This staggering phenomenon, termed a ‘megatsunami,’ resulted from a landslide involving approximately 64 million cubic metres of rock—roughly equivalent to the mass of 24 Great Pyramids. The incident took place in the early morning hours, a fortunate timing that spared numerous tourist cruise ships from potential disaster, according to Dr. Bretwood Higman, a geologist who surveyed the aftermath in Tracy Arm Fjord.
Dr. Higman described the situation as “a close call,” noting that had it occurred later in the day, the consequences could have been catastrophic. “We know that there were people that were very nearly in the wrong place,” he remarked, expressing concern over future occurrences.
Understanding Megatsunamis
Megatsunamis, which are distinct from traditional tsunamis, are typically localised events caused by landslides—often triggered by earthquakes or rockfalls—plunging into water bodies. Unlike oceanic tsunamis, which can travel vast distances following seismic activity, megatsunamis dissipate relatively quickly and pose immediate threats to coastal areas.
Historically, the largest megatsunami recorded occurred in the 1950s, exceeding 500 metres in height. This recent event ranks as the second highest, indicating a worrying trend in the frequency and scale of such occurrences.
The Role of Climate Change
Recent research published in the journal *Science* indicates that climate change-induced glacier melt is exacerbating the conditions leading to these landslides. As glaciers recede, they no longer provide the necessary support to the rock faces that previously relied on their mass. Dr. Stephen Hicks from University College London explained that the retreat of ice exposes cliff bases, allowing rock to suddenly collapse into the fjord below.
The implications of this are dire. As more individuals venture into Alaska’s remote areas—often through tourism focused on appreciating natural beauty and understanding climate impacts—the risks associated with megatsunamis increase significantly. Dr. Higman cautioned that the incidence of these events could be escalating dramatically, potentially becoming ten times more frequent than just a few decades ago.
Implications for Tourism and Safety
In light of the heightened risks, several cruise lines have decided to cease operations in Tracy Arm due to safety concerns. The potential for future megatsunamis necessitates a reevaluation of safety protocols and monitoring systems in regions prone to such geological phenomena. This change in approach will be vital for both protecting human life and preserving the integrity of Alaska’s unique natural landscapes.
Why it Matters
The recent megatsunami event serves as a critical reminder of the profound impact of climate change on geological stability and natural hazards. As glaciers continue to melt, the likelihood of catastrophic landslides and megatsunamis rises, posing significant threats not only to local ecosystems but also to human life and infrastructure in remote areas. The urgency for comprehensive monitoring and safety measures cannot be overstated; proactive steps are essential to safeguard both the environment and the increasing number of visitors drawn to Alaska’s breathtaking vistas.
