A colossal megatsunami triggered by a landslide in Alaska’s Tracy Arm Fjord has emerged as the second highest wave ever recorded, underscoring the urgent threats posed by climate change and glacial retreat. The incident, which occurred last summer yet remained largely underreported, has now come into focus through a detailed scientific investigation revealing the dramatic forces at play.
A Catastrophic Collapse
In August 2025, approximately 64 million cubic metres of rock—equivalent to the mass of 24 Great Pyramids—plummeted into the fjord. This dramatic landslide generated a wave reaching an astonishing height of nearly 500 metres. The timing of the event, occurring in the early hours, fortunately spared tourist vessels from being caught in the aftermath, but it raises significant concerns about future safety in the region.
Dr. Bretwood Higman, an Alaskan geologist who assessed the destruction first-hand, described the situation as “a close call,” highlighting the precariousness of the environment. “We know that there were people that were very nearly in the wrong place,” he noted, expressing his fears about potential future incidents.
Understanding Megatsunamis
Megatsunamis are distinct from traditional tsunamis, which are typically generated by seismic activity beneath the ocean. Instead, megatsunamis occur when large volumes of rock, often triggered by landslides, plunge into water bodies, creating massive waves that dissipate quickly and remain localised. Historical data indicates that the largest megatsunami on record, which occurred in the 1950s, surpassed 500 metres in height, making this latest event a significant point of concern for scientists monitoring geological activity in the region.
The Tracy Arm Fjord, renowned for its dramatic cliffs and glacial landscapes, is particularly susceptible to these phenomena due to its geological characteristics and frequent seismic activity.
The Role of Climate Change
Recent research published in *Science* highlights the correlation between climate change and the increasing frequency of such geological events. As glaciers retreat due to rising global temperatures, the stability of cliff faces is compromised. Dr. Stephen Hicks from University College London noted that glaciers previously helped support the rock formations; their retreat exposes these structures, leading to potential collapses into the fjord below.
The implications are alarming. Dr. Hicks, who has dedicated decades to studying tsunamis, emphasises that the risk of megatsunamis is escalating. “At this point, I’m pretty confident that these are increasing not just a little bit, but increasing a lot,” he stated, suggesting a tenfold rise in frequency over recent decades.
Monitoring and Safety Concerns
In light of these findings, there is an urgent call for enhanced monitoring of potential hazards across Alaska, particularly in areas vulnerable to megatsunamis. Some cruise lines have already announced they will cease operations in Tracy Arm amidst mounting safety concerns, reflecting a growing awareness of the dangers posed by these natural events.
The recent megatsunami serves as a stark reminder of the intricate relationship between climate change and geological stability. With more tourists venturing into these remote areas to witness the beauty of nature—often with a focus on understanding climate change—there is an imminent need to balance exploration with safety.
Why it Matters
The occurrence of this megatsunami is not merely a geological curiosity; it is a clarion call for immediate action in addressing the effects of climate change. As glacial melting accelerates, the risks associated with megatsunamis are likely to rise, endangering both lives and natural ecosystems. Understanding these dynamics is critical for developing effective monitoring systems and safety protocols, ensuring that we can protect both the natural wonders of Alaska and those who seek to experience them.
