A recent geological event in Alaska has unveiled a staggering megatsunami, recorded as the second highest wave of its kind in history. Triggered by a landslide in August 2025, this colossal wave serves as a stark reminder of the destructive potential posed by melting glaciers and the associated geological instability, according to scientists.
A Colossal Geological Event
In a relatively remote fjord in southeast Alaska, an extraordinary wave surged into the waters, leaving devastation in its wake. Although the incident went largely unnoticed at the time, a comprehensive analysis has since revealed that a landslide involving approximately 64 million cubic metres of rock—equivalent to 24 Great Pyramids—plunged into the fjord. This immense volume of rock generated a wave that reached nearly 500 metres in height. Fortunately, the timing of this event during the early hours of the morning spared nearby tourist cruise ships from potential disaster, as noted by researchers involved in the study.
Dr Bretwood Higman, an Alaskan geologist who witnessed the aftermath at Tracy Arm Fjord, described the situation as a “close call.” He expressed his fears that future occurrences may not be as fortunate, stating, “We know that there were people that were very nearly in the wrong place.”
Understanding Megatsunamis
Megatsunamis are distinct from traditional tsunamis, which are primarily triggered by seismic activities in the open ocean. Instead, megatsunamis result from massive landslides—often instigated by earthquakes or the destabilisation of loose rock—that create large waves in localized areas. These waves generally dissipate quickly but can cause catastrophic damage near their source.
The largest recorded megatsunami occurred in the 1950s, exceeding 500 metres in height, making this latest event the second largest documented to date.
The Role of Climate Change
Recent research published in the journal *Science* suggests that climate change is exacerbating the potential for megatsunamis in Alaska. The study highlights how melting glaciers, driven by rising temperatures, are destabilising rock formations. Dr Stephen Hicks, a researcher from University College London, noted that glaciers previously helped to support these rock formations. As the ice retreats, it exposes cliff faces, leading to sudden collapses into the fjord below.
Dr Hicks and his team, who have devoted decades to studying tsunamis, are increasingly concerned. “More people are now going to remote areas—often on tourist cruises aimed at showcasing the natural beauty of the region and educating about climate change—but these locations can be perilous,” he remarked.
Rising Risks and Safety Concerns
Dr Higman has voiced strong concerns regarding the increasing frequency of megatsunamis, asserting, “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 10 times as frequent as they were just a few decades ago.” This alarming prediction underscores the need for enhanced monitoring and assessment of potential hazards in vulnerable areas of Alaska.
In response to these growing safety concerns, several cruise companies have announced plans to cease operations in Tracy Arm, prioritising the safety of their passengers.
Why it Matters
The implications of this megatsunami are profound. As climate change accelerates the melting of glaciers, the risk of geological instability and devastating waves in remote regions is escalating. This situation poses not only a threat to the environment but also to human life, particularly as tourism in these fragile areas increases. Understanding and addressing these risks is crucial for safeguarding both local communities and visitors drawn to the stunning yet perilous landscapes of Alaska.