A colossal megatsunami triggered by a landslide in Alaska last summer has emerged as the second largest of its kind ever documented, underscoring the heightened risks associated with melting glaciers in a warming world. This extraordinary event, which unfolded in the remote fjords of Southeast Alaska, has prompted urgent discussions among scientists regarding the potential for future disasters in these fragile environments.
A Catastrophic Event Unfolds
In August 2025, an immense wave surged through Tracy Arm Fjord, a breathtaking yet perilous region often frequented by cruise ships. Although the event went largely unnoticed at the time, new research has unveiled that it resulted from a staggering landslide, displacing around 64 million cubic metres of rock—an amount comparable to 24 Great Pyramids—into the frigid waters below. The impact was so profound that it generated a wave estimated to reach nearly 500 metres in height.
Dr Bretwood Higman, a geologist from Alaska who witnessed the aftermath first-hand, described the scene as harrowing. “We know that there were people that were very nearly in the wrong place,” he remarked, reflecting on the narrow escape of tourists who could have been caught in the wave’s destructive path. “I’m quite terrified that we’re not going to be so lucky in the future.”
Understanding Megatsunamis
Megatsunamis are a rare phenomenon, typically instigated by a sudden landslide—often triggered by earthquakes or the destabilisation of loose rock—plunging into water bodies. Unlike traditional tsunamis, which can travel vast distances across oceans and result from seismic activity, megatsunamis are generally localised and dissipate quickly. However, their sheer magnitude can be astonishingly destructive.
The largest recorded megatsunami occurred in the 1950s, towering over 500 metres. This latest event in Alaska ranks as the second highest, raising alarms about the increasing frequency of such geological catastrophes in the region.
Climate Change and Increased Risks
Recent studies point to climate change as a significant factor exacerbating the dangers posed by these megatsunamis. Research led by Dr Stephen Hicks at University College London suggests that glacial melt, accelerated by rising global temperatures, is destabilising rock formations that were once securely held in place by ice. As the glaciers retreat, they expose cliff faces to potential collapse, significantly increasing the likelihood of landslides and subsequent megatsunamis.
Dr Hicks emphasised the dual threat facing visitors to these stunning natural landscapes. “More people are now going to remote areas — often these tourist cruises aim to showcase the beauty of the environment and educate on climate change — but they are also dangerous places to be.” With climate change driving these geological shifts, the risks to both locals and tourists are becoming alarmingly pronounced.
Calls for Increased Monitoring
In light of these developments, scientists are advocating for enhanced monitoring and risk assessment in regions of Alaska susceptible to megatsunamis. The potential for more frequent and severe geological events demands urgent attention from both researchers and policymakers. Some cruise companies have already made the decision to suspend operations in Tracy Arm, highlighting the growing concern over safety in these vulnerable areas.
Dr Higman articulated a pressing need for awareness and preparedness: “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.”
Why it Matters
The implications of this megatsunami extend beyond the immediate devastation it caused; they signal a profound shift in our understanding of geological risks in the face of climate change. As our planet warms, the melting glaciers of Alaska not only transform landscapes but also heighten the threat of catastrophic events that could endanger lives and ecosystems alike. This incident serves as a vital reminder of the urgent need to address climate change and to develop robust safety measures for those who venture into our planet’s most vulnerable regions.
