In a remarkable geological event that unfolded last summer, a colossal megatsunami struck a remote fjord in Southeast Alaska, emerging as the second tallest wave ever documented. This devastating incident, triggered by a massive landslide, serves as a stark reminder of the mounting dangers associated with melting glaciers in the region, according to a recent scientific analysis.
A Hidden Catastrophe
During the early hours of the morning in August 2025, a staggering 64 million cubic metres of rock—equivalent to 24 Great Pyramids—plummeted into the waters below, generating a monstrous wave that reached nearly 500 metres in height. The fjord, known as Tracy Arm, is a popular destination for cruise ships drawn to its breathtaking vistas, but this event went largely unnoticed at the time. Researchers now believe that had the tsunami occurred later in the day, the consequences could have been catastrophic for unsuspecting tourists.
Dr Bretwood Higman, a geologist based in Alaska, described the scene he encountered weeks after the disaster. “It was a close call,” he remarked, noting the significant debris scattered across the mountainside and the water’s surface. “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.”
Understanding Megatsunamis
Megatsunamis are generated when a landslide—often triggered by earthquakes or the destabilisation of rock—plunges into a body of water. Unlike traditional tsunamis, which can travel vast distances across oceans due to seismic activity, megatsunamis are typically localised events that dissipate quickly. The largest recorded megatsunami occurred in the 1950s, reaching heights in excess of 500 metres.
Dr Higman, who witnessed the aftermath in Tracy Arm, found the landscape transformed. Trees were uprooted and strewn about, while vast areas of rock were stripped bare, revealing the potent force of the wave. Alaska’s distinctive geography, characterised by steep mountains and narrow fjords, makes it particularly susceptible to such phenomena.
The Climate Connection
Recent research published in the journal Science underscores the growing frequency of these dangerous events, attributing their escalation to climate change. As glaciers melt, they lose the stabilising effect they once had on surrounding rock formations. Dr Stephen Hicks, from University College London, explained how the retreat of glaciers exposes cliff faces, thereby increasing the likelihood of rockfalls into the fjord below.
“More people are now going to remote areas—often these tourist cruises are going to see the natural beauty of the area to actually learn more about climate change—but they are also dangerous places to be,” Dr Hicks cautioned. The researchers warn that the number of megatsunami events has potentially increased tenfold over the past few decades, raising significant safety concerns.
Calls for Monitoring and Safety Measures
In light of the heightened risks, scientists are advocating for enhanced monitoring of areas in Alaska that may be vulnerable to megatsunami activity. Some cruise companies have already announced they will cease operations in Tracy Arm due to safety fears, reflecting a growing awareness of the potential dangers posed by these natural disasters.
Dr Higman noted that the urgency for preventive measures cannot be overstated. “At this point, I’m pretty confident that these are increasing not just a little bit, but increasing a lot,” he said, pointing to the need for comprehensive hazard assessments in the region.
Why it Matters
The unprecedented megatsunami serves as a critical warning about the intertwining threats of climate change and geological instability. As tourists flock to witness the stunning beauty of Alaska’s fjords, the potential for disaster looms large. This event not only highlights the geological risks inherent in these remote landscapes but also underscores the urgent need for proactive safety measures and monitoring to protect both visitors and the fragile ecosystems they seek to explore. The implications of such natural phenomena are far-reaching, reminding us that the impacts of climate change extend beyond environmental degradation to encompass human safety and security.
