In August 2025, a colossal megatsunami surged through a remote fjord in Southeast Alaska, triggered by a significant landslide that has since been identified as the second-largest wave of its kind ever documented. This event, which remains largely underreported, underscores the escalating risks associated with climate change and the melting of glaciers in the region. Scientists warn that such occurrences could become increasingly common as the environment continues to shift.
The Event: A Massive Geological Shift
Last summer, an estimated 64 million cubic metres of rock—equivalent to 24 Great Pyramids—plunged into the waters of Tracy Arm Fjord in under a minute, culminating in a staggering wave that reached nearly 500 metres in height. Dr. Bretwood Higman, a geologist from Alaska who assessed the aftermath, noted that the timing of the event, which occurred in the early hours, likely prevented disaster for the tourist cruise ships that frequent the area. “We know that there were people that were very nearly in the wrong place,” he cautioned, expressing concern that future incidents might not afford such fortunate timing.
The phenomenon of megatsunamis, which can occur when landslides caused by earthquakes or loose rock enter bodies of water, typically dissipates quickly and remains localised. However, they differ significantly from traditional tsunamis, which are often generated by seismic activity and can travel vast distances, wreaking havoc on populated regions.
Unprecedented Scale and Implications
The 2025 megatsunami stands as the second largest recorded, following a historic event from the 1950s that exceeded 500 metres. After the tsunami, Dr. Higman observed the devastation left behind: uprooted trees strewn across the mountainside, vast areas of rock laid bare, and the environment significantly altered. The unique geological features of Alaska, characterised by steep mountains and narrow fjords, make it particularly susceptible to such catastrophic events.
Recent research published in the journal *Science* provides insight into the contributing factors behind this disaster. A team of researchers utilised a combination of field studies, seismic readings, and satellite imagery to piece together the chain reaction that led to the wave’s formation. Dr. Stephen Hicks from University College London explained that the retreat of glaciers, which previously stabilised the rock formations, enabled the sudden collapse of the cliff face into the fjord. “The glacier was helping to hold up this piece of rock,” he stated, highlighting the critical role of glaciers in maintaining geological stability.
Increased Risk and Future Considerations
Experts are increasingly alarmed by the implications of climate change on the frequency and scale of megatsunamis. Dr. Higman expressed his conviction that the incidence of these events has surged significantly, estimating a tenfold increase compared to previous decades. This trend is particularly concerning as more tourists venture into remote Alaskan landscapes, drawn by the beauty of the glaciers and the natural environment, yet simultaneously placing themselves at risk.
In response to the growing hazard, some cruise companies have opted to halt operations in Tracy Arm, prioritising passenger safety. The call for enhanced monitoring of vulnerable areas in Alaska is urgent, as scientists advocate for a proactive approach to understanding and mitigating the risks posed by these geological phenomena.
Why it Matters
The Alaskan megatsunami serves as a stark warning about the interconnectedness of climate change, geological instability, and human activity. As glaciers continue to recede, the potential for catastrophic events increases, posing significant threats not only to the natural environment but also to human life and infrastructure. Understanding and addressing these risks is imperative for safeguarding both the fragile ecosystems of Alaska and the safety of those who seek to experience its breathtaking landscapes.