A colossal wave generated by a landslide in Alaska last summer has been identified as the second highest megatsunami ever recorded. This natural disaster, which occurred in the remote Tracy Arm Fjord, is not only a striking reminder of the power of nature but also highlights the escalating dangers posed by climate change, particularly the rapid melting of glaciers.
The Catastrophic Event
In August 2025, a staggering 64 million cubic metres of rock, equivalent to 24 Great Pyramids, plummeted into the waters of Southeast Alaska. This massive landslide created a wave that reached nearly 500 metres in height, wreaking havoc in its vicinity. The event, which unfolded in the early hours, fortunately spared tourist vessels that often traverse these waters, a fact noted by Dr Bretwood Higman, a geologist who witnessed the aftermath firsthand. “It was a close call,” he remarked, expressing concern for future tourists who might not be so fortunate.
The sheer scale of the disaster, which has only come to light following detailed scientific analysis, underscores the potential for extensive destruction in these remote areas. Dr Higman reported seeing uprooted trees and large sections of rock stripped bare of soil and vegetation, painting a stark picture of the event’s impact.
Understanding Megatsunamis
Megatsunamis differ from traditional tsunamis, which are typically triggered by seismic activity in the ocean. Instead, these giant waves arise from landslides, either initiated by earthquakes or the destabilisation of rocky cliffs. While megatsunamis usually have a more localised impact, their sheer power can be catastrophic within the confines of narrow fjords like those found in Alaska.
The largest recorded megatsunami occurred in the 1950s and exceeded 500 metres in height. The recent event represents the second highest, raising alarm about the frequency of such occurrences as conditions change in response to climate dynamics.
The Role of Climate Change
Recent studies, notably those led by Dr Stephen Hicks from University College London, suggest that glacial retreat, exacerbated by climate change, is contributing to the increasing frequency of these landslides. As glaciers recede, they no longer provide the structural support needed to stabilise rocky cliffs. This loss of support can lead to sudden collapses into the fjord below, as was the case last summer.
Dr Hicks warned that as more visitors flock to these remote regions—drawn by the allure of nature and a desire to understand climate change—the risks associated with megatsunamis are becoming more pronounced. “More people are now going to remote areas—often these tourist cruises are set up to see the natural beauty of the region, but they also present significant risks,” he stated.
Increased Monitoring Needed
The scientific community is now calling for enhanced monitoring of regions in Alaska that could be vulnerable to these catastrophic events. Dr Higman emphasised the urgency of this need, stating, “I’m pretty confident that these events are not just increasing a little bit, but a lot. Perhaps ten times as frequently as they were just a few decades ago.”
In response to these escalating dangers, some cruise companies have begun to reroute their vessels away from areas like Tracy Arm, prioritising passenger safety over the allure of stunning glacial vistas.
Why it Matters
The alarming revelation of the second largest megatsunami on record serves as a critical reminder of the intersection between climate change and geological instability. As glaciers continue to melt at unprecedented rates, the potential for devastating landslides increases, posing significant risks not only to local ecosystems but also to the safety of tourists and communities in these breathtaking yet perilous environments. This event underscores the urgent need for proactive measures to monitor and mitigate the threats posed by a changing climate, as well as the importance of raising awareness among the public about the inherent dangers of these beautiful but volatile landscapes.
