A colossal megatsunami triggered by a dramatic landslide in Alaska has been identified as the second tallest wave in recorded history. Scientists warn that this event, which occurred in August 2025, underscores the escalating risks associated with climate change and melting glaciers. The disaster unfolded in a remote fjord in southeast Alaska, resulting in significant destruction that initially went unnoticed.
A Catastrophic Collapse
Last summer, a staggering 64 million cubic metres of rock—equivalent to 24 Great Pyramids—plummeted into the waters of the Tracy Arm Fjord, generating a wave that reached an astonishing height of nearly 500 metres. The event’s timing, occurring in the early hours, spared tourist vessels from the chaos, but the repercussions remain dire. Geologist Dr Bretwood Higman, who observed the aftermath firsthand, described it as “a close call.” He expressed concern for the future, stating, “I’m quite terrified that we’re not going to be so lucky in the future.”
Understanding Megatsunamis
Megatsunamis typically arise from landslides instigated by earthquakes or the collapse of unstable rock formations into bodies of water. Unlike traditional tsunamis, which can traverse vast ocean distances following seismic activity, megatsunamis are generally localised and dissipate rapidly. The largest recorded megatsunami occurred in the 1950s, towering over 500 metres, but this recent incident stands as a stark reminder of nature’s power.
Dr Higman, who examined the site several weeks post-event, reported a scene of devastation: uprooted trees littering the landscape and extensive areas of bare rock stripped of vegetation. Alaska’s unique geography, characterised by steep mountains and narrow fjords, makes it particularly susceptible to such catastrophic waves.
The Role of Climate Change
Recent research published in the journal Science sheds light on how climate change is exacerbating the risks of megatsunamis. The study reveals that retreating glaciers, driven by rising temperatures, are destabilising cliffs by removing the ice that previously held the rock formations in place. Dr Stephen Hicks from University College London explained, “The glacier was previously helping to hold up this piece of rock, and so when the ice retreated, it exposed the bottom of the cliff face, allowing that rock material to suddenly collapse into the fjord.”
The researchers’ findings are alarming. They predict that the frequency of such dangerous events may have increased tenfold compared to just a few decades ago. As more tourists venture into these stunning yet perilous landscapes to witness the impacts of climate change, the risks associated with megatsunamis become more pronounced.
Growing Safety Concerns
In light of the recent disaster, cruise companies have begun re-evaluating their itineraries, with some halting trips into the Tracy Arm Fjord due to safety concerns. Dr Higman emphasised the urgent need for comprehensive monitoring of areas in Alaska that may be vulnerable to megatsunamis.
He remarked, “At this point, I’m pretty confident that these are increasing not just a little bit, but increasing a lot.” The implications of this research are significant for both the tourism industry and the safety of those who explore Alaska’s natural beauty.
Why it Matters
The emergence of this megatsunami as the second largest on record serves as a critical warning about the escalating dangers posed by climate change. As glaciers continue to melt, the risk of catastrophic landslides and subsequent megatsunamis increases, threatening not only local ecosystems but also the safety of tourists and residents alike. The need for vigilant monitoring and preventative measures has never been more urgent, as our understanding of these natural phenomena becomes increasingly vital in an era of rapid environmental change.
