In an unprecedented event last year, a monumental tsunami struck the breathtaking Tracy Arm Fjord in southeastern Alaska, reaching an astounding height of 1,578 feet (481 metres). This natural disaster, triggered by a massive landslide attributed to climate change, has been confirmed as the second-largest tsunami ever recorded. On 10 August 2025, the wave surged through the fjord, forcefully stripping vegetation from its towering rock walls, leaving a stark reminder of the environmental shifts occurring in our world.
The Catastrophic Landslide
The landslide, which occurred in the early hours of the morning at 5.30 am, sent a staggering volume of rock crashing into the fjord, displacing approximately 83 million cubic yards (64 million cubic metres) of material in just one minute. This colossal collapse was equivalent to 24 times the volume of the Great Pyramid of Giza. Researchers established that the glacier, which had provided crucial support to the mountain, had significantly retreated due to rising global temperatures, ultimately destabilising the rock face.
Dan Shugar, a geomorphologist at the University of Calgary and lead author of the study recently published in *Science*, expressed relief that no cruise ships or vessels were present at the time. “The fact that the landslide occurred this early in the morning was unbelievably lucky. Next time – and there will be a next time – we may not be so lucky,” he cautioned, highlighting the potential dangers posed by such events.
Unraveling the Tsunami’s Scale
Without photographic or video evidence, scientists employed a range of data, including aerial photographs, satellite imagery, seismic readings, and witness accounts, to reconstruct the tsunami’s impact. Tracy Arm, located about 50 miles (80 km) south of Juneau, is renowned for its dramatic cliffs, glaciers, and waterfalls. The researchers determined the wave’s height by analysing the vegetation stripped from the rock walls, which now display stark scars contrasting with the untouched forest above.
“The clearcut vegetation, like a bathtub ring around the fjord, is probably the most striking difference in how the fjord looks now versus last year,” Shugar noted. The line between the stripped rock and the remaining forest serves as a visual testament to the tsunami’s ferocity.
Seismic Signals and Future Warnings
The landslide did not just cause immediate devastation; it also triggered seismic waves that were recorded globally. Stephen Hicks, a geophysicist from University College London and co-author of the study, explained that the event led to a phenomenon known as a seiche, where water sloshed back and forth in the fjord for several days. This event is reminiscent of a similar landslide-generated tsunami in Greenland’s Dickson Fjord, which produced a wave approximately 650 feet (200 metres) tall.
Interestingly, seismic data indicated that small earthquakes had preceded the landslide by about a week, suggesting a potential for developing warning systems in the future. “With the benefit of hindsight, we have found that the landslide was preceded by tiny earthquakes indicating fracturing in the eventual landslide mass. This gives us possible hope of developing warning and forecasting systems, in tandem with other observations,” Hicks remarked.
A Broader Context of Tsunamis
Tsunamis, typically associated with underwater earthquakes or volcanic eruptions, can also be generated by landslides. The record for the tallest tsunami remains with the 1958 event in Lituya Bay, Alaska, which reached approximately 1,700 feet (520 metres). Unlike tsunamis generated by seismic activity, those caused by landslides are the result of material collapsing into the water, creating a powerful wave.
The implications of such natural disasters extend far beyond immediate destruction. Historically, tsunamis have caused catastrophic loss of life and property. For instance, the 2004 Indian Ocean tsunami claimed around 230,000 lives and reached a height of 167 feet (51 metres) in Sumatra. Similarly, the 2011 tsunami in Japan resulted in over 15,000 fatalities and reached heights of approximately 131 feet (40 metres).
Why it Matters
This colossal tsunami serves as a stark wake-up call regarding the profound impacts of climate change on our planet. As glaciers retreat and the stability of our landscapes is threatened, the frequency and intensity of such disasters are set to increase. The Tracy Arm event underscores the urgent necessity for enhanced monitoring and forecasting systems to protect coastal communities from future calamities. As we confront the realities of a changing climate, it becomes imperative to recognise the interconnectedness of our actions and the natural world, fostering a collective responsibility to mitigate the repercussions of our evolving environment.
