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A landslide on Aug. 10, 2025, in Tracy Arm fjord, southeast Alaska, produced a landslide‑generated tsunami with a run‑up of about 481 metres — the second‑largest wave on record.
Researchers led by Dan Shugar at the University of Calgary reconstructed the event using satellite imagery, seismic records, eyewitness accounts and numerical modelling.
They estimate roughly 64 million cubic metres of rock plunged into the fjord in under a minute, generating a long‑period seismic signal equivalent to a magnitude‑5.4 event and a seiche that oscillated inside the fjord for about 36 hours.
The collapse followed rapid retreat and thinning of the South Sawyer Glacier, which had been buttressing the slope; investigators say debuttressing by glacier loss was a key factor.
The tsunami struck in the early morning, and no fatalities were reported, but the fjord is a frequent cruise destination and several operators have since altered itineraries.
Authors of the Science paper warn similar fjords worldwide — including parts of British Columbia, Greenland, New Zealand and Chile — may face rising risks as glaciers and permafrost continue to degrade.








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