Alaska’s 2025 mega tsunami highlights risk to cruise lines as glaciers retreat

A mega tsunami in Alaska last year in a fjord visited by cruise ships is a stark warning of the risks of coastal rockslides and glacier retreat fueled by the climate crisis, a new study warns. Scientists recorded the world’s second-tallest tsunami after it struck the Tracy Arm fjord in south-east Alaska last August after a massive rockslide around the toe of a glacier. The tsunami reached 481 metres (1,578ft) in height; by comparison the Eiffel Tower is 330 metres (1082ft).

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Just hours after the landslide, a sightseeing vessel from Juneau and a National Geographic tour boat – each capable of carrying more than 100 passengers, were due to enter the fjord. The day before, two cruise ships carrying thousands of passengers had already visited the area, with another scheduled to arrive the following day. At the time of the event, Dennis Staley from the US Geological Survey called the tsunami “a historic event”, adding to the Guardian: “I feel like we dodged a bullet.”

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They also noted that the tsunami was only slightly smaller than the world’s tallest, recorded in Lituya Bay, Alaska, in 1958 at 530 metres (1,728ft). The Tracy Arm event also triggered a 36-hour seiche – a standing wave that oscillates within a closed body of water. The study further found that the landslide generated long-period seismic waves equivalent to those of a 5.4 magnitude earthquake.

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In the study, researchers found that landslide-generated tsunamis can “have substantially higher runups (the maximum height water reaches on a slope) than earthquake tsunamis, owing to larger, localized variations in water depth and direct water-column displacement by slope failure – most pronounced in confined water bodies like fjords”.