Alaska glacier collapse triggers one of tallest tsunamis ever recorded

A massive landslide in a remote Alaskan fjord last year triggered a tsunami nearly 500 metres high, making it the second-tallest tsunami ever recorded and raising concerns over the growing risks linked to glacial melting.

The incident occurred in August 2025 in Tracy Arm fjord in southeast Alaska, when around 64 million cubic metres of rock collapsed from a mountainside into the water.

Scientists said the collapse generated a wave measuring 481 metres, higher than the Eiffel Tower, with the entire event unfolding within about a minute.

Research published in the journal Science stated that the landslide was triggered by the rapid retreat of South Sawyer Glacier, which had previously supported the unstable rock formation.

According to Stephen Hicks, the glacier’s withdrawal weakened the mountainside, eventually leading to the collapse into the fjord.

No injuries were reported, though researchers described the incident as a close call after a sightseeing vessel and a National Geographic tour boat carrying more than 100 passengers entered the area hours later.

Scientists warned that climate-driven glacier melt is increasing the likelihood of landslides and tsunami events in mountainous coastal regions.

The study also highlighted rising cruise activity in Alaska, with passenger numbers increasing from around one million in 2016 to an estimated 1.6 million in 2025.

Some cruise operators have since announced plans to stop taking ships into Tracy Arm following the incident.