A huge tsunami hit a cliff in Tonga 7000 years ago and carried a 1200-tonne boulder 200 metres inland, making it the biggest wave-lifted boulder ever found on a cliff
By James Woodford
22 May 2025
Martin Köhler stands in front of the Maka Lahi boulder in Tonga
Martin Köhler/University of Queensland
A 1200-tonne boulder in Tonga was swept inland when a 50-metre-high wave slammed into a 30-metre-tall cliff.
“This is not just a boulder; it’s the biggest wave-lifted boulder ever found on a cliff and the third largest boulder in the world, so it really needed gigantic forces to move it that far across such a high place,” says Martin Köhler at the University of Queensland in Brisbane, Australia.
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While the boulder has long been known to some locals as Maka Lahi, which means large rock, it had never before been studied by scientists.
Köhler and his colleagues were conducting fieldwork in Tonga in July 2024 looking for boulders deposited by tsunamis on cliffs. On their final day in the Pacific nation, villagers told them of a boulder they may wish to see.
“We were definitely not expecting to find such a large boulder basically during the very last minute of our fieldwork and I knew quite quickly that this was a major discovery,” says Köhler.