Martin Köhler stands in front of the Maka Lahi boulder in Tonga
Martin Köhler/University of Queensland
A recent discovery in Tonga has unveiled a remarkable phenomenon where a massive 1200-tonne boulder was swept inland by a colossal 50-metre-high wave crashing into a 30-metre-tall cliff. This extraordinary event has astounded researchers and locals alike.
Renowned geologist, Martin Köhler from the University of Queensland in Brisbane, Australia, expressed his astonishment at the magnitude of this find. He stated, “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.”
Referred to as Maka Lahi by the locals, meaning large rock, this colossal boulder had remained undiscovered by scientists until Köhler and his team stumbled upon it during fieldwork in Tonga in July 2024. Villagers informed them of the boulder on the final day of their expedition, leading to a groundbreaking discovery.
Measuring 14 metres in length, 12 metres in width, and nearly 7 metres in height, the boulder composed of coral reef limestone breccia stood out prominently. Covered in vegetation, it had eluded previous searches for tsunami-deposited boulders, camouflaged within the natural landscape.
Further investigation revealed a massive gash in the clifftop 200 metres away, indicating the point from which the boulder was forcefully torn. Utilizing advanced computer models, the researchers determined that a wave of at least 50 metres in height with a 90-second period would have been required to displace the boulder inland.
Dating analysis estimated the age of the boulder to be 6891 years, predating human settlement on the island by thousands of years. Köhler emphasized the immense scale of this event, stating, “It was, for me, hard to believe that it was a 50-metre wave because we hadn’t really seen or known of such a large wave before. But if you think that this massive boulder is sitting 200 metres inland on a 39-metre-high cliff, then it’s easier to understand.”
Only two other tsunami-deposited boulders on land surpass the size of the Maka Lahi boulder: the Obiishi rock in Japan, weighing 3400 tonnes, and the Maui rock in Tonga, weighing 1500 tonnes. This extraordinary discovery in Tonga sheds light on the powerful forces of nature and the remarkable geological events that have shaped our planet.
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