Biggest Wave Lifted a 1200-Tonne Boulder to a Cliff Top 7000 Years Ago, the Third Largest Boulder in the World

In the remote island nation of Tonga, where the Pacific Ocean meets huge cliffs, the coastline has been a witness to ancient power. Humongous rocks lying in places where they should not be in the first place pose questions about the whereabouts of these rocks. One such incident has shaken the scientific community. A huge boulder is seen on top of a cliff and is surrounded by dense forest. For years, it sat unbothered and unnoticed, even by satellite imaging. That is, until July 2024. On the final day of a field survey in Tongatapu, Tonga’s largest island, a group of geologists stumbled upon what would prove to be the largest cliff-top boulder ever transported by a wave, as per Science Direct.

Locals had always known it as Maka Lahi (large rock), but experts quickly realized it was much more. Martin Köhler, a PhD student from the University of Queensland, remarked, “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,” as per New Scientist. Intriguingly, it measured an astonishing 14 meters long, 12 meters wide, and nearly 7 meters tall, somewhat the size of a two-storey mansion. Maka Lahi weighs in at roughly 1,180 tons. What is extraordinary is not just its size but its current location, 200 meters inland and 39 meters above sea level, above a cliff that should have protected it from all but the most epic of oceanic events.

Köhler and his team conducted extreme modeling to figure out how this monster rock ended up where it did. The results were stunning; the boulder would have required a tsunami wave at least 50 meters high, lasting 90 seconds, with flow speeds exceeding 22 meters per second, to launch it inland from its original position on the cliff edge. Köhler shared, “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,” as per New Scientist. Moreover, geological dating revealed that the boulder was moved approximately 6,891 years ago.

It is believed the wave was most likely triggered by a nearby underwater landslide or a volcanic flank collapse, though the exact origin is still not unraveled. The cliff edge from which Maka Lahi was torn still bears a huge gash. In a statement, Köhler remarked, “It was late in the day, and we were talking to some farmers when they directed us to this boulder… I was so surprised; it is located far inland outside of our fieldwork area and must have been carried by a very big tsunami. It was quite unbelievable to see this big piece of rock sitting there covered in and surrounded by vegetation,” according to IFL Science.

Another important point to note is that only two other boulders transported by tsunamis surpass Maka Lahi in size: Japan’s Obiishi rock and Maui Rock, also in Tonga, but both were moved from far lower elevations, making Maka Lahi the OG in terms of tsunami power, as per IFL Science.