Overview

• The Maka Lahi boulder, weighing 1,200 tonnes and measuring 14 x 12 x 6.7 meters, is the largest known cliff-top boulder globally.
• Discovered on Tongatapu, Tonga, the boulder was moved 200 meters inland and 30 meters uphill by a tsunami during the Holocene epoch around 7,000 years ago.
• Numerical modeling revealed that a 50-meter-high wave lasting 90 seconds with speeds over 22 meters per second was required to dislodge and transport the boulder.
• Researchers traced the boulder’s origin to a coastal cliff, with the study offering new constraints for tsunami hazard assessments in vulnerable coastal regions.
• The discovery, guided by local farmers and published in the May 2025 issue of Marine Geology, underscores the value of integrating local knowledge into scientific research.