Researchers at the University of Tokyo have used a new type of radiocarbon analysis to study a sediment core taken from the Kumano Sea off the coast of Japan. This has revealed multiple "hidden" traces of previously unknown earthquakes in the Nankai Trough, where the country's next megaquake is expected to occur. Reconstructing a more accurate picture of the past will help predict future geophysical events and prepare for potential disasters. The work is published in Radiocarbon.