The highest recorded tsunami run-up from the 2011 Tohoku earthquake was 40.5 meters. It was measured at Miyako in Iwate Prefecture on Japan’s northeastern coast, where the tsunami climbed far above ordinary sea level as it moved inland.
“Run-up height” means the maximum vertical elevation reached by tsunami water on land, measured relative to the sea level at the time of the event. It is different from wave height measured offshore or at the shoreline, so reports can contain several different numbers without contradicting one another. Local geography, coastal shape, river channels and hills can funnel and amplify tsunami flow.
The earthquake struck offshore on 11 March 2011 at 14:46 Japan Standard Time. Its enormous seafloor displacement generated waves that inundated large parts of the Tohoku coast, destroying towns and causing most of the disaster’s deaths. Some popular summaries round the maximum run-up to roughly 40 meters, but 40.5 meters is the specific figure commonly cited for the Miyako measurement. The 2011 event also produced a Pacific-wide tsunami.