Distribution Of Coral Boulders Beached By Huge Tsunamis And Calibrated Radiocarbon Ages Of Fossil Porites Sp. Of Maibahbama, Se Of Miyako Island, Okinawa Prefecture

A large number of coral boulders are scattered on reef flats and along the shores of Sakishi-ma Islands, SW of Japan. Many were considered to have been cast ashore by huge tsunamis. In this report the author analyzes the distribution and calibrates the C-14 ages of coral boulders collected from Maibahbama, southeast of Miyako Island. The calibrated C-14 ages indicate a random distribution; however, some coincided exactly with the 1771 Meiwa tsunami. The tsunami travelled from the epicenter northeast and struck the Higashihenna Promontory, then turned westward leaving a large numbers of coral boulders on Maibahbama. Judging from tsunami deposits overlaying the lowest marine terrace the wave height seems not to have exceeded 10 m.