Shirasu-Daichi

A major three phase eruption of the Aira Caldera formed in the first phase the Osumi pumice fall, had a second phase Tsumaya pyroclastic flow and in the third Ito eruption phase produced the widely distributed Aira-Tn tephra that has been dated at 29,428 to 30,148 years calibrated before present.^[4][5] The Aira-Tn tephra falls from this eruption were up to 0.800 m (2 ft 7.5 in) thick extending to significant depth that would have affected plant life in south eastern South Korea and Honshu.^[1] This and Ito Ignimbrite up to 160 m (520 ft) thick, are the most significant pyroclastic deposits of the plateau.^[6] However an eruption about 11,000 years before present did result in the Satsuma pumice fall^[3] and there have been multiple relatively minor ash falls since from the local active volcanoes.