Tephrostratigraphical interpretation of historical eruptions proved by historic sites and historical sources and reconstruction of paleoenvironment

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In this study, we conducted the drilling survey in order to investigate the tephrostratigraphy of historical eruptions proved by different archaeological sites and historical documents (or sources) in Japan and to reconstruct the paleoenvironment. In the case of volcanoes in the Izu Islands, it has been confirmed that the volcanic products from Niijima, Miyatsukayama, Kozushima and Tenjosan are distributed in south Kantou and Tokai area, based on the result of mineral analysis, refractive index measurement and elemental analysis of tephra (using X-ray Fluorescence Spectrometer). In the central to northern part of Kyusyu, we conducted the field survey on the area around Kujusan in order to understand the stratigraphy of tephra and to determine the age. In the southern part of Kyusyu, we identified and correlated the tephra from both Sakurajima and Kikai caldera, which is now distributed around Kokubu lowland in the north of Kagoshima bay, in order to reconstruct the paleoenvironment of the lowland. This study really contributed to better understanding of stratigraphic relationship between the tephra and the archaeological sites or artifacts throughout Japan and also advanced the clarification of historical eruptions recorded in the ancient documents. The result of this study was presented by oral presentation or poster session in several related academic conferences in addition to the publication of paper in some scientific journals.