Abstract
A brief history of my research over the past 50 years is presented in this paper. The first and most basic concept behind my research is the exploration of recent events for the purpose of understanding the present and near future environments of the earth surface. After studying recent developments in mountain slopes and valleys based on correlations between geomorphology and historical documents for each event, I had the chance to observe a conspicuous tephra derived from Fuji volcano and some artifacts of prehistoric age below the tephra. This experience gave me the idea that tephra shows the strict datum plane for a wide occurrence area and has a high capability of recovering many events in the past, if we have excellent techniques to promote fingerprinting and dating of tephra. Tephra stratigraphy and chronology of Fuji and Hakone volcanoes supplied excellent data for recovering the history of explosive activity during the middle to late Pleistocene and Holocene.
I have worked on several topics, as follows, with all of my work based on tephra stratigraphy and chronology in the Japan area : a) Identification of very widespread tephra layers ; b) Establishment of a tephra-based Quaternary chronology of Japan ; c) Interglacial-glacial sea-level sequences in the Quaternary ; d) Tectonic evolution of mountains and basins of central Honshu using Quaternary and Pliocene tephrochronology ; e) Paleoenvironments during the last deglaciation stage in Japan ; f) Outreach from the earth sciences to society.
