Tephrochronological Study of Volcano Fuji and Adjacent Areas

Abstract

Mt. Fuji, the highest peak in Japan, is one of the largest and most typical strato-volcano of basaltic composition. It was shown in a previous paper (Tsuya , 1940) that this volcano consists structurally of three parts, " Komitake ", " Old Fuji ", and " New Fuji ", erupted successively in the order mentioned. This result was obtained from geological and petrological studies of the volcanic ejecta, especially of lava flows and mudflow deposits. As yet few investigations have been carried out on the stratigraphy of pyroclastic fall deposits or " t ephrochronology ", although such studies help to clarify some of the remaining problems such as the chronology and the nature of volcanic activity and chronological relationships between the evolution of the landform of the adjacent areas and the development of the volcano itself. In the present paper, the writer deals first with the stratigraphic division and chronology of the pyroclastic fall deposits on the lower slopes of the volcano and its surroundings, and then applies these results to the chronology of the activities of the volcano.