Journal of Natural Disaster Science

VOLCANO HAZARD ASSESSMENT OF MOUNT FUJI Natural calamities strike at about the time when one forgets their terror −a Japanese proverb−

Daisuke SHIMOZURU
Professor, Earthquake Research Institute, the University of Tokyo, Bunkyo-ku, Tokyo, 113

(Received 28 Nov., 1983, and in revised form 4 Feb., 1984)

Abstract

A hazard assessment of a possible future eruption of Mount Fuji was made from data in old documents recording the tephra fall of its 1707 eruption. The thickness of basaltic scoriae and ash in 120 localities as far away as Tokyo was found from historical records. An isopach map was drawn from the data which is in good agreement with the isopach map made by Tsuya based on his volcano-stratigraphic study. The major axis of the isopachs coincides with the prevailing wind direction during the corresponding months as recorded at the Weather Observatory on the summit of Mount Fuji. Old documents prove that the delay in the tephra fall between Odawara and Tokyo is approximately one hour, enough time for diaster warnings to be given. An eruption of Mount Fuji in the near future is likely after its long period of dormancy and probably will be explosive as was the 1707 eruption. Thus, the volcanic events of the 1707 eruption are considered a good basis from which to make a hazard assessment of Mount Fuji. A hazard map was drawn from the data collected on this 18th century eruption.

Key words

volcano, volcano hazard, hazard assessment, Mount Fuji, hazard map