Abstract
This study presents ash-fall hazard maps for an eruption of Sakurajima volcano of
similar scale to the Taisho eruption based on tephra transport simulations accounting for
daily variations in wind fields over a 1-year period. Existing hazard maps indicate deposition
of ash on the eastern side of Sakurajima by westerly winds, which reflects the mean annual
wind direction. This study analyzed ash deposition by implementing daily-base computations
with no prior statistical processing. The results reveal that the maximum-class deposits occur
around Kagoshima Chuo Station focused in August, when the wind direction is not annually
predominant one. The resultant hazard map based on the maximum thickness of the deposits
differs from existing maps and provides useful information for creating disaster evacuation
plans. Further hazard maps are proposed based on the frequency of the ash-fall exceeding a
particular thickness and on a highest 1% deposit thickness, and we discuss suitable methods of
expressing ways responding to the users’ class and object.
