Renovated Ballistic Equation of Ejected Blocks and Its Application to the 1982 and 1983 Sakurajima Eruptions(＜Special Section＞Sakurajima Special Issue)

Abstract

We propose a ballistic equation of ejected volcanic blocks that is renovated by considering air resistance, wind velocity and direction dependence of the initial velocity. In the equation, we treat the air resistance as a vector that coincides with the opposite direction of flight. By comparing the calculated results based on the equation of motion and the observed data, such as spatial distribution of landed blocks, initial velocities by successive photos and so on, we tried to reproduce kinematic aspects of the ejected blocks at the 1982 and 1983 eruptions of Sakurajima Volcano, Kyushu, Japan.