火山爆発により放出される火山岩塊・レキの到達距離

Abstract

Effect of some parameters on the range of volcanic blocks and lapilli is examined. They aretopography, diameter and maximum initial velocity of blocks, inclination of explosion axis andvelocity of wind for the former, and velocity of wind and column height for the latter.Some examples of calculated results under certain parameters are as follows. The range ofblocks ejected south to the active crater increases by 3, 6 and 9% due to the fair wind of whichvelocity is 10, 20 and 30%, respectively. Also, the range does by 34, 60 and 69% (maximum) dueto the inclination of explosion axis of which angle is 15, 30 and 51 deg, respectively. Air fall oflapilli could attain a range of 3.5, 6.9 and 10.4 km from the active crater when the column height is3000 m and the velocity of wind is 10, 20 and 30 m/s, respectively. When the column height is4000 m, the range of lapilli above mentioned increase by about 30%.