Study on the evaluation of explosion energy of volcanic eruption and on the blast disaster.

本研究的目的是建立评价火山喷发爆炸能量的方法，并将其与火山爆发引起的地质和灾害分布联系起来。人们普遍认为，火山爆发引起的灾害和火山碎屑沉积的分布与爆炸能量直接相关。如果这个假设成立，如果我们知道能量，我们就可以用数值模拟来预测这些现象的分布。为了证明这一假设，我们进行了以下两个尝试：爆炸能量估算方法的发展，爆炸能量与灾害和火山碎屑沉积分布关系的解释。得出如下结论：(1)火山爆炸产生的火山碎屑浪涌的最大距离仅由爆炸能量决定。(2)火山口直径与爆炸能量的二乘三次方成正比。人造结果(化学爆炸和核爆炸)的关系也适用于火山爆炸。(3)岩浆爆炸的热能到爆炸能量的转换率为0.01-0.4%，云母岩浆爆炸的能量转换率为0.4-7%。(4)上述比率意味着，如果我们用地磁法或任何其他方法获得总热量的信息，就可以估计地质和灾害现象的最大分布距离。(5)1994-1995年我们在阿索火山测得的最大爆炸能量约为5×10^~15。

The purpose of present study is to develope the methods for the evaluation of explosion energy of volcanic eruption, and to relate the energy to the geological and disaster distribution owing to the volcanic explosion.The distributions of the disaster and pyroclastic sediment due to the explosion is generally belived to be related directly to the explosion energy. If this assumption is valid, and if we know the energy, we can predict the distributions of those phenomena using a numerical simulation. To prove this assumption, we made following two attempts ; the development of methods for the evaluation of the explosion energy, the explanataion of relation between the explosion energy and the distributions of disaster and pyroclastic sediment. We could get following results ;(1) The maximum distance of pyroclastic surge due to the volcanic explosion is determined only by the explosion energy.(2) The diameter of volcanic crater is in proportion to the explosion energy to the two over three power. The relation for the artificial results (chemical and nuclear explosions) also holds for the case of volcanic explosion.(3) The energy conversion rates from thermal energy to the explosion energy are 0.01-0.4% for magmatic explosion, and 0.4-7% for phreatomagmatic explosion.(4) The rates mentioned above means that we can evaluate the maximum distance of distributions of geological and disaster phenomena if we know the information on the total heat using geomagnetic method or any other methods.(5) The maximum explosion energy we measured in 1994-1995 at Aso Volcano was about 5*10^<15> erg.