Development of the measurement-system of volcanic shock wave both in the air and in the water

本课题的主要目的是研制一套空气和水中火山爆炸波测量系统，确定火山爆发的爆炸能量和深度。该系统的功能如下：1。采样率：~ 200khz2。数据采集次数：约10000次，制作系统需进行现场爆炸实验。利用这个机会，我们试图建立控制爆炸能量、爆炸深度与火山爆炸表面现象（如弹坑的形成和弹道破片的喷射）之间关系的标度规律。2000年3月31日，日本北海道的乌苏火山在休眠22年后爆发，其特点是多次小规模的潜水式喷发。根据观测结果和标度规则确定了乌苏火山喷发的能量和深度。结果表明，在现场试验中得到的爆炸能量和爆炸深度与爆炸现象的关系实验方程较好地定量地解释了乌苏潜水爆炸的真实现象。观测到的代表性爆炸能量范围为10^10 J ~ 10^ 12 J，代表性深度范围为几乎陨石坑表面到约30 m深。

Main purpose of this project is to make a system for volcanic blast wave measurement both in the air and in the water, and to determine the explosion energy and depth of explosive eruption. The ability of the system is as follows :1. Sampling rate : 〜200 kHz2. Number of data collection : ca. 10000For making the system, field explosion experiment was needed. Using this chance, we have attempeted to establish the scaling rule which govern the relations among explosion energy, explosion depth and surface phenomenon of volcanic explosion such as the crater formation and ejection of ballistic fragment.On 31 March 2000, Usu volcano in Hokkaido, Japan, erupted after 22 years dormancy, and it was characterized by numerous numbers of small-scale phreatic explosion. We have attacked to determine the energy and the depth of Usu eruption based on the observations and the scaling rule. These results indicated that the experimental eqtuations obtained in the field experiment relating the explosion energy and depth to the explosion phenomenon explained well quantitatively the real phenomenon at Usu phreatic explosion. The representative explosion energy observed ranged from 10^10 J to l0^12 J, and the representative depth ranged from almost crater surface to about 30 m deep.