Basic research on eruption history for preparing hazard maps of the active volcanoes in Central Kyushu, Japan

日本九州中部有Turumi-dake火山、kuju火山、Aso火山、云仙火山等4座活火山。我们研究了火山喷发的历史。本研究的结果如下：1。作为云仙火山大学联合研究小组地质小组成员，观察并描述了熔岩穹窿的生长顺序。日本地质调查局将于本财政年度末出版《云仙火山地质图》。被Aso-4火山碎屑流吹倒和烧毁的大树在距离Aso火山口约90公里处被发现。这些树的出现，对遥远地区Aso-4火山碎屑流的温度和速度的估计提供了重要的信息。阐明了近1.5万年来阿苏中大火山的喷发模式。在此基础上，提出了中田县的初步危害图。在火山脚下附近获得了小于6300年的鹤见湖潜水爆炸的现场证据。这项调查的一些结果在一些学术团体的会议上口头提出。

Four active volcanoes, Turumi-dake volcano, kuju volcano, Aso volcano and Unzen volcano, are situated in the Central Kyushu, Japan. We have investigated eruption history of the volcanoes. The results of this study are as follows ;1. The sequence of the growing of lava dome was watched and described as a member of Geological Party, Joint University Research Group for Unzen Volcano.The Geological map of Unzen Volcano will be published by Geological Survey of Japan in the end of this fiscal year.2. Blown down and burnt big trees by the Aso-4 pyroclastic flow were found at about 90 km from the Aso caldera. The occurrence of these trees was very informative for the estimation of temperature and velocity of the Aso-4 pyroclastic flow at distant area.The mode of eruption of Naka-dake, Aso volcano, for the past 15,000 years are clarified. From this result, tentative hazard maps of Naka-dake were proposed.3. The field evidence of the phreatic explosions of Tsurumi-dake in the period younger than 6,300 years was obtained around the foot of the volcano.Some of the results of this investigation were orally presented on some meetings of academic society.