A basic study on volcanic disaster from 'high temperature debris avalanche'

我们检查了九州四个碎片雪崩沉积物的地质产状和磁极性特征。这四个例子是九州岛的松尾井岩屑崩落存款、汤布岳的冢原岩屑崩落存款、云仙火山的岛原岩屑崩落存款和雾岛的小林岩屑崩落存款。结果表明：1）九州火山松野台崩塌存款在松野台崩塌存款的情况下，我们检查了存款中许多块体的磁极性，并获得了一些大块体指示温度高于贫钛钛磁铁矿居里点（约500 ℃）的证据。这一结果对泥石流崩塌存款模型的建立具有重要意义。“高温崩落物”存款的存在表明，具有高温内部的冷却熔岩穹丘的崩溃的可能性。2）汤布岳火山的冢原岩屑崩存款对于冢原岩屑崩存款，我们检查了存款中某些块体的磁极性，3）云仙火山的岛原崩落物存款这一存款是由1792年的马由崩塌形成的，云仙火山4）雾岛火山小林碎屑崩落沉积物小林碎屑崩落存款中含有一些具有高温构造的岩块。今后有必要对该存款中的块体进行磁性特征的研究。

We examined the geological occurrences and characteristics of magnetic polarity of the four debris avalanche deposits in Kyushu. The four examples are Matsunodai debris avalanche deposit of Kuju volcano, Tsukahara debris avalanche deposit of Yufu-dake volcano, Shimabara debris avalanche deposit of Unzen volcano, and Kobayashi debris avalanche deposit of Kirishima volcano. The results are as follows.1) Matunodai debris avalanche deposit of Kuju volcanoIn case of Matsunodai debris avalanche deposit, we examined the magnetic polarity of the many blocks in the deposit, and obtained the evidence that the some big blocks indicate higher temperature than the Curie point, about 500ﾟC, of titan-poor titanomagnetite. This result is very significant for the construction of model for the debris avalanche deposit. The existence of the 'high-temperature debris avalanche' deposit suggests that the possibility of the collapse of cooling lava dome which has high temperature interior. The 'high-temperature debris avalanche' is a new type of the volcanic disaster.2) Tsukahara debris avalanche deposit of Yufu-dake volcanoIn case of Tsukahara debris avalanche deposits, we examined the magnetic polarity of the some blocks in the deposit, but we could not obtain the evidence which indicate the high temperature.3) Shimabara debris avalanche deposit of Unzen volcanoThis deposit was formed by 1792 Collapse of Mayu-yama, Unzen volcano. We could not obtaine the evidence of high temperature for the deposits.4) Kobayashi debris avalanche deposit of Kirishima volcanoThe Kobayashi debris avalanche deposit contains some blocks which have some structures showing the high temperature. It is necessary in future to examine the magnetic characteristics of the blocks in this deposit.