数値シミュレーションによる薩摩硫黄島硫黄岳の火山熱水系の考察

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The thermal activity of Iwodake volcano is characterized by the predominant volcanicgas ejection at the summit crater and the heat discharge from high ground temperature areawhich is distributed widely from the summit crater to hillside of the mountain. The volcanicgas at the summit crater is of magmatic origin and its temperature is observed to be 880°C inmaximum. The total amount of the volcanic gas discharged from the summit area isestimated to be 150kg /sec from the SO2 measurement and the chemical composition of thevolcanic gas. The heat discharge rate form the high ground temperature area at the hillside,which is distributed around the fumaroles is estimated to be 50MW from the surfacetemperature measurement. These thermal activities of Iwodake volcano is thought to becontinued for more than 800 years. A plausible model to explain the long degassing of largeamount of volcanic gas is magma circulation in a conduit which extended from thedeep-seated magma reservoir. The continuous active degassing probably causes thehydrothermal system within the volcano because the volcanic gas ascending the conduit fromthe top of the magma to the surface is diffused to the surrounding formation. Thedevelopment of such hydrothermal system is studied using the mathematical simulation.The result shows that the overall thermal activity of Iwodake volcano such as the volcanic gasejection at the summit crater, widely distributed ground temperature anomaly at hillside andhot springs along the coast can be caused by the degassing activity. The important factors inorder to induce the wide-ranging hydrothermal system are permeability of the volcanicedifice and the depth of the degassing. The simulation indicate that the permeability of10-13m2 and the degassing at sea level are suitable condition for the Iwodake thermal activity.
北海道大学大学院理学研究院自然史科学部門（地球物理学）の論文
2007-03-15

数値シミュレーションによる薩摩硫黄島硫黄岳の火山熱水系の考察

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概要

北海道大学大学院理学研究院自然史科学部門（地球物理学） | 論文

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