三宅島における高濃度火山ガス事象の地域特性

概要

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The purpose of this study is to clarify the regional characteristics of high concentration events of sulfur dioxide (SO_2) at Miyakejima and to provide basic information for volcanic gas disaster prevention based on the wind and synoptic chart, which might be useful for the returning of inhabitants. We discuss the continuous measurement SO_2 data at the foot and flank of Miyakejima volcano, in conjunction with upper wind data at Hachijyojima near-by, synoptic charts, atmospheric conditions and satellite images of volcanic clouds and of the distribution of vegetation. The following results are obtained. The regional characteristics of high SO_2 concentrations are summarized as follows. The winter monsoon wind brings high SO_2 concentrations for many hours to the stations located east of the volcano. At southwest stations, high concentrations of SO_2 are maintained considerably long due to stationary fronts, though the concentration level is lower than that for causes of stations located east. For other directional stations, the position of typhoon and deep low pressure system accompanying cold front, and the path of them and of travelling high pressure system dominantly affects the high SO_2 concentrations. The frequency distribution of high SO_2 concentration events corresponds well to the distribution of vegetation index shown in an image of Terra/ASTER.
日本自然災害学会の論文
2005-02-28