阿蘇カルデラ内の注目すべきボーリング結果について

概要

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One deep drilling was carried out by the Taisei Co., on the northeastern caldera floor, 500 m above sea level, of Aso volcano for the purpose of getting information on both underground structure and hot spring (Fig.1). According to our observation of core samples, we show the drill hole section as Fig.2. Noticeable facts are as follows : 1) From the surface to 320 m in depth, the sediments consisting of volcanic sand bed, tuff bed, gravel bed and clay bed exist. They have deposited in the caldera lake. 2) Underneath the sediments, the Kuzyu pumice flow forming the welded tuff in lower part are laid more than 150 m in thickness. This pumice flow is divided into two parts at -453 m. The upper part is whitish grey and the lower part is grey in colour. Both the flows show the different character in chemical composition as Table 1. 3) The granite of Tamana type exists underneath the Kuzyu pumice flows. The surface of the granite is thought to be an erosion surface.
特定非営利活動法人日本火山学会の論文
1969-04-01