著者

井村 隆介

出版者

特定非営利活動法人日本火山学会

雑誌

火山 (ISSN:04534360)

巻号頁・発行日

vol.40, no.3, pp.119-131, 1995-07-31

被引用文献数

5

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Sedimentological study of the recent deposit of Sakurajima Volcano has exposed some properties of the deposit accumulated by small-scale eruptions. Fall-out deposit of long-term such eruptive activity occur in any nearly concentric circular area around the source. Change of the small-scale eruptive activity manifests as the facies, bulk density and carbon content of the deposit, because such characters of the deposit are reflections of the accumulation rate of pyroclastics. Gray laminated or massive volcanic sand layer indicates a period of highly active volcanism ; brownish loamy volcanic sand layer a less active one and brownish loam or humic soil a dormant or inactive one. The duration of those periods can be estimated from the facies, thickness and bulk density of the deposit and recent fall-out ash data.