1983 年 10 月 3・4 日三宅島火山噴出の降下火砕堆積物  [in Japanese] Pyroclastic Fall Deposits of the October 3-4, 1983, Eruption of Miyakejima Volcano  [in Japanese]

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Abstract

Stratigraphy and thickness distribution of the pyroclastic fall deposits formed during the eruption of Miyakejima volcano on October 3-4, 1983, were studied immediately after the deposition. Of the total mass of 20 million tons erupted, 8.5 million tons were ejected as basaltic scoria to form a complex set of air-fall deposits east of the fissure vents. One million tons of the latter were ejected from the upper fissures as fire-fountain products. The rest was the product of phreatomagmatic explosions which occurred in the lower fissures where ground water chilled the magma to form dense scoria blocks which devastated villages. Explosion craters and a tuff ring were formed along the N-S trending lower fissures. Account of the general distribution of the deposits, nature of the constituents, mutual stratigraphic correlation and correlation with observed sequence are given.

Journal

  • SECOND SERIES BULLETIN OF THE VOLCANOLOGICAL SOCIETY OF JAPAN

    SECOND SERIES BULLETIN OF THE VOLCANOLOGICAL SOCIETY OF JAPAN 29(TOKUBE), S208-S220, 1984

    The Volcanological Society of Japan

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