阿蘇火山, 米塚の噴火年代

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(1) // (,*+*) / ,+3῍,,/ . . ῍ῐ῎῏ ῕ῒῌ῔῎ΐῑ ¥ ¦ + '" ,*+* , / - +- ./ ,*+* , +* - ,/ ./. Eruption Age of Komezuka at Aso Volcano, Japan Yasuo MIYABUCHI Komezuka Volcano, located in the northwestern part of the post-caldera central cones of Aso Volcano, SW Japan, is a basaltic monogenetic volcano comprising a scoria cone (-1*῍-2* m in basal diameter ; 2* m in height) and lava flows (+*./ km, ; /+*1 m-). We obtained +.C ages of -,*1*.* years BP from a buried soil below silty ash underlying Komezuka lava, which corresponds to -,-1*῍-,,+* cal years BP, and ,,10*.* years BP (,,3/*῍ ,,11* cal years BP) from a soil above silty ash overlying Komezuka lava. The age of soil below the lava suggests that the eruption age of Komezuka Volcano is about -,-** cal years BP. The eruption age is consistent with the age of Ojodake Volcano (-,0** cal years BP) whose lava underlies Komezuka lava. In the northwestern part of the post-caldera central cones, Late Holocene monogenetic volcanic activity commenced with sub-plinian eruptions and lava extrusion from Kishimadake Volcano at approximately .,*** cal years BP, followed by sub-plinian eruptions and lava extrusion from Ojodake Volcano at -,0** cal years BP, and ceased with strombolian eruptions and lava extrusion from Komezuka Volcano at -,-** cal years BP. Key words : Komezuka Volcano, scoria cone, lava flow, eruption age, Aso Volcano. + . . 9:;<=>;?@A B4CDE6 F;< L 3/..- m K MNOP@ QJR6SQT. ,**+ 0123456 78 +32/ G

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