阿蘇火山,米塚の噴火年代

概要

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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 (370-380m in basal diameter; 80m in height) and lava flows (10.5km^2; 5×10^7m^3). We obtained ^<14>C ages of 3,070±40 years BP from a buried soil below silty ash underlying Komezuka lava, which corresponds to 3,370-3,210cal years BP, and 2,760±40 years BP (2,950-2,770cal 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 3,300cal years BP. The eruption age is consistent with the age of Ojodake Volcano (3,600cal 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 4,000cal years BP, followed by sub-plinian eruptions and lava extrusion from Ojodake Volcano at 3,600cal years BP, and ceased with strombolian eruptions and lava extrusion from Komezuka Volcano at 3,300cal years BP.
2010-10-31