| Budget Amount *help |
¥5,460,000 (Direct Cost: ¥4,200,000、Indirect Cost: ¥1,260,000)
Fiscal Year 2013: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2012: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
Fiscal Year 2011: ¥2,860,000 (Direct Cost: ¥2,200,000、Indirect Cost: ¥660,000)
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| Research Abstract |
Petrological investigation on the pyroclastic products of the Late stage eruption (ca 17,000 years ago) of Nantai volcano and the Numasawako eruption (BC 3,400 years) of Numasawa volcano shows that the two voluminous pyroclastic eruptions have been generated by mixing between magmas from the independent, multiple magma chambers. Two dacitic magma chambers were formed just prior to the Late stage eruption, and they tapped explosively after the invasions of magmas from the independent mafic magma chambers. Approximately 20,000 years before the Numasawako eruption, single dacitic magma chamber was formed, and the initial tapping of the chamber generated lava dome. Then, the explosive tapping of this dacitic chamber occurred just after the sequential replenishments of two genetically-unrelated mafic magmas that were supplied from the independent magma chambers.
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