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Numazawa volcanoNumazawa volcano has a small 1.5 x 2 km wide caldera which formed during a major eruption about 4600 years BP, producing large quantities of dacitic-to-rhyolitic pumice fall and flow deposits. The caldera is filled by a lake.
Background:Numazawa volcano is dominantly dacitic to rhyolitic, and has a long history of very explosive eruptions. There evidence of an older Pliocene caldera.
Important stratigraphic deposits include:
- the rhyolitic Shibahara pyroclastic-fall deposit 110,00 years before present (BP)
- the dacitic Mukuresawa lava dome 71,000 years BP,
- the dacitic plinian Mizunuma eruption about 45,000 y BP
- the Sozan lava dome at 43,000 y BP
- the So-zan lava dome at about 20,000 y BP,
- the Numazawako pumice flow and plinian eruption about 4600 y BP.