Numazawa

Numazawa is a small, 2-km-wide dominantly dacitic-to-rhyolitic caldera constructed within an older Pliocene caldera. Eruptions of the 110,00 years before present (BP) rhyolitic Shibahara pyroclastic-fall deposit and the 71,000 BP dacitic Mukuresawa lava dome were followed by the dacitic plinian Mizunuma eruption about 45,000 BP, emplacement of the Sozan lava dome at 43,000 BP and the Sozan lava dome at about 20,000 BP. The Numazawako pumice flow and plinian eruption about 4600 years BP resulted in formation of the 1.5 x 2 km Numazawako caldera, now largely filled by a caldera lake.