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 rhyolitic Mukuresawa lava dome were followed by the dacitic Plinian Mizunuma eruption about 45,000 BP, emplacement of the Sozan lava dome at about 40-43 ka and the Maeyama lava dome at about 24,000 cal BP. The Numazawako pumice flow and Plinian eruption about 4,600 years BP resulted in formation of the 1.5 x 2 km Numazawako caldera, now largely filled by a caldera lake.