Kussharo

The 20 x 26 km Kussharo caldera (also spelled Kutcharo or Kuccharo), is the largest of a cluster of calderas in NE Hokkaido. The caldera was formed in a series of major eruptions between about 340,000 and 30,000 years ago. Nakajima, a Holocene post-caldera dacitic-to-rhyolitic lava-dome complex, forms an island in the large lake that fills much of the western half of the caldera.

The Holocene Atosanupuri stratovolcano and lava-dome complex is located near the center of the caldera, east of the crescent-shaped Lake Kutcharo. Many lava domes were formed between about 1000-10,000 years ago. No historical eruptions are known, although intense fumarolic activity occurs on and around Atosanupuri volcano and along the shores of Lake Kutcharo.