イチンスキー

Ichinsky, by far the highest peak in the Sredinny Range, is a massive, 450 km3 edifice. The andesitic Pleistocene-to-Holocene stratovolcano, also known as Icha, contains a 3 x 5 km-wide glacier-covered summit caldera filled by a large post-caldera edifice. Two glacier-capped lava domes form the highest peaks. A dozen late-Pleistocene to Holocene dacitic and rhyodacitic lava domes circle the peak below the caldera rim. Fresh-looking basaltic-to-dacitic lava flows, some with prominent flow ridges, were erupted from flank vents and traveled up to 10-15 km. The largest Holocene eruption took place about 6500 years ago, producing block-and-ash flows that traveled up to 15 km. Fumarolic activity occurs within the caldera and on the lower N flank. In 1956 steam jets rose 250 m above the caldera fumarole field.