The deep blue waters of 6-km-wide Mashu caldera are seen here from its western rim. The small island of Kamuishu in the center of Lake Mashu (right-center) represents the tip of a mostly submerged lava dome. Mashu is a Holocene caldera that truncates a stratovolcano constructed on the ESE rim of the large Kutcharo caldera. Following caldera collapse, a small stratovolcano, Kamuinupuri (whose lower flanks are visible at the far right), was formed beginning about 4000 years ago. Copyrighted photo by Shun Nakano, 2001 (Japanese Quaternary Volcanoes database, RIODB, http://riodb02.ibase.aist.go.jp/strata/VOL_JP/EN/index.htm and Geol Surv Japan, AIST, http://www.gsj.jp/).