Global Volcanism Program | Image GVP-10576
Geologists stand on the narrow cobble beach at the NE base of Sumisujima. Vertical light-colored dikes cut intrusive rocks at the lower right and oxidized tephra layers, breccias, and lava flows forming the pinnacle. The spire is an eroded remnant of the pre-caldera volcano on the outer southern flank of a large submarine caldera. A large segment of the eastern side of the pinnacle slumped into the sea in the past decade.
Copyrighted photo by Kenichiro Tani, 2002 (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/).