- 火山 (ISSN:04534360)
- vol.51, no.1, pp.1-20, 2006-02-28
Volcanic history of Kuchinoerabujima Volcano in the last 30,000 years is reconstructed based on tephra stratigraphy. Kuchinoerabujima is a volcanic island which is a cluster of at least nine volcanic edifices; Gokyo, Jyogahana, Ban-yagamine, Takadomori, Noike, Kashimine, Hachikubo, Furutake and Shintake. Eruptions within the last 30,000 years occurred from Noike, Hachikubo, Furutake and Shintake volcanoes. Two major pumice and scoria eruptions occurred between 15 and 11 ka after an inactive period since ca. 30ka. NoikeYumugi tephra (15-14ka, DRE>0.06km^3), erupted from the summit of Noike Volcano, consists of Yumugi pumice fall deposit and Nemachi pyroclastic flow deposit. Furutake-Megasaki tephra (12-11 ka, DRE ca. 0.8km^3) erupted from Furutake Volcano and consists of Furutake agglutinate, Furutake scoria flow deposit and Megasaki scoria fall deposits. Volcanic edifice of Older Furutake was built during the 12-11 ka eruption. Eruption style changed around 10ka, after the collapse of Older Furutake Volcano. Activities of Yougner Furutake and Shintake Volcanoes are characterized with effusion of lava flow and no major pumice eruption is recognized. Lithic tephra erupted from Younger Furutake and Shitake Volcanoes within the last 10,000 indicates repetitive Vulcanian-type and phreatomagmatic eruptions. All historical eruptions since 1841 occurred at and around Shintake crater and were Vulcanian-type explosions with emission of magmatic materials and phreatic explosions.