Development of the Izu-Oshima Pre-caldera Volcano examined by lacustrine deposits and tephras around the Funoh-Falls in the east coast region, Izu-Oshima Island, Japan

Abstract

The Izu-Oshima volcano (110 km SSW of Tokyo) in northern Izu-Bonin Arc, is one of the most active Quaternary volcanoes in Japan. This volcano originating from basaltic magma has frequently erupted; that is, 12 times of major eruptions occurred during last 1800 years. Studies of its eruption history for this period, named Syn- and post-caldera volcano, have been carried out by Nakamura (1964), Kawanabe (2012) and so on. However, the eruption history older than this period has not been well studied. The history of Izu-Oshima volcano preceding Syn- and post-caldera volcano was divided into the Younger Edifice of pre-caldera and the Older Edifice of pre-caldera, and fall-out tephra group typically exposed along so-called Great Cut of Beds in SW part of the island was identified as volcanic products of the Younger Edifice of pre-caldera (Kawanabe, 2098). Here, we showthe chronological framework of eruption history of the Younger Edifice of pre-caldera using a tephra and several 14C ages in lacustrine sediments distributed around the Funoh-Falls in the east coast region, Izu-Oshima Island.