Permalink : http://hdl.handle.net/2115/80695

JaLCDOI : 10.14943/gbhu.84.1

We examined boring cores excavated at Kyowa and Rankoshi towns to clarify stratigraphy and thickness of deposits of Toya caldera-forming eruption. As a result, there exists thick pyroclastic flow deposits of ca. 20m thick in these areas, and we also recognized fine-grained pyroclastic fall and pyroclastic flow deposits of 10cm-thick each below the thick pyroclastic flow deposits at Rankoshi. Glass compositions of these deposits are in the range of deposits of Toya caldera-forming eruption, suggesting that they are all derived from the eruption and upper pyroclastic flow deposits are more voluminous.