Time scale from mixing to eruption for historical lavas of Chokai volcano: Estimation by residence times of mafic minerals

Abstract

Between AD 871 and 1801, magmatic activities in Chokai volcano occurred at least three times. Based on petrologic data of the historical lavas, previous studies revealed the erupted products were formed by magma mixing. Bulk compositions of lavas are depicted on same linear trends in silica variation diagrams. Here, we report the estimated time intervals between mixing and eruption, based on compositional zoning of mafic minerals in the Chokai historical lavas. Zoning patterns of olivine show that the time intervals were almost one month to four years.