Volcanic Eruptions and Their Tectonic Control in Izu-Oshima and Miyakejima Volcanoes, Japan

Abstract

For the major eruptions of Miyakejima Volcano in 1983 and of Izu-Oshima Volcano in 1986, long and short term predictions were made by means of eruptive regularity based upon causal relation between eruptive activities and regional tectonic stresses. Level change in the bottomfloor of the summit crater of Izu-Oshima Volcano, identification of P₂-phase of swarm earthquakes in and around both volcanoes and marked change of geophysical data before major eruptions were available to predict the major eruptions of both volcanoes. The regularity suggests that the great eruptive energy of Izu-Oshima Volcano since 1986 should not be released until a great earthquake along the Sagami Trough.