Volcanism and Seismicity in the Iwo-jima Volcanoes

Since the first recorded phreatic explosion occurred in 1889, eruptions took place fifteen times in Iwo-jima. Recently, Iwo-jima volcanoes has been studied from geophysical standpoint including seismometrical, geodetic and geothermal investigations. Most of phreatic explosions has been accompanied with high active stage of shallow earthquakes. But explosions are not always accompanied by a swarm of shallow earthquakes.