2.2 硫黄島と周辺海底の地形

抄録

Iwo-jima volcano is a stratovolcano of 1500-2000 m in elevation, having a caldera of about 10 km in diameter. Marine terraces on the island, classified into more than 20 treads, indicate the rate and mode of uplift during the past several centuries. Distribution of active faults, concentrated in Chidorigahara isthmus, are related to the mode of Chidorigahara elliptical uplift. Comparison among the 1934, 1945 and 1981 bathymetries shows that uplift has occurred at shallow waters around the island but it has not reached the caldera rim.