1986 Volume 34 Issue Supplement Pages S241-S248
Under the Fourth Earthquake Prediction Project of Japan starting from 1979, the Research Group for Explosion Seismology conducted a series of explosion seismic experiments to reveal detailed structure of the shallow crust. In this paper, results from two experiments in the Izu Peninsula are shown. Structure of the shallow crust in the peninsula is very complex and is quite valuable for the other geophysical and geological investigations. For example, time terms of the basement layer show a good correlation with Bouguer anomalies when we assume a reduction density of about 2.7 g/cm3. A layer with a velocity of about 4.1 km/s observed in the whole Izu Peninsula may correspond to the Yugashima Group. Our structural models are also useful for discussion of abnormal crustal uplift and seismic activities observed around the Izu Peninsula in recent years. We believe that the middle-size seismic experiment like these Izu experiments may be the most appropriate one in geologically complex regions such as Japan.
