2-D and 3-D Subsurface Density Structure in the Northern Part of the Itoigawa-Shizuoka Tectonic Line Derived by Gravity Surveying

We carried out gravity surveying along a profile of the reflection seismological prospecting in the northern part of the Itoigawa-Shizuoka Tectonic Line (ISTL). Combined use of gravity and seismic data enables us to construct a 2-D subsurface density model. We also present a 3-D model which is consistent with the previous works on gravity and reflection/refraction prospecting. Both 2-D and 3-D models show a reverse fault structure dipping toward the east. We do not find any thrusting structure dipping toward the west as implied from the uplifting of the Hida range.