1990 年 99 巻 1 号 p. 92-97
Horizontal crustal deformation in the northern and central Fossa Magna regions, central Japan, has been revealed by the geodetic distance survey. Regional variations of the horizontal deformation are recognized along the Itoigawa-Shizuoka Tectonic Line. In the northern region, there is no discontinuity of the horizontal deformation between Itoigawa and Otari along the Itoigawa-Shizuoka Tectonic Line, and it seems that the boundary of the horizontal deformation jumps to the Naoetsu-Otari Tectonic Line. It seems that the collision, slightly oblique, occurs, and the gravity anomaly and the earthquake fault suggest that the southwestern Japan has subducted under the northeastern Japan along the Itoigawa-Shizuoka Tectonic Line. In the central region, it seems that the left-lateral strike slip fault motion occurs along the Itoigawa-Shizuoka Tectonic Line. Therefore, it is considered that the northern part of the Itoigawa Shizuoka Tectonic Line may be a convergence boundary and the central part may be a transcurrent boundary.