Abstract
The vertical movement of the land blocks by the 1964 Niigata earthquake of M7.5 is analyzed by the Miyabe's method. In the 1964 Niigata earthquake, for the period of 1961-1964, the tilting of the Honshu land block along the levelling route between Murakami and Atsumi was by 3.2″ to N80°W. Considering the tilting upheaval at Awashima Island, this result indicates that the land block of the Honshu side sliped under the Awashima Island by the high-angle fault dipping westward by the earthquake. Tilting toward the west by the Niigata earthquake is the same with the topographical feature along the Shinano River Seismic Zone where the crust is shortened by the thrust faults and foldings. Estimated rate of shortening is 1.2 cm/yr-1.4 cm/yr. It is presumed that the Shinano River Seismic Zone is the inland portion of the collision plate boundary between the Okhotsk Plate and the Eurasian Plate.
