Hiromu Mukaiyama

Tectonics Deduced from Landsat Images in the Southern Part of Chubu District, Central Japan

A study of regional tectonics using the lineament map drawn from Landsat TM (Thematic Mapper) images was conducted for the southern part of Chubu district, Central Japan. Many long lineaments appeared along boundaries of tectonic blocks which are characterized by directional orientation of small lineaments. Tectonically significant NE-SW lineaments crossing Akaishi Mountains were specially obtained. It was found that the NE-SW lineaments coincide with geological or active faults in Akaishi Mountains and South Fossamagna areas, but they are not along with the sedimentary structure of the Paleogene and Neogene formation distributed in these areas. In the north side area of the NE-SW lineaments, main directions of small lineaments are N-S or E-W and seismic activity in the crust is low. In the south side area, on the contrary, the main directions of them are N-S or NE-SW and seismic activity is high. Moreover, the most north one of the NE-SW lineaments agrees with the boundary of the principal axis of the seismic stress. Many earthquakes, of magnitude more than 4, also occurred on the NE-SW lineaments in Akaishi Mountains. Therefore, the NE-SW lineaments are considered to reflect the active fracture zones and extend to the Median Tectonic Line.