SEGJ Technical Conference

Examination of the deep-seated substructure of the Median Tectonic Line active fault zone in the Iyo-nada Sea by using seismic profiles

Abstract The Median Tectonic Line active fault zone (MTLAFZ) is one of the major active fault systems in Japan, extending from Kyushu to the Kii Peninsula. It is a right-lateral strike-slip fault system and is related to oblique subduction of the Philippine Sea plate. Its distribution corresponds well to the Material Boundary Median Tectonic Line (MBMTL), which separates the Ryoke belt to its north from the Sanbagawa belt to its south. Many geomorphological surveys on the MTLAFZ revealed that its surface trace is very straight and the fault on the surface has a high angle plane. On the other hand, many seismic reflection surveys around the MTLAFZ have shown that the MBMTL dips to the north at 30 to 40 degree. We examine the deep-seated substructure of the MTLAFZ in the Iyo-nada Sea by using seismic profiles because the relations between MTLAFZ and MBMTL are very important issue.