**5. Summary**

A summary of basin-forming processes in an island arc was presented in connection with the development of a damaged area on an active plate margin. The Kinki district in southwest Japan has been a site of vigorous basin formation since the Pliocene. An accelerated Quaternary strain rate around the area is generally interpreted as a result of compressive stress linked to the westerly subduction of the Pacific Plate. Recent geodetic analyses demonstrated a NE-SW tectonic zone (Niigata-Kobe Tectonic Zone), which is an oblique trend of the geologicallydetected active structure with a N-S azimuth (the Itoigawa-Shizuoka Tectonic Line). Based on the contrast in fault architecture and the subsurface structures depicted using geophysical methods, the authors define another cross-arc structural component, the Echizen-Shima Tectonic Line. Forearc deformation closely linked to activity of this tectonic line is discussed in a chapter of this book [46]. Westerly subduction of the Philippine Sea Plate has provoked the transcurrent motion of the forearc sliver and active faulting upon the along-arc Median Tectonic Line. Surrounded by these regional tectonic zones, the Kinki district is studded by countless subordinate faults and suffers from differential motion of crustal blocks, which results in great diversity of basin formation.
