Study of tectonic landforms and late Quaternary slip rates along the northern part of the Itoigawa-Shizuoka tectonic line, between Omachi city and Matsumoto city

• Published in: Active Fault Research Vol. 2006; no. 26; pp. 121 - 136
• Main Authors: Matsuta, Nobuhisa, Suzuki, Yasuhiro, Watanabe, Mitsuhisa, Ishiguro, Satoshi, Sakaue, Hiroyuki, Kumamoto, Takashi, Hirouchi, Daisuke, Ando, Toshihito, Tajikara, Masayoshi, Sawa, Hiroshi, Uchida, Chikara, Sato, Yoshiki, Taniguchi, Kaoru
• Format: Journal Article
• Language: Japanese
• Published: Japanese Society for Active Fault Studies 2006
• Subjects: fault morphology; ISTL active fault system; photogrammetric analysis; single vertical displacement; vertical slip rate; 写真測量; 単位鉛直変位量; 断層変位地形; 糸魚川-静岡構造線断層帯; 鉛直平均変位速度
• ISSN: 0918-1024; 2186-5337
• DOI: 10.11462/afr1985.2006.26_121

We conducted a tectonic geomorphological survey along the northern part of the Itoigawa-Shizuoka Tectonic Line (ISTL) with support from the Ministry of Education, Culture, Sports, Science and Technology of Japan as one of the intensive survey on ISTL fault system. This survey aims to clarify the detailed distribution of the slip rates of this fault system, which provides the essential data set to predict the coseismic behavior and to estimate the strong ground motion simulation. In order to achieve this purpose, the active fault traces are newly mapped along the northern part of the ISTL through interpretations of aerial photographs archived in the 1940s and 1960s at scales of 1: 10,000 and 1: 20,000, respectively. This aerial photo analysis was also supplemented and reinforced by field observations. One of the remarkable results by using this data set is a large number of, here 84, photogrammetrically measured landform transections to quantify the tectonic deformations. We could calculate vertical slip rates of the faults at 74 points, based on the estimated ages of terraces (H: 120 kyrs, M: 50-100 kyrs, Ll: 10-20 kyrs, L2: 4-7 kyrs, L3: 1-2 kyrs). The vertical slip rates distributed in the northern part of the study area show 0.2-5.5 mm/yr on the L terraces (less than 20 kyrs) and 0.05-0.9 mm/yr on the M and H terraces (more than 50 kyrs). The vertical slip rates of the faults located in the central and southern part of the study area are 0.2-3.1 mm/yr.