Reexamination of tectonic geomorphology of the southern part of the Matsumoto Basin and the southwestern margin of the Suwa Basin, along the middle part of the Itoigawa-Shizuoka Tectonic Line active fault system

• Published in: Active Fault Research Vol. 2007; no. 27; pp. 169 - 190
• Main Authors: Suzuki, Yasuhiro, Watanabe, Mitsuhisa, Ishiguro, Satoshi, Sakaue, Hiroyuki, Kumamoto, Takashi, Hirouchi, Daisuke, Tajikara, Masayoshi, Ando, Toshihito, Sugito, Nobuhiko, Sano, Shigeki, Sawa, Hiroshi, Uchida, Chikara, Sato, Yoshiki, Nozawa, Tatsujiro, Matsuta, Nobuhisa, Taniguchi, Kaoru
• Format: Journal Article
• Language: Japanese
• Published: Japanese Society for Active Fault Studies 2007
• Subjects: active fault; distribution of slip rate; Itoigawa-Shizuoka Tectonic Line active fault system; Matsumoto Basin; photogrammetric analysis; Suwa Basin; tectonic geomorphology; 写真測量; 変動地形; 平均変位速度分布; 松本盆地; 活断層; 糸魚川-静岡構造線活断層帯; 諏訪盆地
• ISSN: 0918-1024; 2186-5337
• DOI: 10.11462/afr1985.2007.27_169

We conducted a tectonic geomorphological survey in the southern part of the Matsumoto Basin and the south coast of the Suwa Basin, along the middle part of the Itoigawa-Shizuoka Tectonic Line (ISTL) active fault system. Procedures of this study are as follows; 1) aerial photo analysis and field surveys,2) mapping of geomorphic surfaces and reconstruction of geomorphic evolution,3) mapping of tectonic landforms which explain the geomorphic evolution reasonably,4) photogrammetrical measurement of vertical offset by construction of cross sections and calculation of vertical offset rates,5) measurement of horizontal offset of geomorphic markers and calculation of horizontal rates. Vertical/lateral offset rates were estimated based on vertical/lateral offset of geomorphic markers, such as terraces and ages of them (H: older than 120 ka, M1: 100 ka, M2: 40-65 ka, Lla: 20 ka, Lib: 10 ka, L2: 4-7 ka, L3: 1-2 ka). LiDAR method is also used for measurement of lateral offset Although mapped fault trace in the study area is similar to existing papers, different results were obtained in some areas. One of the remarkable results is that the Gofukuji fault in eastern margin of the Matsumoto Basin connects smoothly with the faults in northern end of the Suwa Basin. These faults have left lateral offset. We obtained 108 vertical/ left lateral offset rates in the study area. The vertical and leftlateral slip rates are estimated to be 0.1-2.0 mm/yr and 0.6-8.5 mm/yr, respectively.