Distribution of active faults and change of seismic activity in and around Japan South Alps
226 , 2016-03-04 , 山梨大学教育人間科学部
Hypocenter maps (flat patterns, east-west and north-south cross sections) in and around Japan South Alps have been made to investigate the relationship between the distribution of active faults and change of seismic activity. At the north and east edges of Japan South Alps, the Itoigawa-Shizuoka Tectonic Line Active Fault System (ISTL-AFS) is located. After the 2011 off the Pacific coast of Tohoku Earthquake (M9.0), seismic activity has become more active along the Gofukuji fault, which is a part of the ISTL-AFS and is located at the northwest of Lake Suwa. However, seismic activity has hardly been observed along the ISTL-AFS in the south region of Lake Suwa before and after the 2011 Earthquake, implying that seismic activity is not concerned with the ISTL-AFS in the south region of Lake Suwa. More active seismic activity occurs along the north-northwest - south-southeast (NNW-SSE) line, which is an extension line of the Gofukuji fault and is not coincident with the ISTL-AFS, so that in the future large earthquakes may occur along this extension line rather then the ISTL-AFS.