Segmentation, subsurface structure, earthquake history, and seismic hazard evaluation of long active faults

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In this project, we have conducted various researches on large active faults in Japan. In northwestern Hokkaido, crustal shortening rate was estimated for the Teshio fault zone (Echigo et al.,2006). In Tohoku district, slip rates and earthquake history were constructed for the active faults in Nagai and Aizu basins (Nakamura et al.,2006). After the 2004 Mid-Niigata Prefecture earthquake, Kim and Okada (2005) conducted geomorphic survey of the epicentral area. High-density gravity survey was also conducted by Toda et al.(2005) in conjunction with seismic reflection survey by ERI, University of Tokyo. In Kinki district, Ishiyama and Mueller (2005) examined relationship between surface deformation and subsurface fault structure for the Yoro-Kuwana fault zone. Komatsubara (2006) constructed slip rate distribution of the fault zone on the western margin of Lake Biwa : the maximum slip rate of 1.2-2.3 mm/yr is identified along the central portion of the fault zone. Toda (2006) compiled data on seismic reflection profiles and gravity surveys in Kinki district and discussed tectonic evolution of the study area. Nishiyama et al.(2005) identified faults that ruptured during the 1662 Kanbun earthquake. Okada (2006) pointed out that the last faulting event on the Median Tectonic Line in Shikoku triggered rupture of the Arima-Takatsuki fault zone. In central Kyushu, slip rates and paleoseismic activities of normal faults in Beppu and Unzen grabens were examined by field mapping and trenching studies (Takemura et al.,2005;Takemura,2006;Matsuoka et al.,2005). In order to better predict strong ground motion associated with large earthquakes on active faults, fault parameters and their statistical treatment were discussed by Kumamoto (2005,2006) and Kumamoto and Hamada (2005).