Active faults and subsurface structure in Kinki Triangle Region, central Japan

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The result of this scientific research is summarized as below.Studies on main active fault systems in the Kinki Triangle region were carried out. There are Rokko-Awaji fault system, Median Tectonic Line fault .system (Wakayama and Tokushima Region), Western and Eastern margin fault system of Kyoto Basin, Hanaore fault system, and Suzuka -Toen fault system and so on. We have carried out geomorphological survey, geophysical prospecting, drilling, trench excavation, and collected the information on deformation mode and subsurface structure along the fault, displacement rate and age for fault activity. Especially, sampling by geoslicer and continuous analysis are shown most recent activities of the faults.Sediment samples from Nohbi Plain, Lake Biwa and Osaka Plain were analysed from the ^<14>C dating and volcanic glass chronology for establishing the chronology of Late Quaternary sediments.Drilling samples by Nojima Fault Prove project indicates vertical displacement during the Quaternary and thermal activity along the fault. Seismic reflection surveys and gravity measurement were carried out crossing the fault traces, and we obtained the information on subsurface structure.We checked the model on the formation of Osaka sedimentary basin on the basis of transcurrent movement of Median Tectonic Line and Arima-Takatsuki Tectonic Line. New method of minor faults analysis was also proposed on the basis of test by artificial data set, and applied to the field data of Quaternary sediments.