| Budget Amount *help |
¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 1989: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1988: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1987: ¥700,000 (Direct Cost: ¥700,000)
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| Research Abstract |
The Atera fault forms a master fault system with predominantly left-lateral component of displacement and has been studied by several trenchings. Comparing these results it has been clarified that the main fault would simultaneously dislocate through the whole trace with large earthquakes, as each trench has the similar recurrence interval. As this fault has rather complex fault pattern, detailed traces and classification of faults were mapped by photo-interpretation on a scale of 1:25,000.
The excavation study for major active faults on land in Japan has been aimed principally at revealing ages of each event of faulting and real recurrence intervals during, at least, the last several thousand years. The precise data of the last prehistoric event are particularly important for evaluating future seismic hazard. Therefore, carbon-14 datings and archaeological methods were used to determine the strata and events. From these investigations, rupture event, recurrence interval, subsurface structure of fault and behaviors of faulting and so on were clarified for the major active faults, especially Atotsugawa fault, Itoigawa-Shizuoka Tectonic Line ( central part), Median Tectonic Line Okamura fault) and Atera fault. Detailed description and information were published with each papers listed on references below.
A comprehensive book entitled with "Active Tectonics in Kyushu" was published from the University of Tokyo Press. Okada is the chief author in this. This book aims to present such data as active tectonics(active fault, folding, regional uplift and subsidence etc.), classification of the geonorphological surfaces, distribution of the landslide, and volcanic elements in the form of sheet maps on the scale of 1:50,000. Especially, this book provides detailed informations on active faults in Kyushu and clarified the zonal arrangements, regional setting and relationship to the earthquakes of active faults.
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