Holocene tectonics under tensional stress field in the mid-kyushu

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1. Submarine active faults distributed in and around the middle part of Kyushu were mapped using by high-resolution seismic survey and sediment sampled by piston coring.2. Submarine active fault found in the Omura Bay has cummulative displacement in the Holonene sdiment. Two cores were sampled from the both-side of the fault. Three times seismic events were recognized from the cores under precise correlation of the cores. The recurrence interval of seismic event estimated 3000 years, and each vertical displacement shows 30cm.3. The Hinagu fault were newly found in the Yatsushiro Sea, which show typical strike-slip drug fault. Fault activities analysed from the cores were two-times at least in the Holocene. Total vertical displacement of the Hinagu submarine fault shows 10 meters among the Holocene sediments.4. In the Ariake Sea, we found three small Holocene gravens extend from east to west.