12:00 PM - 12:15 PM
[SSS12-18] Spatial distribution of active structure and the activity in the offshore extension of the Nagaoka-Heiya-Seien Fault zone.
Keywords:the Nagaoka-Heiya-Seien Fault zone, active structure, high-resolution seismic reflection survey
Results of the seismic reflection survey revealed distinctive subsurface flexure structure along the fault zone. The subsurface structure extends to an uplift bulge (lying NE-SE), and fades out. We recognized surface deformations at several areas, and they possibly indicate the latest event.
We investigated recent sedimentary record based on the newly obtained cores and existing submarine borehole logs. We also reconstructed age-depth curves for the cores based on radiocarbon dating. Sedimentation rates at the footwall(subsiding) side excess those at the hanging-wall(uplifting) side. We calculated averaged vertical
deformation rate as 3.8 m/ky based on both the seismic profiles and the age-depth curves.