JpGU-AGU Joint Meeting 2017

Presentation information

[EJ] Oral

S (Solid Earth Sciences) » S-SS Seismology

[S-SS12] [EJ] Active faults and paleoseismology

Tue. May 23, 2017 10:45 AM - 12:15 PM A04 (Tokyo Bay Makuhari Hall)

convener:Mamoru Koarai(Earth Science course, College of Science, Ibaraki University), Nobuhiko Sugito(Faculty of Humanity and Environment, Hosei University), Nobuhisa Matsuta(Okayama University Graduate School of Education), Ken-ichi Yasue(Japan Atomic Energy Agency), Chairperson:HISAO KONDO(Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology), Chairperson:Tatsuya Ishiyama(Earthquake Research Institute, University of Tokyo)

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.

*Shintaro Abe1, Takashi OGAMI2, Hiroshi Mori3, Kenjiro Mukaiyama4, Naohiro Kazui4 (1.Advanced Industrial Science and Technology, 2.Chuo Univ., 3.Shinshu Univ., 4.Kawasaki Geological Engineering Co.,Ltd)

Keywords:the Nagaoka-Heiya-Seien Fault zone, active structure, high-resolution seismic reflection survey

We conducted offshore active-fault survey on the offshore extension of the Nagaoka-Heiya-Seien Fault zone. We obtained high-resolution multi-channel seismic reflection data (150 km total length) and 2 sedimentary cores. Existing survey data are also examined in this study.
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.