Japan Geoscience Union Meeting 2015

Presentation information


Symbol S (Solid Earth Sciences) » S-SS Seismology

[S-SS28] Active faults and paleoseismology

Wed. May 27, 2015 6:15 PM - 7:30 PM Convention Hall (2F)

Convener:*Takashi AZUMA(National Institute of Advanced Industrial Science and Technology), Nobuhiko Sugito(Faculty of Humanity and Environment, Hosei University), Satoshi Tonai(Department of Applied Science, Faculty of Scienece, Kochi University), Toshikazu Yoshioka(Active Fault and Earthquake Research Center, National Institute of Advanced Industrial Science and Technology)

6:15 PM - 7:30 PM

[SSS28-P25] Morphological features of offshore extension of the Futagawa-Hinagu fault zone

*Masatoshi YAGI1, Izumi SAKAMOTO1, Mikio FUJIMAKI2, Kenji NEMOTO1 (1.Tokai University, 2.Coastal Ocean Reseach Co,LTD)

Keywords:Futagawa-Hinagu fault zone, right-lateral strike-slip fault, flower structure

Futagawa-Hinagu fault zone (mainly right -lateral strike-slip faults) extends from Aso volcano to the Yatsushiro-sea (The Headquarters for Earthquake Research Promotion, 2002). A number of sub-aerial faults exist in the Yatsushiro-sea.
In acroteric part of strike-slip fault annihilation mechanism, develop complex structures (e.g. Kakimi and Kato, 1994). To comprehend these structures, it is necessary construct the research technique with three-dimensionally and high precision (Abe and Aoyanagi, 2004).
We have carried out the high-resolution seismic surveys with a series of cross sectional observations at the Yatsushiro-sea. Survey area divided into two sub-areas 1) North eastern area, and 2) South western area. We describe results for each sub-area as follow:
Sub-area 1
Main fault (MA fault) with NE-SW trending is distributed in this area. In-cross-sections, sub-vertical fault deformed the seafloor and sediments. Also, observed the flower structure. And displacement of faults becomes smaller to the south.
Sub-area 2
MA fault splayed off here. Almost these faults had normal components and forming a graben structure.
As described above, we have captured the features of the deformation structures, three-dimensionally.