Distribution of stress state in the Nankai subduction zone, southwest Japan and a comparison with Japan Trench

• Published in: Tectonophysics 2016-12, Vol.692, p.120-130
• Main Authors: Lin, Weiren, Byrne, Timothy B., Kinoshita, Masataka, McNeill, Lisa C., Chang, Chandong, Lewis, Jonathan C., Yamamoto, Yuzuru, Saffer, Demian M., Casey Moore, J., Wu, Hung-Yu, Tsuji, Takeshi, Yamada, Yasuhiro, Conin, Marianne, Saito, Saneatsu, Ito, Takatoshi, Tobin, Harold J., Kimura, Gaku, Kanagawa, Kyuichi, Ashi, Juichiro, Underwood, Michael B., Kanamatsu, Toshiya
• Format: Article
• Language: English
• Subjects: Accretion; Compression; Convergence; Deepwater drilling; Distribution; Drilling; Earth Sciences; Earthquakes; Expeditions; Exploration; Forearc basins; Japan Trench; Multiship expeditions; Nankai subduction zone; Ocean drilling; Ocean floor; Oceanic trenches; Plate convergence; Plate tectonics; Sciences of the Universe; Seismic activity; Shelf edge; Stress; Stress concentration; Stress state; Subduction; Subduction (geology); Subduction zones; Trenches (pipelines)
• ISSN: 0040-1951; 1879-3266
• DOI: 10.1016/j.tecto.2015.05.008

To better understand the distribution of three dimensional stress states in the Nankai subduction zone, southwest Japan, we review various stress-related investigations carried out in the first and second stage expeditions of the Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) by the Integrated Ocean Drilling Program (IODP) and compile the stress data. Overall, the maximum principal stress σ1 in the shallower levels (~1km below seafloor or in underlying accretionary prism) with σ1 becoming horizontal is also suggested at all deeper drilling sites. We also make a comparison of the stress state in the hanging wall of the frontal plate-interface between Site C0006 in the Nankai and Site C0019 in the Japan Trench subduction zone drilled after the 2011 Mw 9.0 Tohoku-Oki earthquake. In the Japan Trench, a comparison between stress state before and after the 2011 mega-earthquake shows that the stress changed from compression before the earthquake to extension after the earthquake. As a result of the comparison between the Nankai Trough and Japan Trench, a similar current stress state with trench parallel extension was recognized at both C0006 and C0019 sites. Hypothetically, this may indicate that in Nankai Trough it is still in an early stage of the interseismic cycle of a great earthquake which occurs on the décollement and propagates to the toe (around site C0006). •We compiled stress data obtained in 1st and 2nd stage expeditions of NanTroSEIZE.•Overall, the maximum principal stress in the shallower levels is vertical.•The maximum horizontal stress is generally parallel to plate subducting.•An exception of trench parallel SHmax occurs along the shelf edge of Nankai margin.•The stress state at frontal plate interface in Nankai now is dominantly extensional.