[S-SS04] Nankai Trough Seismogenic Zone Experiment toward the final challenge

[SSS04-18] Discussion toward the final challenge of the Nankai Trough Seismogenic Zone Experiment

*金川 久一¹、Moore Gregory²、木下 正高³、Becker Keir⁴ (1.千葉大学大学院理学研究科、2.ハワイ大学マノア校、3.東京大学地震研究所、4.マイアミ大学)

キーワード：Nankai Trough、Seismogenic Zone、IODP

The Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) is a multidisciplinary investigation of fault mechanics and seismogenesis along the megathrust at the Nankai Trough subduction zone, and includes reflection and refraction seismic imaging, direct sampling by drilling, in situ measurements, and long-term monitoring in conjunction with laboratory and numerical modeling studies. During the past 11 IODP expeditions off Kii Peninsula since 2007, 15 sites have been drilled by D/V "Chikyu" down to depths from 100s of meters to more than 3000 meters below seafloor, where the inner and outer wedge of the Nankai margin has been sampled extensively, and two state-of-the-art real-time downhole observatories are now in operation. NanTroSEIZE is now at the final stage with only one more expedition planned for resuming riser drilling toward the megathrust at ~5200 meters below seafloor starting from October 2018. Here we will discuss on this final challenge, i.e., drilling plan including mud weight, logging tool options, cuttings and core analyses, and so on.