TY - JOUR
T1 - In Situ Stress and Pore Pressure in the Deep Interior of the Nankai Accretionary Prism, Integrated Ocean Drilling Program Site C0002
AU - Kitajima, Hiroko
AU - Saffer, Demian
AU - Sone, Hiroki
AU - Tobin, Harold
AU - Hirose, Takehiro
N1 - Funding Information:
1Center for Tectonophysics and Department of Geology and Geophysics, Texas A&M University, College Station, TX, USA, 2Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology, Tsukuba, Japan, 3Department of Geosciences and Center for Geomechanics, Geofluids, and Geohazards, Pennsylvania State University, University Park, PA, USA, 4Department of Civil and Environmental Engineering, University of Wisconsin-Madison, Madison, WI, USA, 5Department of Geosciences, University of Wisconsin-Madison, Madison, WI, USA, 6Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology, Nangoku, Japan
Funding Information:
This research used samples and data provided by the IODP, and we thank the ship’s crew, technicians, and scientific party on the D/V Chikyu during the NanTroSEIZE Expeditions. The data used in this study are freely available upon request to authors and the IODP CDEX SIO7 data center (http://sio7.jamstec.go. jp). This research was supported by a NSF-MARGINS Postdoctoral Fellowship (NSF grant OCE-1049591) to H. K. and D. S., the IODP Expeditions 338 and 348 After Cruise Research Program, Japan Agency for Marine-Earth Science and Technology (JAMSTEC) to H. K., and the Ministry of Education, Culture, Sports, Science and Technology (MEXT) Grant-in-Aid for Scientific Research on Innovative Areas (MEXT KAKENHI grant JP21107004) to H. K. and T. H. We thank Masataka Kinoshita and Susan Ellis for their helpful comments.
Publisher Copyright:
©2017. American Geophysical Union. All Rights Reserved.
PY - 2017/10/16
Y1 - 2017/10/16
N2 - Strength and slip behaviors of subduction megathrusts are controlled by the physical properties and stress state not only of the fault zones themselves but also the adjacent wall rocks in overriding and subducting plates. In the Nankai Trough, a 3 km deep riser borehole at Integrated Ocean Drilling Program Site C0002 was drilled into the Kumano fore-arc basin and the underlying accretionary prism. We quantify the full in situ stress tensor and pore pressure at Site C0002 by integrating drilling data, geophysical logging, and downhole measurements using empirical relations that describe sediment compaction behavior as a function of loading path. The Kumano Basin is loaded in uniaxial vertical strain conditions, whereas the prism below is loaded with greater differential stress, has a modestly elevated pore pressure, and lies in a strike-slip faulting regime. This can be reconciled with slip on the megathrust fault if the horizontal stresses vary with time or depth and/or if shear stress along the megathrust is low.
AB - Strength and slip behaviors of subduction megathrusts are controlled by the physical properties and stress state not only of the fault zones themselves but also the adjacent wall rocks in overriding and subducting plates. In the Nankai Trough, a 3 km deep riser borehole at Integrated Ocean Drilling Program Site C0002 was drilled into the Kumano fore-arc basin and the underlying accretionary prism. We quantify the full in situ stress tensor and pore pressure at Site C0002 by integrating drilling data, geophysical logging, and downhole measurements using empirical relations that describe sediment compaction behavior as a function of loading path. The Kumano Basin is loaded in uniaxial vertical strain conditions, whereas the prism below is loaded with greater differential stress, has a modestly elevated pore pressure, and lies in a strike-slip faulting regime. This can be reconciled with slip on the megathrust fault if the horizontal stresses vary with time or depth and/or if shear stress along the megathrust is low.
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U2 - 10.1002/2017GL075127
DO - 10.1002/2017GL075127
M3 - Article
AN - SCOPUS:85030626421
VL - 44
SP - 9644
EP - 9652
JO - Geophysical Research Letters
JF - Geophysical Research Letters
SN - 0094-8276
IS - 19
ER -