Pressure dependence of fluid transport properties of shallow fault systems in the Nankai subduction zone

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doi: 10.1186/1880-5981-66-90
Author(s): Tanikawa, Wataru; Mukoyoshi, Hideki; Lin, Weiren; Hirose, Takehiro; Tsutsumi, Akito
Author Affiliation(s): Primary:
Japan Agency for Marine-Earth Science and Technology, Kochi Institute for Core Sample Research, Nankoku, Japan
Other:
Marine Works Japan, Japan
Kyoto University, Japan
Volume Title: Earth, Planets and Space
Source: Earth, Planets and Space, 66(1). Publisher: Terra Scientific Publishing Company (TERRAPUB), Tokyo, Japan. ISSN: 1343-8832
Note: In English. 35 refs.; illus., incl. 1 table, sect.
Summary: We measured fluid transport properties at an effective pressure of 40 MPa in core samples of sediments and fault rocks collected by the Integrated Ocean Drilling Program (IODP) NanTroSEIZE drilling project Expedition 316 from the megasplay fault system (site C0004) and the frontal thrust (site C0007) in the Nankai subduction zone. Permeability decreased with effective pressure as a power law function. Permeability values in the fault zones were 8 × 10-18 m2 at site C0004 and 9 × 10-18 m2 at site C0007. Stratigraphic variation in transport properties suggests that the megasplay fault zone may act as a barrier to fluid flow, but the frontal thrust fault zone might not. Depth variation in permeability at site C0007 is probably controlled by the mechanical compaction of sediment. Hydraulic diffusivity at shallow depths was approximately 1 × 10-6 m2 s-1 in both fault zones, which is small enough to lead to pore pressure generation that can cause dynamic fault weakening. However, absence of a very low permeable zone, which may have formed in the Japan Trench subduction zone, might prevent facilitation of huge shallow slips during Nankai subduction zone earthquakes. Porosity tests under dry conditions might have overestimated the porosity. Copyright 2014 The Author(s) and Tanikawa et al.; licensee Springer.
Year of Publication: 2014
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 07 Marine Geology and Oceanography; 18 Geophysics, Solid-Earth; Compaction; Cores; Depth; Expedition 316; Fault zones; Faults; Fluid flow; Hydraulic diffusivity; IODP Site C0004; IODP Site C0007; Integrated Ocean Drilling Program; Japan Trench; Laboratory studies; Marine sediments; Megasplay faults; NanTroSEIZE; Nankai Trough; North Pacific; Northwest Pacific; Pacific Ocean; Permeability; Pore pressure; Porosity; Pressure; Sediments; Subduction zones; Transport; West Pacific
Coordinates: N331300 N331300 E1364300 E1364300
N330114 N330119 E1364757 E1364753
Record ID: 2017026348
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