Stress geomechanical model application; stress tensor evaluation in recent Nankai subduction zone, SW Japan

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Author(s): Wu, Hung-Yu; Chan, Chung-Han
Author Affiliation(s): Primary:
JAMSTEC Japan Agency for Marine-Earth Science and Technology, Kanagawa, Japan
Nanyang Technological University, Singapore
Volume Title: AGU 2016 fall meeting
Source: American Geophysical Union Fall Meeting, Vol.2016; American Geophysical Union 2016 fall meeting, San Francisco, CA, Dec. 12-16, 2016. Publisher: American Geophysical Union, Washington, DC, United States
Note: In English
Summary: Nowadays, IODP keeps investigating the scientific drilling in Nakai of southwest Japan from 2006. During this decade, we collected the massive logging data and core samples in this area for determining the stress evolution in this interseimic period after 1944 Tonakai earthquake. One of key assumption in Nankai seismogenic zone is the stress accumulation on the plate boundary should be the thrust-fault stress regime (Smax>Shmin>Sv). In this research, the slip-deficit model is used to determine the wide scale stress field. The drilled IODP well sites are designed to be the fine control points. Based on the multiple ICDP expeditions near the Nankai trough (C0002A, F, and P) in different depths, the three dimensional stress estimation can be confirmed with the lateral boreholes loggings. Even the recently drilling did not reach the subduction zone, our model provides the considerable results by the reliable boundary conditions. This model simulated the stress orientation and magnitude generated by the slip-deficit model, area seismicity, and borehole loggings. Our results indicated that the stress state keeps in normal-faulting stress regime in our research area, even near the Nankai trough. Although the stress magnitude is increasing with the depth, one of horizontal principal stresses (Shmin) is hardly greater than the vertical stress (over-burden weight) in the reachable depth (>10 km). This result implies the pore-pressure anomaly would happen during the slip and the stress state would be varied in different stages when event occurred
Year of Publication: 2016
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 07 Marine Geology and Oceanography; IODP Site C0002; Integrated Ocean Drilling Program; Kumano Basin; Mechanical properties; Moment tensors; NanTroSEIZE; Nankai Trough; North Pacific; Northwest Pacific; Pacific Ocean; Plate tectonics; Subduction zones; West Pacific
Coordinates: N331800 N331801 E1363801 E1363800
Record ID: 2017046140
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