Estimation of slip rate and fault displacement during shallow earthquake rupture in the Nankai subduction zone

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doi: 10.1186/s40623-015-0208-0
Author(s): Hamada, Yohei; Sakaguchi, Arito; Tanikawa, Wataru; Yamaguchi, Asuka; Kameda, Jun; Kimura, Gaku
Author Affiliation(s): Primary:
Japan Agency for Marine-Earth Science and Technology, Kochi Institute for Core Sample Research, Nankoku, Japan
Other:
Yamaguchi University, Japan
University of Tokyo, Japan
Hokkaido University, Japan
Volume Title: Earth, Planets and Space
Source: Earth, Planets and Space, 67(1). Publisher: Terra Scientific Publishing Company (TERRAPUB), Tokyo, Japan. ISSN: 1343-8832
Note: In English. 46 refs.; illus., incl. sect., 1 table, sketch map
Summary: Enormous earthquakes repeatedly occur in subduction zones, and the slips along megathrusts, in particular those propagating to the toe of the forearc wedge, generate ruinous tsunamis. Quantitative evaluation of slip parameters (i.e., slip velocity, rise time and slip distance) of past slip events at shallow, tsunamigenic part of the fault is critical to characterize such earthquakes. Here, we attempt to quantify these parameters of slips that may have occurred along the shallow megasplay fault and the plate boundary décollement in the Nankai Trough, off southwest Japan. We apply a kinetic modeling to vitrinite reflectance profiles on the two fault rock samples obtained from Integrated Ocean Drilling Program (IODP). This approach constitutes two calculation procedures: heat generation and numerical profile fitting of vitrinite reflectance data. For the purpose of obtaining optimal slip parameters, residue calculation is implemented to estimate fitting accuracy. As the result, the measured distribution of vitrinite reflectance is reasonably fitted with heat generation rate (Q) and slip duration (tr) of 16,600 J/s/m2 and 6,250 s, respectively, for the megasplay and 23,200 J/s/m2 and 2,350 s, respectively, for the frontal décollement, implying slow and long-term slips. The estimated slip parameters are then compared with previous reports. The maximum temperature, Tmax, for the Nankai megasplay fault is consistent with the temperature constraint suggested by a previous work. Slow slip velocity, long-term rise time, and large displacement are recognized in these fault zones (both of the megasplay, the frontal décollement). These parameters are longer and slower than typical coseismic slip, but are rather consistent with rapid afterslip. Copyright 2015 The Author(s) and Hamada et al.; licensee Springer.
Year of Publication: 2015
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 16 Structural Geology; 19 Geophysics, Seismology; Accretionary wedges; Decollement; Displacements; Earthquakes; Expedition 316; Faults; Friction; Geologic thermometry; Heating; IODP Site C0004; IODP Site C0007; Integrated Ocean Drilling Program; Megasplay faults; Models; NanTroSEIZE; Nankai Trough; North Pacific; Northwest Pacific; Pacific Ocean; Shallow-focus earthquakes; Shear stress; Slip rates; Subduction zones; Temperature; Thermal maturity; Tsunamis; Velocity; Vitrinite reflectance; West Pacific
Coordinates: N330114 N330119 E1364757 E1364753
N331300 N331300 E1364300 E1364300
Record ID: 2017014938
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data supplied by Springer Verlag, Berlin, Federal Republic of Germany