Deformable backstop as seaward end of coseismic slip in the Nankai Trough seismogenic zone

被引:38
作者
Nakanishi, A [1 ]
Kodaira, S [1 ]
Park, JO [1 ]
Kaneda, Y [1 ]
机构
[1] Japan Marine Sci & Technol Ctr, Inst Frontier Res Earth Evolut, Yokosuka, Kanagawa 2370061, Japan
关键词
subduction zones; velocity structure; accretionary wedges; coseismic processes;
D O I
10.1016/S0012-821X(02)00866-X
中图分类号
P3 [地球物理学]; P59 [地球化学];
学科分类号
0708 ; 070902 ;
摘要
Wide-angle seismic surveys performed in the last decade have clarified the 3-D crustal structure along the Nankai Trough. The geometry and velocity structure of the southwestern Japan subduction zone are now well constrained. Comparing these observations with the rupture distribution of historic great thrust earthquakes, it appears that the coseismic rupture occurred along plate boundaries deeper than the wedge/backstop boundary (the boundary between the Neogene Quaternary accretionary wedge and the crust forming the backstop). From the view of spatial relationship, both rupture distributions of the last two large events and the crust forming the backstop are considerably retreated from the trough axis in the west and east off the Kii Peninsula. In both areas, seamount or ridge subduction is apparent in seismic results, geomorphological data and geomagnetic data. The landward indentation of the deformable backstop, which corresponds to the crustal block of old accreted sediments, may be formed by seamount subduction according to published results of sandbox modeling. In particular, the subducted seamount may be a structural factor affecting the recession of the crustal block forming the backstop. (C) 2002 Elsevier Science B.V. All rights reserved.
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页码:255 / 263
页数:9
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