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GEOPHYSICAL RESEARCH LETTERS, VOL. 32, L12306, doi:10.1029/2004GL021861, 2005

Initiation of plate boundary slip in the Nankai Trough off the Muroto peninsula, southwest Japan

Takeshi Tsuji

Ocean Research Institute, The University of Tokyo, Tokyo, Japan


Toshifumi Matsuoka

Graduate School of Engineering, Kyoto University, Kyoto, Japan


Yasuhiro Yamada

Graduate School of Engineering, Kyoto University, Kyoto, Japan


Yasuyuki Nakamura

Ocean Research Institute, The University of Tokyo, Tokyo, Japan


Juichiro Ashi

Ocean Research Institute, The University of Tokyo, Tokyo, Japan


Hidekazu Tokuyama

Ocean Research Institute, The University of Tokyo, Tokyo, Japan


Shin'ichi Kuramoto

Center for Deep Earth Exploration, Japan Marine Science and Technology Center, Yokohama, Japan


Nathan L. Bangs

Institute for Geophysics, University of Texas at Austin, Austin, Texas, USA


Abstract

To investigate variations in physical properties accompanying the development of the décollement, we used a neural network analysis of seismic attributes derived from 3D seismic reflection data gathered in the Nankai Trough convergent margin off the Muroto peninsula of southwest Japan. This analysis resulted in a detailed map of the geological features along the décollement and revealed a drastic change in physical properties at the sole of the proto-thrust. Ocean Drilling Program (ODP) data suggest that the décollement physical property change coincides with the initiation of slip. Furthermore, changes in the structure of the accretionary prism and reorganization of the décollement geometry also attend the initiation of plate boundary slip.

Received 28 October 2004; accepted 18 May 2005; published 21 June 2005.

Index Terms: 0500 Computational Geophysics (3200, 3252, 7833); 0900 Exploration Geophysics; 3000 Marine Geology and Geophysics; 8000 Structural Geology; 8100 Tectonophysics.


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Citation: Tsuji, T., T. Matsuoka, Y. Yamada, Y. Nakamura, J. Ashi, H. Tokuyama, S. Kuramoto, and N. L. Bangs (2005), Initiation of plate boundary slip in the Nankai Trough off the Muroto peninsula, southwest Japan, Geophys. Res. Lett., 32, L12306, doi:10.1029/2004GL021861.