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doi:10.2204/iodp.proc.314315316.219.2012

Introduction

Geomechanical measurements of sediment deformation are essential for understanding sediment dynamics and faulting processes in convergent margins. During the interseismic period, faults build up stress that is relieved during earthquakes. Here, we employ slide-hold-slide tests during 16 friction experiments in order to simulate the seismic cycle (Dieterich, 1972). From these experiments, we extract rates of frictional healing and associated rates of compaction during hold periods. We also measure the compressibility and Young’s modulus of the sheared, saturated sediment, which are basic and important elastic parameters. Hydrologic properties of rock and sediment, for example, are controlled by the elastic response of a porous media to applied stresses (e.g., Biot, 1941). The samples we tested were recovered during Integrated Ocean Drilling Program (IODP) Expedition 316, part of the Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) project, in 2007–2008. During this expedition, several sites were drilled and cored along a transect offshore of the Kii Peninsula, Japan (Fig. F1), to investigate shallow fault zones. We studied samples from two sites: IODP Site C0004, which sampled the shallow portion of a major out-of-sequence thrust fault (the megasplay fault), and IODP Site C0007, which sampled the frontal thrust region near the toe of the accretionary prism (Fig. F2).