HR: 1340h
AN: T13B-0472    [Abstracts]
TI: Water-saturated physical modeling of accretionary wedges
AU: * Yamada, Y
EM: yama@electra.kumst.kyoto-u.ac.jp
AF: Kyoto University, Yoshida, Sakyo, Kyoto, 606-8501 Japan
AU: Zhang, M
EM: m.zhang@aist.go.jp
AF: AIST, Higashi 1-1-1, Tsukuba, 305-8567 Japan
AU: Nakajima, H
EM: hidenaka@gmail.com
AF: AIST, Higashi 1-1-1, Tsukuba, 305-8567 Japan
AU: Driss, E
EM: driss@earth.kumst.kyoto-u.ac.jp
AF: Kyoto University, Yoshida, Sakyo, Kyoto, 606-8501 Japan
AB: Accretionary wedges have been an important research target from view points of earthquake mechanism at the subduction zone, sediment deformation that is closely coupled with hydrology, and resource exploration such as methane hydrates. The knowledge obtained from the study may also be useful for site selection of geological disposal of hazardous materials including radioactive nuclear wastes, in coastal areas of tectonically unstable island arc systems like Japan. The wedges have been well-investigated with analogue models in particular sandbox experiments that typically use dry granular materials, thus the inter-granular pore space of the sandbox experiments is filled with air. In natural sediments, however, the pore space is filled with formation water and its pressure has special effects on structural development. In order to accurately simulate the in-situ conditions and to examine the effects of water on the deformation process of accretionary wedge, a new apparatus was recently constructed in AIST, Japan, to perform physical analog experiments of accretionary wedges under water-saturated condition. For comparisons, equivalent experiments with dry materials were also conducted. The physical properties of the materials were also measured with tri-axial compression tests to interpret the experimental observations. Preliminary results obtained from this study showed that the fundamental parameters on structural geometry, such as taper angle and fault spacing, can be correlated well in wet and dry experiments. These are also in good agreement with physical properties obtained by the tri-axial compression tests, suggesting that the internal friction coefficient decreases as the overburden pressure increases. In the under water models, buoyancy decreases apparent grain density and overburden pressure thus the internal friction coefficient also decreases. This also agrees with the structural geometry of the experimental results. These results suggest that under-water experiments are feasible and well-calibrated by dry experiments.
UR: http://earth.kumst.kyoto-u.ac.jp/yamada/index_e.html
DE: 1847 Modeling
DE: 8020 Mechanics, theory, and modeling
DE: 8045 Role of fluids
DE: 8170 Subduction zone processes (1031, 3060, 3613, 8413)
DE: 8194 Instruments and techniques
SC: Tectonophysics [T]
MN: Fall Meeting 2005