Shear strength of sediments approaching subduction in the Nankai Trough, Japan as constraints on forearc mechanics
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- Matt J. Ikari
- MARUM, Center for Marine Environmental Sciences University of Bremen Bremen Germany
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- Andre Hüpers
- MARUM, Center for Marine Environmental Sciences University of Bremen Bremen Germany
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- Achim J. Kopf
- MARUM, Center for Marine Environmental Sciences University of Bremen Bremen Germany
書誌事項
- 公開日
- 2013-08
- 権利情報
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- http://onlinelibrary.wiley.com/termsAndConditions#vor
- DOI
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- 10.1002/ggge.20156
- 公開者
- American Geophysical Union (AGU)
この論文をさがす
説明
<jats:p>The mechanical behavior of the plate boundary fault zone is of paramount importance in subduction zones, because it controls megathrust earthquake nucleation and propagation as well as the structural style of the forearc. In the Nankai area along the NanTroSEIZE (Kumano) drilling transect offshore SW Japan, a heterogeneous sedimentary sequence overlying the oceanic crust enters the subduction zone. In order to predict how variations in lithology, and thus mechanical properties, affect the formation and evolution of the plate boundary fault, we conducted laboratory tests measuring the shear strengths of sediments approaching the trench covering each major lithological sedimentary unit. We observe that shear strength increases nonlinearly with depth, such that the (apparent) coefficient of friction decreases. In combination with a critical taper analysis, the results imply that the plate boundary position is located on the main frontal thrust. Further landward, the plate boundary is expected to step down into progressively lower stratigraphic units, assisted by moderately elevated pore pressures. As seismogenic depths are approached, the décollement may further step down to lower volcaniclastic or pelagic strata but this requires specific overpressure conditions. High‐taper angle and elevated strengths in the toe region may be local features restricted to the Kumano transect.</jats:p>
収録刊行物
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- Geochemistry, Geophysics, Geosystems
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Geochemistry, Geophysics, Geosystems 14 (8), 2716-2730, 2013-08
American Geophysical Union (AGU)
