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Elastoplastic Deformation in a Wedge-Shaped Plate Caused by a Subducting Seamount

M. Ding1 J. Lin2
1MIT/WHOI Joint Program in Oceanography, Cambridge, MA, USA
2Woods Hole Oceanographic Institution, Woods Hole, MA, USA

Snapshots showing a sequence of faults cutting though the entire plates: (a) right-dipping normal fault; (b) left-dipping normal fault; (3) right-dipping thrust fault; and (d) left-dipping thrust fault. ╬Áp is the second invariant of the plastic strain tensor, with blue color indicating elastic regions. Deformation of the modeled domain is exaggerated by a factor of 50.

We used COMSOL Multiphysics 4.3 to simulate the 2D elastoplastic deformation and plastic strain in a wedge-shaped plate above a subducting interface. The modeling results reveal that a pair of conjugate normal faults would first appear in the thinner part of the plate. Subsequently, a second pair of conjugate thrust faults would form in the thicker part of the plate. The duration of the seamount movement required for these faults to cut through the entire plate is larger for deeper seamounts, greater dipping angles of the plate, and for the Mohr-Coulomb than for Von Mises criteria. Our models provide a quantitative way to investigate the time-dependent lithospheric deformation and fault formation processes during seamount subduction.

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