Abstract
Subduction zones often extend many thousands of kilometers along strike and can exhibit significant along-strike variations in the thickness, geometry and/or rheology of the overriding plate, the subducting slab, or the interface between the two. Because of the extensiveness of subduction zones along-strike, many previous studies have used 2D subduction models to simulate an infinitely long zone with variable degrees of model complexity. While 2D models can evaluate how a wide range of parameters affect a homogenous along-strike system, how such endmembers interact with each other in three-dimensions is poorly understood. We develop self-consistent 3D subduction models using the finite element code ASPECT to examine how along-strike variations affect subduction dynamics. We set up a three-dimensional model that includes a thermally-defined dense subducting plate, a buoyant and stiff overriding plate, and a constant-viscosity crust/interface. We vary three parameters along-strike: 1) thickness of the interface shear zone, 2) viscosity of the interface shear zone, and 3) thickness of the overriding plate (which controls the length of the interface shear zone). We explore how varying each of these parameters affects slab morphology, overriding plate strain distribution, and subduction, convergence, and trench rollback velocities. Preliminary results suggest that along-strike changes in interface properties (e.g., the weakness or thickness) do not drastically alter slab morphologies, and that the 3D system is most affected by the strongest or thickest portions of the interface. However, there are noticeable along-strike differences in overriding plate strain accommodation- subduction segments with thicker/stronger interfaces distribute strain over a wider region. Along-strike changes to overriding plate thickness leads to drastic differences in both slab morphology and surface strain accommodation. In this case, slab dip decreases as overriding plate thickness increases. This leads to a wider surface strain distribution in the overriding plates within regions where it is thicker. Additional results will be presented at the meeting after further analysis.