Our modeling results indicate that fluids introduced along the base of the mantle wedge beneath the fore arc are initially dragged downdip by corner flow due to the small grain size and low permeability immediately above the slab. As grain size increases with depth, permeability increases, resulting in upward fluid migration. Fluids released beneath the arc and the back arc are also initially dragged downdip, but typically are not transported as far laterally before they begin to travel upward. As the fluids rise through the back-arc mantle wedge, they become deflected toward the trench due to the effect of mantle inflow. The combination of downdip migration in the fore arc and trench-ward migration in the back arc results in pathways that focus fluids beneath the arc.
