Thermal models of subduction zones revisited

Abstract:

At present, one of the prevailing hypotheses on the causes of intermediate-depth seismicity in subduction zones is that it stems from dehydration reactions. To assess this, accurate thermal models of subduction zones that predict where the dehydration reactions would occur are necessary for optimal comparison to observed intermediate-depth seismicity.

Here, we present two-dimensional models of subduction with a fixed kinematic slab and overriding plate and a dynamic mantle wedge to solve for the thermal structure of the subduction zone and the flow in the wedge. To obtain an accurate thermal structure of the subduction zone, we use temperature-dependent thermal conductivity, density, and heat capacity. We also use more complex plate cooling models for the oceanic plate beyond the commonly used half-space cooling model and plate cooling model.

We initially test the effect of the temperature-dependent thermal parameters and advanced oceanic plate cooling model for a general subduction zone geometry by comparing it to the commonly used alternatives of constant thermal parameters and the half-space cooling model and plate cooling model (Stein and Stein, 1992). We test various different implementations of the temperature-dependency of the thermal parameters. We then aim to apply this method to various subduction zones around the world and compare to the observed intermediate-depth seismicity.