A comparison of mantle convection models featuring plates

Oceanic plates are an integral part of the Earth's mantle and thus play an important role in its dynamics and evolution. To allow plate behavior to arise naturally in numerical mantle convection models, self-consistent plate generation methods apply a fully rheological approach (featuring a temperature-, pressure- and stress-dependent viscosity). However, due to the extreme local viscosity changes that the self-generation of model plates entails, their computational requirements are demanding. Alternative plate modeling methods specify the existence of plates explicitly but can also obtain dynamically determined velocities (e. g., by employing a force-balance method). Here we present modifications to a force-balance model by utilizing a rheology-dependent viscosity profile. Accordingly, plate viscosity and plate thickness are no longer prescribed by the modeler but now follow as a dynamic consequence of the temperature and stress dependence of the viscosity and the model's evolution. We describe the new method and present benchmark results for a rheologically self-consistent mantle convection model and the modified force-balance plate model. Our results show that both plate modeling methods lead to the same system behavior for a wide range of system parameters making the new method a powerful tool to also achieve plate-like surface motion naturally.