Numerical Simulation of the Mantle Convection

The dynamics and evolution of the Earth's mantle are considered to be influenced by several complexities of the physical processes. In order to understand the mantle convection in the Earth, a numerical simulation is a very effective tool. Therefore, we have been improving the models which take into account of such difficult aspects as the large variation of viscosity and the existence of phase transitions. On the other hand, models of the internal structure and evolution of the mantle have been proposed based on the seismological and geological observations. The seismic tomography reveals the large scale flow of mantle convection, while the geologic data suggest that the mode and activity of the mantle convection vary episodically. Our goal is to construct the models of the mantle convection which are consistent with these observational results. In this fiscal year, our effort was focused on the improvement of the model involving the phase transition around the 660 km depth. We discuss the implication for the dynamics and evolution of the Earth's mantle.