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Subduction and Heat Flow

GEOPHYSICS
Quantitating the heat flux at the core-mantle boundary is important for understanding the cooling of the core, the convection of the mantle, and the movement of tectonic plates. This heat flux has been estimated indirectly as the heat flowing out at volcanic hotspots, about 2 terawatts. Labrosse has developed a refined numerical model that includes convection between isothermal layers and internal heating in the mantle. The simulations show that most of the hot plumes upwelling from the boundary do not make it all the way to the surface, so that looking only at hotspots (generated by the hot plumes) will underestimate the total heat flow from the core into the mantle. It appears that the downward flow of cold plumes from the surface toward the core, such as occurs at subduction zones, dominates the permeation of rising plumes and the heat flux across the core-mantle boundary, which is estimated from these simulations to total 6 terawatts. — LR 

Earth Planet. Sci. Lett. 199 , 147 (2002).