Heat Flow of the Earth

1.1 Background Earth’s evolution reflects the history of heat transfer from the interior [53, 1101 via the fundamental processes of plate tectonics, conduction through continental lithosphere, and hotspot volcanism [103]. As a result, considerable attention has been directed toward understanding Earth’s thermal history, the variation in the temperature field in space and tune. The primary directly observable quantity for heat flow is the temperature gradient near the surface, which is in turn used to estimate the flow of heat from the interior and hence draw inferences about the thermal structure and evolution. The challenge is the classical one of using the measured temperature and temperature gradient at an object’s surface to infer the temperature field within the body, T(x,t), a function of position x and time t. Near the earth’s surface, the temperature gradient is essentially vertical, so the outward heat flow qs is