The heat flux emerging from Earth towards the surface.
The mean value is 70.9 mW/m2 over continental crust and 105.4 mW/m2 over oceanic crust (see [1]).
See also
Physics / Thermodynamics / Heat Transfer / Heat flow / Heat Flux
Reference
Davies, J. H., & Davies, D. R. (2010). Earth's surface heat flux. Solid Earth, 1(1), 5–24.