The distributions of number and energy of earthquakes versus depth are not uniform as well: 76%of the total earthquakes dissipates about 60%of the total energy in the first ~ 50 km; only 6%of events dissipates about 20%of the total amount of energy in a narrow depth interval, at the lower boundary of the upper mantle (550-680 km). Therefore, only the remaining 20%of energy is released along most of the depth extent of subduction zones (50-550 km). Since the energetic release along slabs is a minor fraction of the total seismic budget, the role of the slab pull appears as ancillary, if any, in driving plate tectonics. Moreover the concentration of seismic release in the not yet subducted lithosphere suggests that the force moving the plates acts on the uppermost lithosphere and contemporaneously all over the Earth's outer shell, again supporting a rotational/tidal modulation.