Abstract

Although Alfred Lothar Wegener proposed his continental drift hypothesis more than 100 years ago, there has been constant contention regarding the driving source of plate motions. The current geodynamic theory is mainly based on traditional mechanics. The crust is extremely thin in comparison to the earth’s radius, which may be caused by a more complex mechanical system: the mechanics of shells. The mechanics of shells reveals the mechanical effect of the tide-generating force on the earth’s crust. We present a formula that can be used to calculate the membrane stress resulting from the fluctuation of the mantle tide wave in the crust and estimate its magnitude. Although the tidal force is small, the membrane stress is high. Our investigation suggests that the membrane stress is the fundamental reason for rifting and rupture processes at mid-ocean ridges. It is thus the dynamic source for seafloor spreading and plate motion, which offers a reasonable interpretation of various significant problems that are unexplained by mantle convection theory. And there must be the plate tectonics affected by the tidal force is in the terrestrial planets or other celestial bodies.

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