What is the mechanism driving tectonic plate movement?

• A. Convection currents of rising and falling magma
• B. Solar energy input at the surface
• C. Tidal forces from the Moon
• D. Differences in atmospheric pressure over continents

Answer: (A)

Mantle convection is the main driver of tectonic plate movement. Heat from Earth’s interior causes mantle rock to rise in hot regions and sink in cooler regions, creating a slow, global circulation beneath the lithosphere. These convection currents drag the rigid plates above on the viscoelastic asthenosphere, with upwelling at mid-ocean ridges pushing plates apart and sinking slabs at subduction zones pulling them back. Solar energy, tidal forces, and atmospheric pressure don’t generate the deep, long-term mantle flow needed to move these plates.