mantle convection

Mantle convection is the process by which heat from Earth's interior causes the mantle's material to circulate in a circular pattern. This circulation is believed to be the primary driver of tectonic plate movement. The heat source for these currents is thought to be the decay of radioactive elements within the Earth.12

This convective circulation is a form of solid-state creep, where warmer, buoyant material rises and cooler, denser material sinks. While the exact mechanisms are still debated, forces like "slab pull" (where a sinking oceanic plate drags the rest of its plate) and "ridge push" (gravity pulling denser rocks away from elevated mid-ocean ridges) also contribute to plate movement. Seismic tomography provides 3D images of Earth's interior, revealing warmer, slower-moving areas beneath oceanic ridges and cooler, faster regions beneath subduction zones.213