why do tectonic plates move

Tectonic plates move primarily because of forces generated by processes inside the Earth, especially heat-driven dynamics in the mantle. This movement is driven by three main mechanisms: mantle convection currents, ridge push, and slab pull. Mantle convection involves heat from radioactive decay and the Earth's core warming the mantle, causing hotter, less dense mantle material to rise and cooler, denser material to sink, creating circular currents that slowly move the rigid tectonic plates above. Ridge push occurs at mid-ocean ridges where new, hot, and elevated crust pushes older crust away due to gravity. Slab pull is the dominant force, where dense oceanic plates sink into the mantle at subduction zones, pulling the rest of the plate along with them. Together, these processes cause the plates to move slowly over the more ductile asthenosphere beneath them.