Tectonic plates move primarily due to forces generated by heat within the Earth's interior, which drive convection currents in the mantle. These convection currents cause the hot, semi-fluid mantle rock to slowly flow, carrying the rigid plates of the lithosphere on top with it
. Key mechanisms of plate movement include:
- Mantle Convection: Heat from radioactive decay in the Earth's core causes mantle rock to heat up, become less dense, and rise. As it cools near the surface, it sinks back down, creating circular convection currents that drag plates along
- Slab Pull: The most significant force driving plate motion. When a dense oceanic plate sinks into the mantle at a subduction zone, gravity pulls the rest of the plate along with it, effectively pulling plates apart or together
- Ridge Push: At mid-ocean ridges, newly formed, hotter, and less dense crust is elevated compared to older, cooler crust. Gravity causes this higher crust to push the plate away from the ridge, contributing to plate movement
- Slab Suction: Small-scale convection currents near subduction zones can also push plates further away from ridges and back into the mantle, aiding their motion
Tectonic plates are relatively rigid and float on the more ductile asthenosphere beneath them, which allows them to move independently. Their movement results in geological phenomena such as earthquakes, volcanic activity, mountain building, and ocean basin formation
. In summary, tectonic plates move because of mantle convection currents driven by Earth's internal heat, combined with gravitational forces like slab pull and ridge push that act on the plates' edges, causing them to slowly shift over the Earth's surface at rates typically measured in centimeters per year
