Question

How can gravity's role in tectonic plate motion be described

Answer 1

One of the main driving force for tectonic plate motion is gravity.

The subduction is the process where under gravity the oceanic lithosphere dives beneath another plate and thats how one plate meets another plate.This sink of oceanic lithosphere is responsible for dragging of rest of the tectonic plates. This is how the plates move.

Answer 2

In ridge push, the mantle wells upward because of the convection and elevates the edges of spreading oceanic plates. Because these plates are higher at the spreading center, they are forced downhill due to gravity and eventually flatten out to the ocean floor.