What is the main driver of tectonic plate movement?

The primary driver of tectonic plate movement is the convection currents in the mantle. These currents are caused by the heat from the Earth’s core, which creates varying temperatures within the mantle. As the hot mantle material rises toward the Earth's crust, it cools and then sinks back down when it cools sufficiently. This cycle of rising and sinking material generates large-scale movements within the mantle, which in turn exert force on the tectonic plates situated above it.

The convection currents facilitate the sliding of these plates over the semi-fluid asthenosphere, leading to their movement. This process is fundamental to phenomena such as earthquakes, volcanic activity, and continental drift. Other factors, while they may contribute to the dynamics of plate movement at certain boundaries, primarily arise from or influence this fundamental process of mantle convection.