What is the primary force that drives the movement of tectonic plates?

The primary force that drives the movement of tectonic plates is convection currents in the mantle. This process occurs due to the heat generated from the Earth's core, which causes the mantle material to circulate. As hotter, less dense material rises to the surface, it cools down and becomes denser, sinking back down. This continuous cycle creates a flow pattern, which exerts a drag on the overlying tectonic plates, causing them to move.

Convection currents are crucial because they provide the necessary mechanism for plate tectonics, facilitating the shifting and interaction of plates at their boundaries. This movement can lead to a variety of geological activities, such as earthquakes, the formation of mountains, and volcanic eruptions.

While gravity plays a role in the tectonic processes (for example, by influencing subduction), it is not the primary driving force. Similarly, magnetic forces from the Earth's core are not directly responsible for plate movement, and static friction between plates would actually impede movement rather than drive it. Thus, convection currents in the mantle are essential for understanding how tectonic plates are set in motion.