Answer:
The energy that drives this movement is heat within the earth, this heat comes from two main sources which are;
1) residual heat left over from the formation of our planet billions of years ago.
2) The radioactive decay of naturally occurring chemical elements (notably uranium, thorium, and potassium ) in the earth releases energy in the form of heat. These two sources of heat warm Earth’s mantle and cause it to rise and sink, this rising and sinking creates a convectional movement of earth mantle.