For divergent boundary: when the crust of the earth fractures it allows magma to reach the surface. For convergent boundary: When one of the converging plates move underneath the other, a process also known as subduction; the new magma rises and can erupt to form volcanos. For the Hotspot: magma pushes through cracks in the crust to form volcanos. Hope this helps!!
I think they're set in a vertical motion. Up to the crest and down towards the trough. Something about kinetic energy
The graph table population is continuously increasing until 2007
