First of all, it erupts because of the movements of the earth's surface. The Earth is composed of the lithosphere, mantle, and crust. The lithosphere has the several plates like a puzzle, and they move little by little. By moving, they bring about the mantle convection. For this reason, an oceanic ridge and trench that are created.
make rock layers in the area at the earth's crust are collide and there was a crooked