First of all, it erupts because vibration or shaking of the earth's surface. The earth is composed of the lithosphere, mantle, and crust. When the earthquake occurred, the area of crust may have weaknesses, for example, may have a crack or crevice of rock layers. Then, the earth's crust move collide with enormous pressure, make rock layers in the area at the earth's crust are collide and there was a bent of crust. Earth's crust will begin to crack and separate from each other in the direction in a straight line or horizontal.