Step-by-step explanation:
Any rock will melt once it reaches a high enough temperature. This liquid rock is known as magma when it is beneath the crust of the Earth. If it bubbles to the surface and pushes its way out, it is known as lava. This happens most often in a volcano.
Magma rising from the depth occurs when hot mantle rock rises to shallower depths in the Earth because it is less dense than surrounding rock and because the weight of the overlying rock creates pressure that squeezes magma upward.