Lava

Once it reaches the surface, it is called lava. Volcanic hazards are potentially damaging processes or materials produced by volcanic activity, such as lava flows, ash fall and pyroclastic flows.

Below the surface, molten rock is called magma; once it erupts, it is called lava. Magma may collect beneath a volcano in a magma chamber before rising through the crust. Lava cools and solidifies, and repeated eruptions can build up a volcanic mountain.