A volcano is built when magma below the surface of earth rises and starts to form gas bubbles from the gas that is dissolved in it like the soda which has carbon dioxide dissolved. The gas exerts extremely high pressure and it sometimes cause volcanoes to erupt. When eruption occurs it allow high pressurized gasses and lava to escape from magma reservoir with earth’s geothermal energy. The most common type of volcanoes are cone shaped with summit crater. Mauna Loa is largest volcano on our earth and the largest volcano on our solar system is Olympus Mons on the planet Mars.
It is the mixture molten rock, semi molten rock and solid particles found inside the earth’s surface. When magma is ejected through volcano it is called lava. Heat to melt rock comes from earth’s geothermal energy.
It is the magma after eruption having temperature 700 C – 1200 C in liquid state. It doesn’t flow inside the earth that is the difference between the lava and magma which flows inside earth. Lava is mainly composed of silicon and oxygen. It get mixed with other elements during its travel.