Volcanoes are mountains and gateways to Earth’s crust. These openings allow magma, volcanic ash and gas to escape during volcanic eruptions. When a volcano erupts it can result in a huge, fiery explosion, throwing scalding lava into the air, or a gentle stream of lava running down the volcano’s surface.
Often volcanoes are found where tectonic plates meet. These rocks make up the Earth’s crust and are continuously moving, causing plates to rub against each other. The friction created by the movement of these plates creates a high temperature that turns the crust into molten hot rock, called magma. Regions with volcanoes formed during the movement of tectonic plates are called hotspots.
High pressures in the Earth’s crust pushes magma up cracks in the tectonic plates until it emerges above ground level. When magma reaches the surface, it is called lava. As lava cools and hardens into volcanic rock, it forms a solid mountain of lava. Every time a volcano erupts, pouring lava over the surface, it adds to the body of the volcano.
Not all volcanoes form in the same way. The viscosity of the lava that’s released determines how steep or gentle the volcano’s slope will become. This is dependent on how quickly lava cools to form the rock.
Volcanoes can also be found underwater in the form of submarine volcanoes. Because the lava instantly comes into contact with cool water, underwater eruptions often go unnoticed. If the top of these volcanoes come close to the water’s surface, it’s possible to see steam and debris being thrown above the sea. There are estimated to be over 1 million submarine volcanoes. Larger ones have the potential to grow above the water and become islands.