There are two main types of volcanoes: composite and shield.
There are two main types of volcanoes. The first, called a shield volcano, is usually found in the middle of tectonic plates; examples include volcanic island chains like Hawaii. The second type of volcano is called a composite volcano; these are the cone-shaped volcanoes most people think of when they imagine a volcano, and they are typically found in subduction zones. While there are different kinds of volcanoes, there are several basic physical features that most have in common.
Magma Chamber
The magma chamber is a pool of molten rock that sits beneath the Earth's crust. Volcanic eruptions occur when the magma, which is less dense than the surrounding mantle, reaches the surface of the Earth's crust.
Lava
Lava is the liquid rock that is ejected from a volcano during an eruption. The lava flows out at extremely high temperatures that exceed 700 degrees Celsius, and once it cools, it hardens into igneous rock.
Main Vent
This vent, also called a conduit, is the place where the magma reaches the surface of the Earth's crust. The conical shape of the volcano forms around the main vent as ash, rock and other debris settles and builds up after a volcanic eruption.
Crater
The vents of a volcano are located at the bottom of its crater, which is a gaping, circular depression that resembles a hole.
Pyroclastic Flow
A pyroclastic flow describes the rapidly-moving gases and molten rock that are expelled during volcanic eruptions, and which travel down the volcano at speeds that can reach up to 700 km/hour.
Ash Cloud
An ash cloud mushrooms out above the volcano during eruptions and is comprised of small bits of rock and debris. These clouds can disperse over impressive spans of land; the tiny particles can be harmful to aircraft, so larger volcanic eruptions can immensely disrupt air travel.
Volcanic Bombs
Volcanic bombs are large, solidified chunks of lava that harden while they are still flying through the air.
Secondary Vent
Larger volcanoes often have secondary vents, which are different outlets for magma, gas and debris aside from the large outlet provided by the main vent. These vents can form secondary cones.
Sills and Dikes
A sill is a horizontal crack in a volcano that houses hardened magma. Dikes, on the other hand, are vertical cracks in a volcano that also contain hardened magma.
Tags: Earth crust, rock that, hardened magma, main types, main types volcanoes, main vent
