Volcanoes are geological structures through which magma from within the Earth rises to the surface. They usually originate as a consequence of the movement of tectonic plates , although there are exceptions, such as the volcanoes of Hawaii, which arise in hot spots, that is, in areas where there are magma plumes.
To fully understand the origin of volcanoes, it is necessary to understand what our planet is like. Planet Earth is divided into several layers from the core to the surface. Between these layers is the earth’s crust, a layer that begins at the surface, reaches 70 km deep and is made up of rocks. The crust is not uniform, but is cracked in different parts, giving rise to what we know as tectonic plates . As we have said before, when tectonic plates move they cause volcanic eruptions . These eruptions can be either terrestrial or underwater.
Tectonic plates can move in different ways, causing different types of volcanoes, as well as earthquakes. If an oceanic plate (with more density) passes under a continental one (thinner), it will partially melt due to the high temperatures inside the Earth. Magma or molten material will reach the crater’s surface and erupt as lava, gas, or solid elements. These types of volcanoes are called continental boundary volcanoes . The mid-ocean volcanoes are those that originate as a consequence of a separation movement of the tectonic plates. As they separate, an opening is created through which the magma will emerge. Finally, hot-spot volcanoes are those that originate in volcanic areas formed by mantle plumes, that is, by hot, molten material that rises from the Earth’s mantle.
The stages in the formation of a volcano would be, broadly speaking, the following:
– Magma is formed inside the Earth, where there are very high temperatures.
– Magma rises to the top of the earth’s crust.
– Magma comes out through cracks in the crust and through the main crater in the form of an eruption.
– Solid fragments of volcanic material (pyroclasts) are deposited on the surface of the crust and form the main volcanic cone.
And where are the volcanoes? There are five main volcanic zones:
– The Circumpacific volcanic zone . It corresponds to the Pacific Ring of Fire and includes the following countries: Chile, Ecuador, Peru, Colombia, Central America, Mexico, Bolivia, Argentina, USA, Canada, Russia, Taiwan, Japan, Indonesia, Philippines, New Guinea and New Zealand .
– The Mediterranean-Asian volcanic zone . It covers from the Atlantic to the Pacific. It includes Italy and the southeastern area of Spain (Almería and Murcia, for example).
– The Indica volcanic zone . It goes around the Indian Ocean until it reaches the Circumpacific volcanic zone.
– The African volcanic zone . It goes from Mozambique to Turkey.
– The Atlantic volcanic zone . It extends along the center of the Atlantic Ocean (the Canary Islands, for example).
