Volcanoes are powerful geological structures from which magma emerges, that is, they are masses of molten rock from the interior of the planet. When magma reaches the earth’s surface, it is more popularly called lava.
Now, there is a great variety of volcanoes that are distributed throughout the planet and even on other planets. These can be classified according to their activity, eruptions and shape.
Types of volcanoes according to their activity
Let’s start this interesting post with the types of volcanoes that exist according to their activity.
- Active volcanoes . They are those volcanoes that remain dormant and can erupt at any time . This occurs with most volcanoes, but as examples we can cite the volcano of the Cumbre Vieja volcano, on the island of La Palma, Spain (it is now erupting), the Etna volcano in Sicily, Italy (it is currently erupting) , the Fuego volcano in Guatemala (it is also currently erupting) and the Irazú volcano in Costa Rica.
- Dormant volcanoes . Also called sleepers, they are volcanoes that maintain a minimum of activity . Despite its low activity, it can occasionally erupt. A volcano is considered inactive when centuries have passed without volcanic eruptions. The Teide volcano in the Canary Islands of Spain and the Yellowstone super volcano in the United States are examples of dormant volcanoes. However, these two examples in recent years have shown movements, mild earthquakes in their area, which indicates that they are still “alive” and could become active at some point, they are not extinct or displaced.
- Extinct volcanoes . They are volcanoes in which their last eruption dates back more than 25,000 years . However, the researchers do not rule out that at some point they may erupt again. It is also called like that, those volcanoes that the tectonic movements have displaced from their source of magma . The Diamond Head volcano in Hawaii is an example of extinct volcanoes.
Next we will develop the types of volcanoes according to the types of volcanic eruptions that there are.
- Hawaiian volcanoes . The lava that these volcanoes expel is fluid and no gases are released or explosions are generated during the eruption. Therefore, the eruptions are silent. Most of the volcanoes in Hawaii have this type of eruption, hence its name. We can specifically mention the Hawaiian volcano called Mauna Loa.
- Strombolian volcanoes . Unlike the one just described, the strombolian volcanoes present a viscous, little fluid lava and the eruptions include successive explosions. In fact, the lava crystallizes as it rises through the conduits, and then the volcanic activity is reduced to launching semi-consolidated lava balls, called volcanic projectiles. The name of this type of volcano refers to the Stromboli volcano in Italy, which has registered rhythmic explosive eruptions every 10 minutes.
- Vulcan volcanoes . In this case, they are very violent eruptions that can destroy the very volcano in which they develop. Lava is characterized by being very viscous and with enormous amounts of gas. As an example, we can mention the Vulcano volcano in Italy, whose volcanic activity gave rise to this type of volcano.
- Fighting volcanoes . These are volcanoes with very viscous lava that consolidates quickly, forming a plug in the crater. The great pressure generated by the internal gases causes the opening of lateral cracks and, sometimes, the plug is violently expelled. As an example we can mention the Monte Peleé volcano on the island of Martinique, from which the name for this type of volcano was taken.
- Hydromagmatic volcanoes . The eruption is produced by the interaction of the magmatic mass in contact with groundwater or surface waters. Depending on the magma / water ratio, large amounts of steam can be released. This type of volcanism is frequent in the volcanoes of the Campo de Calatrava region in Spain.
- Icelandic volcanoes . In this type of volcano, the lava is fluid and the eruptions are expelled from fissures in the ground, not from the crater of the volcano. In this way, vast lava plateaus originate. Most of these volcanoes are in Iceland, that is the reason for their name. A concrete example is the Krafla volcano, located in Iceland.
- Underwater volcanoes . Although it is surprising, at the bottom of the sea there are also active volcanoes. Of course, marine eruptions are usually brief. In some cases, the expelled lava can reach the surface and, as it cools, forms volcanic islands. As an example of underwater volcanoes, there is the Kavachi volcano near the Solomon Islands.
Types of volcanoes according to their shape
Finally, volcanoes can be classified according to their shape. Let’s see here their types and examples:
- Shield volcanoes . These are large volcanoes. They are characterized by having a diameter considerably greater than their height. The shape of this type of volcano is given by the successive accumulation of eruptions. As an example, most of the volcanoes of the Galapagos Islands have this type of shape, as is the Wolf volcano.
- Stratovolcanoes . As its name suggests, this type of volcano is made up of layers of basaltic lava interspersed with layers of rock. Its shape is conical and originate from explosive eruptions alternated with quiet eruptions. As an example of stratovolcanoes, we can mention the Colima volcano in Mexico.
- Volcanic calderas . They originate as a result of large explosions or subsidence of the magma chamber. As the main characteristic, we can talk about its shape, which resembles that of a large crater. The Bandama caldera, in Gran Canaria, is an example of this type of volcano.
- Cinder or slag cones . These are the most abundant volcanoes on planet Earth and are characterized by being small in size, rarely exceeding 300 meters in altitude. As their name refers, they are made up of accumulations of ash and / or slag. In Peru, more than 45 slag cones have been located specifically in the Arequipa and Cusco region.
- Lava dome. This last type of volcano originates when the lava is not very fluid, then it accumulates and extrudes the crater. As the lava accumulates, a kind of dome forms at the apex of the volcano. An example is the lava dome of the Chaitén volcano in Chile.