The parts of a volcano They are the crater, the caldera, the volcanic cone, the chimney and the magmatic chamber. The volcano is a geological structure formed by the outlet pressure of the magma contained within the Earth.
Magma is the molten rock in the Earth's mantle that forms due to the high temperatures of the planet's core. This is composed of cast iron at high temperatures (4,000 ºC).
The upper layer of the mantle is made of silicates (asthenosphere) and they are in solid, semi-solid and molten states (magma). This generates high outlet pressures that, when encountering a weak geological point, pushes the magma towards the earth's surface..
The process of exiting the magma to the outside forms the volcano, whose name comes from the Latin Volkanus. It is the name that the Romans gave to Hephaestus, the Greek god of fire and blacksmithing, also known as Vulcan..
The structure of a volcano is determined by the type of magma, the eruption process, the vent system, and environmental conditions. Regarding the latter, it must be taken into account if the volcano acts under air, under glaciers or under water..
Also, there are various types of volcanoes, ranging from a crack in the ground to huge stratovolcanoes. These types of volcano are identified depending on either their location or their morphological structure..
Due to their location there are terrestrial, subglacial and submarine volcanoes and their morphology is defined by the geology and physiography of the place where they arise. In this sense, the parts of the volcano and their characteristics will vary from one type to another..
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The origin of a volcano is the accumulation of magma and gases in an underground chamber, called a magmatic chamber. In this chamber the necessary pressure is generated to push the magma upwards, breaking the earth's crust.
Magma is molten or partially molten rock due to the high temperatures inside the planet, plus associated gases. The molten rocky material is mainly silica from the earth's mantle.
This can reach temperatures of up to 1,000 ° C (very fluid) forming basalt on cooling. It can also be a less hot material (600-700 ° C) that crystallizes in the form of granite when it cools.
There are two fundamental sources of magma since it can come from molten material in the subduction of the earth's crust or from greater depths..
It consists of the sinking of the earth's crust from the ocean floor below the continental plates. This occurs when oceanic plates collide with continental plates, the first being pushed into the Earth's interior..
Inside the Earth, the crust is melted into the mantle and then part of that material returns to the surface through volcanic eruptions. The determining force of subduction is the push of the oceanic plates by the rocks arisen in the volcanoes of the oceanic ridges..
The rise of the magma due to the pressure generated due to the high temperatures, forms an outlet conduit called a chimney. The chimney is the main duct of the volcano's ventilation system and will drift through the weakest parts of the earth's crust..
A volcano can have one or more chimneys, which can branch out, this forms the vent system of the volcano or ventilation system. In some cases the chimney is made up of a set of small fissures that connect.
A volcano can have a series of secondary chimneys that arise laterally in relation to the main chimney that opens in the crater of the volcano..
When the magma reaches the surface, it breaks the superficial crust and is projected to the outside and this opening is called a crater and can be a cavity of greater or lesser diameter..
The shape of the crater is given by the type of lava, type of volcanic eruption, environment and geology of the terrain..
It is a depression formed in the center of a volcano shaped like a cauldron or pot inside which is the crater. It is formed by the collapse of the volcanic structure over a shallow magma chamber.
Not all volcanoes have a caldera as such, especially young volcanoes that are not very developed.
It can be formed by the collapse of the magmatic chamber, already emptied by previous eruptions due to the weight and instability of the structure. An example of this type is the caldera de las Cañadas del Teide in Tenerife (Canary Islands, Spain).
It can also originate due to a phreatic explosion in the magmatic chamber, collapsing the upper structure. The phreatic explosion occurs when magma comes into contact with groundwater, generating an enormous vapor pressure.
This type of boiler is the one presented by the Caldera de Bandama in Gran Canaria (Canary Islands, Spain).
As the pressure of rising magma builds, the earth's surface rises. When the volcanic eruption occurs, that is, the exit of the magma to the outside, the lava radiates from the crater and cools.
In this process, a cone is formed that gains height with successive eruptions. The classic volcanic cone is observed in stratovolcanoes. Not so in shield volcanoes, maars and even less so in yours..
The forms, products and scales of volcanic eruptions vary considerably from case to case. This generates a diversity of types of volcanoes, with their own structures depending on their process of origin..
It is important to consider these elements to understand the structural variations of volcanoes..
In the case of the effusive eruption, the magma rises from the inside of the magma chamber and comes out as a coherent fluid called lava. It is basaltic lava that reaches high temperatures and is not very viscous, so gases do not accumulate and explosions are reduced..
As lava flows outside like rivers, it cools and forms rock bodies called lava flows..
In turn, in the explosive eruption, the magma is very viscous due to the higher content of silica and clogs the conduits, accumulating gases which generate explosions. The magma is fragmented into more or less solid pieces (pyroclasts) and violently thrown outside by the pressures of the accumulated gases..
These gases are made up of volatile compounds that generate expansive bubbles that end up bursting..
It is made up of random layers of lava and highly consolidated pyroclasts reaching great heights. Represents the classic image of a volcano, as seen from Mount Fuji in Japan.
They form a raised volcanic cone with a central crater at the top of proportionally narrow diameter.
Here it is very fluid lava, so it reaches great distances before cooling away from the crater. Because of this, a cone with a broad base and relatively low elevation is formed..
Examples of this type of volcanoes are the Hawaiian shield volcanoes and the Eyjafjallajökull volcano in Iceland..
It is a volcano with a double volcanic cone, due to the fact that a second cone is formed inside the caldera. A classic volcano of this type is Monte Somma, which is a stratovolcano in whose caldera is the famous Vesuvius..
These are subglacial volcanoes, that is, they erupt under a glacier, so the lava comes into contact with the ice. This causes the ice to slowly melt as the lava cools, forming layers of hyaloclastite (volcanic rock formed under water).
The end result is flat-topped lava mountains with nearly vertical flanks like the subglacial Herðubreið volcano in Iceland..
They are formed by fragments of lava ejected by a single chimney that accumulate forming a small cone with a bowl-shaped crater. A typical slag cone is that of the Macuiltepetl volcano (Veracruz, Mexico).
When lava is very viscous, it does not flow great distances, accumulating around the ejection cone and above the chimney. An example is the Dome of Las Derrumbadas in Puebla (Mexico).
They are also called tuff ring or tuff cone and are formed by a phreatomagmatic eruption. That is, a violent expansion of water vapor when the rising magma meets groundwater.
This generates an accumulation of water vapor that violently breaks the surface forming a wide circular or oval boiler. Here the edges of the cone are low with the large diameter caldera generally filling with water after the eruption as in the Tres maars Duan in Germany..
In the following video you can see an active volcano:
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