Parts of a Volcano - Summary and Schematics

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Volcanoes are amazing geological structures that arouse the interest of many when they begin to erupt. In itself, it is very curious how such a structure is capable of expelling huge volumes of lava and it is even more curious to understand when and why they erupt. To satisfy a little more curiosity about volcanoes, in this Green Ecologist article we will dedicate ourselves to explaining the parts of a volcano and also the materials that these expel when erupting. If it is of your interest, we invite you to continue reading.

Magmatic chamber

If you wonder how many parts does a volcano haveWe could say that in general terms volcanoes have 6 parts, but many more could be detailed. To order its parts, we will start from its lowest part, the magmatic chamber. This can be defined as a huge deposit at great depths where magma accumulates, which is the molten rock mass that during an eruption rises to the surface.

Here you can learn much more about what magma is, types, where it is found and how it is formed.


The fireplace is nothing but the conduit connecting the magma chamber to the outside. Then, during a volcanic eruption, magma rises to the surface through this conduit. Due to the enormous pressure generated by the magma as it rises, it sometimes breaks fragments of rock from the chimney and carries them with it during the eruption.

Volcanic cone

The volcanic cone is a product of the accumulation of solidified lava from successive eruptions that occurred over time. Depending on the number of eruptions that have occurred, the volcanic cone can vary in thickness and size. In addition, depending on the type of lava that has been expelled, different types of cones originate, which ultimately give rise to the types of volcanoes:

  • Stratovolcanoes. These are volcanoes whose cone is formed by layers of lava alternated with layers of rock.
  • Slag cone. They are volcanoes whose cone is made of volcanic slag, which is a set of volcanic fragments larger than ash.
  • Cinder cone. Those volcanoes that present a cone formed by pyroclastic ash (fragments of volcanic material) the size of silt or sand.

In turn, there are secondary cones of a volcano, which are formations caused by the accumulation of solidified lava on the main cone. These have in their interior a secondary chimney, connected to the main chimney and, from them, lava is also expelled.

We also recommend reading this other post about the different types of volcanoes according to different classifications.


The fissures are cracks or crevices found in the volcanic cone for which there are also expel the lava. They originate from the rupture generated by the powerful pressure exerted by gases and magma when they erupt.


The crater is the opening at the top of the volcano. Thanks to this hole, during the eruption the lava, gases and other volcanic materials reach the outside. Although craters are usually rounded and have a large perimeter, each volcano has a unique crater in shape and size. Even a volcano can present more than one crater, as is the case of volcanoes with secondary cones which typically culminate in a crater known as a lateral crater.

Eruptive column

It is a column formed by gases and pyroclastic materials that are expelled from a volcano and can be viewed above the main crater and the side craters. Due to the great pressure with which these gases are expelled, the column can acquire a kilometer height. In general, the eruptive column is perfectly observed just before the volcano begins to erupt.

Learn about the Types of volcanic eruptions by reading this other article.

Materials that a volcano expels

The materials expelled by a volcano should not be confused with its parts. However, thanks to the different types of materials and their characteristics, various types of volcanoes originate. Although all the materials expelled by a volcano are usually grouped under the term magma, in reality, a somewhat more detailed classification can be made.

  • At first magma is, as we mentioned earlier, molten rock mass inside the Earth. Now when magma rises to the surface it is called lava. Lava it can be more or less viscous depending on its silica content and depending on its viscosity, it can give rise to different types of volcanic eruptions. Generally speaking, the more silica content more viscous is lava.
  • On the other hand, magma has large amounts of gases, the most abundant are water vapor, carbon dioxide and sulfur dioxide, among others. The enormous pressure generated by the gases contained in the magma also determine the type of volcanic eruption. However, gases are not only expelled during eruptions, but also from fumaroles and solfataras.
  • Finally, the pyroclasts or tephra They are fragments of solidified magma that is expelled during the eruption and distributed with the wind. According to its size, the pyroclast can be classified into: ash, particles smaller than 2 millimeters in diameter, lapilli, particles up to 64 millimeters in diameter and volcanic bombs, particles greater than 64 millimeters in diameter.

Now that you have learned all this about the parts of volcanoes and the materials they expel in their eruptions, we recommend that you continue learning about them with these other articles on How volcanoes are formed, the Difference between magma and lava (you can also see the video below on this topic) and The most dangerous volcanoes in the world.

If you want to read more articles similar to Parts of a volcanoWe recommend that you enter our Nature Curiosities category.

  • Duque Escobar, G. (2003). Geology Manual for Engineers. Civil Engineering Department.
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