Volcanoes: Types, Formation, and Volcanic Eruption

A volcano can be defined as a mountain or a landform through which the molten rocks erupt through the planet’s surface. Ever since we were kids, we have often looked at the night sky and wondered about the mysteries that exist in the great beyond but have you ever been fascinated by what goes inside the land on which we stand? The pressure inside the Earth's crust gives rise to the volcanic eruptions that we might have seen in movies and been fascinated with. Through these volcanic eruptions, igneous rocks and gases shoot up all over splashing the air with the fragments of this lava. In this article, we will have a look at what volcanoes are, what is a volcanic eruption, and the causes behind them.

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What is a Volcano?

A volcano refers to an opening in the crust of the earth. Through this opening molten metal and Lava erupt through a volcanic eruption. The volcanoes are formed on the boundaries of the plates that are in a continuous motion inside the earth, known as the tectonic plates. The crust of the Earth is made up of 17 such tectonic plates. The Earth is divided into various regions such as

• Crust
• Upper Mantle
• Mantle
• Outer core
• Inner core

Volcanic eruptions also result in environmental pollution as the eruptions release various harmful elements and toxic gases in the atmosphere such as ash. A volcanic eruption can be easily visualized similar to the opening of a soft drink bottle wherein the pressurized gases seem to erupt or spew towards the outside. 

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Formation of volcanoes

A volcanic mountain or a volcano is formed as a result of the eruption of the magma on the surface from within the upper Mantle area of the Earth. The eruption of the magma on the surface leads to a flow of lava which leads to the deposition of ash. As the eruption of the volcano continues to take place, a new layer of the lava keeps on adding to the surface which accumulates to result in the formation of a mountain.

Magma is a form of a liquid rock that is formed inside the volcano while lava is the liquid rock that comes in contact with the air. 

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Different volcanic stages

The different forms of volcanoes depend upon various factors such as

• The eruption type
• The erupted material's nature
• The change that occurs since the volcanic eruption

Hence, volcanoes can be basically categorized into three categories which are as follows

• Active volcanoes

An active volcano is one that is expected to erupt at a present time or is already erupting.

• Dormant volcanoes

Dormant volcanoes are the ones that are not currently erupting and that are not predicted to erupt even in the near future

• Extinct volcanoes

An extinct volcano is one that is never expected to have another eruption.

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Causes behind the volcanic eruption

The eruption of the volcanoes begins with the process of magma formation towards the lower section of the crust of the Earth. The Earth's crust is formed of massive slabs which are known as plates. These plates fit together like pieces of a puzzle. Earthquakes and volcanic eruptions are caused as a result of the friction generated due to the movement of the plates.

During the eruption, the molten rocks or magma rises above the surface of the Earth. When the mantle of the Earth melts, the formation of magma takes place. This melting occurs as a result of the high pressure that is exerted on the Earth's mantle. This pressure is due to the movement of the tectonic plates that either results in a push or pull movement towards each other. 

As the magma rises from the floor of the volcanoes, bubbles are observed within the volcano. On the other hand, a runny magma erupts from the surface of the Earth's crust even before it flows over the surface. An explosive eruption takes place when too much pressure is applied during the volcano formation process. The volcano erupts and as a result, the magma flows out.

The magma travels upward with pressure and the force hits the solid rocks and various other materials that create a new passage to the surface of the Earth. Once the magma has erupted in the air, it is then known as the lava.

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Types of volcanoes

Volcanoes are basically categorized into four types which are

• Cinder cones
• Composite volcanoes
• Shield volcanoes
• Lava volcanoes

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Let us understand the various types of volcanoes in-depth:

Cinder cones

• Cinder cones are the simplest form of a volcano. 
• This type of volcano is formed when the blobs of Lava and the volcanic particles are erupted and are ejected from the volcano. 
• The lava is violently blown in the air and the pieces all scatter around the volcanic vent. 
• With time, this eruption accumulates to form a circular or an oval shape with a crater of a bowl shape at the top. 
• These types of volcanoes rarely grow over 1000 feet above their surroundings.

Composite volcanoes

• Composite volcanoes are some of the grandest volcanoes of Earth. 
• They are also known as stratovolcanoes.
• Their shape resembles symmetrical cones having larger dimensions.
• They are composed of alternating layers of volcanic ash, lava flows, bombs, blocks, and cinders.
• These types of volcanoes may rise up to 8000 feet above the surface.

Shield volcanoes

• A shield volcano is commonly built up entirely of fluid lava flows.
• Shield volcanoes are developed horizontally and have very gentle slopes.
• They are formed as a result of effusive eruptions that are ejected out in all directions.
• They rarely have any violent eruptions. Most of the time basic lava simply flows out of these volcanoes.

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Lava domes

• The lava domes volcanoes have tiny stature.
• When lava is too viscous that it can't flow to great distances, lava domes are formed.
• As this volcano grows, its outer surface hardens as it cools and lava continues to accumulate within the volcano.
• Eventually, the internal pressure shatters the surface and leads to the spilling or ejection of loose fragments of volcanoes down its sides.
• These types of volcanoes are generally found on the flanks of the composite volcanoes that are larger comparatively.

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Effects of volcanic eruptions on the environment

• Lots of harmful elements and toxic gases are released into the atmosphere during a volcanic eruption. Some of these harmful gases include sulphur oxides and oxides of carbon which are very harmful to our ozone layer and lead to its degradation.
• These gases when mixed with the rain also lead to the formation of acid rain.
• When the high-temperature ash has erupted in the environment, it also might hit airplanes in the sky as it is released and injected into the atmosphere of the Earth.
• When the pyroclastic materials that are released are mixed with the water near rivers and lakes, marine life is impacted. It also leads to water pollution.
• The volcanic eruptions might also result in earthquakes that have readings as high as 7 or more on the Richter scale.
• Tsunamis are also caused as a result of the devastation caused by volcanic eruptions.

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Volcanic eruptions in the solar system

• Many planets in the solar system like our Earth have experienced a lot of volcanic eruptions since its inception.
• Mars has many dormant volcanoes.
• A few moons of Jupiter have an active system of volcanoes.
• The basalt surface of the planet Venus has been formed as a result of many volcanic eruptions on the surface. Basalt refers to a form of igneous rock that is formed through the cooling of the lava from volcanic eruptions. Basalt is rich in magnesium and iron elements.
• Hence, we can conclude that any celestial body that is hot enough to generate molten metal will experience volcanic eruptions.

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Things to Remember

• A volcano refers to an opening in The crust of the earth. Through this opening molten metal and Lava erupt through a volcanic eruption.
• Volcanic eruptions also result in environmental pollution as the eruptions release various harmful elements and toxic gases in the atmosphere such as ash.
• A volcanic mountain or a volcano is formed as a result of the eruption of the magma on the surface from within the upper Mantle area of the Earth.
• The eruption of the volcanoes begins with the process of magma formation towards the lower section of the crust of the Earth.
• Many planets in the solar system like our Earth have experienced a lot of volcanic eruptions since its inception.
• The basalt surface of the planet Venus has been formed as a result of many volcanic eruptions on the surface.
• Some of the harmful gases emitted or released during a volcanic eruption include sulphur oxides and oxides of carbon which are very harmful to our ozone layer and lead to its degradation.

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