Volcanic eruption

To refer to volcanic eruptions we must also refer to volcanoes , which can be described as structures through which gases , molten rock and other materials come to the surface from the interior of the earth and that can be classified as active when They are erupting, latent that are not currently erupting, or extinct, which refers to volcanoes that have been erupting but are no longer active. When volcanoes expel all the material that is inside, that is when an eruption occurs volcanic , which can even turn into a natural disaster .

What its a volcanic eruption?

A volcanic eruption is the discharge of lava and gases that come out through the chimney of a volcano and that it produces when the magma is expelled out of the volcano forming fiery pyroclastic flows .

  • What does it consist of
  • Characteristics of a volcanic eruption
  • Types
  • Process
  • Causes
  • Consequences
  • How to prepare
  • How to act during a volcanic eruption
  • What to do after
  • Importance
  • Examples of large volcanic eruptions

What does it consist of

A volcanic eruption consists of a series of explosions or emanations of lava , ash and toxic gases that come from the interior of the earth and that happens through volcanoes produced by the overheating of the magma that is inside the earth.

Characteristics of a volcanic eruption

The main characteristics of a volcanic eruption are:

  • Volcanic activity can come from active , dormant , extinct volcanoes .
  • The volcanic eruption will depend on the temperature , composition , viscosity and the elements that are present in the magma.
  • During a volcanic eruption gases , lava and solid or pyroclastic products are expelled .
  • They are produced when the temperature of the magma that is inside the earth’s mantle increases significantly.
  • The output of the magma can be liquid , solid or gaseous .
  • There may be flares so explosive depending on the volume pyroclastic held by the volcano .


In volcanoes there can be several types of volcanic eruptions, among which we mention:

Magmatic : this is the best known type of volcanic eruption. They are eruptions that produce a large amount of clastic sedimentary rocks at the moment of explosive decompression after the release of gas. In turn, magmatic eruptions can be subdivided into several types that are:

  • Hawaiian : it is a type of little violent eruption that manages to expel an abundance of lava in a fluid or liquid way.
  • Strombolian : it is an eruption that causes a series of violent gas explosions , which forms dense clouds of very dense smoke and a rain of pyroclasts .
  • Vulcanian : in this type of eruption, the lava solidifies, covering the chimney of the volcano, which causes the pressure of the gases to increase in the internal part of the volcano, a situation that then causes the materials to be expelled very violently .
  • Pliniana : This type of eruption causes volatile gases to pile up in the magma and all the contents come out in the form of a column .
  • Peleana : the viscosity of the lava in this type of eruption obstructs the chimney of the volcano, thus forming domes .
  • Phreatomagmatic : in this type of eruption, the contents inside the volcano are expelled by means of a thermal contraction when it comes into contact with magma and water . They can be Surtseyan , Submarine, and Subglacial .
  • Water tables : its main characteristic is the expansion of steam . In other words, they occur if cold soil or water touches magma or rock that is on the contrary hot, thus producing overheating and cracking of the rock.


Let us remember that the eruption of a volcano is a process that consists of a violent emission that occurs on the earth’s surface that comes from the interior of a volcano . The expulsion of materials in a volcano occurs mainly by the accumulation of gases , hot rocks , ash and incandescent material that accumulates inside the earth for years. This pressure causes everything that is accumulated to be released including magma .

Many of the volcanic eruptions are related to the movement of plates that melt to form magma . When this magma manages to flow and rise enough to reach the surface , it drags the rocks it encounters with it and melts them producing a violent eruption .


We must know that the interior of the earth is always in constant motion and many of the processes happen there. Generally, volcanic eruptions are presented as a consequence of the increase in temperature suffered by the magma which is found inside the mantle, which produces a volcanic eruption that ends up expelling boiling lava . They are closely related to the movement of the tectonic plates under the lithosphere . The strength of each eruption will depend on the viscosity and gases .


Some of the consequences that arise when a volcanic eruption occurs are the following:

  • Problems with transport by plane .
  • Effects on cities and towns that, depending on the eruption and atmospheric conditions , will affect to a greater or lesser extent, could even cause deaths.
  • Important effects on the environment as these eruptions release into the air a series of substances such as sulfur dioxide, fluorine , chlorine , hydrogen sulfide and others.
  • Contamination in the surface sources of drinking water by ash, gases or toxic substances, by the death of animals in the water intakes or in the channels of the captured water.
  • Contamination of groundwater sources if ash is abundant.
  • Contamination in plants of drinking water, by falling volcanic ash on ponds coagulation , decantation or filters.
  • Pollution of ponds , lakes , rivers or reservoirs
  • Works and buildings that are located above ground level due to the damage caused by lava, stones or large rocks that can be thrown a great distance by the eruption.
  • Depending on the severity of the eruption and the area affected, there can be deaths of both people and animals .

How to prepare

To prepare for a possible volcanic eruption, we must know the plan established by the emergency personnel . On many occasions the alarms are turned on to warn of an imminent eruption and the media will be pending. You must know in advance the evacuation procedures of the area and have previously developed a family evacuation plan to know where you can take your family and pets in case of emergency.

Having a good supply of food and water is also an essential part as there could be a shortage of it for a few days. They maintain a kit of first aid , radio with batteries and a map of the region are also necessary aspects. If you cannot find a suitable shelter to stay safe, it is best to find high ground to avoid coming into contact with the lava.

How to act during a volcanic eruption

When a volcano erupts in the area where we reside, we must immediately proceed to evacuate the area and avoid coming into contact with explosions , lava and hot gases . Special care must be taken with mud flows as they can move with greater speed than people. You should wear appropriate clothing that covers the entire body, use glasses and masks to breathe and avoid dangerous places.

What to do after

After a volcanic eruption we must:

  • Stay away from volcanic ash
  • Do not drive a car through it, since it damages vehicles
  • After the eruption, the water to be consumed should be boiled .
  • Keep the radio or television on so you can hear news about possible evacuations .
  • Keep an emergency kit for news and possible instructions
  • If you have a respiratory disease , you should not leave your home until it is confirmed that there is no risk.
  • Ash should be cleaned from the roofs , since it is heavy and can cause cave-ins.
  • Check carefully if the electricity , water , gas and telephone work correctly.
  • Help injured or trapped people. Ask the emergency services for help .


Volcanic eruptions have been important in the life of man since the beginning of time because through volcanic rocks were manufactured the first axes , grinders and tips launches . At present, some volcanic materials are used to make a great variety of objects and instruments , and many of these materials are extracted for the construction of cement , buildings and roads .

Thanks to volcanism , aquifers and springs are formed from the water that is contained in the rocks of volcanoes. In addition, thanks to volcanism, we can obtain geothermal energy , in other words the energy found inside the earth in the form of heat to be able to generate electricity and heating .

Examples of large volcanic eruptions

  • Santa María (1902): a Guatemalan volcano dormant for 500 years that produced an eruption of 20 billion cubic meters of debris. It destroyed the southwest face of the volcano, leaving a crater 1 kilometer in diameter, and its ash reached San Francisco , California.
  • Santorini (1610 BC): It was an island and today we know it by the name of Greece , but during the eruption, the volcano was completely destroyed. From this it is believed the myth of Atlantis was born .
  • Krakatoa Volcano (1883): one of the best known in history . It happened in Indonesia and release released 9 cubic kilometers of magma , completely destroying the island and altering sunsets sun around the world.
  • Tambora Eruption, Indonesia (1815): it threw 160 cubic kilometers of debris, enough to cover the island of Manhattan in a layer of ash a mile and a half thick and lowered the global temperature by as much as 3 degrees.
  • Ilopango volcano, El Salvador : during its first explosion, it left the entire center of the country covered in pumice and ash, destroying the Mayan cities . It is considered the greatest catastrophe in the history of mankind.

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