We explain everything about volcanoes, how they are formed, their parts, and other characteristics. Also, the main volcanoes in Mexico.
What is a volcano?
A volcano is an opening in the Earth’s crust, through which magma or lava can emerge, along with gases, ash and other materials from the depths of the Earth. They can be found on other planets and satellites in space.
Volcanoes are quite frequent in the Earth’s crust, especially in regions of intense seismic activity, and can be found on the continental shelf or on the ocean floor. Its eruptions, which is what the spill of boiling magma outwards is called, are usually cyclical and sporadic, varying in intensity and destructive potential.
They are considered one of the main sources of rock materials in the Earth’s crust. Furthermore, they are one of the main natural environmental threats, capable of producing enormous forest fires, throwing tons of material into the atmosphere (gases and ash, above all) and therefore altering the chemical balance of the Earth’s biosphere.
Many mass extinctions in Earth’s geological history are attributed to intense and/or prolonged episodes of volcanic activity.
Volcanoes are studied by geologists and have an important correlation with terrestrial seismic activity, such as earthquakes and tectonic movements. Volcanoes take their name from the Greek god Hephaestus, Vulcan.
Characteristics of volcanoes
Volcanoes can have many shapes, but they generally consist of a conical structure resulting from the deposition of materials after successive eruptions. They can reach heights of even 8000 meters above sea level.
The materials that make them up can be diverse, depending on the type of volcano and the nature of the subsoil where they are produced.
On the other hand, they have a long and diverse life cycle, which consists of three stages:
- Activity or dormant state- When volcanoes can erupt at any time;
- Inactivity or dormancy- When volcanoes show certain signs of activity, but have not had eruptions in centuries;
- Extinction status- When they have not had an eruption in 25,000 years or more, although it is not possible to completely rule out their revival at a certain time.
How are volcanoes formed?
In general, volcanoes form at the edge of tectonic plates, especially where one has subducted beneath the other, that is, where two plates have collided and one of the two deforms downward, submerging. in the hot magma of the lithosphere.
Thus, its local concentration increases, which eventually produces a burst back toward the surface. However, there are “hot spots” devoid of plate contact, where magma is naturally more likely to emerge.
Volcanoes are a natural phenomenon of readjustment of the surface layers of the planet. They tend to produce new igneous rocks and cover the surface of materials that, when cooled, will form new reliefs.
Types of Volcanoes
There are various types of volcanoes, depending on their place of formation and their specific shape. The most frequent are:
- Stratovolcano
- slag cone
- volcanic caldera
- shield volcano
- Volcano submarine
Stratovolcano
A type of volcano of great height and conical shape, made up of numerous layers or strata of hardened lava, the result of previous eruptions, as well as lapilli and hardened ashes. They usually exceed 2500 meters in height and are found on continental plates.
Slag cone
Conical mounds of volcanic material accumulated around a volcanic vent. This material is known as “slag”, it is usually glassy and contains bubbles of trapped gas, as the magma cools rapidly. Its height can vary between ten and hundreds of meters high.
Volcanic caldera
Unlike the previous ones, they have a sunken or depression shape, a product of landslides or internal collapses of the volcano, which usually house thermal water, geysers or even volcanic islands.
Shield volcano
These are large volcanoes, formed by basaltic layers resulting from successive eruptions. They have a gentler slope, that is, less pronounced, and generally have recurring eruptions over thousands or millions of years.
Volcano submarine
Formed in geological cracks on the ocean floor, generally in the regions close to the oceanic ridges. Their eruptions usually greatly alter the chemistry of the surrounding seas and add new layers of matter to the ocean floor, since the magma cools very quickly due to the water. There could be thousands or millions of them today, since the study of the seafloor is a relatively new possibility in geology.
Parts of a volcano
As we have seen, volcanoes can have very diverse shapes, but a “classic” or stereotypical volcano basically consists of:
- A magmatic chamber- Which is the enormous deposit of molten rock at great pressures that underlies volcanoes.
- A chimney- Which is the stretch that connects the chamber with the outside, and can be long or short depending on the shape of the volcano (especially whether or not it has a magmatic chamber).
- A throat- Which is the opening of the chimney just in its final stages.
- A vent- Which is the opening itself through which the magma comes into contact with the air and releases gases into the atmosphere.
- A crater or “mouth” of the volcano- Which is the limit between the volcanic “mountain” and the beginning of the vent.
- Secondary cones- In case there are branches of the chimney, which make up two or more volcanoes in one.
- An eruptive column – Which is the jet of gas and other materials that is ejected into the atmosphere at the beginning of a volcanic eruption.
Volcanic eruption
A volcanic eruption is known as the violent emission of gases, ash and boiling magma towards the earth’s surface, from the bowels of a volcano. They occur when the temperature of the molten rock inside the Earth’s mantle rises and an internal explosion occurs, sending the liquid to the surface.
This process can last an indefinite amount of time, until the temperature and pressure of the magma in the subsurface drop to acceptable levels and everything returns to normal.
Volcanic eruptions appear to be cyclical in some cases. However, it has not been possible to decipher what type of periodicity governs them, although they are almost always preceded by telluric movements and the emission of fumaroles (escapes of gases and vapors from the subsoil at very high temperatures). Must Read:- Legend, Ecosystem, Scheme
Volcanoes of Mexico
The Mexican territory is extremely volcanic, as is Central America and the so-called Pacific Ring of Fire, which reaches the Mexican coast. It is estimated that there are around 566 volcanoes, not all recognized as such, the main ones being the following:
Popocatépetl
Located about 72 km southeast of the Mexican capital, it has a symmetrical conical shape and the enormous altitude of 5,500 meters above sea level, so its summits are covered with perennial glaciers. It is the second highest volcano in Mexico, but probably the best known.
The Citlaltépetl
The highest volcano in all of North America, it rises to about 5,747 meters above sea level, and is an active volcano. Known as Pico de Orizaba, it is located on the territorial limit of the states of Puebla and Veracruz.
The Tacaná volcano
Located on the border between Mexico and Guatemala, it rises to about 4,092 meters above sea level and has thermal springs between 1,500 and 2,100 meters high, from which water flows at about 40-55 °C, in a place known as Agua Caliente. Video: Ascent to the Tacaná volcano.
The Nevado de Colima
An old volcanic massif located in the state of Jalisco and which is about 4,260 meters high, has not had any type of volcanic activity for some time. As its name indicates, its slopes are usually covered in snow during winter (November to March). Video: Ascent to Nevado de Colima.
Turtle Island in Baja California Sur
This island of volcanic origin located in the Gulf of California, 40 km from the coast, is part of a caldera shield volcano approximately 1 km wide and 100 meters deep.
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