PACIFIC RING OF FIRE: LOCATION, CHARACTERISTICS, MAIN VOLCANOES - GEOGRAPHY - 2025

The Pacific ring of fire or ring of fire refers to the volcanic and seismic activity that occurs in the perimeter of the Pacific Ocean. This is due to the displacements of the lithospheric plates that make up the earth's crust in that region of the planet.

The bottom of the Pacific Ocean constitutes one of the largest plates into which the Earth's lithosphere is divided. In turn, the Pacific plate interacts with another series of lithospheric plates generating ruptures and displacements.

Pacific Ring of Fire. Source: Presidency of the Mexican Republic / CC BY (https://creativecommons.org/licenses/by/2.0)

In the case of the Pacific plate, it is an oceanic tectonic plate, therefore it is more dense than the continental crust. This is because it is made up of iron and magnesium silicates, unlike the continental plates of sodium, potassium and aluminum silicates.

In this sense, when it comes into contact with continental plates, subduction occurs, that is, the oceanic crust sinks under the continental plate. In addition, in the Pacific there are processes of divergence between plates, originating new ocean floor in the so-called oceanic ridges of the Pacific.

This generates strong volcanic activity in these areas, since at these points the earth's crust breaks, releasing magma (molten basalt). Similarly, when the other plates present in the Pacific area interact, subduction processes take place in some areas and obduction in others.

From this intense tectonic activity of plates and the derived volcanic and seismic activity, the name of belt or ring of fire arises. Although more than a ring, it is a horseshoe, since the preponderant activity occurs in the eastern, northern and western limits.

The Pacific coast of America is one of the most active areas, with great volcanic activity occurring in countries such as Mexico, Colombia, Peru, Argentina and Chile.

Location

Global earthquakes from 1900 to 2013.

The Pacific ring of fire or ring of fire is located around the entire perimeter of the Pacific Ocean, for around 40,000 km. This perimeter consists of the sequence of interaction fronts of the various plates of the Pacific Ocean area with the oceanic plate of the Peaceful.

Likewise, it contemplates the contact lines of these other plates with each other, such as those of North America, Juan Fusco, Diego Rivera, Cocos and Nazca to the east, as well as a series of microplates.

While to the north it also limits with the North American plate and the Okhotsk plate, and to the south with the Antarctic plate. While to the west the limits go from the Australian plate, through the Kermadec, Tonga, Carolina, Philippine Sea, Mariana, to that of Okhotsk (Russia).

Likewise, a significant number of small plates interact with the northeastern part of the Australian lithospheric plate. This includes nearly the entire American Pacific coast, mainland Asia and Southeast Asia, and Oceania (Australia, New Zealand, and related islands).

Fire Belt Features

Tectonic plates

The earth's crust is not continuous, it is divided into a large number of plates called lithospheric plates or tectonic plates. These plates arise when the lithosphere or upper layer of the Earth fragments due to the movement of the asthenosphere.

The asthenosphere is the upper layer of the mantle and is located immediately below the lithosphere and is made up of molten basalt. Its fluidity is due to the circulatory movement generated by temperature differences.

The movement of these plates relative to each other produces structural stresses that generate breaks in the ocean floor where the crust is thinner. This forms the so-called oceanic ridges in which there is great volcanic activity.

Molten basalt outcrops through these cracks, which forms new ocean floor by pushing old soil layers divergent.

That pushed underwater soil, when it comes into contact with the limit of a continental plate, submerges under it (subduction). This occurs because the oceanic crust is less dense than the continental crust.

If, on the contrary, two continental plates collide, obduction occurs, that is, the integration of both plates raising the crust (mountain range). Another type of interaction between plates is the transformant, referred to when two plates rub laterally when moving in opposite directions.

Direction of plate movements in the Pacific

The lithospheric plate of the Pacific is divergent at its limit with the Cocos, Nazca and Antarctic plates. In other words, it is a new seabed formation area, called the Pacific ridge.

This pushes the Pacific plate to the north, northeast, and east, where it collides with other plates and causes subduction. This subduction occurs by colliding with the North American plate to the northeast and the western Pacific, Australian and Philippine Sea plates.

At the same time, the Nazca plate grows from the oceanic ridge that forms the border with the Pacific plate. Therefore, it is pushed east and collides with the South American plate and subducts in it.

In all these shock lines, submarine, emerging and terrestrial volcanoes have formed.

Volcanic and seismic activity

The movements of the lithospheric plates produce tensions and tears that generate seismic movements (tremors and earthquakes). For example, between 1970 and 2014, an average of 223 tremors per year occurred in the Pacific Rim.

These seismic movements were of magnitude between 6 and 7 on the Richter scale and therefore considered strong.

On the other hand, the tears in the crust allow the emergence of outcrop pathways of the magma, forming volcanoes. Due to the great tectonic activity of the Pacific Ocean plates, there is great volcanic activity throughout its periphery.

This perimeter where there are regular events of volcanic eruptions, both surface and underwater, is what is called the Pacific Belt or Ring of Fire. Although more than a ring it is a horseshoe, since the greatest volcanic activity is concentrated in the west, north and east areas.

In the line of divergence between the Pacific plate and the Antarctic plate, volcanic activity is lower. Although there are inactive volcanoes such as the Sidley of 4,285 masl and the Erebus of 3,794 masl.

This Ring of Fire includes more than 4,000 volcanoes distributed in 24 regions or discontinuous volcanic arcs, where there are at least 400 main volcanoes. This represents about 75% of the volcanoes on the planet.

In this dynamic of plate movement and volcanic activity, both volcanic island arches and continental volcanic arches form in the Pacific. The first case is the product of the collision of oceanic plates, while the second is the product of the collision of an oceanic plate with a continental one.

An example of a volcanic island arc is that of the New Hebrides, the Aleutians, and the Bismarck Archipelago, both in the western Pacific. While examples of continental volcanic arches are the huge volcanic Belt of the Andes and the Neovolcanic Axis of Mexico.

Main volcanoes of the fire belt

Mexico

This country has a Pacific coast to the west, with geology influenced by the interaction of the North American, Cocos, Caribbean and Diego Rivera plates. That is why Mexico is an active area of ​​the Pacific Ring of Fire.

As an example, the interaction between the North American and Caribbean plates in central Mexico stands out, which produced the transversal Neovolcanic Axis. This is a continental volcanic arc that crosses Mexico from west to east.

Colima volcano (Mexico). Source: Nc tech3 / CC BY-SA (http://creativecommons.org/licenses/by-sa/3.0/)

In Mexico there are about 566 volcanoes, with at least 14 active, among them the Colima volcano or Volcán de Fuego that erupted in 2017. As well as the Popocatepetl in central Mexico that erupted in 2019.

On the other hand, the highest mountain in Mexico is a volcano, the Pico de Orizaba or Citlaltépetl, near the capital city and its last eruption was in 1846.

In addition, the collision of the Pacific plate with the North American plate caused the emergence of a volcanic island arc in Mexican waters; the Revillagigedo archipelago, where the Bárcena volcano is located.

Colombia

The geology of the Colombian territory is influenced by the interaction of the Nazca, Caribbean and South American plates and the North Andes microplate. The collision between the Nazca plate and that of South America lifted the Andes mountain range, whose most northwestern foothills are in Colombia.

Tectonic activity at the limits of these plates has generated the emergence of volcanoes. The volcano with the greatest activity is the Galeras, located in the south of the country in the department of Nariño in the Central Andean mountain range.

The Galeras volcano has an altitude of 4,276 meters above sea level and had its last eruption in 2010. Another active volcano is the Nevado del Ruiz or Mesa de Herveo, the volcanic belt of the Andes located further north.

Galeras volcano (Colombia). Source: DSCN8766.JPG: Josecamilomderivative work: Crisneda2000 / CC BY-SA (https://creativecommons.org/licenses/by-sa/2.5)

The eruption of this volcano in 1985 caused the tragedy of Armero, where this town was buried, killing 31,000 people. In March 2020 the Nevado del Ruiz manifested activity by emitting clouds of ash.

On the other hand, the highest point of the Colombian central Andean mountain range is the Nevado del Huila volcano with 5,364 meters above sea level.

Peru

The subduction of the Nazca oceanic plate under the South American continental plate has caused the oceanic trench of Peru 8,050 meters deep. In return, the rise of the Peruvian Andes was generated along the Pacific coast.

In this process the volcanic activity has been enormous, for which Peru has about 400 volcanoes, forming the Volcanic Arc of Peru. Of these, around 17 volcanoes are considered active, among them Ubinas, which had a strong recent activity.

Sabancaya volcano (Peru). Source: Gallery of the Ministry of Defense of Peru / CC BY (https://creativecommons.org/licenses/by/2.0)

The Ubinas erupted in 2019 forcing an evacuation of the surroundings, displacing 1,000 people in Peru and about 2,000 in Bolivia. Other volcanoes are the Sabancaya that erupted in 2016 and the Tungurahua that erupted in 2011.

While the stratovolcanic complex of Coropuna is the highest in the country with 6,425 meters above sea level, located in southern Peru.

Argentina

The tectonic activity product of the subduction of the Nazca plate under the South American formed the Argentine Andes and generates its volcanic activity. In this country there are around 57 volcanoes, of which about 37 are active.

For example, Tuzgle is a stratovolcano with 5,486 meters above sea level, located in the extreme north of Argentina whose last eruption was 10,000 years ago. The Palei-Aike volcanic field is also considered active at only 300 meters above sea level in the extreme south.

Tuzgle Volcano (Argentina). Source: Bachelot Pierre JP / CC BY-SA (https://creativecommons.org/licenses/by-sa/3.0)

The Ojos del Salado volcano in Catamarca is shared with Chile and is the highest volcano in the world at 6,879 m. Another border volcano is Copahue, which has been having eruptions since 2012, the last being in 2018.

While in the province of Mendoza, on the border with Chile is the Planchón-Peteroa volcanic complex, with activity in 1991, 1998, 2010 and 2011. This complex is formed by the extinct Azufre volcano, the Peteroa volcano, and the Planchón volcano. forming on the previous ones.

Chile

In Chile the orogenic and volcanic activity is the product of the interaction of the South American plate with the Nazca, Antarctic and Scottish (Scotia) plates. Chile being the territory with the second largest and most active volcanic chain on the planet, after Indonesia.

It is about 2,000 volcanoes, of which about 500 are geologically active. Of these, 36 volcanoes have had historical activity, that is, there is a documented record.

Among the assets are Quizapú or Cerro Azul, to the north of the Chilean Andes and Chaitén to the south in the Los Lagos region. The latter erupted in 2008, forcing the population of Chaitén and others nearby to evacuate, and in 2015 the Villarica and Calbuco volcanoes erupted.

Calbuco Volcano (Chile). Source: Nicolás Binder from Seno de Reloncaví, Chile / CC BY-SA (https://creativecommons.org/licenses/by-sa/2.0)

For its part, the Lascar volcano has registered 32 eruptions from 1848 to 2013, being a volcano with explosive eruptions. Another very active volcano is Lonquimay, which erupted in 1988 with a high content of fluorine in the ash, which when diluted in the water caused poisoning to livestock.

References

1. Alfaro, P., Alonso-Chaves, FM, Fernández, C. and Gutiérrez-Alonso, G. (2013). Plate tectonics, an integrative theory of how the planet works. Conceptual and didactic foundations. Teaching of Earth Sciences.
2. Bonatti, E. and Harrison, C. (1976). Hot lines in the Earth's mantle. Nature.
3. Fox, PJ and Gallo, DG (1984). A tectonic model for ridge-transform-ridge plate boundaries: Implications for the structure of oceanic lithosphere. Tectonophysics.
4. López, A., Álvarez, CI and Villarreal, E. (2017). Migration of seismic sources along the Pacific ring of fire. La Granja: Journal of Life Sciences.
5. Rodríguez, M. (2004). Chapter 6: Plate Tectonics. In: Werlinger, C (Ed.). Marine Biology and Oceanography: Concepts and Processes. Volume I.
6. SERNAGEOMIN (2018). Chile: volcanic territory. National Geology and Mining Service.
7. Yarza de De laTorre, E. (2003). The volcanoes of the Transversal Volcanic System. Geographical Research, Bulletin of the Institute of Geography, UNAM.