Volcano. What is Vulcan? Volcanoes: characteristics and types An active volcano is called

Volcanoes are beautiful, but at the same time they are scary. They frighten with their power and the fact that they can become the culprits of death and destruction. And although volcanic eruptions are not a frequent occurrence and are under the control of scientists, many active volcanoes still pose a danger to people living near them. Here are the 10 most active volcanoes on Earth.

10 PHOTOS

Mauna Loa is one of the most large volcanoes on Earth in terms of volume and sole area. It is also one of the five volcanoes that form Hawaiian Islands. This is an active volcano that has been erupting for approximately 700,000 years. The last eruption of the volcano occurred on March 24, 1984.

Taal Volcano is located on the island of Luzon in the Philippines, about 50 km from the capital Manila. This is one of the active volcanoes in the Philippines and has erupted many times. The last eruption was in 1977.

Ulawun is one of the most active volcanoes in Papua New Guinea. And one of the most dangerous. The first eruption was recorded in 1700. Since then, 22 eruptions have been recorded. So in 1980, an eruption devastated an area of 20 square meters. km.

It is one of the most active volcanoes in Africa and one of the eight volcanoes in the Virunga Mountains. It has erupted at least 34 times since 1882. Nyiragongo's last destructive eruption occurred on January 17, 2002, when lava destroyed approximately 40% of the city of Goma.

Merapi is the most active volcano in Indonesia, having erupted regularly since 1548. The volcano is located near the city of Yogyakarta and thousands of people actually live on the slope of the volcano.

Galeras has been active for at least a million years. It is located in southern Colombia, close to the border with Ecuador. Today it is the most active volcano in Colombia. After a 10-year sleep, the volcano woke up in 1988, and in 1993 a disaster occurred that resulted in the death of six scientists and three tourists.

Sakurajima is an active stratovolcano and former island. It is often called Vesuvius of the East. A cloud of smoke is almost always visible above the volcano. The danger of the volcano is that densely populated areas of the city of Kagoshima are located next to it.

Popocatepetl is an active volcano and the second highest peak in Mexico (5426 m). Residents of Puebla, 40 km from the volcano, enjoy the magnificent view of its snow-capped peak. The last major eruption was in 2000. Fortunately, scientists were able to warn the government and people were evacuated from the dangerous area.

This is the most dangerous and active supervolcano, the eruption of which will lead to catastrophic consequences. A Yellowstone eruption could lead to species extinction and even the end of the world.

Ancient people naively mistook volcanic eruptions for the wrath of the gods, however, many people still think so today. But the enlightened part of humanity has long understood that the matter here is not at all about the gods. Under the Earth's mantle there is an ocean of molten magma, which in some places presses harder than usual on the earth's crust and breaks through to the surface, pouring out in the form of lava flows from volcanic vents. Although lava flows burn everything in their path, they are not the worst thing in volcanic eruption, because there are also deadly pyroclastic flows, ash clouds, acid rain, volcanic bombs and earthquakes accompanying the eruption. As for the TOP 10 most dangerous volcanoes in the world, in a matter of hours after the eruption they can change everything around them beyond recognition.

1. Yellowstone supervolcano, USA

In the 60s of the last century, scientists discovered that a vast area in Yellowstone national park is a giant caldera of an ancient supervolcano. More than 3 million daredevils come every year to see the caldera’s increasing activity every year. Of course, it is very interesting to watch the work of geysers and hot springs, but they are potentially harbingers of catastrophic events.
Scientists have determined that the last time this supervolcano exploded was approximately 640 thousand years ago. If this were to happen again today, 87,000 people living near Yellowstone would likely die. A powerful eruption could completely change the landscape of the western United States, and huge masses of volcanic ash would cause climate change around the world and threaten the lives of people and animals. The explosion of such a volcano would become a full-scale global catastrophe, comparable to the fall of a large meteorite. Scientists suggest that at a depth of 8 kilometers under the caldera, a giant bubble of magma slowly rises, which heats the groundwater to a boil - hence the numerous hot springs and geysers. Unfortunately, science is still unable to make accurate predictions regarding eruptions, so we can only hope that it won't be too soon.

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2. Vesuvius, Italy

The last time Vesuvius, which has a height of 1281 meters, erupted in 1944. All schoolchildren are familiar with this volcano from the famous painting by Karl Bryullov “The Last Day of Pompeii”, which picturesquely depicts the strong eruption of 79 that destroyed all local settlements, the most famous of which were the cities of Pompeii and Herculaneum. The ash of the pyroclastic flow that covered Pompeii preserved everything that did not have time to burn, and after large-scale excavations a very interesting museum open air.
Vesuvius erupts about once every 20 years, although last eruption took place in 1944. Despite this, people continue to actively settle in the immediate vicinity of the mountain and even on it itself. Therefore, any powerful eruption of Vesuvius may again be accompanied by large casualties.

3. Popocatepetl, Mexico

With a height of 5426 meters, the Popocatepetl volcano last erupted in 2000. It is only about 50 kilometers from Mexico City. During the last eruption, authorities saved 41 thousand from certain death. local residents, evacuating them in time. But with 9 million Mexicans now living within the blast radius of the volcano, a potential explosion could spell disaster. The activity of the volcano and the densely populated surroundings make Popocatépetl very dangerous. The peaks of the volcano are covered with glacier. According to historical data, after 1519 there were over 20 eruptions of this volcano.

4. Sakurajima, Japan

The volcano is not very high (1117 meters), and last erupted in 2015. Due to its high activity, it is called the “eastern Vesuvius”. At one time, the volcano rose from under the water near the coast of Japan, but after the 1914 eruption, lava flows formed a “bridge” connecting the volcano to the “mainland”. Every year, thousands of micro-eruptions of Sakurajima occur, during which ash is ejected from its vent and spread throughout the surrounding area. In the event of a powerful eruption, the city of Kagoshima with a population of 700 thousand people will be in danger.

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5. Galeras, Colombia

The last time this tall (4276 m) volcano erupted was in 2010. It is located on the border with Ecuador. Volcanologists have determined that this volcano has been active for at least a million years. Its first documented eruption took place in 1580. Galeras remained inactive for a decade after 1978, after which it began to erupt regularly again. On the eastern ridge of the volcano is the city of Pasto, where 450 thousand Colombians live, risking their lives.

6. Merapi, Indonesia

The 2,930-metre tall Merapi volcano, which means “mountain of fire”, last staged a show in 2010. In Indonesia, it is the most active of the active volcanoes, pouring out a huge volume of lava, for which it has no equal in the world. The volcano has been active for at least 10,000 years. The latest eruption killed 353 Indonesians and left 320,000 homeless. The city authorities then finally developed an evacuation plan.

7. Nyiragongo, Democratic Republic of Congo

The last time this 3,470 m high volcano erupted was in 2011. It has a very large crater that periodically fills with lava, and then the lava lake disappears. But sometimes things go wrong, for example, in 1977, when under the pressure of lava the crater wall collapsed, and liquid molten stone rushed down to the villages at the speed of a locomotive. As a result, thousands of people were killed and injured by the lava. In 2002, under similar circumstances, another 147 people died, and 120 thousand people were left homeless.

8. Ulawun, Papua New Guinea

The 2,334-meter active volcano last erupted in 2013. Local residents respectfully call him “father.” This symmetrical peak grew on the island of New Britain. Since the beginning of the 18th century, 22 powerful eruptions of the Ulavun volcano have been recorded. Residents living next to it still witness its periodic weak eruptions. Although now the mountain looks impeccable from the point of view of decorating the landscape, after a strong eruption it is unlikely to retain its exterior, and significant areas of the surrounding lands will be destroyed.

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9. Tal, Philippines

This volcano is very small in height - only 311 meters, and its last eruption was observed in 1965. This volcano grew in the middle of Lake Tal on Philippine island Luzon. Manila, the capital of the country, is very close, so for its population of 1.6 million people, the volcano is not at all a hypothetical threat. This “baby” has erupted 33 times since 1572. Although many tourists come to this island every year, they are immediately warned to stay away from the volcano. The most powerful eruption of the last century occurred here in 1911. Then the volcano was able to kill more than 1,330 people, and all living creatures within a radius of 10 kilometers died.

10. Mauna Loa, Hawaii

This tall (4,169 meters) volcano last erupted in 1984. In general, it has been active for at least 700 thousand years. But, fortunately, most of its eruptions are weak, only occasionally lava flows acquire high speed and become dangerous for those located on the slopes settlements. Basically, the volcano spews viscous lava, which slowly creeps along the surface, so residents have time to evacuate. But volcanologists believe that the likelihood of a catastrophic eruption of this volcano is very high. In addition to eruptions, Mauna Loa is also dangerous due to destructive landslides, which, although rare, are extremely dangerous.

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Despite their deadly nature, various volcanoes have long attracted people. Previously, people were attracted by fertile soils, enriched with minerals and trace elements due to the activity of volcanoes, now tourists are attracted by the beauty and majesty of these natural objects.

Where are the largest volcanoes on the world map?

Most of the modern active volcanoes are located in Pacific volcanic ring- the area in which the largest number of eruptions and 90% of earthquakes on our planet occur.

The second most powerful seismic zone is the Mediterranean fold belt, which stretches from the Indonesian islands to.

The strongest eruption in history

The most destructive eruption in terms of its consequences is considered to be the catastrophe that occurred in 1883 during the explosion Krakatoa volcano located in . During this cataclysm, more than 36 thousand people died, more than 165 cities and villages were completely destroyed, and ash was released to a height of 70 kilometers.

The force of the explosion during the eruption exceeded the force of a nuclear bomb over Hiroshima by 10 thousand times. Most deaths are a consequence of huge tsunami caused by the eruption. The island on which Krakatoa was located was almost completely destroyed during the disaster. The sound of the explosion spread over a distance of 5 thousand kilometers from the epicenter of the disaster.

Earth's Greatest Active Volcanic Mountains

The largest active volcanoes in the world by volume:

Mauna Loa, Hawaii, with a volume of 80 thousand cubic kilometers;
Kilimanjaro(Tanzania), which is considered dormant but could potentially become active, has a volume of 4,800 cubic kilometers;
Volcano Sierra Negra, located on Galapagos Islands(Ecuador) has a volume of 580 cubic kilometers.

Which country has the largest source of lava?

In terms of size, there is no equal to the Hawaiian volcano Mauna Loa, which has a volume of 80 thousand cubic kilometers. The title of the highest is disputed by 2 volcanoes from South America:

Llullaillaco, located on the border of Argentina and Chile with an altitude of more than 6 thousand meters;
Cotopaxi, located in Ecuador with an altitude of 5897 meters.

Description with names

There are between 1000 and 1500 active volcanoes on our planet. Many of them are located near densely populated areas and pose a threat to human life. The most dangerous volcanoes, which are under special surveillance, are included in UN Decade Volcanoes list.

Merapi

Merapi, which means in Indonesian "mountain of fire", recognized as one of the most dangerous volcanoes in Asia. It is located in the south of the island of Java in Indonesia, and its peak rises to a height of 3 thousand meters.

Significant eruptions of Merapi occur at intervals of approximately 7 years; throughout its history, Merapi has repeatedly caused the death of many people. In 1930, the eruption killed 1,400 people, and in 2010 more than 350 thousand people had to be evacuated, killing 353 island residents.

Located near Merapi Yogyakarta city, in the agglomeration of which more than 2 million people live. Due to its activity and danger to human life, Merapi is included in the list of Volcanoes of the Decade.

Sakurajima

Sakurazdima Volcano (Japan) is located on Kyushu island, its peak rises to a height of 1110 meters. The first eruption recorded by chronicles occurred in 963, and the most powerful one dates back to 1914, but thanks to the tremors that preceded it, most of the local residents managed to evacuate, and “only” 35 people died.

Since the mid-20th century, the volcano has been constantly active. Happen every year thousands of small explosions and ash emissions.

In 2013, there was a large ash emission reaching a height of 4000 meters.

Sakurajima is also on the list of Volcanoes of the Decade.

Aso

Volcano Aso is also located on Kyushu island in Japan. The highest point of Aso is at an altitude of 1592 meters. During the period of observation of the volcano, about 165 large and medium eruptions occurred, many of which resulted in human casualties.

The last time people died as a result of a volcanic eruption was in 1979, when 3 people died and 11 were injured. But Aso is dangerous not only for its eruptions, poisonous volcanic gas fumes They regularly poison tourists who try to conquer Aso. The last such incident occurred in 1997, when two climbers died.

The last eruption of Aso was noted in 2011, ash emission occurred to a height of up to 2 kilometers.

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Nyiragongo

Nyiragongo is located in the territory DR Congo in the Virunga mountain system (Africa). In the crater of the volcano there is the world's largest lava lake, the depth of which can reach 3 kilometers. In 1977, the crater wall ruptured, causing a large flow of lava into the surrounding area, ultimately killing 70 people.

During observations of Nyiragongo since 1882, it was recorded 34 major volcanic eruptions. A feature of the Nyiragongo eruptions is the extremely rapid flow of lava, reaching speeds of 100 kilometers per hour. During a major eruption in 2002, 400 thousand residents of the city of Goma, located near the volcano, were evacuated. Nevertheless, 147 of them died as a result of this cataclysm, and the city itself suffered significant damage.

All these factors make Nyiragongo one of the the most dangerous volcanoes on the planet, for which he was rightly included in the list of Volcanoes of the Decade.

Galeras

The Galeras volcano is located in Colombia near the city of Pasto, whose population is more than 400 thousand people. Its height exceeds 4200 meters. Due to its danger, Galeras was included in the list of Volcanoes of the Decade that pose the greatest threat in the foreseeable future.

It is believed that over the past 7,000 years, Galeras has experienced at least 6 major eruptions, the last of which was recorded in 1993.

Mauna Loa

The Mauna Loa volcano is located on Hawaiian Islands belonging to the United States of America. This giant volcano occupies more than half the area of Hawaii, the height of the peak above sea level is 4169 meters, but most of the volcano is located under water. Together with the underwater part, its height from base to top reaches 9170 meters, which exceeds the height of Everest.

Mauna Loa erupts according to what is called Hawaiian type with an outpouring of lava, but without explosions and large ash emissions. Observations of the volcano have been carried out only since 1832, but during this time 39 major eruptions of Mauna Loa have been recorded. This volcano was included in the list of Volcanoes of the Decade due to the huge lava flows accompanying the eruption and the densely populated area in its immediate vicinity.

The summit of the volcano and its slopes were included in the list World Heritage UNESCO.

Colima

The most active volcano in Central America is located in the state of Jalisco. Thanks to her activity, Colima received the nickname "little Vesuvius", its height exceeds 3800 meters.

Over the past 450 years, more than 40 large and medium-sized volcanic eruptions have been recorded, the last of which occurred on September 12, 2016. More than 400 thousand people live near Colima, making it the most dangerous volcano America. For this reason, the volcano was included in the list of Volcanoes of the Decade.

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Vesuvius

Most famous volcano of the world is located on the Apennine Peninsula in. The lonely peak of Vesuvius, 1281 meters high, rises above the vast fields of the province of Campania and is part of the Apennine mountain system.

Located just 15 kilometers from Naples, Vesuvius has repeatedly gone down in history with its catastrophic eruptions; about 80 major ones alone were recorded. In 79 AD, the most destructive eruption of Vesuvius, during which famous cities perished:

Pompeii;
Oplontis;
Herculaneum;
Stabiae.

It is believed that at least 16 thousand people died during this disaster.

The last one happened in 1944. this moment eruption of Vesuvius, cities were destroyed during this natural disaster Weight And San Sebastiano, 27 people became victims. Since then, Vesuvius has not shown strong activity, but the danger of a new eruption always remains. Vesuvius is one of the main attractions of the province of Campania and a visit to it is included in sightseeing tour when traveling to Naples.

Etna

Another famous volcano in Italy is located in the east of the island of Sicily and is the highest volcano, rising to a height of 2329 meters. Etna erupts several times a year. History has recorded several major eruptions of this volcano that led to devastating consequences:

Was destroyed in 122 AD Catania city;
In 1169, during the large-scale eruption of Etna, they died 15 thousand people;
In 1669, Catania suffered again, houses were destroyed 27 thousand people;
In 1928, the ancient Maskali city.

Despite the danger of the volcano, the inhabitants of the island continue to settle on its slopes. The reason for this is fertile soil, enriched with minerals and trace elements contained in cooled lava flows and ash.

Etna is one of the main natural attractions of Sicily; tourists from all over the world come to see the volcano and climb to its top.

Popocatepetl

Volcano Popocatepetl, or El Popo, as locals affectionately call it, is located in Mexico, 70 kilometers from the capital of this country, Mexico City. The height of the volcano is almost 5500 meters. Popocatépetl has erupted more than 15 times over the past 500 years, with the most recent one occurring as recently as 2015. An extinct volcano is located near Popocatepetl. Iztaccihuatl.

A trip to these volcanoes is an integral part of the excursion program when visiting Mexico City.

Klyuchevskaya Sopka

Most high volcano Eurasia is located on the Kamchatka Peninsula and is considered the most famous of the many volcanoes of Kamchatka. Highest point beyond Caucasus Mountains reaches an altitude of 4750 meters. It is the most active volcano in Eurasia, with an average of almost every year. The last significant eruption occurred in 2013, the height of the ash emission was 10-12 kilometers. The eruption was accompanied by mud flows and ashfall.

Cotopaxi

The active Cotopaxi volcano is located in South America on the territory of the state Ecuador part of the Andes mountain system. The height of the peak of Cotopaxi is 5897 meters. In the entire history of observations, 86 eruptions have been recorded, the largest of which led to the complete destruction of the city of Latacunga in 1786. The last activity of Cotopaxi was noticed in 1942, after which the volcano is still dormant.

Famous extinct giants

In addition to active volcanoes, on our planet there are many extinct volcanoes that do not show volcanic activity.

Supreme

The tallest extinct volcano on the planet, Aconcagua, is located in Argentina and is part of mountain system Andes. Aconcagua is not only the highest an extinct volcano in the world, but also the highest peak in America, the Western and Southern Hemispheres. The height of Aconcagua exceeds 6950 meters.

Sleeping giants

Many extinct volcanoes are now considered simply mountains, although some of them could potentially “wake up” and begin to become active. Such volcanoes, which may become active in the future, are called "sleeping".

Famous Mount Kilimanjaro in Tanzania (Africa) is a dormant volcano that is not active. Scientists believe that one day Kilimanjaro may wake up, then this potential volcano will become one of the highest in the world, because the height of Kilimanjaro is 5895 meters above sea level.

Colossal supervolcano Yellowstone was considered extinct, but scientists have found that there is little activity in it, so now Yellowstone is classified as a dormant volcano. The giant last erupted almost a million years ago.

It is believed that if Yellowstone wakes up, a potential eruption will become one of the largest disasters in the history of the Earth, every third inhabitant of the planet will die, and several US states will be completely destroyed.

Yellowstone eruption will provoke many earthquakes, giant tsunami waves and other volcanic eruptions, which will affect almost every inhabitant of the planet. The ash ejected by the volcano will cover the surface of the earth from the sun for a year and a half, and a volcanic winter will occur throughout the planet.

However, not all scientists believe that the consequences of this cataclysm will be so serious. In any case, the eruption of this volcano remains one of the main potential threats to humans.

The largest extinct volcano in Russia is 5642 meters. It is located on the border of the republics of Kabardino-Balkaria and Karachay-Cherkessia. Belongs to the list highest peaks six parts of the world. Scientists consider the activity of the volcano not so much completed as fading.
The largest volcano of our time cannot be visited and is very difficult to see, since it is under water. Array Tamu located at the bottom Pacific Ocean and is located approximately 1,600 kilometers east of the Japanese Islands. Its dimensions are 650 by 450 kilometers; in scale, the array is one of the largest not only on Earth, but in the entire solar system. The last volcanic eruption occurred 140 million years ago.
Dormant volcanoes Big and Small Ararat are now located on the territory and belong to the category of volcanoes that do not exhibit volcanic activity. Peak Greater Ararat, reaching 5165 meters, is the highest point in Turkey.
One of the highest peaks of the Caucasus, Mount Kazbek is also an extinct volcano. Kazbek is located on the border with Russia, the highest point of the mountain is located at an altitude of more than 5 kilometers. During research in one of the caves of Kazbek it was found volcanic ash from an eruption that supposedly occurred 40 thousand years ago.

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Watch a video about these and other volcanoes in the world:

Volcanic eruptions are dangerous primarily due to their direct impact - the release of tons of burning lava, under which entire cities can perish. But, in addition to this, side factors such as the suffocating effects of volcanic gases, the threat of tsunamis, isolation from sunlight, distortion of the terrain and local climate changes also pose a danger.

Merapi, Indonesia

Merapi is one of the largest volcanoes on the Indonesian islands. It is also one of the most active: large eruptions occur once every seven to eight years, and small ones - once every two years. At the same time, smoke appears from the top of the volcano almost every day, not allowing local residents to forget about the threat. Merapi is also famous for the fact that in 1006 the entire medieval Javanese-Indian state of Mataram was seriously damaged by his activities. The volcano is especially dangerous because it is located near the large Indonesian city of Yogyakarta, which is home to about 400 thousand people.

Sakurajima, Japan

Sakurajima has been in constant volcanic activity since 1955, with its last eruption occurring in early 2009. Until 1914, the volcano was located on a separate island of the same name, but frozen lava flows connected the island to the Osumi Peninsula. Residents of the city of Kagoshima are already accustomed to the restless behavior of the volcano and are constantly ready to take refuge in shelters.

Aso Volcano, Japan

The last time volcanic activity was recorded at the volcano was quite recently, in 2011. Then the ash cloud spread over an area of more than 100 km. From that time to the present, about 2,500 tremors have been recorded, which indicates the activity of the volcano and its readiness to erupt. Despite the direct danger, about 50 thousand people live in the immediate vicinity, and the crater is popular tourist site for daredevils. In winter, the slopes are covered with snow and people go skiing and sledding in the valley.

Popocatepetl, Mexico

One of the largest volcanoes in Mexico is located literally fifty kilometers from. This is a city with a population of 20 million people who are in constant readiness to evacuate. In addition to Mexico City, the following are located in the neighborhood: big cities, like Puebla and Tlaxcala de Xicotencatl. Popocatepetl also gives them a reason to be nervous: emissions of gas, sulfur, dust and stones occur literally every month. In recent decades, the volcano has erupted in 2000, 2005 and 2012. Many climbers strive to climb to its peak. Popocatepetl is famous for the fact that in 1955 it was conquered by Ernesto Che Guevara.

Etna, Italy

This Sicilian volcano is interesting because it has not only one main wide crater, but also many small craters on the slopes. Etna is constantly active, with small eruptions occurring every few months. This does not prevent the Sicilians from densely populating the slopes of the volcano, since the presence of minerals and trace elements makes the soil very fertile. The last major eruption was in May 2011, and minor emissions of ash and dust occurred in April 2013. By the way, Etna is the most big volcano c: it is two and a half times larger than Vesuvius.

Vesuvius, Italy

Vesuvius is one of the three active volcanoes in Italy, along with Etna and Stromboli. They are even jokingly called the “hot Italian family.” In 79, the eruption of Vesuvius destroyed the city of Pompeii and all its inhabitants, who were buried under layers of lava, pumice and mud. One of the last major eruptions, in 1944, killed about 60 people and almost completely destroyed the nearby towns of San Sebastiano and Massa. According to scientists, Vesuvius destroyed nearby cities about 80 times! By the way, this volcano has set many records. Firstly, it is the only active volcano on the mainland, secondly, it is the most studied and predictable, and thirdly, the territory of the volcano is a nature reserve and a national park where excursions are held. You can only go up on foot, since the lift and funicular have not yet been restored.

Colima, Mexico

The volcanic mountain consists of two peaks: the already extinct Nevado de Colima, which is covered with snow most of the time, and the active Colima volcano. Colima is particularly active: it has erupted more than 40 times since 1576. A strong eruption occurred in the summer of 2005, when authorities had to evacuate people from nearby villages. Then a column of ash was thrown to a height of about 5 km, spreading a cloud of smoke and dust behind it. Now the volcano is fraught with danger not only for local residents, but also for the entire country.

Mauna Loa, Hawaii, USA

Scientists have been monitoring the volcano since 1912 - there is a volcanological station on its slopes, as well as solar and atmospheric observatories. The height of the volcano reaches 4169 m. The last strong eruption of Mauna Loa destroyed several villages in 1950. Until 2002, the seismic activity of the volcano was low, until an increase was recorded, which indicates the possibility of eruptions in the near future.

Galeras, Colombia

The Galeras volcano is very powerful: its diameter at the base exceeds 20 km, and the width of the crater is about 320 m. The volcano is very dangerous - every few years, due to its activity, the population of the nearby town of Pasto has to be evacuated. The last such evacuation took place in 2010, when about 9 thousand people found themselves in shelters due to the threat of a strong eruption. Thus, the restless Galeras keeps local residents in constant suspense.

Nyiragongo, Republic of Congo

The Nyiragongo volcano is considered the most dangerous in all: it accounts for about half of all cases of volcanic activity recorded on the continent. Since 1882, there have been 34 eruptions. Nyiragongo lava has a special chemical composition, so it is unusually liquid and flowing. The speed of erupted lava can reach 100 km/h. In the main crater of the volcano there is a lava lake, the temperature of which heats up to 982 Cº, and the bursts reach a height of 7 to 30 m. The last largest eruption occurred in 2002, then 147 people died, 14 thousand buildings were destroyed, and 350 thousand people left homeless.

It is worth noting that scientists have been studying the activity of volcanoes for many years and modern technology recognizes the beginning of their seismic activity. Many volcanoes have webcams that allow you to monitor what is happening in real time. People living nearby are already accustomed to this behavior of volcanoes and know what to do when an eruption begins, and emergency services have the means to evacuate local residents. So every year the likelihood of casualties from volcanic eruptions becomes less and less.

Volcanoes are geological formations on the surface of the Earth's crust or the crust of another planet where magma comes to the surface, forming lava, volcanic gases, rocks (volcanic bombs) and pyroclastic flows.

The word “volcano” comes from ancient Roman mythology and comes from the name of the ancient Roman god of fire, Vulcan.

The science that studies volcanoes is volcanology and geomorphology.

Volcanoes are classified by shape (shield, stratovolcanoes, cinder cones, domes), activity (active, dormant, extinct), location (terrestrial, underwater, subglacial), etc.

Volcanic activity

Volcanoes are divided depending on the degree of volcanic activity into active, dormant, extinct and dormant. An active volcano is considered to be a volcano that erupted during a historical period of time or in the Holocene. The concept of active is quite inaccurate, since a volcano with active fumaroles is classified by some scientists as active, and by others as extinct. Dormant volcanoes are considered to be inactive volcanoes where eruptions are possible, and extinct volcanoes are considered to be those where they are unlikely.

However, there is no consensus among volcanologists on how to define an active volcano. The period of volcanic activity can last from several months to several million years. Many volcanoes exhibited volcanic activity tens of thousands of years ago, but are not considered active today.

Astrophysicists, from a historical perspective, believe that volcanic activity, caused, in turn, by the tidal influence of other celestial bodies, can contribute to the emergence of life. In particular, it was volcanoes that contributed to the formation of the earth's atmosphere and hydrosphere, releasing significant amounts of carbon dioxide and water vapor. Scientists also note that too active volcanism, such as on Jupiter's moon Io, can make the planet's surface uninhabitable. At the same time, weak tectonic activity leads to the disappearance of carbon dioxide and sterilization of the planet. “These two cases represent potential boundaries for planetary habitability and exist alongside the traditional parameters of habitable zones for systems of low-mass main sequence stars,” the scientists write.

Types of volcanic structures

In general, volcanoes are divided into linear and central, but this division is arbitrary, since most volcanoes are confined to linear tectonic disturbances (faults) in the earth’s crust.

Linear volcanoes or fissure-type volcanoes have extensive supply channels associated with a deep split in the crust. As a rule, basaltic liquid magma flows out of such cracks, which, spreading to the sides, forms large lava covers. Along the cracks, gentle spatter shafts, wide flat cones, and lava fields appear. If the magma has a more acidic composition (higher silicon dioxide content in the melt), linear extrusive ridges and massifs are formed. When explosive eruptions occur, explosive ditches can appear tens of kilometers long.

The shapes of central-type volcanoes depend on the composition and viscosity of the magma. Hot and easily mobile basaltic magmas create vast and flat shield volcanoes (Mauna Loa, Hawaiian Islands). If a volcano periodically erupts either lava or pyroclastic material, a cone-shaped layered structure, a stratovolcano, appears. The slopes of such a volcano are usually covered with deep radial ravines - barrancos. Volcanoes of the central type can be purely lava, or formed only volcanic products- volcanic scoria, tuffs, etc. formations, or be mixed - stratovolcanoes.

There are monogenic and polygenic volcanoes. The former arose as a result of a single eruption, the latter as a result of multiple eruptions. Viscous, acidic in composition, low-temperature magma, squeezed out of the vent, forms extrusive domes (Montagne-Pelé needle, 1902).

In addition to calderas, there are also large negative forms of relief associated with subsidence under the influence of the weight of erupted volcanic material and a pressure deficit at depth that arose during the unloading of the magma chamber. Such structures are called volcanotectonic depressions. Volcanotectonic depressions are very widespread and often accompany the formation of thick strata of ignimbrites - volcanic rocks of acidic composition, having different genesis. They are lava or formed by sintered or welded tuffs. They are characterized by lens-shaped segregations of volcanic glass, pumice, lava, called fiamme, and a tuff or tofo-like structure of the main mass. As a rule, large volumes of ignimbrites are associated with shallow magma chambers formed due to the melting and replacement of host rocks. Negative relief forms associated with central-type volcanoes are represented by calderas - large rounded failures several kilometers in diameter.

Classification of volcanoes by shape

The shape of a volcano depends on the composition of the lava it erupts; Five types of volcanoes are usually considered:

Shield volcanoes, or "shield volcanoes". Formed as a result of repeated ejections of liquid lava. This form is characteristic of volcanoes that erupt low-viscosity basaltic lava: it flows for a long time both from the central vent and from the side craters of the volcano. Lava spreads evenly over many kilometers; Gradually, a wide “shield” with gentle edges is formed from these layers. Example - Mauna Loa volcano in Hawaii, where lava flows directly into the ocean; its height from its base on the ocean floor is approximately ten kilometers (while the underwater base of the volcano is 120 km long and 50 km wide).
Cinder cones. When such volcanoes erupt, large fragments of porous slag are piled up around the crater in layers in the shape of a cone, and small fragments form sloping slopes at the foot; With each eruption the volcano gets higher. This is the most common type of volcano on land. They are no more than a few hundred meters in height. An example is the Plosky Tolbachik volcano in Kamchatka, which exploded in December 2012.
Stratovolcanoes, or "layered volcanoes". Periodically erupt lava (viscous and thick, quickly solidifying) and pyroclastic matter - a mixture of hot gas, ash and hot stones; as a result, deposits on their cone (sharp, with concave slopes) alternate. Lava from such volcanoes also flows out of cracks, solidifying on the slopes in the form of ribbed corridors that serve as the support of the volcano. Examples - Etna, Vesuvius, Fuji.
Dome volcanoes. They are formed when viscous granite magma, rising from the depths of the volcano, cannot flow down the slopes and hardens at the top, forming a dome. It clogs its mouth, like a cork, which over time is expelled by the gases accumulated under the dome. Such a dome is now forming over the crater of Mount St. Helens in the northwestern United States, formed during the 1980 eruption.
Complex (mixed, composite) volcanoes.

Eruption

Volcanic eruptions are geological emergencies that can lead to natural disasters. The eruption process can last from several hours to many years. Among various classifications General types of eruptions are distinguished:

Hawaiian type - emissions of liquid basaltic lava, often formed lava lakes, should resemble scorching clouds or red-hot avalanches.
Hydroexplosive type - eruptions that occur in shallow conditions of oceans and seas are characterized by the formation of a large amount of steam that occurs when hot magma and sea water come into contact.

Post-volcanic phenomena

After eruptions, when the activity of the volcano either stops forever, or it “dormants” for thousands of years, processes associated with the cooling of the magma chamber and called post-volcanic processes persist on the volcano itself and its surroundings. These include fumaroles, thermal baths, and geysers.

During eruptions, a volcanic structure sometimes collapses with the formation of a caldera - a large depression with a diameter of up to 16 km and a depth of up to 1000 m. As the magma rises, the external pressure weakens, associated gases and liquid products escape to the surface, and a volcanic eruption occurs. If the ancients are brought to the surface rocks, and not magma, and the gases are dominated by water vapor formed by heating groundwater, then such an eruption is called phreatic.

Lava that rises to the earth's surface does not always reach this surface. It only lifts layers of sedimentary rocks and hardens in the form of a compact body (laccolith), forming a peculiar system low mountains. In Germany, such systems include the Rhön and Eifel regions. In the latter, another post-volcanic phenomenon is observed in the form of lakes filling the craters of former volcanoes that failed to form a characteristic volcanic cone (the so-called maars).

Heat sources

One of the unresolved problems of volcanic activity is determining the heat source necessary for local melting of the basalt layer or mantle. Such melting must be highly localized, since the passage of seismic waves shows that the crust and upper mantle are usually in a solid state. Moreover, the thermal energy must be sufficient to melt huge volumes of solid material. For example, in the USA in the Columbia River basin (Washington and Oregon states) the volume of basalts is more than 820 thousand km³; the same large strata of basalts are found in Argentina (Patagonia), India (Deccan Plateau) and South Africa (Great Karoo Rise). Currently there are three hypotheses. Some geologists believe that the melting is caused by local high concentrations of radioactive elements, but such concentrations in nature seem unlikely; others suggest that tectonic disturbances in the form of shifts and faults are accompanied by the release of thermal energy. There is another point of view, according to which the upper mantle under conditions of high pressure is in a solid state, and when, due to fracturing, the pressure drops, it melts and liquid lava flows through the cracks.

Areas of volcanic activity

The main areas of volcanic activity are South America, Central America, Java, Melanesia, Japanese islands, Kurile Islands, Kamchatka, northwestern USA, Alaska, Hawaiian Islands, Aleutian Islands, Iceland, Atlantic Ocean.

Mud volcanoes

Mud volcanoes - small volcanoes, through which it is not magma that comes to the surface, but liquid dirt and gases from the earth’s crust. Mud volcanoes are much smaller in size than ordinary ones. Mud typically comes to the surface cold, but the gases emitted by mud volcanoes often contain methane and can ignite during the eruption, creating what looks like a miniature volcano eruption.

In our country mud volcanoes most common on Taman Peninsula, are also found in Siberia, near the Caspian Sea and Kamchatka. On the territory of other CIS countries, the most mud volcanoes are in Azerbaijan; they are found in Georgia and Crimea.

Volcanoes on other planets

Volcanoes in culture

Painting by Karl Bryullov “The Last Day of Pompeii”;
Movies "Volcano", "Dante's Peak" and a scene from the film "2012".
The volcano near the Eyjafjallajökull glacier in Iceland during its eruption became the subject of a huge number of humorous programs, television news stories, reports and folk art discussing events in the world.

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