In the depths of planet Earth, processes of volcanism (volcanic activity) are constantly taking place, based on the movement of magma to the surface along the faults of tectonically moving plates of the earth's crust. The formidable, uncontrollable element of volcanoes creates a colossal threat to life on earth, but it extends the beauty and scale of its external manifestation.
Photo 2 - Pacific Ring of Fire on the map
The greatest concentration of active volcanoes can be traced on the islands and shores of the Pacific and Atlantic oceans, forming the Pacific Ring of Fire. The rupture zones of the volcanic ring are New Zealand, the coast of Antarctica, over 200 kilometers along the California Peninsula, about 1,500 kilometers north of Vancouver Island.
There are 540 volcanoes in the world. The Pacific Ring of Fire region, home to about 500 million people, is home to 526 volcanoes.
The first classification of eruption types was proposed in 1907 by the Italian scientist G. Mercalli. Later, in 1914, it was supplemented by A. Lacroix and G. Wolf. The basis is the names of the first volcanoes with characteristic eruptive properties.
Photo 3 – Mauna-Loa volcano
Hawaiian type compiled based on the eruption of the Mauna Loa volcano in the Hawaiian archipelago. Lava pours out from the central vent and side craters. There are no sudden outbursts or rock explosions. The fiery stream spreads over long distances, freezes, and forms a flat “shield” around the perimeter. The dimensions of the “shield” of the Mauna Loa volcano are already 120 km long and 50 km wide.
Photo 4 - Stromboli volcano on the Aeolian Islands (Italy)
Strombolian type classified based on observations of the Stromboli volcano in the Aeolian Islands. Outpourings of strong flows of more viscous lava are accompanied by explosions with the ejection of large solid pieces of rock and basalt slag from the depths of the volcano.
Photo 5 - the Vulcano volcano is named after the ancient Roman god of fire Vulcan
Vulcano type. The volcano located on the Aeolian Islands is named after the ancient Roman god of fire, Vulcan. It is characterized by the eruption of lava with high melt viscosity. The volcano's crater is periodically clogged with magma products. Under colossal pressure, an explosion occurs with the release of lava, ash, and rock fragments to great heights.
Photo 6 – eruption of Mount Vesuvius
Photo 7 – Vesuvius volcano in the present tense
Ethno-Vesuvian (Plinian) type corresponds to the characteristics of the eruption of Mount Vesuvius near Naples. Periodic blockages of the volcano's mouth, powerful explosions, ejections of volcanic bombs from several centimeters to one meter over long distances, mud flows, colossal emissions of ash and lava are clearly visible. The temperature of lava flows is from 8000 °C to 10000 °C.
Photo 8 – Mount Etna
Photo 9 – eruption of the Mont Pele volcano in 1902
Peleian type is based on the nature of the Mont Pelée volcano on the island of Martinique in the Lesser Antilles group of islands in the Atlantic Ocean. The eruption is accompanied by powerful jets of gases, creating a huge mushroom cloud in the atmosphere.
Photo 10 - an example of pyroclastic flows (a mixture of rocks, ash and gases) during a volcanic eruption
The temperature inside the molten ash cloud can exceed 7000°C. Viscous lava in the main mass accumulates around the crater, forming a volcanic dome.
Photos 11, 12 - an example of a gas type volcanic eruption
Gas or phreatic type eruptions in which no lava is observed. Under the pressure of magmatic gases, fragments of solid ancient rocks fly into the air. The phreatic type of volcanoes is associated with the release of superheated groundwater under pressure.
Photo 13 – Icelandic subglacial volcano Grimsvotn
Sub-ice type eruptions refers to volcanoes located under glaciers. Such eruptions form spherical lava, lahars (a mixture of hot magma products with cold waters). There is a threat of dangerous floods and tsunami waves. To date, only five eruptions of this type have been observed.
Plumes of steam, ash and smoke reached a height of 100 meters.
Scientists have found that there are many more volcanoes in the oceanic waters (about 32 thousand) than on land (about 1.5 thousand). Almost all the high elevations of the oceans are active or already extinct volcanoes. Leadership belongs to the Pacific Ocean.
One of the most amazing and mysterious geological formations on Earth are volcanoes. However, many of us have only a superficial understanding of them. What is the nature of volcanism? Where and how does a volcano form?
Before considering how a volcano is formed, it is worth delving into the etymology and meaning of the term. In ancient Roman myths, Vulcan is mentioned by name, whose home was underground. If he was angry, the earth began to shake, and smoke and flames erupted from the depths. This is where the name of such mountains comes from.
The word "volcano" comes from the Latin "vulcanus", which literally means fire. Volcanoes are geological formations that arise directly above cracks in the earth's crust. It is through these cracks that lava, ash, a mixture of gases with water vapor and rocks erupt onto the surface of the earth. The sciences of geomorphology and volcanology are studying this mysterious phenomenon.
Classification and structure
All volcanoes, according to the nature of their activity, are active, dormant and extinct. And by location - terrestrial, underwater and subglacial.
To understand how a volcano forms, you must first take a closer look at its structure. Each volcano consists of the following elements:
- vent ( main channel at the center of geological formation).
- Dyke (channel with erupted lava).
- Crater (large hole at the top in the form of a bowl).
- (solidified pieces of erupted magma).
- Volcanic chamber (an area below the earth's surface where magma is concentrated).
- Cone (the so-called “mountain” formed by erupted lava and ash).
Despite the fact that the volcano looks like a huge mountain, its underground part is much larger than what is on the surface. Craters are often filled with water.
Why do volcanoes form?
The process of volcano formation begins with the formation of a magma chamber underground. Gradually, liquid hot magma heats up in it, which puts pressure on the earth's crust from below. It is for this reason that the earth begins to crack. Magma erupts upward through cracks and faults, and in the process of its movement it melts rocks and significantly widens the cracks. This is how a volcanic vent is formed. How is a volcano formed? During the eruption, various rocks come to the surface, which subsequently settle on the slope, resulting in the formation of a cone.
Where are the volcanoes?
Where do volcanoes form? These geological formations are distributed extremely unevenly on Earth. If we talk about the pattern of their distribution, then a large number of them are located near the equator. There are much fewer of them in the southern hemisphere than in the northern hemisphere. In the European part of Russia, Scandinavia, Australia and Brazil they are completely absent.
But if we talk about Kamchatka, Iceland, the Mediterranean, the west coast of North and South America, Indian and Pacific Ocean, Central Asia And central Africa, then there are plenty of them here. They are mainly located near islands, archipelagos, coastal zones continents. The dependence of their activity and processes associated with the movement of the earth’s crust is generally recognized.
How does a volcano erupt?
How and why processes lie in the bowels of the Earth. During the accumulation of magma, a large amount of thermal energy is generated. The temperature of the magma is quite high, but it is not capable of melting because the crust presses on it from above. If the layers of the earth's crust put less pressure on the magma, the hot magma becomes liquid. It gradually becomes saturated with gases, melts rocks on its way and in this way makes its way to the surface of the earth.
If a volcanic vent is already filled with frozen and solidified lava, then an eruption will not occur until the amount of magma pressure is sufficient to push out this plug. always accompanied by an earthquake. Ash can be thrown up to a height of several tens of kilometers.
Volcanoes are mountain-shaped formations from which hot magma erupts. How is a volcano formed? When there are cracks in the earth's crust, hot magma erupts toward its surface under pressure. The slopes of a volcano are formed as a result of the sedimentation of rocks, lava, and ash near the vent.
IN Ancient Rome The name Vulcan was borne by a mighty god, the patron of fire and blacksmithing. We call volcanoes geological formations on the surface of the land or on the ocean floor, through which lava emerges from the deep bowels of the earth to the surface.
Often accompanied by earthquakes and tsunamis, large volcanic eruptions have had a significant impact on human history.
Geographical object. The importance of volcanoes
During a volcanic eruption, magma comes to the surface through cracks in the earth's crust, forming lava, volcanic gases, ash, volcanic rocks and pyroclastic flows. Despite the danger that these powerful natural objects pose to humans, it was thanks to the study of magma, lava and other products of volcanic activity that we were able to gain knowledge about the structure, composition and properties of the lithosphere.
It is believed that thanks to volcanic eruptions, protein forms of life were able to appear on our planet: the eruptions released carbon dioxide and other gases necessary for the formation of the atmosphere. And volcanic ash, settling, became an excellent fertilizer for plants due to the potassium, magnesium and phosphorus it contained.
The role of volcanoes in regulating the climate on Earth is invaluable: during an eruption, our planet “releases steam” and cools, which largely saves us from the consequences of global warming.
Characteristics of volcanoes
Volcanoes differ from other mountains not only in their composition, but also in their strict external outlines. From the craters at the top of the volcanoes, deep narrow ravines formed by flows of water stretch down. There are also entire volcanic mountains formed by several nearby volcanoes and the products of their eruptions.
However, a volcano is not always a mountain breathing fire and heat. Even active volcanoes can appear as straight cracks on the surface of the planet. There are especially many such “flat” volcanoes in Iceland (the most famous of them, Eldgja, is 30 km long).
Types of volcanoes
Depending on the degree of volcanic activity there are: current, conditionally active And extinct (“dormant”) volcanoes. The division of volcanoes by activity is very arbitrary. There are cases when volcanoes, considered extinct, began to exhibit seismic activity and even erupt.
Depending on the shape of volcanoes there are:
- Stratovolcanoes- classic “fire mountains” or volcanoes central type cone-shaped with a crater at the top.
- Volcanic fissures or fissures- fractures in the earth's crust through which lava comes to the surface.
- Calderas- depressions, volcanic cauldrons formed as a result of the failure of a volcanic peak.
- Panel- so called because of the high fluidity of the lava, which, flowing for many kilometers in wide streams, forms a kind of shield.
- Lava domes - formed by the accumulation of viscous lava above the vent.
- Cinder or tephra cones- have the shape of a truncated cone, consist of loose materials (ash, volcanic stones, blocks, etc.).
- Complex volcanoes.
In addition to land-based lava volcanoes, there are underwater And mud(they spew out liquid mud, not magma) Underwater volcanoes are more active than land-based ones; 75% of the lava erupted from the bowels of the Earth is released through them.
Types of volcanic eruptions
Depending on the viscosity of lavas, the composition and amount of eruption products, there are 4 main types of volcanic eruptions.
Effusive or Hawaiian type- a relatively calm eruption of lava formed in craters. The gases released during an eruption form lava fountains from drops, threads and lumps of liquid lava.
Extrusion or dome type- is accompanied by the release of gases in large quantities, leading to explosions and the emission of black clouds from ash and lava debris.
Mixed or Strombolian type- abundant lava output, accompanied by small explosions with the release of pieces of slag and volcanic bombs.
Hydroexplosive type- typical for underwater volcanoes in shallow water, accompanied by big amount steam released when magma comes into contact with water.
The largest volcanoes in the world
The tallest volcano in the world Ojos del Salado, located on the border of Chile and Argentina. Its height is 6891 m, the volcano is considered extinct. Among the active "fire mountains" the highest is Llullaillaco- volcano of the Chilean-Argentine Andes with a height of 6,723 m.
The largest (among terrestrial) volcano in terms of area occupied is Mauna Loa on the island of Hawaii (height - 4,169 m, volume - 75,000 km 3). Mauna Loa also one of the most powerful and active volcanoes in the world: since its “awakening” in 1843, the volcano has erupted 33 times. The largest volcano on the planet is a huge volcanic massif Tamu(area 260,000 km2), located at the bottom of the Pacific Ocean.
But the most powerful eruption ever historical period produced "low" Krakatoa(813 m) in 1883 in the Malay Archipelago in Indonesia. Vesuvius(1281) - one of the most dangerous volcanoes in the world, the only active volcano in continental Europe - is located in southern Italy near Naples. Exactly Vesuvius destroyed Pompeii in 79.
In Africa, the highest volcano is Kilimanjaro (5895), and in Russia it is a double-peaked stratovolcano Elbrus(North Caucasus) (5642 m - western peak, 5621 m - eastern).
August 18, 2016Volcanic eruptions have always given rise to catastrophic associations in people's minds...
Boiling hot lava, vast clouds of volcanic ash eclipsing the Sun, dying people and entire cities are the subject of many paintings, books and films. Nowadays, volcanoes with a “bad reputation” that continue to erupt are popular among tourists, thrills. We will tell you about the five most famous active volcanoes on Earth.
Vesuvius
On the conscience of this relatively low (1300 meters above sea level) volcano on the shores of the picturesque Bay of Naples are two destroyed ancient Roman cities, Pompeii and Herculaneum.
Vesuvius has erupted more than once in Italian memory, last time- in 1944. Eruptions were always accompanied by destruction and casualties; in 1805, the city of Naples was even destroyed. However, the area around the volcano is densely populated - volcanic ash fertilizes the land.
Krakatoa
The only one famous volcanoes, who managed to be reborn after he destroyed himself. In 1883, the most destructive eruption in the history of mankind occurred at the Krakatoa volcano, located on the island of the same name between Java and Sumatra.
The tsunami wave washed away 295 Indonesian cities and villages into the sea, killing 35 thousand people. Both the island of Krakatoa and the volcano itself were destroyed. However, in 1927, the volcano broke through the ocean and declared itself with a new eruption. The new volcano was named Anak Krakatau, and it is believed that it has a serious impact on the climate of the entire Earth. The last activity of the Krakatoa volcano was observed in 2014.
Fujiyama
The Japanese have a peculiar attitude towards Fuji; they do not experience mortal horror, rather the opposite. Followers of the Shinto religion consider Fuji a shrine, a symbol of the immortality of the soul, and even built a temple on its top, next to the post office and meteorological station. Fuji, along with tourists from all over the world, is visited annually by thousands of Shinto pilgrims.
Hekla
Since then, about three dozen significant eruptions have occurred. All are completely different from one another and unpredictable. Some are short, a few days, others can last for months. And the eruption, which began in March 1947, ended only in April 1948. Icelanders believe that the longer the volcano’s “hibernation” lasts, the more catastrophic the consequences of the earthquake will be.
Klyuchevskaya Sopka
Outside the Caucasus, Klyuchevskaya Sopka is the most high mountain in Russia (4800 meters). And the highest active volcano on the Eurasian continent. Klyuchevskaya Sopka is the most active of Kamchatka's 29 active volcanoes; the last eruption occurred in 2013.
Despite the restless and unpredictable nature of the volcano, climbers and mountain tourists often climb Klyuchevskaya Sopka. The volcano also attracts tourists with an amazing natural phenomenon - lenticular clouds. Large white clouds hover over the crater of Klyuchevskaya Sopka and remain motionless even in very strong winds.
It is difficult to find a person who would not at least once be interested in volcanoes. Most have read books about them, watched with bated breath footage from eruption sites, at the same time admiring the power and magnificence of the elements and rejoicing that this is not happening near them. Volcanoes are something that leaves no one indifferent. So what is it?
Structure of the volcano
Volcanoes are special geological formations that arise when hot mantle material rises from the depths and reaches the surface. Magma rises up through cracks and faults in the earth's crust. Where it breaks out, active volcanoes are formed. This occurs at the boundaries of lithospheric plates, where faults arise due to their separation or collision. And the plates themselves are involved in movement when the mantle material moves.
Most often, volcanoes take the form of conical mountains or hills. Their structure clearly distinguishes a vent - a channel through which magma rises, and a crater - a depression at the top through which lava flows. The volcanic cone itself consists of many layers of activity products: solidified lava and ash.
Since the eruption is accompanied by the release of hot gases, glowing even during the day, and ash, volcanoes are often called “fire-breathing mountains.” In ancient times they were considered the gateway to the underworld. And they got their name in honor of the ancient Roman. It was believed that fire and smoke were flying from his underground forge. Such Interesting Facts about volcanoes fuels curiosity among a wide variety of people.
Types of volcanoes
The existing division into active and extinct is very arbitrary. Active volcanoes are those that have erupted within human memory. Eyewitness accounts of these events have been preserved. There are a lot of active volcanoes in the areas of modern mountain building. This is, for example, Kamchatka, the island of Iceland, East Africa, Andes, Cordillera.
Inactive volcanoes are those that have not erupted for thousands of years. Information about their activity was not retained in people's memories. But there are many cases when a volcano, which was considered inactive for a long time, suddenly woke up and brought a lot of troubles. The most famous of them is the famous eruption of Vesuvius in 79, glorified by Bryullov’s painting “The Last Day of Pompeii.” 5 years before this disaster, the rebels were hiding on its top, and the mountain was covered with lush vegetation.
The extinct volcanoes include Mount Elbrus, the highest peak in Russia. Its double-headed apex consists of two cones merging at their bases.
Volcanic eruption as a geological process
An eruption is the process of releasing hot magmatic products in solid, liquid and gaseous states onto the earth's surface. It is individual for each volcano. Sometimes the eruption is quite calm, liquid lava pours out in streams and flows down the slopes. It does not interfere with the gradual release of gases, so strong explosions do not occur.
This type of eruption is typical for Kilauea. This volcano in Hawaii is considered one of the most active in the world. Its crater, with a diameter of about 4.5 km, is also the largest in the world.
If the lava is thick, it will occasionally clog the crater. As a result, the released gases, finding no way out, accumulate in the crater of the volcano. When the gas pressure becomes very high, a powerful explosion occurs. It lifts large volumes of lava into the air, which subsequently falls to the ground in the form of volcanic bombs, sand and ash.
The most famous explosive volcanoes are the already mentioned Vesuvius and Katmai in North America.
But the most powerful explosion, which led to cooling throughout the world due to volcanic clouds, through which they could hardly break through Sun rays, occurred in 1883. Then I lost most of it. The column of gas and ash rose up to 70 km into the air. The contact of ocean water with hot magma led to the formation of a tsunami up to 30 m high. In total, about 37 thousand people became victims of the eruption.
Modern volcanoes
It is believed that there are now more than 500 active volcanoes in the world. Most of them belong to the zone of the Pacific “Ring of Fire”, located along the boundaries of the lithospheric plate of the same name. About 50 eruptions occur every year. At least half a billion people live in the area of their activity.
Volcanoes of Kamchatka
One of the most famous areas of modern volcanism is located in Russian Far East. This is an area of modern mountain building that belongs to the Pacific Ring of Fire. Volcanoes of Kamchatka are included in the list World Heritage UNESCO. They are of great interest not only as objects scientific research, but also as natural monuments.
This is where the highest active volcano in Eurasia, Klyuchevskaya Sopka, is located. Its height is 4750 m. Plosky Tolbachik, Mutnovskaya Sopka, Gorely, Vilyuchinsky, Gorny Zub, Avachinskaya Sopka and others are also widely known for their activity. In total, there are 28 active volcanoes in Kamchatka and about half a thousand extinct ones. But here are some interesting facts. A lot is known about the volcanoes of Kamchatka. But along with this, the region is known for a much rarer phenomenon - geysers.
These are springs that periodically emit fountains of boiling water and steam. Their activity is associated with magma that rises through cracks in the earth’s crust close to the earth’s surface and heats the groundwater.
The famous Valley of Geysers, located here, was discovered in 1941 by T. I. Ustinova. It is rightfully considered one of the wonders of nature. The area of the Valley of Geysers is no more than 7 square meters. km, but there are 20 large geysers and dozens of springs with boiling water. The largest - the Giant Geyser - throws out a column of water and steam to a height of about 30 m!
Which volcano is the tallest?
This is not so easy to determine. Firstly, the height of active volcanoes can increase with each eruption due to the growth of a new layer of rocks or decrease due to explosions that destroy the cone.
Secondly, a volcano that was considered extinct may awaken. If it is high enough, it can push back the existing leader.
Thirdly, where to calculate the height of the volcano - from the base or from sea level? This gives completely different numbers. After all, the cone that has the greatest absolute height may not be the largest compared to the surrounding area, and vice versa.
Currently, among the active volcanoes, Lluillayllaco is considered to be the largest. South America. Its height is 6723 m. But many volcanologists believe that Cotopaxi, located on the same continent, can claim the title of the greatest. It may have a lower height - “only” 5897 m, but its last eruption was in 1942, and that of Lluillailhaco - already in 1877.
Hawaiian Mauna Loa can also be considered the highest volcano on Earth. Although its absolute height is 4169 m, this is less than half of its true height. The cone of Mauna Loa starts from the very ocean floor and rises more than 9 km. That is, its height from the base to the top exceeds the size of Chomolungma!
Mud volcanoes
Has anyone heard of the Valley of Volcanoes in Crimea? After all, it is very difficult to imagine this peninsula shrouded in the smoke of eruptions, and the beaches filled with hot lava. But you don't have to worry, because we're talking about about mud volcanoes.
This is not such a rare phenomenon in nature. Mud volcanoes are similar to real ones, but they do not emit lava, but streams of liquid and semi-liquid mud. The cause of eruptions is the accumulation of large amounts of gases, most often hydrocarbons, in underground cavities and cracks. The gas pressure activates the volcano, a high column of mud sometimes rises several tens of meters, and the ignition of the gas and explosions give the eruption a rather menacing appearance.
The process can last several days, accompanied by a local earthquake and underground rumble. As a result, a low cone of frozen mud is formed.
Areas of mud volcanism
In Crimea, such volcanoes are found on the Kerch Peninsula. The most famous of them is Jau-Tepe, which really scared local residents with its short eruption (only 14 minutes) in 1914. A column of liquid mud was thrown 60 m up. The length of the mud flow reached 500 m with a width of more than 100 m. But such large eruptions are rather an exception.
The areas where mud volcanoes are active often coincide with oil and gas production sites. In Russia they are found on the Taman Peninsula, on Sakhalin. Among neighboring countries, Azerbaijan is “rich” in them.
In 2007, the volcano became active, flooding a vast area with its mud, including many buildings. According to the local population, this happened due to the drilling of a well, which disturbed the deep layers of rocks.
Edinburgh Castle in Scotland was built on top of an extinct volcano. And most Scots don't even know about it.
It turns out that volcanoes can be actors! In the film “The Last Samurai”, Taranaki, considered the most beautiful in New Zealand, played the role of the sacred Japanese mountain Fuji. The fact is that the surroundings of Fuji with its urban landscapes were in no way suitable for filming a film about the events of the late 19th century.
In general, New Zealand volcanoes do not have to complain about the lack of attention from film directors. After all, Ruapehu and Tongariro became famous largely thanks to the film “The Lord of the Rings,” in which they depicted Orodruin, in the flames of which the One Ring was created and subsequently destroyed there. The Lonely Mountain in Erebor in The Hobbit is also one of the local volcanoes.
And Kamchatka geysers and waterfalls became the backdrop for the filming of the film “Sannikov Land”.
The eruption of Mount St. Helens (USA) in 1980 is considered the most powerful eruption of the entire 20th century. The explosion, equal in power to 500 bombs dropped on Hiroshima, sent ash across four states.
Eyjafjallajökull became famous for throwing ash and smoke into chaos in air traffic. European countries in the spring of 2010. And its name has baffled hundreds of radio and television announcers.
The Philippine volcano Pinatubo last erupted in 1991. At the same time, two American military bases were destroyed. And after 20 years, the Pinatubo crater was filled with rainwater, forming an amazing beautiful lake, the slopes of the volcano are overgrown with tropical vegetation. This made it possible travel agencies Organize a vacation with swimming in a volcanic lake.
Eruptions often produce interesting rocks. For example, the lightest stone is pumice. Numerous air bubbles make it lighter than water. Or the "Pele's hair" found in Hawaii. They are long thin threads breeds Many buildings in the capital of Armenia, Yerevan, are built from pink volcanic tuff, which gives the city a unique flavor.
Volcanoes are a formidable and majestic phenomenon. Interest in them is caused by fear, curiosity, and thirst for new knowledge. It’s not for nothing that they are called windows to the underworld. But there are purely utilitarian interests. For example, volcanic soils are very fertile, which has forced people to settle near them for centuries, despite the danger.
