Description of the structure of the volcano. Earth's catastrophic past

Volcanoes- These 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 ancient roman god fire of 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, may contribute to the emergence of life. In particular, it was volcanoes that contributed to the formation earth's atmosphere and hydrosphere, releasing a significant amount 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 view volcanoes are divided into linear and central, however, this division is conditional, since most volcanoes are confined to linear tectonic disturbances (faults) in 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 fluid 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 by 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 shape is characteristic of volcanoes that erupt low-viscosity basaltic lava: it long time flows from both the central vent and the side craters of the volcano. Lava spreads evenly over many kilometers; Gradually, a wide “shield” with gentle edges is formed from these layers. An example is the 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.

Volcanic eruption

Volcanic eruptions are classified as geological emergency situations which can lead to natural disasters. The eruption process can last from several hours to many years. Among the various classifications there are common types eruptions:

Hawaiian type - emissions of liquid basaltic lava, often forming lava lakes, which 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 ancient rocks, and not magma, are brought to the surface, and water vapor formed during heating predominates among the gases groundwater, then such an eruption is called phreatic.

Rising to earth's surface lava does not always reach this surface. It only raises layers of sedimentary rocks and hardens in the form of a compact body (laccolith), forming a unique system of 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, Kuril Islands, Kamchatka, northwestern USA, Alaska, Hawaiian Islands, Aleutian Islands, Iceland, Atlantic Ocean.

Mud volcanoes

Mud volcanoes are small volcanoes through which it is not magma that comes to the surface, but liquid mud 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 are most common on the Taman Peninsula; they are also found in Siberia, near the Caspian Sea and in 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 became a hero during its eruption huge number humorous programs, TV news stories, reports and folk art discussing events in the world.

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In February 1943, in one of the regions of Mexico, people witnessed a rare and amazing sight: a new volcano was born in the middle of a corn field! In just three months, a cone-shaped mountain 300 meters high was formed. As a result, two cities were destroyed, and a vast area was buried under a layer of ash and lava.

How does the process of volcano formation proceed? First of all, remember that the temperature in the depths of the Earth increases as it approaches the center of the Earth. At a depth of 35–40 km, most rocks is in a molten state.

When minerals are out solid state turn into liquid, they increase in volume. As a result, new mountain ranges rise at various points on the earth's surface. This leads to a decrease in pressure in the thickness of the earth's crust, and huge lakes of magma - molten minerals - can appear under the newly formed mountains.

Magma rises up, filling the cracks that appeared during the process of mountain building. When the pressure in underground lakes becomes too great, the stone vaults, unable to bear it, bend upward, and a new volcano is formed.

During the eruption, a mixture of hot gases, molten rocks and solid debris is pushed to the surface from the depths. As they cool, they form a cone-shaped top of the volcano, in the center of which there is a depression called a crater. In the middle of the crater there is a hole - a vent leading into the thickness of the earth's crust.

The material ejected through the vent to the surface is mainly a mixture of gases, but large amounts of lava and solid particles in the form of ash and ash are also erupted.

Lava is actually magma flowing from a volcano, but differs from the latter in its physical and chemical properties. Changes occur when magma rises to the surface and its temperature and pressure decrease sharply.

Why are volcanoes located in certain places?

There are no volcanoes in the area of cities such as New York, London or Paris, and they are unlikely to appear there in the future. However, in some areas of the globe there are several volcanoes located in one place.

The Pacific coast of Central America is one of the most active areas of volcanic activity in the world. And in fact, more than two-thirds of active volcanoes are located in this place, as well as many that ceased their activity relatively recently.

And the reason is this: in these places the earth’s crust is very weak compared to other areas of the globe. Where there is a weak section of the earth's crust, a volcano appears.

This is how it is formed. As we already know, the Earth's core is very hot. As depth increases, temperature also increases. At a depth of 25 km, the temperature is so high that all rocks (here the temperature reaches 1000-1100 ° C) are in a molten state.

When a rock melts, it increases in volume - it needs more space. In some areas of the Earth new mountain systems formed not so long ago (this means several thousand years ago). Below them and in this area the pressure is lower than in other areas. This is a kind of weak spot in the earth's crust.

Molten rock, called “magma,” intrudes into these areas, creating molten rock reservoirs. Magma rises through cracks formed by the uplift of the earth's rocks. When the pressure in such a reservoir exceeds the forces that hold the magma underground, the molten rock bursts out, forming a volcano. The eruption stops with the end of the release of accompanying gas.

During an eruption, they are mainly released gaseous substances, as well as a large amount of molten rock “lava”, solid particles in the form of ash. An eruption is an explosion of gases, but some of the lava turns to dust, and during the eruption we see a cloud of black smoke.

A volcano is a geological formation on the surface of a planet where molten internal rocks come to the surface of the earth, forming lava, volcanic gases and stones, in the form of volcanic bombs and pyroclastic flows. Translated from Latin vulkanus - fire

News

15.03.19 // United Kingdom
Artificial intelligence will warn about an upcoming eruption

11.02.19 // China, USA, Ecuador
Galapagos volcanoes are fed by a mantle plume

24.01.19 // Russia, France
No volcanic activity was found under Lake Vostok

Our planet consists of several layers, like a hard-boiled egg. The surface layer, about 50 km thick, is called the earth's crust (like the shell of an egg). In some places, especially at the bottom of the oceans, this layer is thinner. Below, under the crust layer to a depth of 900 km, is the upper mantle. Beneath it, up to 2900 km, the lower mantle extends (both mantles are like the white of an imaginary egg). And even lower, to about 6300 km, the core (yolk) is located. The upper mantle is the place on the planet where the hot stuff of volcanoes is formed.

As you move from the surface deeper into the planet, the temperature increases by one degree every 33 meters. It is clear that at a depth of tens of kilometers the temperature reaches such values that rocks will melt. But increasing pressure restrains this process, and a certain balance is established. The Earth's crust consists of several solid lithospheric plates located on a layer of the mantle. They swim on its surface, moving at a speed of 2 - 3 centimeters per year. When moving at the boundaries of lithospheric plates, faults are formed, which are called rifts.

Internal structure of the volcano

Shifts in the earth's crust - faults, subsidence, uplift - lead to an imbalance between temperature and pressure in the bowels of the planet, a drop in pressure and the formation of magma - a molten mixture of minerals saturated with gases. A focus is formed. However, as it turned out, near-surface foci can also be observed. The melt, making its way through steam and gases, rushes to the surface of the earth - an explosion and volcanic eruption occurs. The flow releases excess pressure and pours out lava. At the site of the explosion, a funnel remains - a caldera, which is a bowl-shaped depression from where lava flows.

If the gaseous component of the magma is large, the lava breaks into small drop-shaped structures and the eruption takes on the appearance of a fiery fountain. If there is not too much gas and steam, the lava flows freely. When the active activity of the volcano ends, gas and steam still continue to escape from cracks on the slopes of the volcano, forming so-called fumaroles.

Thus, the emergence and eruption of volcanoes is tied to places of increased internal activity of the planet. There are three particularly active regions on Earth: the Pacific coast, the Mediterranean-Indonesian belt and the Atlantic belt, located at the junction of the continental and oceanic plates.

Features of volcanoes

In general, the mechanism of volcano formation is quite typical, but some features are introduced by additional factors, such as the location of the volcano’s formation, the characteristics of the magma chamber, the characteristics of the magma itself, and so on. They talk about different types volcanoes depending on their specific properties. So, they are divided into active, dormant and extinct. An active volcano is considered to have erupted in historical time or in the Holocene. Dormant volcanoes are considered to be inactive volcanoes that may erupt. Extinct - on which it is unlikely.

There are fissure and central volcanoes. Fissures may not rise high above the ground, having the appearance of cracks from which magma flows. In some parts of the world, entire basalt rivers are known, covering hundreds of square kilometers of area. So on the territory of Siberia, the thickness of these flows reaches several kilometers - the so-called Siberian traps. They are formed by the breakthrough of magma into the upper layers of the earth's crust with outpouring through cracks. This event took place about 240 million years ago, when the surface of the planet was still quite actively forming. Central volcanoes usually have the shape of a cone from which gas and magma emerge during an eruption. Such volcanoes have a channel through which magma rises - a vent - and one or more craters, from where it then pours out.

Volcanoes that rise above the ground (mountain volcanoes) are divided into several categories. Cone-shaped (stratovolcanoes) have a classic shape - a truncated cone with a crater at the top: Etna (Italy), Krakatoa (Indonesia), Popocatepetl (Mexico), Pinatubo (Philippines). They are usually formed in coastal zone and on islands in the subduction zone, where the continental layer is pushed onto the oceanic layer. These volcanoes are distinguished by rare but powerful eruptions. They have a layered structure ("strato" - layer), which is replenished with each eruption. Lava and pyroclastic ("broken by fire") fragments gradually form a gentle slope of the volcano, since the lava is quite viscous.

Shield volcanoes are the largest, but this is not noticeable by appearance. Most often they resemble a gladiator's shield lying on the ground. An example is Belknam Crater in the Cascade Mountains of central Oregon. Their low slopes are deceptive. Beneath them are magma lakes larger than terrestrial mountains. Their lava is less viscous and moves further from the eruption site, which gives these volcanoes their flat shape. Their eruptions are frequent and are accompanied by a long outpouring of lava, due to which such volcanoes reach enormous sizes.

Dome volcanoes so called because the viscous granitic magma cannot flow down the slope and solidifies at the top, forming a dome and plugging the vent. Over time, it will be torn off by accumulated gases.

Slag cones are formed by the accumulation of large fragments of porous slag around the crater, and small ones form a slope. Such volcanoes are insignificant in height and, as a rule, erupt once.

An interesting hypothesis is that of “hot spots”, which explains the appearance of volcanic ridges consisting of chains of volcanoes. These points are fixed and represent certain zones within which mantle jets reach the earth's surface. Active volcanoes arise above them and, in the case of an underwater location, islands may appear. When lithospheric plates move, volcanoes move along with them and move away from the mantle flow, falling asleep. A "hot spot" ( plume) burns through the lithospheric plate directly above it, forming a new volcano. Over time, a chain of volcanoes is formed - a volcanic ridge.

Yellowstone, an ancient supervolcano in America, about which there is now so much talk, is also suspected of having a “hot spot”. Supervolcanoes are the most insidious of the entire explosive family. When they erupt, they explode themselves, destroying rather than creating tall structures. Their magma chambers are colossal, but there is no such recognizable crater. They are not like volcanoes. So in Yellowstone there are several places of ancient lava outcrops. It is believed that they are explained by the presence of a plume, which, due to the movement of the lithospheric plate, each time makes a new hole to discharge the accumulated magma. Let us recall that this supervolcano erupted five times - 6 million years ago, 4 million years ago, 2.1 million years ago, 1.27 million years ago and 640 thousand years ago. And now scientists believe that the chances of a new super-eruption are quite high. The giant wakes up and some symptoms are very alarming to researchers.

Underwater volcanoes

There are also zones of volcanic activity in the oceans, where underwater volcanoes operate and chains of seamounts and islands form. These are volcanoes of island arcs and active continental margins, the eruptions of which are often catastrophic. Most of the volcanoes that rise above sea level belong to them. Oceanic rift zones often develop cracks and fissures through which magma flows. The thickness of the earth's crust at the bottom of the ocean is less and it is more easily destroyed.

Almost all islands and seamounts in the inland ocean are either active volcanoes or were active in the past. In the southern part Pacific Ocean there is a whole belt of island and underwater volcanoes of the “hot spot” type (for example, the Hawaiian Islands and the Emperor Underwater Ridge). It is located perpendicular to the rift zone of the East Pacific Rise and is located in the area where the rate of divergence is maximum. Volcanism marginal seas poorly studied. Shallow volcanoes are located on the crust continental type and are few in number.

There are more than 1,500 active volcanoes known on Earth. Of these, 95% are located at the points of convergence (divergence) of two plates. Another 5% are formed by “hot spots”. And 80% of total number are underwater and located along ocean ridges and faults.

In general, you and I owe something in this life to these hot guys - volcanoes. It was they who created the atmosphere and water shell of the planet, and, in many ways, the surface too. And not only. Anthropologists noticed that all secondary civilizations chose to live in places with increased tectonic activity, with the presence of volcanoes in the vicinity. Apparently, here the nights were warmer, the cooling volcanic fields could be used as an oven, on them you can find boiled animals, whose meat was quickly tasted by the ancestors. Astrophysicists believe that a reasonable middle ground was important, since too active volcanic activity can make the planet uninhabitable, drowning it in flows of lava and gas, and weak tectonic activity leads to the disappearance of carbon dioxide and sterilization of the planet. So, volcanoes, let's live together!

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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 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 significant influence on the history of mankind.

Geographical object. The importance of volcanoes

During a volcanic eruption, magma emerges through cracks in the earth's crust to the surface, forming lava, volcanic gases, ash, volcanic rocks and pyroclastic flows. Despite the danger that these powerful natural objects, 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 that were considered extinct began to show seismic activity and even erupt.

Depending on the shape of volcanoes there are:

Stratovolcanoes- classic “fire mountains” or volcanoes of the 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 a large number 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 in the entire historical period was produced by the “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).

There is, perhaps, not a single person on earth who would not be fascinated by an incredible action - a volcanic eruption.

It's dangerous, it's scary and it's incredibly beautiful! It is beyond human control to stop or prevent a volcanic eruption, but it is possible to find out the causes of volcanoes and their activity.

· reasons

Volcanism itself is a process in which huge amounts of hot magma come to the surface of the earth from beneath its depths through an open volcanic crater. Plasma-shaped hot rivers of boiling lava destroy all life in their path. Emissions of sulfur dioxide and carbon dioxide pollute the atmosphere and cause acid rain.

During the eruption from the crater terrible force Huge stones and other volcanic debris are flying.

causes of volcanoes

The main reason is internal structure planets. In the context globe consists of three layers: core, mantle, and crust. The magma that flows out during an eruption is the upper layer of the mantle, the so-called asthenosphere.

· Why do magma emissions occur?

The earth's crust consists of several lithospheric plates. They move slowly, sliding through liquid hot magma. Periodically, the plates run over each other or move apart. Lithospheric plates, with their mass, exert pressure on the plasma-like liquid. That is why, when cracks form, boiling magma comes out.

reasons for the eruption

Processes in the depths of our planet are in continuous dynamics.

As a result, lava is formed. An excess of lava underground leads to its regular emissions in one or another part of the globe.

What kind of magma is there?

Explaining in simple language magma comes in two types:

- regular

- sour.

An ordinary one easily conducts gases, and therefore, when it approaches the mouth of a river of fiery lava, it pours out of the crater without explosions or rockfalls.

Flows of acidic magma contain high blood pressure due to gases accumulated inside.

Lava comes out with an explosion, clouds of smoke, ash and is accompanied by a hail of stones. Such eruptions are especially dangerous. Due to the columns of ash, which sometimes reach more than 13 thousand meters in the air, air travel is prohibited, and it becomes impossible to breathe within a radius of tens of kilometers.

Volcanic eruption is a phenomenon in which water spills out from the depths of the Earth onto the earth's surface. magma flows and various rock fragments. Magma that reaches the surface is called lava. During a volcanic eruption, thick clouds of ash also erupt from the vent. And lightning can flash in these black clouds, for which the phenomenon is called a dirty thunderstorm, although you can often hear another name - volcanic lightning.

Description

Volcanoes are such small (and sometimes large) mountains that have a vent - a vertical channel leading through the earth's crust deep into the lithosphere (the hard shell of the planet). Although, it is worth noting that volcanoes are not always mountains, sometimes they are only a small hill, and sometimes they even appear out of the blue, although very rarely. But what they all have in common is that they can spew magma.

To summarize, volcanoes are cracks in the surface of the planet leading to the Earth’s mantle, where magma is located.

And there are a lot of such faults on our planet. They are available on each continent. And since main reason Since the formation of volcanoes consists in the movement of lithospheric plates, in some regions of the planet entire chains of these objects are formed.

Fortunately for us, most of the volcanoes on the planet, in given time They do not pose a threat, since they have either been extinct for a long time or are dormant.

In addition, a considerable part of them is under water, usually at the bottom of the oceans. Well, active volcanoes on land also don’t worry everyone very much, since eruptions occur with some regularity, which makes them predictable. Well, tracking this phenomenon using seismological instruments is also not difficult.

Causes of volcanic eruptions

There is a lot going on in the depths of our planet. various processes. Much there is in constant motion.

Of course, the lithosphere has been practically unstudied, but the available information allows us to assert that the processes occurring in the bowels of the Earth are extremely interesting.

It is because of them that large amounts of magma accumulate in some places underground. And since she has nowhere to go from there, she begins to gradually rise. Volcanoes are channels that allow excess magma to splash out, reducing pressure in some areas of the lithosphere.

It is worth noting that the eruption is not always as colorful as many people think.

The fact is that magma itself comes in two types. Ordinary magma allows gases to pass through well, so when it rises through the vent, no explosions, destruction, or the like occur. It simply flows calmly to the surface. But acidic magma practically does not allow gases to pass through, so when it rises, high pressure is formed, which is why the eruption occurs in the form big bang, as a result of which magma flies out to the earth's surface.

Types of eruptions

There are various types volcanic eruptions.

This depends on many factors, but, in general, these types are not tied to anything specific. That is, one volcano can have various types eruptions. Or he may possess only one, over a long period of time.

Types of volcanic eruptions are usually named after famous volcanoes where this type observed.

Plinian type.
Dangerous due to its unpredictability. During eruptions of this type, unpredictable powerful explosions occur, during which, in addition to lava, a huge amount of ash is released.
Peleian type.
Huge flows of viscous lava, flowing from the vent, linger at its edges (due to viscosity), as a result of which they grow and form lava domes.
After which the lava streams rush down.
The crack of thunder.
Liquid magma rises through cracks to the crater, after which it bursts out with a large number of explosions.
Gas or phreatic type.
During this type of eruption, lava does not flow out of the vent. From there, only clouds of gases burst out and fragments of solid rocks are thrown out.
Hydroexplosive eruptions.
They occur in shallow waters of seas and oceans.
Accompanied by the appearance of huge clouds of steam formed due to boiling water.
Icelandic type. It is characterized by the presence of very liquid lava, which flows not only through the crater, but also through the slightest cracks.
Eruption of ash flows.
They were observed only in ancient times. They are streams of minerals, volcanic glass, magma and ash surrounded by a gas shell, rushing at great speed.
Strombolian type.
Viscous streams of lava and hot slag are ejected from the vent in explosions of varying power.
Sub-ice type.
As the name suggests, the main action takes place under the ice.
They are dangerous due to possible floods due to melting.

Consequences of volcanic eruptions

Volcanic eruptions are considered very dangerous natural phenomena. Sometimes the consequences can be simply terrifying. But even if there is no destruction or casualties, this phenomenon still causes a lot of harm to both nature and people. Where lava passes, scorched earth remains for many years. The ash clouds emitted pollute the air.

Sulfur rain may begin to fall from the clouds.

Causes of volcanic eruptions

Also, as a result of this phenomenon, water bodies are polluted, and if the phenomenon occurs in places where drinking water and so it is not enough, then it can become a disaster.

Particularly powerful volcanic eruptions capable of causing disaster not only on a single piece of land, but over vast territories. And they can cause trouble for the whole world. There is a possibility that ash clouds rising into the atmosphere will completely cover the sky, blocking the Sun's access to the earth's surface. Due to the lack of heat, winter will come, and precipitation consisting of sulfuric acid will fall on the ground, all because of the same ash.

Fortunately, such powerful eruptions are very rare, and measures to counteract them exist.

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A central-type volcano is a cone-shaped geological formation that is topped by a crater, a depression shaped like a funnel or bowl.

Magma is a molten fiery mass that has a predominantly silicate composition. It is born in the earth's crust, where its hearth is located, and having risen to the top, it pours out onto the surface of the earth in the form of lava. An eruption is usually accompanied by the release of small splashes of magma, which form ash and gases, which, interestingly, are 98% liquid.

They are joined by various impurities in the form of flakes of volcanic ash and dust. What is the structure of a volcano))

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