Volcanoes and their consequences. Volcanic eruption: volcanoes of the globe

The lands located at the foot of the volcanoes are one of the most fertile territories on our planet, because the eruptions produced by the volcano's mouth saturate the soil with a huge amount of nutrients and minerals. Even if the volcano has been sleeping for a long time and does not manifest itself in any way, the wind blowing stones on it carries the substances necessary for the earth in different directions. Therefore, people constantly settle not only at the foot of volcanoes, but also on the slopes of the mountains, and do not pay the slightest attention to the periodically arising tremors in the region. In vain. Everyone knows the fate of the inhabitants of Pompeii, who were buried almost 2000 years ago. The tragedy could well have been avoided if they had paid attention to the more frequent earthquakes with a magnitude of five or six.

Volcanic eruption: volcanoes of the globe

Where is the origin of volcanoes? Fire-breathing mountains appear over the places of collision of lithospheric plates with each other, in the weakest places crustthrough which our planet throws out hot magma, combustible gases and the most diverse volcanic material, which later these mountains form.


As for the word "volcano", then it itself is of Latin origin - this is how the locals called the god of fire in ancient Rome. It is interesting that the mountain was the first to receive such a name (it was there, according to local residents, that the Vulcan smithy was located).

Exist different types volcanoes. Currently, geologists count about one and a half thousand active volcanoes on our planet, not counting underwater ones. As for the latter, about 20% of the total number of all volcanoes existing in the world, including extinct ones, are located in the oceanic and sea depths.

It is to them that we owe new areas of land, sometimes appearing in the middle of the endless ocean: after underwater volcanoes erupt huge amounts of lava, their tops eventually reach the ocean surface and form islands (for example, Hawaiian or Canary Islands).

To go there, you just need to order tickets here:

The largest number of volcanoes (two-thirds) are located in the so-called Pacific Ring of Fire, framing the edges of the huge Pacific plate, which is in constant motion and collides with neighboring plates all the time.

Volcanic eruption: video

The role of volcanoes in the life of the planet and humans

It is impossible to diminish the role of volcanoes in the life of our planet. First of all, because if it were not for them, it is quite possible that the Earth would still be a heated space ball: it was the fire-breathing mountains that at one time brought water vapor out of the bowels of the globe, thereby cooling the lithosphere and the atmosphere of the planet.

According to geologists, a single eruption of a fiery mountain on one of the Indonesian islands more than 75 thousand years ago plunged our entire planet into the Ice Age, and sulfuric acid was formed in the atmosphere.
Throughout the history of the globe, they have been actively involved in the creation and destruction of various land areas. For example, quite recently, in 1963, near the southwestern coast of Iceland, one of the underground volcanoes created the small island of Surtsey, with an area of \u200b\u200b2.5 square meters. km.

In the distant past (in the 16-17 centuries BC), the island of Santorini (Aegean Sea) was almost completely destroyed by another similar volcano. In this case, the decisive role was played by a long dormant volcano, which suddenly, with unexpected force, demolished the top of the mountain and spewed out lava for long days (until it almost completely destroyed the island, thereby destroying the Minoan civilization and causing a huge tsunami). All that remains of the island after the end of the eruption is a large crescent island with the largest caldera in the world.

The causes of the volcanic eruption

Studying, let's see what the Earth is like in a section. In fact, it resembles an egg, in the center of which, surrounded by the mantle and lithosphere, is an extremely hard core.
From above, our planet is protected by a rather thin, but at the same time - a hard shell, in other words, the earth's crust, the lithosphere. On land, its thickness usually varies from 70 to 80 km, on the ocean floor - in the region of twenty.

Under the lithosphere is a viscous, like hot resin, layer of a hot mantle: its temperature in the depths of the planet reaches a thousand degrees (the closer to the center of the Earth, the hotter it is). To obtain its temperature readings, volcanologists use special electrical thermometers "thermocouple" - devices made of glass melt in it almost immediately. The life of our planet from the inside looks like this:

The part of the mantle that is closer to the lithosphere and that that is near the core constantly mixes with each other: the hot one rises up, the cold one goes down.
Since the mantle itself has an extremely viscous structure, it may seem from the outside that the earth's crust is floating in it, going a little deeper under the pressure of its own weight.

Having reached the earth's crust, the gradually cooling lava moves along it for some time, after which, having cooled down, it goes down.
Moving along the lithosphere, magma sets in motion separate areas of the earth's crust (in other words, lithospheric plates), which because of this periodically collide with each other.
Part of the lithospheric plate, which is below, plunges into a hotter mantle and almost immediately begins to melt, forming magma - a viscous mass consisting of molten rocks and containing various gases and water vapor. Despite the fact that the formed magma is not as thick as the mantle, it still remains a rather viscous consistency.
Since magma is much lighter in structure than the surrounding rocks, it rises upward again and gradually accumulates in magma chambers that are located along all the places where lithospheric plates collide.

Role of magma
But then magma, by its behavior, resembles yeast dough: it increases in volume and occupies absolutely all the free territory that it can reach, rising from the bowels of our planet along all the cracks accessible to it.

Having reached the least densely sealed places, under the influence of the gases contained in it, they try to leave it in any way (this process is called magma degassing), it breaks through the earth's crust and, knocking out the "plug" of the volcano, breaks out.

Eruption
The more tightly the mountain is plugged, the stronger the eruption will be. Usually, experts (VEI) designate the strength of volcanic emissions from 0 (weakest) to 8 (strongest) points. For example, volcanologists assessed the active activity of Mount St. Helens in 1980 as moderate, although the eruption itself was equated in power to the explosion of five hundred atomic bombs.

Rising upward and escaping from the confined space, magma almost immediately loses gases and water vapor, and becomes lava (magma depleted in gases), capable of moving at a speed of about 90 km / h. The gases that break free are flammable and explode in a volcano crater (a volcano crater is a funnel-shaped depression at the top or slope of a volcanic cone), leaving behind a huge funnel (caldera) in the mountain. The volcano erupts as follows:

Volcano structure

After the magma knocks out the plug of the volcano, the pressure in the magma chamber (its upper part) instantly drops. Dissolved gases below continue to boil and remain part of magma.
The closer to the vent, the more gas bubbles become. When there are too many of them, they decisively rush upward, outward, raising with them molten magma.
At the same time, near the crater of the volcano, a foamy mass accumulates, in a frozen version known to us as pumice.
Once free, the gases completely leave the magma, which, because of this, transforms into lava and carries ash, steam and fragments of rocks from the depths of the globe (among which there are often blocks the size of a house). As for the eruption itself, it is also characterized by the alternation of weak and powerful explosions.
The height of the rise of substances ejected from the Earth's interior usually varies from one to five kilometers, but it can be much higher. For example, in the 50s of the last century, the height of the ejected debris from the Bezymyanny volcano (Kamchatka) reached 45 km, and the emissions themselves scattered around the district over a distance of several tens of thousands of kilometers.
In the case of an extremely strong eruption, the volume of volcanic emissions can be several tens of cubic kilometers, and the amount of ash can be so huge that absolute darkness appears, which can usually be observed only in a space completely closed from light.


Volcanic eruption products are classified into different types. They can be gaseous (volcanic gases), liquid (lava) and solid (volcanic rocks). Depending on the nature of the products of volcanic eruptions and the composition of magma, structures of various shapes and heights are formed on the surface.

Completion of the process
When gases leave the magma with noise and explosions, the pressure that previously appeared in the magma chamber is significantly reduced, and the eruption stops. After that, the erupting mouth of the volcano is covered by the cooling lava, and sometimes it does it quite firmly, and sometimes not quite. And then gases (fumaroles) or fountains of boiling water (geysers) continue to burst onto the earth's surface in small quantities, and the volcano itself is considered active.

This means that magma will soon begin to collect again below, and, having reached a certain volume, the eruption will begin again. A prime example is, which shocked the whole world in 1883.

Types of volcanoes

Volcanologists have often wondered what kind of types of volcanoes? During the research, several types were identified:
The operating.

The mouth of a volcano is considered active if it constantly or periodically ejects magma and there is documentary evidence of this phenomenon. If emissions are not recorded anywhere, but volcanoes actively emit hot gases and boiling fountains, they are also referred to this type.
Asleep. A volcano is called sleeping if there is no recorded information about its eruption, but at the same time it retained its shape and small earthquakes and tremors constantly occur under it, and new portions of magma enter the magma chamber. At the same time, there are many cases when volcanoes were silent for more than a thousand years, and then woke up and resumed their active activity.

Extinct... Extinct (ancient) volcanoes were actively working in the distant past, but at the moment they are heavily destroyed, washed out and do not show any volcanic activity, and the lithospheric plates in this area are absolutely not moving anywhere. An example of an extinct volcano is the mountain on which the capital of Scotland is located: according to scientists, the last time it spewed out lava more than 300 million years ago (dinosaurs did not exist at that time and close).

Fissured... Lava does not always burst out of the mountain with noise and explosions. If it finds an easier way out to the surface, then it flows out absolutely silently (such a phenomenon can be observed, for example, in the Hawaiian Islands), and spreads over a huge territory. After the lava cools, it transforms into a solid rock layer (basalt). Moreover, after each next eruption, its thickness increases significantly (often up to ten meters at a time). Such types of volcanoes are called linear (fissure) and their eruptions are characterized by a rather calm nature.

Central... Volcanoes are also of the central type. It is he who makes the greatest amount of noise, explosions, and the consequences of his activities both for people and for the environment are quite dire. It is characterized by a central channel (volcano mouth), which brings magma to the surface. It ends with an expansion (crater), which over time, as the volcano grows, gradually moves upward. Often in the crater of such a mountain, a lake is formed, consisting of liquid lava. If the magma consists of a more viscous consistency, it clogs the mouth of the volcano very tightly, which subsequently leads to extremely strong emissions.

How to survive a volcanic eruption

Despite the danger, people continue to live at the foot of a dangerous neighbor, volcanologists have developed whole complex activities, the purpose of which is to warn the local population about the impending danger, and in case of getting into a dangerous situation, to know how to act in order to save your life.

First of all, it is imperative to follow all the warnings of volcanologists about the possible beginning of a volcanic eruption. If it is not possible to leave the dangerous territory, at the first warning of the danger, it is necessary to stock up on autonomous sources of lighting and heaters, as well as water and food for several days. If it was not possible to leave the dangerous area before the eruption began, all window and door openings, as well as ventilation and smoke channels, must be tightly and securely closed.

Eruption near the city

Pet owners should definitely bring them into completely enclosed spaces. If volcanic emissions find a person on the street, he must in any way protect the body (primarily the head) from falling stones and ash.

Since a volcanic eruption is usually accompanied by various natural disasters (floods, mudflows), at this time it is necessary to go away from rivers and valleys so as not to be in the flood zone or not be buried under the mud (it is advisable to be at this time on some hill) ...

After surviving an eruption, before going outside, you must cover your mouth and nose with a gauze bandage, and wear protective glasses and clothing to prevent burns. Do not rush out of the disaster zone by car immediately after the ash falls - it will be disabled almost immediately. After leaving the room, it is necessary to clean the roof of the house (shelter) from ash and other volcanic emissions, otherwise it may collapse, unable to withstand a huge load.

The volcano is a stunning natural object, alluring with its danger and enchanting with its beauty. Fortunately, I have not seen volcanoes with my own eyes, although we have them in Russia. An active volcano is a dangerous natural toy that can harm not only people, but nature as a whole. From time to time, volcanoes erupt, splashing magma from the bowels.

Causes of volcanic eruptions

In short, a volcanic eruption is the process of magma emerging onto the surface of the earth's crust. There are several reasons for the eruption, but the main one is internal structure Earth. Our planet is made up of different layers. The upper part of the planet's mantle is liquid - magma.

The earth's crust is not solid, it is covered with various cracks. The rock blocks move, collide with each other. Considering that the lithospheric plates are heavy, under their own weight, they seem to push the hot magma out from under them. An eruption occurs.

Killer Vesuvius

Vesuvius is an active volcano located not far from the Italian Naples. The height of the volcano is about 1281 meters. This volcano is considered one of the most dangerous and largest in the world. In 79, he erased from the planet:

• Stabiyu - an ancient Italian city;
• Herculaneum is an ancient Roman city;
• Pompeii is an ancient Roman city.

During its "life" the volcano has erupted more than 80 times. The last eruption took place in 1944. This eruption brought the strongest destruction to the surrounding territories.

Now there is a national park around the volcano.

Volcanology

Currently, such a type of science as volcanology is widely developing. This is the science of volcanoes and everything related to them. The main task of scientists-volcanologists is to study and timely identify changes in the behavior of volcanoes. Science investigates individual eruption processes, helps to determine with high accuracy the time of a volcanic eruption.

In order to study the natural mystery more thoroughly, laboratories are being set up in the zones of active volcanoes.

For me personally, at one word "volcano", a chill runs down my spine. But anyway, someday I will definitely be able to see the volcano live!

A truly amazing sight is a volcanic eruption. But what is a volcano like? How does a volcanic eruption take place? Why do some of them spew huge lava flows at different intervals, while others sleep peacefully for centuries?

What is a volcano?

Outwardly, the volcano resembles a mountain. There is a geological fault inside it. In science, a volcano is usually called a formation of geological rocks located on the surface of the earth. Through it, magma erupts outside, which is very hot. It is magma that subsequently forms volcanic gases and rocks, as well as lava. Most of the volcanoes on earth were formed several centuries ago. Today, new volcanoes appear on the planet occasionally. But this happens much less frequently than before.

How do volcanoes form?

If we briefly explain the essence of the formation of a volcano, it will look like this. Under the earth's crust there is a special layer under strong pressure, consisting of molten rocks, and it is called magma. If cracks suddenly begin to appear in the earth's crust, then elevations form on the surface of the earth. It is through them that magma comes out under strong pressure. On the surface of the earth, it begins to disintegrate into hot lava, which then solidifies, causing the volcanic mountain to become larger and larger. The emerging volcano becomes such a vulnerable spot on the surface that it spews volcanic gases with high frequency to the surface.

What is a volcano made of?

In order to understand how magma erupts, you need to know what a volcano is made of. Its main components are: a volcanic chamber, a vent and craters. What is a volcano focus? This is where magma forms. But not everyone knows what a crater and crater of a volcano is? A vent is a special channel that connects the hearth with the surface of the earth. A crater is a small bowl-shaped depression on the surface of a volcano. Its size can reach several kilometers.

What is a volcanic eruption?

Magma is constantly under strong pressure. Therefore, there is a cloud of gases above it at any time. Gradually they push the red-hot magma to the surface of the earth through the mouth of the volcano. This is what causes the eruption. However, one small description of the eruption process is not enough. To see this spectacle, you can use the video, which you need to watch after you have learned what the volcano consists of. Likewise, on the video you can find out which volcanoes do not exist at the present time and how the volcanoes that are active today look like.

Why are volcanoes dangerous?

Active volcanoes are dangerous for a number of reasons. The dormant volcano itself is very dangerous. He can "wake up" at any time and begin to spew lava flows spreading over many kilometers. Therefore, you should not settle near such volcanoes. If an erupting volcano is located on the island, a dangerous phenomenon such as a tsunami may occur.

Despite their danger, volcanoes can serve humanity well.

Why are volcanoes useful?

• During the eruption, a large number of metals appear that can be used in industry.
• The volcano gives rise to the strongest rocks that can be used for construction.
• The pumice stone from the eruption is used for industrial purposes, as well as in the production of stationery and toothpaste.

Volcanic eruptions: causes and consequences. Volcanoes - 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. Volcanic eruptions are geological emergencies that can lead to natural disasters.

Eruption- This is the release of molten matter of the earth's crust and mantle, which is called magma, to the surface of the planet. The eruption process can last from several hours to many years. Among the various classifications, there are general types of eruptions:

Hawaiian type - Ejections of liquid basalt lava, often lava lakes are formed, should resemble scorching clouds or hot avalanches.

Hydroexplosive type - eruptions occurring in the shallow conditions of the oceans and seas are characterized by the formation of a large amount of steam arising from the contact of hot magma and sea water.

Dome - squeezing and pushing out viscous lava.

Volcanic- characterized by the release of a large amount of rock debris, lava, ash. (There are also underwater eruptions).

The eruption of the volcano is associated with melted rising from great depths lavas.Lava differs from magma in that it does not contain gases, they volatilize during an eruption .. The appearance of such melts is caused by the transition of solid rocks into a liquid state, which means an increase in their volume by 5-10%. The change in volume due to the hydrostatic pressure developing in the liquid melt causes this melt to rise upward. The penetration of the melt onto the day surface depends on the strength and solidity of the earth's crust. If the latter is dissected by faults, then relatively quiet eruptions occur, sometimes accompanied by its gushing (eruptions of the Hawaiian type).

But the melt may find itself in an environment that makes it difficult to rise to the earth's surface. In this case, the melt solidifies at depth, forming a large granite massif, or causes the rocks located above it to melt.

According to J. Forhugen, the amount of gases in the lava is decisive. At high pressure, water and gases are dissolved in magma. When approaching earth surface the pressure begins to drop, the water turns into a gaseous state. The gas-rich lava “boils” from the bubbles accumulating in it (like sparkling water in a bottle). When there are a lot of gas bubbles, they combine with each other and the lava is fragmented into tiny particles. The lava crystallization that has begun increases the water vapor pressure. An increase in vapor pressure in such a gas chamber ultimately leads to an explosion that destroys the rock layers covering it from above. The gaseous emulsion accumulated in the depths of still liquid lava is thrown into the atmosphere, the smallest bubbles immediately freeze and in the form of volcanic ash are carried through the air, and then fall back to the ground. This phenomenon can also be triggered by the movement of tectonic plates and earthquakes.

Consequences of volcanic eruptions

The most dangerous phenomena for humans and the environment during volcanic eruptions are the resulting volcanic eruption products... They are liquid, solid and gaseous. Accordingly, volcanoes can erupt:

lava flows; (The most widespread are basalt lava flows. Initially heated to 1000-1200 ° C, basalt lavas remain fluid, cooling down to a temperature of 700 ° C. The speed of movement of basalt lavas is up to 40-50 km / h. Coming out of a flat place, they spread over vast areas) ;

volcanic mud flows; (during volcanic eruptions, volcanic mud flows may occur, which represent great danger for humans and the environment);

solid volcanic products;

scorching volcanic cloud; (during the eruption of volcanoes, a scorching cloud can form from the accumulation of hot ash and gases, which poses a mortal threat to people and the environment.);

volcanic gases;

volcanic bombs (solid volcanic products are thrown into environment from the mouth of a volcano during powerful explosive eruptions. The most common solid volcanic products are volcanic bombs. Volcanic bombs are rock fragments more than 7 cm long);

Volcanic particles smaller than 2 mm are called ashes... This ash is not a combustion product. It looks like a collection of dust. These are fragments of volcanic glass, which are instantly frozen thin walls of expanding gas bubbles released from magma during an explosive eruption. When thrown upwards, they will then fall to the ground in the form of glassy ash.

The eruption of terrestrial volcanoes causes the formation of deadly pyroclastic flows, varying in their power. They are made of hot gas and ash, and they rush along the slopes at great speed. In addition, toxic substances are released into the atmosphere and hot lava flows to the surface. The consequences of underwater volcanic eruptions are directly related to the formation of deadly waves and tsunamis. Subglacial faults, as a result of their large eruption, depending on one or another geological and geographical location, can lead to the formation of landslides, powerful mudflows and the collapse of the glaciers themselves. Volcanic eruptions are usually associated with loss of ground cover, air pollution, pollution of water bodies, lakes, rivers, and hence drinking water. We should also mention failures in the operation of various infrastructures, the destruction of residential buildings and non-residential premises, famine and the spread of various kinds of infections. The consequences of the eruption of powerful volcanoes have a direct impact on climate change and can trigger the onset of the so-called volcanic winter. The ash and gases formed during the explosion will reach the atmospheric layer and, like a blanket, will completely cover the Earth. The sun's rays will cease to penetrate, and sulfuric acid will fall on the surface in the form of precipitation. The effect that will result from such processes will be similar to the consequences of a nuclear winter. Eruptions of this kind are quite rare, and today scientists are doing everything possible to reduce the likelihood of their occurrence.