What makes magma flow in volcanic chambers
Volcanoes and their consequences. Volcanic Eruption: Volcanoes of the World
The land at the foot of the volcanoes is one of the most fertile areas on our planet because the eruptions that the volcanic slot causes saturate the soil with a large amount of nutrients and minerals. Even if the volcano has slept 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 not only settle at the foot of the volcanoes, but also on the slopes of the mountains and pay no attention in the least to the periodic tremors in the region. Vain. Everyone knows the fate of the people of Pompeii who were buried almost 2,000 years ago. The tragedy could have been avoided by paying attention to the more frequent five or six magnitude earthquakes.
Where do the volcanoes come from? Fire-breathing mountains appear above the collision points of the lithospheric plates at the weakest points, through which our planet emits hot magma, combustible gases and the most diverse volcanic material that later form these mountains.
The word "volcano" itself is of Latin origin - that's how the locals called the fire god in ancient Rome. It is interesting that the mountain was the first to receive such a name (according to local residents, the volcanic forge was located there).
There are different types of volcanoes. Geologists currently count around one and a half thousand active volcanoes on our planet, not underwater. In the latter, about 20% of the total number of all existing volcanoes in the world, including the extinct ones, are located in the depths of the ocean and the sea.
We owe them new land areas that sometimes appear in the middle of the endless ocean: After underwater volcanoes erupt in large amounts of lava, their tips finally reach the surface of the sea and form islands (e.g. Hawaii or Canary Islands). .
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The greatest number of volcanoes (two-thirds) are located in the so-called Pacific Ring of Fire, which frames the edges of the huge Pacific plate, which is in constant motion and constantly colliding with neighboring plates.
Volcanic eruption: video
The role of volcanoes in the life of the planet and people
It is impossible to diminish the role of volcanoes in the life of our planet. First, because without them it would be entirely possible that the earth is still a heated space ball: It was the fire-breathing mountains that once brought water vapor from the bowels of the globe to cool the lithosphere and the planet's atmosphere.
According to geologists, a single eruption from a fiery mountain on one of the Indonesian islands plunged our entire planet into the Ice Age more than 75,000 years ago, and sulfuric acid formed in the atmosphere.
Throughout the history of the world, they have been actively involved in the creation and destruction of various areas of land. For example, recently, in 1963, near the southwest coast of Iceland, one of the underground volcanoes created the islet of Surtsey, an area of 2.5 square meters. km.
In the distant past (in the 16th-17th centuries BC) the island of Santorini (Aegean Sea) was almost completely destroyed by another similar volcano. In this case, a long dormant volcano played the decisive role, which suddenly tore off the top of the mountain with unexpected force and spewed lava for long days (until it almost completely destroyed the island, thereby destroying the Minoan civilization and a large tsunami). All that is left of the island after the eruption ends is a large crescent island with the largest caldera in the world.
The causes of the volcanic eruption
Let's see what the earth is like in one section. In fact, it resembles an egg with an extremely hard core at its center, surrounded by the mantle and the lithosphere.
From above, our planet is protected by a rather thin, but at the same time protected, shell, i.e. by the earth's crust, the lithosphere. On land, its thickness usually varies from 70 to 80 km, on the seabed - in the region of twenty.
Under the lithosphere there 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 get the temperature readings, volcanologists use special electrical thermometers "thermocouples" - devices made of glass melt in them almost instantly. The life of our planet from the inside looks like this:
The part of the mantle closer to the lithosphere and near the core is constantly mixing with each other: the hot one rises, the cold one falls.
Since the mantle itself has an extremely viscous structure, from the outside it appears as if the earth's crust appears to be floating in it, as it has gone a little deeper under the pressure of its own weight.
After reaching the earth's crust, the gradually cooling lava moves along the earth's crust for some time. After cooling down, it sinks.
While moving along the lithosphere, magma sets separate areas of the earth's crust in motion (in other words, lithospheric plates) which, as a result, periodically collide with one another.
Part of the underlying lithospheric plate is immersed in a hotter mantle and begins to melt almost immediately. This forms magma - a viscous mass that consists of molten rock and contains various gases and water vapor. Despite the fact that the magma formed is not as thick as the mantle, it still remains a fairly viscous consistency.
Since magma has a much lighter structure than the surrounding rocks, it rises again and gradually accumulates in magma chambers located in all places where lithospheric plates collide.
Roll of magma
But then magma is similar in behavior to yeast dough: it increases in volume and absolutely occupies all the free area it can reach, rising from the bowels of our planet along all the cracks accessible to it.
Having reached the least tightly sealed places, under the influence of the gases contained in them, they try to leave them in some way (this process is called magma degassing), they break through the earth's crust and knock out the "plug" Volcano erupts.
The more firmly the mountain is clogged, the stronger the eruption will be. Usually, experts (VEI) determine the strength of volcanic emissions from 0 (weakest) to 8 (strongest) points. For example, volcanologists rated Mount St. Helens' active activity as moderate in 1980, although the eruption itself has been equated in power with the explosion of five hundred atomic bombs.
Magma rises and escapes from the narrow space. It loses gases and water vapor almost immediately and turns into lava (magma that is depleted in gases), which can move at a speed of around 90 km / h. The gases that dissolve are flammable and explode in a volcanic crater (a volcanic crater is a funnel-shaped depression at the top or slope of a volcanic cone), leaving a giant funnel (caldera) in the mountain. The volcano erupts as follows:
After the magma knocks out the plug of the volcano, the pressure in the magma chamber (its upper part) drops immediately. The gases dissolved underneath continue to boil and remain part of the magma.
The closer to the vent, the more gas bubbles there will be. When there are too many of them, they resolutely rush up and out, picking up molten magma with them.
At the same time, near the volcano's crater, a foamy mass accumulates in a frozen version known to us as pumice stone.
As soon as they are free, the gases completely leave the magma, which for this reason turns into lava and transports ash, steam and rock fragments from the depths of the globe (under which there are often houses the size of a house). The eruption itself is also characterized by the alternation of weak and strong explosions.
The magnitude of the rise in substances emitted from the Earth's interior usually varies between one and five kilometers, but can be much higher. For example, in the 1950s, the height of the debris ejected from the Bezymyanny volcano (Kamchatka) reached 45 km, and the emissions themselves were spread over the area over a distance of tens of thousands of kilometers.
In the event of an extremely strong eruption, the volume of volcanic emissions can be tens of cubic kilometers, and the amount of ash can be so great that absolute darkness occurs, which can normally only be observed in a room completely protected 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 type of products from volcanic eruptions and the composition of magma, structures of different shapes and heights form on the surface.
Completion of the process
When gases with noises and explosions escape from the magma, the pressure previously created 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 so firmly and sometimes not entirely. And then gases (fumaroles) or fountains with boiling water (geysers) continue to burst onto the surface of the earth in small quantities, and the volcano itself is considered active.
This means that the magma will soon collect again below and the eruption will start again after reaching a certain volume. A prime example is what shocked the world in 1883.
Types of volcanoes
Volcanologists have often wondered what for types of volcanoes? Several types were identified during the research:
The mouth of a volcano is considered active when it expels magma continuously or regularly and there is documentary evidence of this phenomenon. When emissions are nowhere recorded, but volcanoes are actively emitting hot gases and boiling wells, they are also known as this type.
Asleep. A volcano is said to be dormant when there is no information about its eruption. At the same time, it has kept its shape and small earthquakes and tremors keep appearing under it, and new pieces of magma enter the magma chamber. At the same time, there have been many cases when volcanoes were silent for more than a thousand years, and then woke up and resumed their active activity.
Extinct... Extinct (old) volcanoes worked actively in the distant past, but at the moment they are badly destroyed, washed out and showing no volcanic activity, and the lithospheric plates in this area are moving absolutely nowhere. An example of an extinct volcano is the mountain on which the capital of Scotland is located: According to scientists, it last spat out lava more than 300 million years ago (there were no dinosaurs at the time).
Fissured... Lava doesn't always burst from the mountain with noise and explosions. If it finds an easier way out to the surface, it flows out absolutely noiselessly (such a phenomenon can be observed, for example, in the Hawaiian Islands) and spreads over a vast area. After the lava has cooled, it turns into a solid layer of rock (basalt). In addition, its thickness increases significantly after each next eruption (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 causes most of the noise, explosions and the consequences of his activities for both people and the environment. It is characterized by a central channel (volcanic mouth) that brings magma to the surface. It ends with an expansion (crater) that gradually moves upward over time as the volcano grows. Often a lake is formed in the crater of such a mountain, which consists of liquid lava. If the magma is of a more viscous consistency, it clogs the mouth of the volcano very tightly, which subsequently leads to extremely heavy 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 of the impending danger and to know how to act for their life in the event of a dangerous situation to rescue.
First of all, it is imperative to heed all warnings from volcanologists about the possible start of a volcanic eruption. If it is not possible to leave the dangerous area, then at the first warning of the danger, it is necessary to buy autonomous sources of lighting and heating, as well as water and food, for several days. If it was not possible to leave the dangerous area before the outbreak began, all window and door openings as well as ventilation and smoke ducts must be tightly and securely closed.
Outbreak near the city
Pet owners should definitely bring them to completely enclosed spaces. When volcanic emissions find a person on the street, they must somehow protect the body (mainly the head) from falling rocks and ash.
Since a volcanic eruption is usually accompanied by various natural disasters (floods, mud flows), at this time it is necessary to move away from rivers and valleys in order not to be in the flood zone or to avoid being buried under the mud (it is advisable around this time to be on a hill) ...
After surviving an outbreak, you must cover your mouth and nose with a gauze bandage and wear protective glasses and clothing before going outside to avoid burns. Don't rush your car out of the disaster area immediately after the ash falls - it will deactivate 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 and not withstand a large load.
The volcano is a breathtaking natural object that seduces with its danger and enchants with its beauty. Fortunately, I haven't seen any volcanoes with my own eyes, even though 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 and squirt magma out of the intestines.
Causes of volcanic eruptions
In short, a volcanic eruption is the process by which magma leaks onto the surface of the earth's crust. There are several reasons for the outbreak, but the main one is Earth's internal structure. Our planet consists 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 boulders move, collide with each other. When you consider that the lithospheric plates are heavy under their own weight, they seem to be pushing the hot magma out from under them. An outbreak occurs.
Vesuvius is an active volcano not far from Naples, Italy. The height of the volcano is about 1281 meters. This volcano is considered to be one of the most dangerous and largest in the world. In the year 79 he erased from the planet:
- Stabiyu - an old Italian city;
- Herculaneum is an ancient Roman city;
- Pompeii is an ancient Roman city.
During its "life" the volcano erupted more than 80 times. The last eruption occurred in 1944. This outbreak brought the greatest destruction to the surrounding areas.
Now there is a national park around the volcano.
At present, such a science as volcanology is developing on a large scale. This is the science of volcanoes and everything related to it. The main task of scientists and volcanologists is to study changes in the behavior of volcanoes and identify them in good time. Science examines the individual eruption processes and helps to determine the time of the volcanic eruption with high accuracy.
Laboratories are being set up in the zones of active volcanoes in order to investigate the natural secret more closely.
Personally, I have a shiver when I hear the word "volcano". But one day I will definitely be able to see the volcano live!
A really amazing sight is a volcanic eruption. But what is a volcano like? How does a volcanic eruption take place? Why do some of them spit out huge streams of lava at different intervals while others sleep peacefully for centuries?
What is a volcano?
Outwardly, the volcano resembles a mountain.There's a geological flaw in it. In science, a volcano is commonly referred to as a formation of geological rocks that are on the surface of the earth. Magma erupts through them, which is very hot. It is magma that subsequently forms volcanic gases and rocks, as well as lava. Most of the earth's volcanoes were formed a few centuries ago. Today, new volcanoes occasionally appear on the planet. However, this happens much less often 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, under strong pressure, there is a special layer made of molten rock called magma. When cracks suddenly appear in the earth's crust, bumps form on the earth's surface. Through them, magma comes out under strong pressure. On the earth's surface, it begins to dissolve into hot lava, which then solidifies and makes the volcanic mountain grow larger and larger. The resulting volcano becomes such a vulnerable point on the surface that it emits volcanic gases to the surface at high frequencies.
What is a volcano made of?
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 crater. What is a volcanic focus? Magma is created here. But not everyone knows what a crater and crater of a volcano is? A vent is a special channel that connects the hearth to 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 under constant pressure. Therefore, there is always a gas cloud over it. Gradually they push the glowing magma through the mouth of the volcano to the surface of the earth. This is the reason for the outbreak. However, a brief description of the eruption process is not enough. To see this spectacle you can use the video that you have to watch after learning what the volcano is made of. In the same way, you can find out in the video which volcanoes do not currently exist and what the volcanoes that are active today look like.
Why are volcanoes dangerous?
Active volcanoes are dangerous for several reasons. The dormant volcano itself is very dangerous. He can "wake up" at any time and spit out lava flows that extend over many kilometers. Therefore, you should not settle near such volcanoes. If there is an erupting volcano on the island, a dangerous phenomenon such as a tsunami can occur.
Despite their danger, volcanoes can serve humanity well.
Why are volcanoes useful?
- A large number of metals that can be used in industry will appear during the outbreak.
- The strongest rocks that can be used for construction arise from the volcano.
- The pumice stone from the eruption is used for industrial purposes, as well as for making rubber bands 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 and forms lava, volcanic gases, rocks (volcanic bombs) and pyroclastic currents. Volcanic eruptions are geological emergencies that can lead to natural disasters.
eruption- This is the release of molten material from the earth's crust and mantle, called magma, to the surface of the planet. The eruption process can take several hours to many years. Among the various classifications, there are general types of eruptions:
Hawaiian guy - Ejections of liquid basaltic lava, often forming lava lakes, should resemble scorching clouds or incandescent avalanches.
Hydroexplosive type - Eruptions that occur in the shallow conditions of the oceans and seas are characterized by the formation of a large amount of steam, which is caused by 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 a molten ascent from great depths lavas.Lava differs from magma in that it does not contain gases, they evaporate during an eruption. The appearance of such melts is caused by the transition from solid rock to a liquid state, which means an increase in their volume by 5-10%. The change in volume due to the hydrostatic pressure generated in the liquid melt causes this melt to rise. The penetration of the melt on the surface depends on the strength and strength of the earth's crust. When the latter is broken down by mistake, relatively calm eruptions occur, sometimes accompanied by its gushing (Hawaiian type eruptions).
However, the melt may be in an environment that makes it difficult to rise to the surface of the earth. In this case, the melt solidifies in the depths and forms a large granite massif or causes the rocks 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 the surface of the earth the pressure begins to fall, the water changes into a gaseous state. The gas-rich lava "boils" out of the bubbles that have accumulated in it (like sparkling water in a bottle). When there are many gas bubbles, they combine and the lava is fragmented into tiny particles. The started lava crystallization increases the water vapor pressure. An increase in the 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 the still liquid lava is thrown into the atmosphere, the smallest bubbles freeze immediately and are carried through the air in the form of volcanic ash 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 result products for volcanic eruptions... You are liquid, solid and gaseous. Accordingly, volcanoes can erupt:
lava flows;; (Basalt lava flows are the most widespread. Initially heated to 1000-1200 ° C, basalt lavas remain liquid and cool to a temperature of 700 ° C. The speed of movement of basalt lavas is up to 40-50 km / h. They come from a flat place and are spread over large areas.
volcanic mud flows;; (During volcanic eruptions, volcanic mud flows can occur, which pose great danger to humans and the environment);
solid volcanic products;
scorching volcanic cloud;; (During the eruption of volcanoes, the accumulation of hot ash and gases can form a scorching cloud that poses a deadly threat to humans and the environment.)
volcano bombs (Solid volcanic products are thrown into the environment from the mouth of a volcano during strong explosive eruptions. The most common solid volcanic products are volcanic bombs. Volcanic bombs are fragments of rock more than 7 cm in length.
Volcanic particles smaller than 2 mm are mentioned ash... These ashes are not a product of combustion. It looks like a build-up of dust. These are fragments of volcanic glass, which are instantly frozen thin walls of expanding gas bubbles released during an explosive eruption of magma. When thrown upwards, they fall to the ground in the form of glassy ash.
The eruption of terrestrial volcanoes leads to the formation of deadly pyroclastic currents, which differ in their strength. Made up of hot gas and ash, they race down 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, due to their large eruptions, depending on one or the other geological and geographical location, can lead to the formation of landslides, strong mud fluxes and the collapse of the glaciers themselves. Volcanic eruptions are usually associated with loss of land cover, air pollution, pollution of water bodies, lakes, rivers and thus drinking water. Separately, there are deficiencies in the operation of various infrastructures, the destruction of residential and non-residential buildings, hunger and the spread of various types of infections. The consequences of the eruption of mighty volcanoes have a direct impact on climate change and can provoke the onset of what is known as volcanic winter. The ashes and gases formed during the explosion reach the atmospheric layer and completely cover the earth like a blanket. The sun's rays no longer penetrate and sulfuric acid falls on the surface in the form of precipitation. The effects of such processes are similar to those of a nuclear winter. Eruptions of this type are quite rare, and scientists today are doing everything possible to reduce the likelihood of their occurrence.
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