Today we look at this interesting subject, as volcanoes.The structure of volcanoes and their classification are described in detail in this article.
Volcanoes got its name by the name of Vulcan, god of fire.They are geological formations that occur over the cracks and channels in the crust.Large volcanoes that erupt before your eyes, with nothing incomparable spectacle.On the earth's surface through cracks and channels emitted lava, rock fragments and hot gases from magmatic sources.Volcanoes are usually composed of individual products of eruptions of the mountain.These may reach a height larger.For example, the largest volcanoes in Africa - Kilimanjaro is (5895 meters), Cameroon (4100 meters) and the Teide (3,718 meters).
extinct, dormant and active volcanoes
to the active are those that are currently erupt periodically or continuously.For example, the active volcanoes in Africa - is Nyiragongo, Meru, Karisimbi, Phaco, Teide.Asleep - these volcanoes, eruptions of which there is no information, however, they have kept their shape and local earthquakes occur beneath them.Extinct referred blurry and badly damaged, not active volcanoes.Photo of an active volcano Arenal, located in Costa Rica, is presented below.
division fissure volcanoes and central
Volcanoes share in the form of bringing channels to crack central.Considering the structure of the volcano (scheme shown below), it should be noted that in the upper mantle magma chambers may be at a depth of about 50-70 km (eg, Kamchatka volcano Klyuchevskaya Sopka).They may also be in the earth's crust at a depth of 5-6 meters (Italian volcano Vesuvius) or deeper.
Long-term and short-term eruptions
Volcanic eruptions can be long (from several years to several hundred years) and short-term, which is measured in hours.It can be attributed to their precursors acoustic phenomena, volcanic earthquakes, changes in the composition and magnetic properties of fumarole gases, as well as some other phenomena, marks before volcanoes erupt.Photo erupting volcano is presented below.
How eruption begins?
Usually it begins what is happening strengthening the emissions.They are thrown out at first with the cold, dark lava fragments, and then with the red-hot.In some cases, these emissions are accompanied by an outpouring of lava.From 1 to 5 kilometers, depending on the strength of explosions varies the lift amount of lava fragments of saturated water vapor and heat gases.And the biggest volcano eruption may dispose of the product and to even greater heights.For example, in 1956 in Kamchatka during the eruption of the volcano Nameless it was 45 kilometers.At a distance of a few thousand to tens of thousands of kilometers of the ejected material is transferred.Its volume sometimes reaches a few cubic kilometers.The concentration of volcanic ash in the atmosphere for some eruptions can be so large that there is darkness, comparable with the darkness indoors.It was observed, in particular, the village Keys, located 40 km from the volcano Nameless, in 1956.
Layout volcano presented below will help you understand its structure.
What eruption?
eruption - is the alternation of strong and weak explosions and lava flows.Maximum power called the bombings culminating paroksizom.Reducing the force of explosions and then a gradual cessation of eruptions observed after them.Dozens of cubic kilometers of lava streamed throw the biggest volcanoes.The photo below shows the structure of the volcano.This scheme gives a clear idea of how it erupts.
types of eruptions
not always the same volcanic eruption.They are 4 types depending on the viscosity of the lava and the number of products (solid, liquid and gaseous): an explosive (Vulcan), extrusion (dome), mixed (Strombolian) and effusive (Hawaiian).
Hawaiian style, often creating a shield volcano, is characterized by relatively calm outpouring of basalt (liquid) lava that formed in the craters and lava flows flaming liquid lake.Contained in a small amount of gases formed fountains, which emit drops and lumps of molten lava, pulling in thin glass filaments during the flight.
in Strombolian type, which usually create strato-volcanoes, along with a fairly abundant outpourings of lava andesite and basaltic composition is dominated by small explosions, during which slag pieces are ejected, as well as various spindly and twisted bomb.
The dome type is gaseous substances play an important role.They produce explosions and emissions of large black clouds, crowded lots of lava rubble.Small streams form a viscous andesitic lava.
Products eruptions
solid, gaseous and liquid products are different volcanic eruptions.Volcanic gases are released both during eruptions (called eruptive), and during the calm of the volcano (furamolnye) from cracks located on the slopes of the volcano and from its crater, pyroclastic rocks and lava flows form the hot springs, walkingthrough groundwater.
Lava - a red-hot or very viscous liquid, mostly silicate mass which is poured out by volcanic eruptions on the surface of the Earth (see. In the photo below in the context of the volcano).When it solidifies formed volcanic rock.
Volcanics (volcanic rock) - rocks that are formed as a result of volcanic eruptions.There are, depending on whether the character is an eruption, extrusive or effusive (diabase, liparites, trachytes, andesites, basalts, etc.), Pyroclastic or volcanic-clastic (volcanic breccia, tuff) volcanic rocks.
Volcanic phones
tectonic fault (tectonic break) - it is happening because of the crustal movements violation of the integrity of rocks (thrust faults, reverse faults, shifts, discharges and others.).
The photo below shows the layout of the volcano.
Depending on the composition and nature of the magma eruptions occur on the surface of buildings of varying heights and shapes.Every time is a unique structure of the volcano.The image above - it is merely an example.Volcanic units consist of a crack or a tubular channel vents (upper part of the channel), vulkanooblomochnyh products and accumulations of lava surrounding from different sides of the channel, and the crater (funnel-shaped or cup-shaped groove on the side or top of the volcano with a diameter of from a few meters to several kilometers).The most common forms are cone-shaped, with a predominance of emissions of various detritus and dome (viscous lava when squeezed).
not only through the top of the main crater of the eruption occurs, but also through the side (otherwise known as parasitic) craters that have volcanoes.Structure volcanic characterized in that the craters are on the side slopes and at some distance from the primary vertices.Often, in single eruptions of gases that penetrate to the earth's surface channel formed funnel-shaped depressions.They are bordered by the annular shaft, consisting of blocks of different breeds.Often these craters are filled with water.They are called Maar.Sometimes strong eruptions are accompanied by the fact that the breaking of the volcanic structures.Often this applies to areas which are close to volcanoes.The structure of volcanoes, and sometimes leads to its collapse.Depressions, which are formed at the same time, reaching a diameter of several to several tens of kilometers.They are called calderas.
Underwater volcanoes
volcanic structure we discussed.It should be noted that one of them is underwater species, located on the water bottom.Today, the geographical coordinates of the volcanoes of this type are concentrated mainly within three volcanic zones: the Atlantic, the Mediterranean-Indonesian and Pacific.According to a study of the past of our planet from the geological point of view, in its scope and in terms of product release coming from the bowels of the earth, they are significantly higher than on land.If the annual land from 20-30 eruptions on average comes to 1.5 cubic kilometers of molten magma per year, that of undersea volcanoes in the same period erupted 12-15 times more material.Active submarine volcanoes sustain life in the ocean near the surface.And from it, in turn, depends on the amount of greenhouse gases absorbed by the ocean.
eruptions of underwater volcanoes
If the reservoir is located above the volcanic hearth pyroclastic material during the eruption of saturated water and then spreads around the hearth.For the first time such deposits have been described in the Philippines.They were formed in the course of what happened in 1968, the eruption of Taal volcano, which is on the bottom of the lake.Deposits of this type are often subtle wavy layers of pumice.The islands can be formed as a result of volcanic eruptions.This, for example, located in the Indian Ocean, the volcanic island of Reunion.
reasons volcanic activity
the close relationship between the movable portions of the earth's crust and volcanic activity zones indicate the geographical distribution of volcanoes.Formed in such fault zones are the channels through which the Earth's surface is moving magma.This occurs apparently due to various tectonic processes.When the pressure of the gases dissolved in the magma, it is at a depth greater than the pressure of the overlying, they begin to move to the ground, dragging the magma.Perhaps during crystallization of magma creates gas pressure when the steam and residual gases enriched its liquid part.Magma like boils.At the outbreak as a result of the allocation of more gases at high pressure.It can also be one of the causes of the eruption.
formation and structure of the volcano - very interesting topics.In this article we looked at them only briefly.The internal structure of the volcano is still interested in a lot of researchers.They still engaged in its study.
the first time during his school years, we are familiar with what the volcano.Geography gives us the opportunity to get closer to an understanding of how to construct our planet.The land conceals many mysteries, to be the next generation.Of course, in the school we are told only the highlights when we study the structure of the volcano.Class 5 - not the age when you should go into this topic.However, sometimes it can be done and should be.We hope you have learned something new for myself in this article.
