Depending on the amount of gases, their composition and temperature, there are three main forms of eruptions: effusive, explosive and extrusive.
If gases are released from magma relatively calmly, an outpouring occurs - effusion of lava.
When gases are separated quickly, the melt instantly boils up and the magma explodes into expanding gas
bubbles causing a powerful explosive eruption - an explosion.
If the magma is viscous and its temperature is low, then
the melt is slowly squeezed to the surface -
extrusion of magma.
Types of volcanoes
The Hawaiian type is a very liquid, highly mobile basaltic lava that forms huge flat shield volcanoes. There are no explosions. Lava lakes are frequent, gushing to a height of hundreds of meters. Lava flows spread over tens of kilometers.
Strombolian type - more viscous basic lava, which is ejected by explosions from the vent, forming relatively short and more powerful flows. Volcano Stromboli regularly throws into the air a "charge" of bombs and pieces of red-hot slag.
Fissure volcanoes (A) and
panel board central (B) types
Stratovolcano
Diagram of the structure of the stratovolcano
1 - caldera at the summit, 2 - summit cone, 3 - side lava volcanoes, 4 - extrusive cone on the slope, 5-
the main cone of the volcano with alternating lava flows and tuff covers, 6 - earlier acid tuffs in the volcanotectonic depression, 7 - peripheral magma chamber.
Types of volcanoes
The Plinian type (Vesuvian) of eruptions was named after the Roman scientist Pliny the Elder, who died in the eruption of Vesuvius in 79 AD. e., which destroyed three large cities - Herculaneum, Stabia and Pompeii.
Powerful, often sudden explosions are accompanied by the release of huge amounts of tephra, forming ash and pumice streams. Pompeii and Stabia were buried under tephra, and Herculaneum was littered with mud-stone streams.
As a result of the explosions, the magma chamber was empty, the summit of Vesuvius collapsed and a caldera was formed, in which, a hundred years later, a new volcanic cone - modern Vesuvius.
Types of volcanoes
Plinian eruptions are very dangerous and occur suddenly, often without any preliminary preparation.
The grandiose explosion in 1883 of the Krakatoa volcano in the Sunda Strait between the islands of Sumatra and Java belongs to the same type. The sound was heard at a distance of up to 5000 km, and the volcanic ash reached almost a hundred kilometers in height. The eruption was accompanied by a tsunami in 25-40 m, in which about 40,000 people died in coastal areas. A giant caldera has formed on the site of the Krakatoa group of islands.
Formation of lakes in calderas
Types of volcanoes
Peleus type - the formation of grandiose incandescent avalanches or scorching clouds, as well as the growth of extrusive domes of extremely viscous lava.
On the volcano Mont Pele ( about Martinique, Lesser Antilles) On May 8, 1902, an explosion destroyed the summit of a dormant volcano. A gigantic heavy "scorching" cloud escaping from the vent instantly destroyed the city of Saint-Pierre with 40,000 inhabitants. It consisted of a suspension in the hot air of incandescent fragments of ash, pumice, crystals, and volcanic rocks. Possessing a high density, the cloud rushed down the slope of the volcano at high speed.
After the eruption, an extrusive "needle" of viscous magma began to protrude from the vent, which, having reached a height of 300 m, soon collapsed.
History of the name About 20 centuries ago, a mountainous island in the Mediterranean Sea near Sicily began to spew smoke and fire. Explaining this strange phenomenon, people believed that the forge of the Roman god Vulcan was located in the mountain. The ash clouds, they argued, were smoke from his forge, and the lava spray were sparks from an anvil. They called this islet "Vulcano" - from the Latin word "Volcano".
Volcano (Greek - Hephaestus). In Greek and Roman mythology, the fire god and blacksmith who forged weapons for many gods and heroes. He was a tutor ancient man and taught him how to use fire. He was lame from birth or as a result of being thrown from Olympus to earth by Jupiter in a fit of rage.
Poets about volcanoes Vesuvius mouth opened the smoke poured out in a club flame Widely developed like a battle banner. The earth is agitated from the staggering columns Idols are falling! The people, driven by fear, Crowds, old and young, under the inflamed ashes, Under the stone rain, flees out of the hail. A.S. Pushkin VOLCANOES Silent extinct volcanoes, ash falls to their bottom. There the giants rest after the evil they have done. B. Akhmadulina Volcanoes are blown up. Defeated Ocean ... Arthur Rimbaud
The structure of the volcano A typical volcano is a hill with a pipe passing through its thickness, called a volcano vent, and with a magma chamber (an area of magma accumulation) from which the vent rises. When a high pressure is created in the magma chamber, a mixture of magma and hard stones - lava - rises up the vent and is thrown into the air. This phenomenon is called a volcanic eruption.
Ash is the smallest volcanic product in the form of a powdery mass. During explosive eruptions, it is thrown onto the earth's surface with a volume of often many cubic kilometers and rises in the form of a cloudy cloud to a height of several tens of kilometers. Powerful ash deposits covering the slopes and foothills of volcanoes in a multi-meter layer are destroying large forests and even cities. Ash is the smallest volcanic product in the form of a powdery mass. During explosive eruptions, it is thrown onto the earth's surface with a volume of often many cubic kilometers and rises in the form of a cloudy cloud to a height of several tens of kilometers. Powerful ash deposits covering the slopes and foothills of volcanoes in a multi-meter layer are destroying large forests and even cities.
Left, right - bombs like a bread crust, in the middle - in the form of a spindle. Volcanic bombs have an unusually wide variety of shapes and sizes among debris. They are formed from pieces of lava raised to a certain height by gases that are intensely released from the hot melt.
Volcanoes are divided into: Active Active - these are those volcanoes that are currently erupting or are observed periodically, at some intervals of time. If magma does not pour out, and the volcano "smokes" or "smokes", then it is also considered active. Asleep Volcanoes are considered to be asleep, which manifested their activity in a historical period of time and retained their shape; weak tremors and earthquakes periodically occur in their depths. Extinct Extinct - volcanoes that operated in the distant past; they have blurry and destroyed cones
Hawaiian type On the main island of Hawaii is the Mauna Loa volcano. Its characteristic feature is that basaltic melts pour out here relatively calmly, without explosions. The melt is weakly saturated with gases and has a low viscosity, although unusually spectacular lava fountains sometimes occur. As a result of such an eruption, the volcano has very gentle slopes, on which there are several craters.
Stromboli type Although the melt here is basaltic, that is, it has a basic composition, it has a certain viscosity. Therefore, there is an alternation of outpouring of lava flows and explosions. Explosions release bombs, lapilli, ash and basalt slag. Stromboli - the volcano of the Aeolian Islands - is notable for the fact that it constantly operates, being a kind, unusually bright lighthouse Mediterranean Sea
Volcano type The volcano of the island of Vulcano, located in the Aeolian Islands, is also quite famous. It is characterized by an eruption of relatively acidic volcanic products (andesite-dacites). Due to the high viscosity of the melt, clogging of the vent of the volcano occurs. The accumulated vapors and gases explode this plug and together with other finely crushed particles various forms and sizes throw them on great height... This is what they often say: explosive eruptions of the Vulcan type.
Vesuvian type Named by name famous volcano Vesuvius, located in Italy, near Naples. The ancient Roman scientist Pliny the Younger described it very colorfully, in connection with which this type of eruption is often called Plinian. This type is characterized by strong explosive eruptions due to periodic blockage of the volcanic vent, as well as the subsequent outpouring of lava flows.
Pompeii disappeared under a 7-8 meter layer of ash and rubble, which continually fell on the streets and houses. Herculaneum was flooded with hot lava and boiling mud. Stabia was almost completely destroyed. Only on August 27, three days after the beginning of the eruption, the sun first glimpsed, illuminating three dead city... August 24, 79 g people paid with their lives for their carelessness: suddenly into the blue sky above Gulf of Naples a lava plug shot up, for many millennia tightly plugging the mouth of the Vesuvius crater.
The inhabitants of Pompeii, buried under the ashes, died of suffocation. However, the caverns in the layer of solidified ash, where their bodies had previously been, retained the shape and postures of the unfortunate for many years. When these caverns were filled with plaster mortar, people saw sculptures of the dead. A cast of a choking woman, preserved in the ashes Sculptural images dead cast of dog
Pele type The Mont Pele volcano (Bald Mountain), which gave the name to the next type of eruption, is located on the island of Martinique (the Lesser Antilles group in Atlantic Ocean). It is characterized by incandescent ash clouds and the growth of domes in the crater of the volcano. For the first time, a directional explosion was observed here, covering a large area.
An "active" volcano is a volcano that has been erupting in recent years. Most of active volcanoes of the Earth are found in only a few countries
The large fissure Tolbachik eruption is referred to as the largest known basaltic eruption in the Kuril-Kamchatka belt. The eruption lasted for almost a year and a half (July December 1976). The height of the jet of incandescent gases reached a height of 2.5 km, and an ash cloud - 12 km. As a result of the eruption, 4 cones of the New Tolbachik volcanoes were formed, and the vast forested area around them turned into a scorched desert. Over the years that have passed since then, the cones did not have time to cool down to the end, so when you stand not at the top of the cone, you feel the heat coming from the bottom. The ash desert is gradually being developed by lichens, dwarf willow and other pioneer plants.
The following morphological types of volcanoes are distinguished: cone-shaped - the result of frequent eruptions without strong explosions; shield, flat volcanoes - devices for the outpouring of liquid lavas volcanic ridges that have arisen when the outflow centers move along the cracks; volcanic ridges that have arisen when the outflow centers move along the cracks; caldera caldera volcanoes; volcanoes from the somma volcanoes from the somma that arose within the calderas after their renewal; dome volcanoes.
Guyot Guyot's underwater volcanic activity [named after the discoverer of the American geographer and geologist A. Guyot (Guyot; A. Guyot;)], isolated flat-topped volcanic seamounts. They are found in groups or in the form of single uplifts, mainly in Pacific... Separate G. are also in the Atlantic and Indian oceans... The peaks of G. are located at depths from 200 to 2000 m. It is believed that the alignment of the peaks of G. is the result of abrasion. Since abrasion affects only up to a depth of the order of m, it is assumed that the majority of G. experienced subsidence together with the oceanic bottom forming their base.
Volcanoes are very dangerous, but they also bring benefits to humans. Various igneous rocks are used as building materials and abrasives. The sulfur produced by the volcano is found in many beneficial chemicals. A volcanic material called pumice is found in some toothpastes. Sapphires, zircons, copper, silver, gold - all of these can be mined from volcanic rocks. Some of the largest diamonds were also found in them.
Volcanoes of the Universe A nameless volcano near the north pole of Io (moon of Jupiter). Galileo (artificial probe) photographed the eruption of this volcano, the dust column rose to an altitude of about 430 km. An even higher column of ash and dust was also seen - it rose to an altitude of more than 480 km. With the help of the equipment installed on the Galileo, it was possible to determine the composition of the volcanic outburst. They were snowflake-like particles composed of sulfur dioxide molecules.
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Volcanic eruptions remind us of the formidable and indomitable forces that are hidden in the bowels of the Earth.
The mystery of the causes of volcanism has always aroused fear and keen interest in people, and the tragic consequences of eruptions forced them to explore this element.
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Volcano formation
When a magma chamber forms in the bowels of the Earth, the molten liquid magma presses down on the tectonic plate with such force that it begins to crack. Along cracks and faults, magma rushes upward, melting the rock and expanding the cracks. This is how the excretory canal is formed. It passes in the center of the volcano, through which molten magma pours out from the crater of the volcano in the form of fiery liquid lava. The products of the eruption - pumice, lava, tuff - settle on the slopes of the volcano, forming a cone. At the top of the volcano there is a depression - a crater. At the bottom of the crater, you can see the mouth of the volcano - the opening of the outlet channel through which ash, hot gases and water vapors, lava and rock fragments are spewed out. The vents of the volcano can be gaping - empty or filled with molten lava. If the lava solidifies in the vent, then a solid plug is formed, which can only be pierced by a strong volcanic eruption, and a powerful explosion occurs.
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Active volcanoes
Volcanoes occasionally spew molten rock, ash, gases, and rocks. This is because deep below them there is a magma chamber, similar to a huge furnace, in which the rock melts, turning into fiery liquid lava.
Those volcanoes are also considered active if any evidence of their eruptions has survived in the history of mankind.
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Extinct volcanoes
Extinct volcanoes were active only in prehistoric times. The hearth under them has long gone extinct, and they themselves are so badly destroyed that only the studies of geologists reveal traces of ancient volcanic activity.
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Dormant volcanoes
Dormant volcanoes in historical time did not erupt, but at any moment their catastrophic eruption can begin, because the magma chamber under them has not died out. Dormant volcanoes show signs of life: they can smoke - smoke comes from their crater, gases and steam are released from cracks in the mountain, hot springs flow. The longer a dormant volcano is at rest, the more dangerous it is: the power of its explosive awakening can be catastrophic.
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Types of eruptions
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Explosive eruptions
A volcanic explosion occurs when volcanic gases are released from thick magma. During such eruptions, the tops of the mountains are destroyed and millions of tons of ash are thrown into the sky to a great height. Ashes, gases and steam rise into the sky for tens of kilometers in the form of curly clouds.
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Effusive eruptions
During an effusive volcanic eruption, liquid lava flows freely with the formation of lava flows and sheets
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Volcanic gases
Volcanic phenomena are associated with the action of gases. If the magma is very liquid, gases are released unhindered and do not threaten explosions. Gases can foaming even viscous magma, forming porous pumice, pulverizing magma into small particles - volcanic ash and sand - and, combining with them, form a deadly scorching cloud. And finally, gases can scatter debris from the mouth of the volcano for hundreds of meters. rocks.
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Bezymyanny volcano
The Bezymyanny volcano is located near Klyuchevaya Sopka. He was considered extinct, and the power of his awakening was enormous. On March 30, 1956, a terrible explosion blew away the entire upper part of the volcano. Ash clouds shot up almost 40 km, from
a powerful jet of hot gas, volcanic sand and ash escaped from the vents, which burned out all the vegetation for 25 km around the volcano. A lava dome began to grow from the craters. Now the base of this dome is 750 m, and the height is 320 m. Fortunately, despite all the fury of the eruption, no one died - not a single living soul was in the hours of the eruption within a radius of 45 km from the volcano.
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Tolbachinskaya Sopka
Volcano Tolbachik - very active volcano... At its summit, 3085 m high, there was a huge caldera with a crater 300 m in diameter and 150 m deep. From time to time, a small lake of hot lava appeared in the crater. In 1975-1976, a fissure eruption of the Icelandic type occurred. It lasted 520 days continuously.
In a very short time, many cracks more than a kilometer long were formed. All this was accompanied by the spilling and gushing of lava. During the eruption of Tolbachik, two cubic kilometers of volcanic products were thrown to the surface from the depths of the Earth. This is the largest known volcanic eruption in Kamchatka and the Kuril Islands.
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Mayon volcano, the most active on the island of Luzon. On October 23, 1776, it caused the deaths of 2,000 people when a huge amount of lava was thrown out of its crater.
Mayon volcano
The longest eruption of Mayon was observed in 1897. It lasted from 23 to 30 June and claimed 400 lives.
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Stromboli volcano
In the south of Italy, near the island of Vulcano. Situated volcano island Stromboli - It has a very restless character and has been active for several millennia with almost no interruption. From time to time, explosions occur in its crater, and hot slag and volcanic bombs fly upwards for tens, and sometimes hundreds of meters, but lava usually does not flow from it.
One of the most strong eruptions Stromboli was noted in 1930, and at the beginning of the fifteenth century there were already seven of them.
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1.1. The Hawaiian type of eruption is characterized by a low (10, rarely 15) explosive index and represents a calm outpouring of liquid basaltic lava, accompanied by weak explosions. Basalt lava flows with characteristic wavy, rope (pakhoye-lavas) and small-block (aa-lavas) surfaces, interbedded with a small amount of pyroclastic material, occur at an angle of 2-3 °, rarely 5 °. Pyroclastic material is usually ejected in a liquid state, forming shaped bombs (spherical, ellipsoidal, pear-shaped, disk, tape, cylindrical, slag). The formation of slags is characteristic, which in the near-crater part are sintered into agglutinates. The thinnest material produced by explosions is tear-shaped ("Pele's tears") and hair-like ("Pele's hair") debris. It is possible to throw out crystals (crystal pillars) in the form of prepared plagioclase individuals up to 3-5 cm in diameter. The lava temperature is 1200–1100 ° С, the viscosity coefficient is 103–104 poise. 1.1. The Hawaiian type of eruption is characterized by a low (10, rarely 15) explosive index and represents a calm outpouring of liquid basaltic lava, accompanied by weak explosions. Basalt lava flows with characteristic wavy, rope (pakhoye-lavas) and small-block (aa-lavas) surfaces, interbedded with a small amount of pyroclastic material, occur at an angle of 2-3 °, rarely 5 °. Pyroclastic material is usually ejected in a liquid state, forming shaped bombs (spherical, ellipsoidal, pear-shaped, disk, tape, cylindrical, slag). The formation of slags is characteristic, which in the near-crater part are sintered into agglutinates. The thinnest material produced by explosions is tear-shaped ("Pele's tears") and hair-like ("Pele's hair") debris. It is possible to throw out crystals (crystal pillars) in the form of prepared plagioclase individuals up to 3-5 cm in diameter. The lava temperature is 1200–1100 ° С, the viscosity coefficient is 103–104 poise. This type is typical for shield volcanoes. Hawaiian Islands... Described for the volcanoes Nyiragongo (Africa), Plosky Tolbachik (Kamchatka), and the Southern Outburst BTTI (Kamchatka).
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1.3. The volcanic type of eruption is widespread and is usually combined with the Strombolian type. The composition of volcanic products is andesite and dacitic, less often basaltic andesite and rhyolite. In this type of eruption, heated, but not plastic, explosive material of various sizes is thrown out, and lava flows are rare. Lava flows are usually short with a blocky surface. The boulders are much larger than in the basaltic and basaltic andesite flows of the Strombolian eruptions. Characteristic are peculiar volcanic bombs - of the "bread crust" type, with a smooth, highly fractured surface. Explosive index 60-80 and more. The shape of the fragments is angular, their dimension ranges from silty (0.01 mm) to lumps with a diameter of 1 m and more, but ash (less than 2.0 mm) particles predominate, which are most often represented by angular (acute-angled) fragments of volcanic glass. Slag, as a rule, is absent. The admixture of foreign and resurgent material is more than 10%. 1.3. The volcanic type of eruption is widespread and is usually combined with the Strombolian type. The composition of volcanic products is andesite and dacitic, less often basaltic andesite and rhyolite. In this type of eruption, heated, but not plastic, explosive material of various sizes is thrown out, and lava flows are rare. Lava flows are usually short with a blocky surface. The boulders are much larger than in the basaltic and basaltic andesite flows of the Strombolian eruptions. Characteristic are peculiar volcanic bombs - of the "bread crust" type, with a smooth, highly fractured surface. Explosive index 60-80 and more. The shape of the fragments is angular, their dimension ranges from silty (0.01 mm) to lumps with a diameter of 1 m and more, but ash (less than 2.0 mm) particles predominate, which are most often represented by angular (acute-angled) fragments of volcanic glass. Slag, as a rule, is absent. The admixture of foreign and resurgent material is more than 10%. Ash material during volcano-strombolian explosions rises to a height of up to a few kilometers and, depending on the strength and direction of the wind, covers significant areas near the volcano. The finest material (10-15%), mainly vitroclastic, belongs to the outside of the volcanic edifice and is part of the soil-pyroclastic covers and volcano-terrigenous deposits. The ash of volcanic eruptions is not characterized by a porous, drop-like, melted form of fragments. So for the ash fragments of the Karymsky volcano of the eruptions of 1966, 1979. a shape close to isometric with angular protrusions of crystals was noted, but sharply angular shapes were not observed. According to EF Maleev (1982), the mineral composition of the ash changes as the particle size increases. In large fractions, the amount of crystals is 10-15%, and in small fractions - 40-45%, which is probably due to the separation of volcanic glass and its removal to separate areas. In the ashes, about 10% of resurgent and retroclastic debris, which, after weak explosions, again fell into the crater and, undergoing repeated heating, acquired a red color. The lava temperature is 1050–950 ° С, the viscosity coefficient is 105–106 poise. The prototype is described on the island of Vulcano in the Aeolian Islands group. The volcanic type of eruption is typical for the Avachinsky and Karymsky volcanoes (Kamchatka), widely manifested in combination with the Strombolian type at the Northern Outburst of the BTTI (Kamchatka).
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Slide Description:1.7. The phreatic (Bandaysan, ultravolcanic) type of eruption produces only explosive material in a cold and rarely hot state. Characteristically a large number of debris of rocks of the basement of the volcano (75-100%) in the absence of juvenile material. Phreatic eruptions can partially destroy the volcanic edifice, which leads to the accumulation of huge masses of coarse-clastic material of near-crater facies in the lower parts of the relief. Usually these are complex mixtures of lava and tuff fragments with differently oriented bedding. Explosiveness index 100. Rock fragments are emitted by steam due to contact of superheated (thermal) waters with groundwater or when lava sinks in a volcano channel below the groundwater level. 1.7. The phreatic (Bandaysan, ultravolcanic) type of eruption produces only explosive material in a cold and rarely hot state. A large amount of rock fragments of the basement of the volcano (75-100%) in the absence of juvenile material is characteristic. Phreatic eruptions can partially destroy the volcanic edifice, which leads to the accumulation of huge masses of coarse-clastic material of near-crater facies in the lower parts of the relief. Usually these are complex mixtures of lava and tuff fragments with differently oriented bedding. Explosiveness index 100. Rock fragments are emitted by steam due to contact of superheated (thermal) waters with groundwater or when lava sinks in a volcano channel below the groundwater level. The peculiarity of phreatic eruptions is a rapid (within several tens of seconds) increase in power, which usually does not decrease until the end of the eruption. The famous French volcanologist Garun Taziev observed in 1976 a similar phenomenon from start to finish (more than 30 minutes) on the Soufriere volcano (Guadeloupe island), thirteen eruptions of which were phreatic. The most famous example of this type is the eruption of the Bandai-San volcano (Japan, 1888). Phreatic explosions are also possible when lava flows enter the glaciers covering the slopes of stratovolcanoes. So in July 1993, during the eruption of Klyuchevskoy volcano, the introduction of a lava flow into the Erman glacier was accompanied by a series of powerful phreatic explosions, which reached an altitude of 2-3 km (Fedotov et al., 1995). The above classification is clear, but is applicable mainly to simple eruptions. Complex eruptions can be characterized by several types of activity simultaneously. At the same time, they are so intertwined with each other that it can be difficult to break eruptions into segments with a certain type of activity. Thus, the unique Great Fissure Tolbachik eruption in Kamchatka (1975-1976) was characterized by the manifestation of elements of almost all types of activity: Vulcan, Strombolian, Peleian, Plinian and Hawaiian.
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Technological map Task 1
I want to know
What is a volcano ?
- Volcano- (from Latin vulcanus - fire, flame), a conical mountain, from the throat of which hot gases, steam, ash, rock fragments, as well as powerful streams of hot lava are emitted, which spread over the surface of the earth.
- A volcano is a geological formation on the surface of the earth's crust or the crust of another planet, where magma comes to the surface, forming lava, volcanic gases, and rocks.
- Volcanoes are conical mountains composed of the products of their eruption.
Technological map Task 2.
The volcano is …………………………………………………………………………………… ...
…………………………………………………………………………………………………… ...
………………………………………………………………………………………………… .....
Volcano structure
- A chamber of magma is a place under the earth's crust,
where magma is collected.
- The mouth of a volcano is a channel through which magma rises.
- A volcano crater is a bowl-shaped depression at the top of a mountain.
- Lava is an outpouring magma.
Technological Map Task 3 Complete the scheme "The structure of the volcano"
Eruption- this is the exit to the surface of the planet of molten matter of the earth's crust and mantle of the Earth, called magma .
Historical disaster of volcanic origin
K. Bryullov "The Last Day of Pompeii"
Causes of volcanic eruptions
Earthquake;
Pressure drop in the magma chamber. And with a sudden decrease in pressure, magma melts, gases expand and rush out.
Signs of a volcanic eruption
Almost always, a volcanic eruption can be predicted. The most characteristic signs of the "awakening" of the volcano are:
- - increasing the release of gases and
mineral waters on its
- - temperature increase;
- - underground hum.
Types of volcanic eruptions
If gases are released from magma relatively calmly, then it pours out to the surface, forming lava flows. This eruption was named effusive.
If gases are released quickly, the magmatic melt boils up, as it were, and it bursts with expanding gas bubbles.
A powerful
explosive eruption,
which received
title explosive.
If the magma is very viscous and its temperature is low, then it is slowly squeezed out to the surface. Such an eruption is called extrusive.
Types of volcanoes
Most common central volcanoes Is a hill, mountain or hill with a depression at the top – crater , from which magma emerges to the surface. When a volcano erupts, discarded
debris from it,
ash, pouring lava
remain on its slopes.
The height of the mountain increases
Xia, and with it the crater
moves higher and
Another type of volcano - linear, or fractured . Their occurrence is associated with the rise of liquid basaltic magma through a crack in the earth's crust. Liquid lava spreads over vast areas, forming lava sheets. Such a volcano looks like a crack on the surface of the Earth.
Active volcanoes
Krakatoa
Fujiyama
Klyuchevskaya Sopka
Extinct volcanoes
Kilimanjaro
TEST
1.Geological formation that occurs above channels and cracks in the earth's crust, along which ash, lava, hot gases, water vapor, and rock fragments are erupted onto the earth's surface
a) earthquake
b) seaquake
c) volcano
2. The word "volcano" comes from the name of the ancient Roman god:
a) the underworld
3. Find two causes of a volcanic eruption
a) flood
b) earthquake
c) pressure drop in the magma chamber
d) tsunami
4. Find three signs of a volcanic eruption
a) increased output of gases and mineral waters;
b) temperature rise;
c) underground hum.
d) lowering the temperature
5. Choose the wrong classification of volcanoes a) in shape b) in the amount of erupted lava c) in activity
d) by location
Answers to the test
3 - b, c
4 - a, b, c
Homework
Chapter 2, clause 5, tasks from the technological map Task of a creative nature:
(optional and optional)
make a model of the volcano;
make a selection of facts about the volcanic eruption
