Types of volcanic eruptions. Presentation "Volcanoes" Actions in case of a volcanic eruption

Type of eruption
Expl
ozivny
th
turkey
c(E,
%)
Characteristic
Lav.
Temperature,
°C.
Coeff.
viscosity, poise
Compound
volcanics
Basalts
Liquid.
T – 12001100°.
– 103-104
Strombolians
cue
3050,
sometimes
Yes
100
Basalts,
andesitebasal
You
Liquid,
semi-plastic
s.
T – 11501050°.
– 104-105
Vulcan
60-80
And
more
Andesites,
dacites (less commonly
andesitebasal
you and
rhyolites)
Viscous.
Lava
flows are rare.
T – 1050-950.
– 105-106
Plinian
(Vesuvian
90 and
more
Rhyolites,
dacites.
Rarely
andesites
basalts
Lava
outpourings
very rare.
T 1050
Peleian
100
Andesites,
dacites,
rhyolites
100
Rhyolites,
dacites,
andesites
Hawaiian
10,
rarely
about 15
Katmai
And
No lava
characteristic
No lava
characteristic
Types of volcaniclastic rocks
Characteristics of pyroclastic material
juvenile
resurgent,
alien
(quantity)
Curly
bombs,
slags
teardrop-shaped (“Pele’s tears”),
hair-like (“Pele’s hair”)
vitroclasts,
Sometimes
idiomorphic
crystalloclasts
(crystallapilli)
Not
characteristic
Small block
lava clastites
Agglutinates. Various tuffs
dimensions, different structures. Comeclastic tuffs and
crystalloclastic
Figured bombs, lapilli, slags
angular shape
Minor
Blocky
lava clastites
Tuffs of various sizes.
Prevail
psephytic.
Xenotuphas (rare)
Form
wreckage
angular,
bread crust bombs
More than 10%
Blocky
lava clastites
Tuffs of various sizes.
Prevail
ash
vitroclastic, pumice-clastic. Xenotuphas
Pumiceous
lithoclasts,
angular
crystalloclasts,
horn-shaped vitroclasts
A lot of
–
Tuffs
ash
crystallovitroclastic,
pumice-clastic. Xenotuphas
Angular,
acute-angled
fragments of various sizes with
predominance
ash.
heated up to 400-600 C
A lot of,
Very
a lot of
–
Ash tuffs. Xenotuphas,
eruptive breccias
Hot (600-800 C),
gas-saturated material
(pyroclastic flows),
porous lithoclasts,
euhedral crystalloclasts,
pointed vitroclasts
10-20%
Tufolavs
(clast lavas)
lavaclastic
pyroclastic
Ignimbrites.
Xenoignimbrites.
agglomerate
Tuffs

1.1. The Hawaiian type of eruption is characterized by low (10.
rarely 15) explosive index and represents a calm
outpouring of liquid basaltic lava accompanied by weak
explosions. Basaltic lava flows with characteristic
wavy, rope (pahoehoe-lava) and small-block
(aa-lavas) surface, interbedded with a small
amount of pyroclastic material, lie at an angle
2-3°, rarely 5°. Pyroclastic material is usually
ejected in a liquid state, forming shaped bombs
(ball, ellipsoidal, pear-shaped, disk,
tape, cylindrical, slag). Characteristic
formation of slags, which are sintered in the near-crater part
into agglutinates. The thinnest material formed when
explosions, is drop-shaped (“Pele’s tears”) and
hair-like (“Pele’s hair”) fragments. Maybe
throwing out crystals (crystallopillas) in the form
prepared plagioclase individuals up to 3-5 cm in size
in diameter. Lava temperature 1200–1100° C, coefficient
viscosity 103–104 poise.
This type is typical for Hawaiian shield volcanoes
islands. Described for Nyiragongo volcanoes (Africa), Flat
Tolbachik (Kamchatka), Southern breakthrough of the GTTI (Kamchatka).

1.2. The Strombolian type of eruption is most common when
volcanic eruptions producing basic products. For this
type characterized by emissions of incandescent luminous material and
outpouring of more viscous lava flows than in Hawaiian
eruption Explosive index 30-50, sometimes up to 100. Composition
volcanic products basalt and basaltic andesite. Viscosity
lava can range from liquid to semi-plastic, which
causes a wide variety of explosive materials:
shaped bombs (spherical, ellipsoidal,
cake-shaped), lapilli, slags of angular shape. Size
pyroclastics varies widely: from large blocks to
ash particles, but more often coarse fragments (2-10 mm) predominate
material. Discarded together with juvenile material
resurgent and alien, represented by the fragments of the foundation
volcano Lava temperature 1150–1050 °C, viscosity coefficient 104–
105 poise.
The prototype of the eruption is described at the Stromboli volcano (Mediterranean
sea). The Strombolian type was noted during the Klyuchevskoye eruption
volcano (Kamchatka) Northern breakthrough, GTTI (Kamchatka) (Fig. 2),
Alaid and Tyatya (Kuril Islands).
Fig.2. Strombolian type of eruption at the Northern Breakthrough of the GTFE
(first cinder cone June 1975)

Strombolian type of eruption at the Northern breakthrough of the GTFE (first cinder cone June 1975)

1.3. The volcanic type of eruption is widespread and usually combined
with Strombolian. The composition of volcanic products is andesitic and
dacite, less commonly basaltic andesite and rhyolite. With this type of eruption
heated, but not plastic, explosive material of various types is ejected
lava flows are large and rare. Lava flows are usually short with
blocky surface. The blocks are much larger than in basalt and
basaltic andesite flows of Strombolian eruptions. Characteristic
peculiar volcanic bombs - like “bread crust”, having a smooth
heavily cracked surface. Explosive index 60-80 or more. Form
fragments are angular, their size ranges from dusty (0.01 mm) to blocks with a diameter
1 m or more, but ash particles (less than 2.0 mm) predominate, which are more often
are represented in total by angular (acute-angled) fragments of volcanic
glass Slags are usually absent. Admixture of alien and resurgent
material more than 10%.
During volcano-Strombolian explosions, ash material rises to
height up to a few kilometers and depending on the strength and direction of the wind
covers significant areas near the volcano. Finest material
(10-15%), mainly vitroclastic, belongs outside
volcanic structure and is part of the soil-pyroclastic covers
and volcano-terrigenous deposits. For the ashes of Vulcan eruptions, no
characteristically porous, drop-shaped, melted form of the fragments. So for
fragments of ash from the Karymsky volcano eruptions of 1966, 1979. noted
the shape is close to isometric with angular protrusions of crystals, but sharply
no angular shapes were observed. According to E.F. Maleev (1982), mineral
the composition of ash changes as the particle size increases. In large
in fractions the number of crystals is 10-15%, and in small fractions - 40-45%, which
probably explained by the separation of volcanic glass and its removal to
separate areas. The ashes contain about 10% resurgent and retroclastic
debris, which after weak explosions again fell into the crater and,
being subjected to repeated heating, they acquired a red color.
The lava temperature is 1050–950 °C, the viscosity coefficient is 105–106 poise.
The prototype was described on the island of Vulcano in the Aeolian Islands group. Vulcan
the type of eruption is typical for the Avachinsky and Karymsky volcanoes (Kamchatka),
widely manifested in combination with Strombolian at the Northern Breakthrough

1.4. The Plinian type of eruption is characterized by a large
amount of explosive material and almost complete absence
Lav. Explosive index 90 or more. This type is characterized by
strong gas saturation of the magma, which manifests itself in significant
crushing volcanic products and releasing them to a large
height. Explosions are usually vertical, and therefore the occurrence patterns
pyroclastics and the degree of their differentiation depend on the direction and
explosion force. Juvenile material is often pumice,
crystalloclasts are usually fragmented, vitroclasts have
horn-shaped. Together with juvenile materials, it is taken out to
25% of alien material represented by rock fragments
base of the volcano.
The Plinian type of eruption is more typical for volcanoes,
erupting products of acidic composition (but there may be andesitic and
basalt) and therefore was widely used in
previous eras when acidic volcanism manifested itself powerfully. IN
within the Kuril-Kamchatka arc, the Plinian type was observed when
eruption of the Ksudach volcano in 1907
Named after the ancient Roman scientist Pliny the Younger,
who described the eruption of Vesuvius in 79 AD. Fresh temperature
pyroclastic material at Vesuvius supposedly had
1050°C (Vlodavec, 1984). Sometimes described as Vesuvian type
eruptions (Rudich, 1978; Vlodavec, 1984).

1.5. The Peleian type of eruption is characterized by directional
explosions that result in the formation of scorching clouds consisting of
a mobile suspension of gases and finely crushed volcanic material.
The temperature of a scorching cloud is 400-600° C. A scorching cloud thrown out of
Mont Pelee volcano (1902) had a temperature of about 800 ° C, and according to
According to Lacroix's observations, the temperature of the sintering cloud at the exit of the bocca
was about 1100° C and 210–230° C at a distance of 6 km from the crater (Vlodavets,
1984). Explosiveness index 100. Pyroclastic material
predominantly juvenile, with an admixture of alien and resurgent,
formed as a result of the destruction of a volcanic structure. Compound
pyroclastic material ranging from andesitic to rhyolitic. Form
fragments are angular and acute-angled, ranging in size from large blocks to dust with
the predominance of the latter. As a result of Peleian-type eruptions
rapid (within a few minutes) deposition occurs
pyroclastic material over an area from several tens to
thousands of kilometers, accompanied by air separation: near
lithoclasts and crystalloclasts accumulate in a volcanic structure, and
in the distance – vitroclasts. Thickness of pyroclastic deposits
material is measured in centimeters and less often in the first tens
centimeters.
Directional explosions are formed due to periodic breakthroughs
gases accumulating in the volcano channel under a plug of viscous lava,
frozen in the crater of a volcano. It is typical to squeeze the cork over the dome in
in the form of a monolithic obelisk. On the Mont Pele volcano there is such an obelisk
height 375 m and diameter 100 m. The formation of obelisks is typical for
volcanoes with very viscous, practically non-flowing lava with a coefficient
viscosity 108–1010 poise. Volcanogenic coarse clastic rocks here
are specific and are formed mainly due to the destruction of the dome or in
extrusion movement process. V.I. Vlodavets (1973) identifies for such
volcanoes have a dome type of eruption.

1.6. The Katmai type of eruption is characterized by the formation of hot
(600-800° C) and gas-saturated pyroclastic flows of juvenile
material, up to 10-30 km long, filling the lower parts of the relief.
The main feature of this type of eruption is the location
the epicenter of the explosion at a considerable depth. This leads to the fact that gases are not in
able to crush and throw out a powerful column of juvenile material into
atmosphere and lifts it only to the edge of the crater, where it, being strongly
gas-saturated, pours out like a liquid stream (Maleev, 1982). At the same
time Rittmann A., 1963 explains the mechanism of formation
pyroclastic ignimbrite flows due to their close location to
the day surface of the explosive level of viscous magmas (see Chapter 4).
Pyroclastic flows are divided into ignimbrite, pumice, ash,
agglomerate. Partial destruction possible during the Katmai eruption
volcanic structure (Bezymyanny volcano, 1956, Shiveluch, 1964) (Fig.
3).
Pyroclastic material is represented by porous blocks with rounded,
due to chipping, corners (reminiscent of boulders), often good
prepared crystals and angular sharp-angled particles
volcanic glass. As pyroclastic flows move
chipping of the corners and edges of the crystals occurs. Alien material
is present in an amount of 10-20% and is represented by fragments of rocks from previous
eruptions.
A classic example of this type is the eruption of Mount Katmai in Alaska.
in 1912. In Kamchatka, similar eruptions were observed for volcanoes
Avachinsky, Nameless, Shiveluch. Although the mechanism of the Nameless eruption
volcano (1956) (Fig. 4) was the same as on Katmai volcano, but
their volcanic products turned out to be different. This is due to the fact that
Katmai Volcano's initial temperature was high, resulting in sintering
ash and ignimbrite formation. This did not happen on Bezymyanny, because...
the temperature of the gas-ash cloud was lower, which makes it possible to isolate
for this there is its own nameless type of eruption (Maleev, 1977).

The destroyed volcanic structure of Bezymyanny Volcano during the Katmai eruption of 1956.

Destroyed volcanic
construction of the Bezymyanny volcano
during the Katmai eruption
1956

Katmai type of eruption of Bezymyanny volcano (1956).

1.7. Phreatic (Bandaisan, ultravolcanic) type of eruption
produces only explosive material in a cold and rarely hot state.
Characteristic a large number of fragments of volcano basement rocks (75-100%) in the absence of juvenile material. Phreatic eruptions can
partially destroy the volcanic structure, which leads to the accumulation of
in lower parts of the relief of huge masses of coarse clastic material
near-crater facies. These are usually complex mixtures of lava and tuff fragments with
differently oriented layering. Explosiveness index 100. Debris
rocks are emitted as steam due to the contact of superheated
(thermal) waters with groundwater or when lava descends in the volcano channel below
groundwater level.
The peculiarity of phreatic eruptions is the rapid (within
several tens of seconds) power gain, which usually does not decrease to
end of the eruption. The famous French volcanologist Harun Taziev observed in
1976 similar phenomenon from start to finish (more than 30 minutes) on a volcano
Soufriere (Guadeloupe Island), which has had thirteen eruptions
phreatic. The most famous example of this type is
eruption of the Bandai-san volcano (Japan, 1888).
Phreatic explosions are also possible when lava flows are introduced into
glaciers covering the slopes of stratovolcanoes. So in July 1993, during
eruption of Klyuchevsky volcano, introduction of a lava flow into the Erman glacier
accompanied by a series of powerful phreatic explosions that reached
heights of 2-3 km (Fedotov et al., 1995).
The above classification is illustrative, but is applicable mainly
thus leading to simple eruptions. Complex eruptions can
characterized by several types of activity simultaneously. At the same time they
are so intertwined with each other that the eruptions can be divided into segments with
certain types of activities can be difficult. So unique Big
fissure Tolbachik eruption in Kamchatka (1975-1976)
characterized by the manifestation of elements of almost all types of activity:
Vulcanian, Strombolian, Peleian, Plinian and Hawaiian.

• 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 among people, and the tragic consequences of eruptions forced them to study this element.

• Volcano formation

• When a magma chamber forms in the depths of the Earth, molten liquid magma presses from below on the tectonic plate with such force that it begins to crack. Magma rushes upward along cracks and faults, melting the rock and widening the cracks. This creates an exit channel. It passes through the center of the volcano, through which molten magma pours out from the crater of the volcano to the outside in the form of fiery liquid lava. The products of the eruption - pumice, lava, tuffs - 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 crater of the volcano - the opening of the outlet channel through which ash, hot gases and water vapor, lava and rock fragments erupt. Volcano vents can be gaping, empty, or filled with molten lava. If lava hardens in a crater, a solid plug is formed, which can only be broken through by a strong volcanic eruption, resulting in a powerful explosion.

• Types of volcanoes

• Active volcanoes

• Volcanoes spew out molten rock, ash, gases, and rocks from time to time. This happens because deep below them there is a magma chamber, similar to a huge furnace in which rock melts, turning into fiery liquid lava.

• Those volcanoes are also considered active if there is any evidence of eruptions in human history.

• Extinct volcanoes

• Extinct volcanoes were active only before historical time. The hearth beneath them has long gone out, and they themselves are so badly destroyed that only geological research reveals traces of ancient volcanic activity.

• Dormant volcanoes

• Dormant volcanoes have not erupted in historical times, but a catastrophic eruption may begin at any moment, because the magma chamber beneath them has not gone 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 gush out. The longer a dormant volcano remains dormant, the more dangerous it is: the power of its explosive awakening can be catastrophic.

• Types of eruptions

• Explosive eruptions

• A volcano explosion occurs when volcanic gases are released from thick magma. During such eruptions, mountain tops are destroyed and millions of tons of ash are thrown into the sky to great heights.
• Ash, gases and steam rise tens of kilometers into the sky in the form of curly clouds.

• Effusive eruptions

• During an effusive volcanic eruption, liquid lava flows freely to form lava flows and sheets

• Extrusive eruptions

• A huge amount of burning gases and hot lava dust is emitted from the crater of the volcano. Spreading around the volcano with tremendous speed, this scorching cloud burns everything over a very large area with lightning speed.

• Eruption products

• Everything that comes out of the bowels of the Earth during volcanic eruptions is called eruption products.

• They are liquid, solid and gaseous.

• The liquid products of an eruption include lava.

• Lava- this is magma that spills onto the surface of the earth

• Types of lava flow.

• It has a smooth or slightly wrinkled surface and is composed of liquid lava. When hardened, such lava forms a flat, smooth surface, sometimes with long wriggling wrinkles in the form of snakes and thick ropes. It is often called “rope lava.”

• It has an uneven surface with cracks. This lava is very thick and viscous, so the flow moves slowly. When the lava begins to cool, it cracks into pieces, but they continue to move like clockwork on the hot lava that has not yet had time to cool. The upper hardened layer of lava resembles piles of slag, which is formed from the combustion of coal.

• Lava flow "ah-ah"

• Pa-hoe-hoe lava flow

• Pyroclasts

• Rock fragments that are thrown out by gases during volcanic eruptions are called pyroclasts

• Volcanic gases

• Volcanic phenomena are associated with the action of gases. If the magma is very liquid, gases are released freely and do not threaten explosions. Gases can foam even viscous magma, forming porous pumice, disperse magma into small particles - volcanic ash and sand - and, combining with them, form a deadly scorching cloud.
• And finally, gases can scatter rock fragments hundreds of meters from the crater of a volcano.

• Volcanoes in Kamchatka

• Bezymyanny Volcano

• Bezymyanny volcano is located near Klyuchevaya Sopka. It was considered extinct, and the power of its awakening was gigantic. On March 30, 1956, a terrible explosion destroyed the entire upper part of the volcano. Clouds of ash shot up almost 40 km, from

• From the vent, a powerful stream of hot gas, volcanic sand and ash burst out, 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 within a radius of 45 km from the volcano during the hours of the eruption.

• Tolbachinskaya Sopka

• Volcano Tolbachik - very active volcano. At its peak, 3085 m high, there was a huge caldera with a crater 300 m in diameter and 150 meters deep. From time to time, a small lake of hot lava appeared in the crater. In 1975-1976, an Icelandic-type fissure eruption occurred. It lasted continuously for 520 days.

• In a very short time, many cracks more than a kilometer long 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.

• Volcano in the Philippines

• Mayon Volcano, the most active on the island of Luzon. On October 23, 1776, it caused the death of 2,000 people when huge amounts of lava were ejected from its crater.

• Volcano Mayon

• Mayon's longest eruption occurred in 1897. It lasted from June 23 to June 30 and claimed 400 lives.

• Volcanoes of the Mediterranean

• Volcano Stromboli

• In the south of Italy, near the island of Vulcano. Located volcano island Stromboli. He has a very restless character, and he has been acting for several millennia almost without interruption. From time to time, explosions occur in its crater, and hot slag and volcanic bombs fly up tens and sometimes hundreds of meters, but lava usually does not flow from it.

• One of the most powerful eruptions of Stromboli was noted in 1930, and since the fifteenth century there have already been seven of them.

• Volcanoes of the Atlantic

• In the south of Iceland there is a volcanic mountain range Lucky, in which there are more than a hundred cones.
• The ridge reaches a height of 818 m and a length of 25 km.

• June 8, 1783.
• Not far from the town of Vatnajökull in southeast Iceland, powerful eruption Laki volcano. It lasted 8 months, the length of the flow of lava that came to light was almost 70 kilometers, and the volume of this mass, moving at a speed of over 45 km/h, was equal to 12,000 cubic meters and occupied an area of ​​579 square kilometers.

• Volcano Laki

• Volcanoes of Africa

• Mount Kilimanjaro

• Kilimanjaro is volcanic mountain range in east Africa
• The massif consists of three peaks - Kibo, Mawenzi and Shira. The Mawenzi and Shira volcanoes have long been extinct, and Kibo continues to smoke volcanic gases through openings on the slopes.

• Volcanoes of the Pacific Ocean

• Mount St. Helens

• IN North America, in the Cordillera, Mount St. Helens is perhaps the lowest among other peaks - its height is only 2950 meters.
• On March 20, 1980, four powerful tremors shook the area, and on March 27, 47 tremors with a force of up to three points. At noon of the same day, a deafening explosion was heard near the very top.
• This monstrous explosion claimed the lives of 62 people.

Working with a geographic map

• Show the following volcanoes on the map:
• Nameless, Tolbachik Sopka, Mayon, Stromboli, Lucky, Kilimanjaro, St. Helens
• Show on the map the volcanoes that erupted in the last year

• Questions about the material covered

• 1.What types of volcanoes are there?

• 3.What types of eruptions do you know?

• 5.What are the products of the eruption?

• 2.How are volcanoes formed?

• 4.Give brief description each type of eruption.

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 clouds of ash, they argued, were smoke from his forge, and the splashes of lava were sparks from his anvil. They called this island "Vulcano" - from the Latin word "Volcano".

Vulcan (Greek - Hephaestus). In Greek and Roman mythology, he is the god of fire and a blacksmith who forged weapons for many gods and heroes. He was the teacher of ancient man and taught him 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 opened the smoke, a cloud of flames gushed out, It developed widely, like a battle flag. The earth is shaking from the shaky columns. Idols are falling! The people, driven by fear, in crowds, old and young, under the inflamed dust, under the rain of stones, flee from the city. A.S. Pushkin VOLCANOES Are silent extinct volcanoes, ash falls to the bottom. Giants rest there after committing evil. B. Akhmadulina Volcanoes are blown up. The Ocean is defeated... Arthur Rimbaud

The structure of a volcano A typical volcano is a hill with a pipe running through its thickness, called a volcano vent, and a magma chamber (an area where magma accumulates) from which the vent rises. When high pressure is created in a magma chamber, a mixture of magma and hard rocks - lava - rises up the vent and is thrown into the air. This phenomenon is called a volcanic eruption.

Ash is the finest volcanic product, having the appearance of a powdery mass. During explosive eruptions, it is thrown onto the surface of the earth with a volume often of many cubic kilometers and rises in the form of a cloud cloud to a height of several tens of kilometers. Thick deposits of ash, covering the slopes and foothills of volcanoes in layers of many meters, destroy large forests and even cities. Ash is the finest volcanic product, having the appearance of a powdery mass. During explosive eruptions, it is thrown onto the surface of the earth with a volume often of many cubic kilometers and rises in the form of a cloud cloud to a height of several tens of kilometers. Thick deposits of ash, covering the slopes and foothills of volcanoes in layers of many meters, destroy large forests and even cities.

On the left, on the right - bombs like bread crusts, in the middle - in the form of a spindle. Volcanic bombs have an unusually wide variety of shapes and sizes among fragmental material. 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 volcanoes are those that are currently erupting or erupting periodically, at certain intervals. If magma does not pour out, but the volcano “smoke” or “smoke,” then it is also considered active. Dormant Volcanoes are considered to have fallen asleep if they were active during a historical period of time and have retained their shape; weak tremors and earthquakes periodically occur in their depths. Extinct Extinct are volcanoes that were active once in the distant past; they have blurred and destroyed cones

Hawaiian type On the main island of Hawaii is the Mauna Loa volcano. Feature it consists in the fact that basaltic melts flow here relatively calmly, without explosions. The melt is weakly saturated with gases and has low viscosity, although unusually spectacular lava fountains sometimes appear. As a result of such an eruption, the volcano has very gentle slopes on which several craters are located.

Stromboli type Although the melt here is basaltic, that is, it has a basic composition, it has some viscosity. Therefore, there is an alternation of outpourings of lava flows and explosions. Explosions release bombs, lapilli, ash and basalt slag. Stromboli - a volcano of the Aeolian Islands - is notable for the fact that it is constantly active, being a unique, unusually bright beacon Mediterranean Sea

Type Vulcano The volcano of the island of Vulcano, located in the Aeolian Islands, is also very famous. It is characterized by the eruption of relatively acidic volcanic products (andesite-dacite). Due to the high viscosity of the melt, the volcano's crater becomes clogged. The accumulated vapors and gases explode this plug and, together with other finely crushed particles of various shapes and sizes, throw them out to great heights. That's what they often say: Vulcan-type explosive eruptions.

Vesuvian type Named by name famous volcano Vesuvius, located in Italy, near Naples. The ancient Roman scientist Pliny the Younger described it very colorfully, and therefore this type of eruption is often called Plinian. This type is characterized by strong explosive eruptions due to periodic blockage of the volcano's vent, as well as the subsequent outpouring of lava flows.

Pompeii disappeared under a 7-8 meter layer of ash and rubble, which continuously fell onto 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 start of the eruption, the sun appeared for the first time, illuminating three dead city. On August 24, 79, people paid with their lives for their carelessness: suddenly a lava plug shot up into the blue sky over the Bay of Naples, tightly clogging the mouth of the Vesuvius crater for many millennia.

The inhabitants of Pompeii, buried under the ash, died of suffocation. However, the caverns in the layer of hardened ash, where their bodies had previously been located, retained the shape and posture of the unfortunates for many years. When these caverns were filled with gypsum mortar, people saw sculptural images of the dead. Cast of a suffocating woman, preserved in ashes Sculptural images of the dead Cast of a dog

Pelée type The Mont Pelée (Bald Mountain) volcano, which gives its name to the next type of eruption, is located on the island of Martinique (a group of Lesser Antilles islands in the Atlantic Ocean). It is characterized by hot ash clouds and the growth of domes in the crater of the volcano. For the first time, a directed explosion was observed here, covering a large area.

An "active" volcano is a volcano that is erupting recent years Most of the Earth's active volcanoes are located in only a few countries

The large fissure Tolbachik eruption is considered one of the largest known basaltic eruptions in the Kuril-Kamchatka belt. The eruption lasted almost a year and a half (July December 1976). The height of the jet of hot gases reached a height of 2.5 km, and the ash cloud reached 12 km. As a result of the eruption, 4 cones of the New Tolbachin volcanoes were formed, and the huge forested area around them turned into a scorched desert. Over the years that have passed since then, the cones have not had time to cool completely, so standing at the top of the cone, you feel the heat coming from below. The ash desert is gradually being reclaimed 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 arose when eruption centers moved along cracks; volcanic ridges that arose when eruption centers moved along cracks; calderacaldera volcanoes; volcanoes with sommavolcanoes with somma that arose within calderas after their renewal; dome volcanoes.

Underwater volcanic activity Guyots Guyots [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 Ocean. There are also some G. in the Atlantic and Indian Oceans. The mountain peaks are located at depths from 200 to 2000 m. It is believed that the alignment of the mountain peaks is the result of abrasion. Since abrasion affects only to a depth of about m, it is assumed that most of the mountains experienced subsidence along with the ocean floor that forms 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 released by the volcano is part of many useful chemicals. Volcanic material - pumice - is included in some toothpastes. Sapphires, zircons, copper, silver, gold - all this can be mined from volcanic rocks. Some of the largest diamonds were also found in them.

Volcanoes of the Universe Nameless volcano near the north pole of Io (a satellite of Jupiter). Galileo (an artificial probe) photographed the eruption of this volcano; a column of dust rose to a height of about 430 km. An even higher column of ash and dust was also spotted - rising to a height of more than 480 km. Using the equipment installed on Galileo, it was possible to determine the composition of the volcanic ejecta. These were particles that resembled snowflakes, made up of sulfur dioxide molecules.

Volcanologists and geomorphologists study the characteristics of volcanoes and the phenomena of volcanism.

Structure: hearth, vent, crater. A source is a place in the earth's crust or mantle. A vent is a channel through which magma rises. A crater is a hole, a funnel, a bowl at the top of a volcano mountain.

Volcanoes are classified by location, shape and activity.

By activity: extinct, dormant, active. This classification is quite arbitrary. Extinct ones have not erupted for more than 1000 years: they are preserved general shape, the crater and slopes are subject to changes. Sometimes they are active. Example: Mont Pelée in Martinique, Valley of Volcanoes in Buryatia, Kalara volcanoes.

Dormant volcanoes are volcanoes in which the probability of eruption is higher than that of extinct ones. Some of them are called supervolcanoes - Toba in Sumatra, Taulo in New Zealand, the volcanoes of Kamchatka.

Active ones are the main object of interest for volcanologists; they erupt frequently. They are located in the belts of young mountains, where mountain building continues. There is no consensus among scientists on how to accurately classify these geological formations. The most active volcanism: South and Central America, Hawaii, Japan, Sunda Islands.

They are classified by location: subglacial, terrestrial, underwater. The following types are distinguished by shape: dome, cinder cone, shield-shaped, stratovolcano, complex type.

Based on the general design, formations of central and linear types are distinguished. The first have a central channel through which lava comes to the surface. The second type is fissure, the channels through which the lava rises have an elongated shape. Scientists distinguish the area type, but no such type has been recorded on Earth, at least in our time. They are believed to have existed when the planet was forming.

The eruption is considered an emergency, a disaster. It can happen in an hour, a month, a year, several years. Consequences of the eruption: formation of caldera depressions, geysers, fumaroles. Low mountains and islands may appear. Lakes form in craters.

Types of eruption: Hawaiian (basaltic lava comes to the surface, accompanied by smoky clouds, fiery avalanches), hydroexplosive (a lot of steam is released, confined to water bodies).

A mud-type volcano is a formation, as a result of whose activity mud and gases, rather than magma, come to the surface. Found in Russia and Central Asia.

The largest formations: San Pedro, Cotopaxi, Ojos del Salado in the Andes, Elbrus in the Caucasus, Fuji in Japan, Etna and Vesuvius in Italy, Klyuchevskaya Sopka in Kamchatka.

Recorded not only on Earth. If on other planets of the solar system and their satellites.

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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 among people, and the tragic consequences of eruptions forced them to study this element.

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Volcano formation
When a magma chamber forms in the depths of the Earth, molten liquid magma presses from below on the tectonic plate with such force that it begins to crack. Magma rushes upward along cracks and faults, melting the rock and widening the cracks. This creates an exit channel. It passes through the center of the volcano, through which molten magma pours out from the crater of the volcano to the outside in the form of fiery liquid lava. The products of the eruption - pumice, lava, tuffs - 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 crater of the volcano - the opening of the outlet channel through which ash, hot gases and water vapor, lava and rock fragments erupt. Volcano vents can be gaping, empty, or filled with molten lava. If lava hardens in a crater, a solid plug is formed, which can only be broken through by a strong volcanic eruption, resulting in a powerful explosion.

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Active volcanoes
Volcanoes spew out molten rock, ash, gases, and rocks from time to time. This happens because deep below them there is a magma chamber, similar to a huge furnace in which rock melts, turning into fiery liquid lava.
Those volcanoes are also considered active if there is any evidence of eruptions in human history.

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Extinct volcanoes
Inactive volcanoes were active only in prehistoric times. The hearth beneath them has long gone out, and they themselves are so badly destroyed that only geological research reveals traces of ancient volcanic activity.

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Dormant volcanoes
Dormant volcanoes have not erupted in historical times, but a catastrophic eruption may begin at any moment, because the magma chamber beneath them has not gone 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 gush out. The longer a dormant volcano remains dormant, 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 volcano explosion occurs when volcanic gases are released from thick magma. During such eruptions, mountain tops are destroyed and millions of tons of ash are thrown into the sky to great heights. Ash, gases and steam rise tens of kilometers into the sky in the form of curly clouds.

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Effusive eruptions
During an effusive volcanic eruption, liquid lava flows freely to form 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 freely and do not threaten explosions. Gases can foam even viscous magma, forming porous pumice, disperse magma into small particles - volcanic ash and sand - and, combining with them, form a deadly scorching cloud. And finally, gases can scatter rock fragments hundreds of meters from the crater of a volcano.

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Bezymyanny Volcano
Bezymyanny volcano is located near Klyuchevaya Sopka. It was considered extinct, and the power of its awakening was gigantic. On March 30, 1956, a terrible explosion destroyed the entire upper part of the volcano. Clouds of ash shot up almost 40 km, from
From the vent, a powerful stream of hot gas, volcanic sand and ash burst out, 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 within a radius of 45 km from the volcano during the hours of the eruption.

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Tolbachinskaya Sopka
Tolbachik Volcano is a very active volcano. At its peak, 3085 m high, there was a huge caldera with a crater 300 m in diameter and 150 meters deep. From time to time, a small lake of hot lava appeared in the crater. In 1975-1976, an Icelandic-type fissure eruption occurred. It lasted continuously for 520 days.
In a very short time, many cracks more than a kilometer long 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 death of 2,000 people when huge amounts of lava were ejected from its crater.
Volcano Mayon
Mayon's longest eruption occurred in 1897. It lasted from June 23 to June 30 and claimed 400 lives.

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Volcano Stromboli
In the south of Italy, near the island of Vulcano. The volcano island of Stromboli is located. It has a very restless character, and it has been active for several millennia almost without interruption. From time to time, explosions occur in its crater, and hot slag and volcanic bombs fly up tens and sometimes hundreds of meters, but lava usually does not flow from it.
One of the most powerful eruptions of Stromboli was noted in 1930, and since the fifteenth century there have already been seven of them.