Type of eruption
Explore
ozivny
th
index
with (E,
%)
Characteristic
lava.
Temperature,
°C.
Coeff.
viscosity, poise
Compound
volcanites
Basalts
Liquid.
T - 12001100°.
– 103-104
Strombolians
cue
3050,
sometimes
Yes
100
Basalts,
andesibasal
you
liquid,
semi-plastic
s.
T - 11501050°.
– 104-105
Vulcan
60-80
and
more
andesites,
dacites (rarely
andesibasal
you and
rhyolites)
Viscous.
lava
streams 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
Lava is not
characteristic
Lava is not
characteristic
Types of volcanoclastic rocks
Characterization of pyroclastic material
juvenile
resurgent,
alien
(qty)
curly
bombs,
slags.
Drop-shaped (“tears of Pele”),
hairy ("Pele's hair")
vitroclasts,
sometimes
idiomorphic
crystal clasts
(crystallapilli)
Not
typical
small blocks
lavoclastites
Agglutinates. Tufas of various
dimensions, various structures. The tuffs are comeclastic and
crystal-clastic
Figured bombs, lapilli, slags
angular shape
Minor
blocky
lavoclastites
Tufas of various sizes.
Dominated
psephytic.
Xenotufas (rare)
The form
debris
angular,
breadcrust bombs
Over 10%
blocky
lavoclastites
Tufas of various sizes.
Dominated
ash
vitroclastic, pumice clastic. xenotufas
pumiceous
lithoclasts,
angular
crystal clasts,
rammed vitroclasts
Lot
–
tuffs
ash
crystal vitroclastic,
pumice clastic. xenotufas
angular,
acute-angled
fragments of various sizes with
predominance
ash.
hot up to 400-600 C
Lot,
very
lot
–
Ash tuffs. xenotufas,
eruptive breccias
Hot (600-800 C),
gas rich material
(pyroclastic flows),
porous lithoclasts,
idiomorphic crystal clasts,
acute-angled vitroclasts
10-20%
Tufolavy
(clastolaves)
lavoclastic
pyroclastic
Ignimbrites.
Xenoignimbrites.
agglomerate
tuffs

1.1. The Hawaiian type of eruption is characterized by low (10,
rarely 15) an explosive index and represents a calm
outpouring of liquid basaltic lava, accompanied by weak
explosions. Basalt lava flows with characteristic
wavy, rope (pahoehoe-lavas) and small-block
(aa–lavas) are superficial, interbedded with little
amount of pyroclastic material, lie at an angle
2-3°, rarely 5°. Pyroclastic material is usually
ejected in a liquid state, forming shaped bombs
(spherical, ellipsoidal, pear-shaped, disc,
tape, cylindrical, slag). Characteristically
the formation of slags, which are sintered in the near-crater part
into agglutinates. The thinnest material produced by
explosions, is a drop-shaped ("Pele's tears") and
hair-like ("Pele's hair") fragments. Maybe
ejection of crystals (crystallapilli) in the form
prepared individuals of plagioclase up to 3-5 cm in size
across. Lava temperature 1200–1100° С, coefficient
viscosity 103–104 poise.
This type is typical for shield volcanoes in Hawaii.
islands. Described for Nyiragongo volcanoes (Africa), Flat
Tolbachik (Kamchatka), Southern breakthrough of the BTTI (Kamchatka).

1.2. The Strombolian type of eruption is most common in
volcanic eruptions, giving products of the main composition. For this
type are characterized by emissions of hot luminous material and
outpouring of more viscous lava flows than at the Hawaiian
eruption. Explosive index 30-50, sometimes up to 100. Composition
volcanic products are basaltic and basaltic andesite. Viscosity
lava can vary from liquid to semi-plastic, which
causes a wide variety of explosive material:
figured bombs (spherical, ellipsoidal,
flatbread), lapilli, angular slags. The size
pyroclastics varies widely: from large blocks to
ash particles, but coarse clastic (2-10 mm) predominates
material. Discarded together with juvenile material
resurgent and alien, represented by the ruins of the foundation
volcano. Lava temperature 1150–1050°C, viscosity index 104–
105 poise.
The prototype of the eruption is described on the Stromboli volcano (Mediterranean
sea). The Strombolian type was noted during the Klyuchevskoy eruption
volcano (Kamchatka) of the Northern breakthrough, BTTI (Kamchatka) (Fig. 2),
Alaid and Tyatya (Kuril Islands).
Fig.2. Strombolian-type eruption at the Northern Breach of the GTFE
(first cinder cone June 1975)

Strombolian-type eruption at the BTFE Northern Breach (first cinder cone June 1975)

1.3. The Vulcan type of eruption is widespread and usually combined
with Strombolian. The composition of volcanic products is andesitic and
dacitic, less often basaltic andesite and rhyolitic. With this type of eruptions
heated, but not plastic, explosive material of various
coarseness and rare lava flows. Lava flows are usually short
blocky surface. The blocks are much larger than in basalt and
basaltic andesite flows of Strombolian eruptions. Characteristic
peculiar volcanic bombs - such as "breadcrust", having a smooth
heavily cracked surface. Explosive index 60-80 or more. The form
fragments are angular, their dimension is from silty (0.01 mm) to blocks with a diameter
1 m or more, but ash (less than 2.0 mm) particles predominate, which are more often
are represented by angular (acute-angled) fragments of volcanic
glass. Slags are usually absent. An admixture of alien and resurgent
material more than 10%.
Ash material during volcano-strombolian explosions rises to
height up to a few kilometers and depending on the strength and direction of the wind
covers large areas near the volcano. The smallest 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,
characteristically porous, tear-like, melted form of fragments. So for
fragments of the ashes of the Karymsky volcano eruptions in 1966, 1979. noted
the shape is close to isometric with angular protrusions of crystals, but sharply
angular shapes were not observed. According to E.F. Maleev (1982) mineral
the composition of the ashes changes as the particle size increases. In large
fractions, the amount of crystals is 10-15%, and in small ones - 40-45%, which
probably due to the separation of volcanic glass and its removal to
separate sections. The ashes contain about 10% resurgent and retroclastic
debris, which, after weak explosions, again fell into the crater and,
subjected to repeated heating, they acquired a red color.
The temperature of the lava is 1050–950 °C, the viscosity coefficient is 105–106 poise.
The prototype is described on the island of Vulcano in the group of the Aeolian Islands. Vulcan
the type of eruption is typical for Avachinsky, Karymsky volcanoes (Kamchatka),
widely manifested in combination with Strombolian on the Northern Break

1.4. The Plinian type of eruption is characterized by a large
the amount of explosive material and the almost complete absence
lava. Explosive index 90 or more. This type is characterized
strong gas saturation of the magma, which manifests itself in a significant
crushing volcanic products and ejecting them to a large
height. Explosions are usually vertical, and therefore the occurrence forms
pyroclastics and the degree of its differentiation depend on the direction and
explosion forces. Juvenile material is often pumice,
crystal clasts are usually fragmented, vitroclasts have
spiky shape. Together with juvenile materials, it is taken out up to
25% alien material represented by rock fragments
the base of the volcano.
The Plinian type of eruption is more characteristic of volcanoes,
spewing products of an acidic composition (but may be andesitic and
basaltic) and therefore was widely used in
previous epochs, when acid volcanism was powerfully manifested. AT
within the Kuril-Kamchatka arc, the Plinian type was observed at
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. Temperature of fresh
pyroclastic material near Vesuvius was presumably
1050°С (Vlodavets, 1984). Sometimes described as Vesuvian type
eruptions (Rudich, 1978; Vlodavets, 1984).

1.5. The Peleian type of eruption is characterized by directed
explosions, as a result of which scorching clouds are formed, consisting of
mobile suspension of gases and finely divided volcanic material.
The temperature of the scorching cloud is 400-600 ° C. The scorching cloud ejected from
volcano Mont Pele (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 from the bocca
was about 1100° С and 210–230° С at a distance of 6 km from the crater (Vlodavets,
1984). Explosivity 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 from andesitic to rhyolitic. The form
fragments are angular and acute-angled, ranging in size from large boulders to dust with
the dominance of the latter. As a result of eruptions of the Peleic type
rapid (within a few minutes) precipitation occurs
pyroclastic material in an area from several tens to
thousands of kilometers, accompanied by air separation: near
volcanic edifice accumulate lithoclasts and crystal clasts, and
in the distance - vitroclasts. Power 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 mouth of a volcano. Characteristic is the squeezing of the cork over the dome in
in the form of a monolithic obelisk. On the Mont Pele volcano, such an obelisk has
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
the extrusion process. V.I. Vlodavets (1973) singles out for such
volcanoes dome type eruption.

1.6. The Katmai type of eruption is characterized by the formation of red-hot
(600-800° С) and gas-saturated pyroclastic flows of juvenile
material, up to 10-30 km long, filling the lowered 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 the gases are not in
able to crush and throw out a powerful column of juvenile material in
atmosphere and raises 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 (Rittmann A., 1963) explains the mechanism of formation
pyroclastic ignimbrite flows due to their proximity to
the day surface of the explosive level of viscous magmas (see Chap. 4).
Pyroclastic flows are divided into ignimbrite, pumice, ash,
agglomerate. Partial destruction possible during Katmai eruption
volcanic edifice (Bezymyanny volcano, 1956, Shiveluch, 1964) (Fig.
3).
Pyroclastic material is represented by porous blocks with rounded,
due to chipping, corners (reminiscent of boulders), often well
prepared crystals and angular, acute-angled particles
volcanic glass. As pyroclastic flows move
chipping of corners and faces of crystals occurs. foreign material
is present in an amount of 10-20% and is represented by fragments of rocks of previous
eruptions.
Classical for this type is the eruption of the Katmai volcano in Alaska.
in 1912. In Kamchatka, similar eruptions were observed for volcanoes
Avachinsky, Nameless, Shiveluch. Although the eruption mechanism of the Nameless
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
the initial temperature of the Katmai volcano was high, which led to sintering
ash and the formation of ignimbrites. This did not happen on Bezymyanny because
the temperature of the gas-ash cloud was lower, which makes it possible to isolate
for this, its own nameless type of eruption (Maleev, 1977).

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

Ruined volcanic
construction of Bezymyanny volcano
during the Katmai eruption
1956

Katmai type Bezymyanny volcano eruption (1956).

1.7. Phreatic (bandaisan, ultravolcanic) type of eruption
produces only explosive material in a cold and rarely hot state.
Characteristically a large number of fragments of volcano basement rocks (75100%) in the absence of juvenile material. Phreatic eruptions can
partially destroy the volcanic structure, which leads to accumulation in
lower parts of the relief of huge masses of coarse clastic material
near-crater facies. Usually these are complex mixtures of lava and tuff fragments with
multi-oriented layering. Explosive index 100. Debris
rocks are ejected by steam due to the contact of superheated
(thermal) waters with groundwater or when lava sinks in the volcano channel below
groundwater level.
The peculiarity of phreatic eruptions lies in the rapid (during
several tens of seconds) a set of power, which usually does not decrease to
end of the eruption. The famous French volcanologist Garun Taziev observed in
1976 similar phenomenon from start to finish (over 30 minutes) on a volcano
Soufrière (Guadeloupe), whose thirteen eruptions were
phreatic. The best known example of this type is
eruption of Bandai-San volcano (Japan, 1888).
Phreatic explosions are also possible when lava flows intrude into
glaciers covering the slopes of stratovolcanoes. So in July 1993, during
eruptions of the Klyuchevskoy volcano intrusion of a lava flow into the Erman glacier
was accompanied by a series of powerful phreatic explosions that reached
heights 2-3 km (Fedotov et al., 1995).
The above classification is illustrative, but applicable, mainly
way, to simple eruptions. Complex eruptions can
be characterized by several types of activity at the same time. At the same time they
are so intertwined with each other that to break the eruptions into segments with
certain type of activity can be difficult. So unique Great
fissure Tolbachik eruption in Kamchatka (1975-1976)
characterized by the manifestation of elements of almost all types of activity:
Vulcan, Strombolian, Peleian, Plinian and Hawaiian.

slide 1

slide 2

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 explore this element.

slide 3

Volcano formation
When a magma chamber forms in the bowels of the Earth, molten liquid magma presses down on the tectonic plate with such force that it begins to crack. Magma rushes upward along cracks and faults, melting through the rock and expanding the cracks. This is how the exit channel is formed. It passes in the center of the volcano, along it molten magma pours out from the vent of the volcano outward 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 is a depression - a crater. At the bottom of the crater, you can see the vent 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 the lava solidifies in the vent, then a solid plug is formed, which can only be broken by a strong volcanic eruption, and a powerful explosion occurs.

slide 4

active volcanoes
Volcanoes spew molten rock, ash, gases, and rocks from time to time. This is because deep below them is a magma chamber, similar to a huge furnace, in which the rock is melted, turning into fiery liquid lava.
Those volcanoes are also considered active, the eruptions of which have been preserved any evidence in the history of mankind.

slide 5

Extinct volcanoes
Extinct volcanoes were active only in prehistoric time. The hearth beneath them has long been extinguished, and they themselves are so badly destroyed that only geologists' studies reveal traces of ancient volcanic activity.

slide 6

dormant volcanoes
Sleeping volcanoes have not erupted in historical time, but at any moment their catastrophic eruption may begin, because the magma chamber under them has not died out. Sleeping volcanoes show signs of life: they can smoke, smoke comes out of their crater, gases and steam are released from cracks in the mountain, hot springs beat. The longer a dormant volcano is at rest, the more dangerous it is: the power of its explosive awakening can be catastrophic.

Slide 7

Eruption types

Slide 8

explosive eruptions
A volcano 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.

Slide 9

Effusive eruptions
During an effusive volcanic eruption, liquid lava spreads freely with the formation of lava flows and covers

Slide 10

Volcanic gases
Volcanic phenomena are associated with the action of gases. If the magma is very liquid, the gases are released unhindered and do not threaten to explode. Gases can foam even viscous magma, forming porous pumice, spray 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 mouth of a volcano.

slide 11

Volcano Nameless
Bezymyanny volcano is located near Klyuchevaya Sopka. He was considered extinct, and the power of his awakening was gigantic. On March 30, 1956, a terrible explosion demolished the entire upper part of the volcano. Clouds of ash shot up almost 40 km, from
A powerful jet of hot gas, volcanic sand and ash escaped from the vent, 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 the fury of the eruption, no one died - not a single living soul was during the hours of the eruption within a radius of 45 km from the volcano.

slide 12

Tolbachinskaya Sopka
Tolbachik Volcano is a very active volcano. At its summit, 3085 meters high, there was a huge caldera with a crater 300 meters in diameter and 150 meters deep. From time to time, a small lake of red-hot lava appeared in the crater. In 1975-1976, an Icelandic-type fissure eruption occurred. It continued continuously for 520 days.
In a very short time, many cracks more than a kilometer long were formed. All this was accompanied by flooding and gushing of lava. During the Tolbachik eruption, two cubic kilometers of volcanic products were ejected from the depths of the Earth to the surface. This is the largest known volcanic eruptions in Kamchatka and the Kuril Islands.

slide 13

Mayon Volcano, the most active on the island of Luzon. On October 23, 1776, he caused the death of 2,000 people when a huge amount of lava was thrown out of his crater.
Volcano Mayon
Mayon's longest eruption was observed in 1897. It lasted from 23 to 30 June and claimed 400 lives.

Slide 14

Volcano Stromboli
In southern Italy, near the island of Vulcano. Situated 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 red-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 in the beginning of the fifteenth century there were already seven of them.

Technological map Task 1

I want to know

What is a volcano ?

• Volcano- (from Latin vulcanus - fire, flame), a conical mountain, from the neck of which hot gases, steam, ash, rock fragments are ejected, as well as powerful streams of red-hot lava that 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 stones.
• Volcanoes are mountains of a conical shape, composed of the products of their eruption.

Technological map Task 2.

A volcano is………………………………………………………………………………………...

…………………………………………………………………………………………………… ...

………………………………………………………………………………………………… .....

The structure of the volcano

• A magma chamber is a place under the earth's crust

where magma collects.

• The vent of a volcano is a channel through which magma rises.
• A volcano crater is a bowl-shaped depression on the top of a mountain.
• Lava is erupted magma.

Technological map Task 3 Complete the scheme "Structure of the volcano"

Eruption- this is the exit to the surface of the planet of the molten substance of the earth's crust and mantle of the Earth, called magma .

Historic catastrophe 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, the magma melts, the gases expand and rush out.

Signs of a volcanic eruption

Volcanic eruption is almost always predictable. The most characteristic signs of the "awakening" of the volcano are:

• - increased gas output and

mineral waters on it

• - temperature increase;
• - underground noise.

Types of volcanic eruptions

If gases are released from the magma relatively quietly, then it pours out to the surface, forming lava flows. This eruption is called effusive.

If the gases are released quickly, the magmatic melt is as if instantaneous boiling up and it is torn apart by expanding gas bubbles.

There is 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.

Volcano types

Most common central type volcanoes is a hill, mountain or hill with a depression at the top – crater , from which magma comes to the surface. thrown out during a volcanic eruption

fragments of rock from it,

ash, pouring lava

remain on its slopes.

The height of the mountain increases

Xia, and with it the crater

moving higher and

Another type of volcanoes - linear, or fissure . Their occurrence is associated with the rise of liquid basalt magma along 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. A geological formation that occurs above channels and cracks in the earth's crust, through which ash, lava, hot gases, water vapor, rock fragments erupt onto the earth's surface

a) an earthquake

b) sea quake

c) a volcano

2. The word "volcano" comes from the name of the ancient Roman god:

a) underworld

3. Find two causes of a volcanic eruption

a) 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 increase;

c) underground noise.

d) lowering the temperature

5. Choose the wrong classification of volcanoes a) by shape b) by the amount of erupted lava c) by 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 a volcano;

make a selection of facts about a volcanic eruption

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1.1. The Hawaiian type of eruption is characterized by a low (10, rarely 15) explosive index and is a calm outpouring of liquid basaltic lava accompanied by weak explosions. Basalt lava flows with characteristic wavy, rope (pahoehoe-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 (ball, ellipsoidal, pear-shaped, disk, band, cylindrical, slag). The formation of slags is characteristic, which in the near-crater part sinter into agglutinates. The thinnest material formed during explosions is drop-shaped ("Pele's tears") and hair-like ("Pele's hair") fragments. It is possible to eject crystals (crystallapilli) in the form of prepared plagioclase individuals up to 3-5 cm in diameter. The temperature of the lava is 1200–1100°C, 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 is a calm outpouring of liquid basaltic lava accompanied by weak explosions. Basalt lava flows with characteristic wavy, rope (pahoehoe-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 (ball, ellipsoidal, pear-shaped, disk, band, cylindrical, slag). The formation of slags is characteristic, which in the near-crater part sinter into agglutinates. The thinnest material formed during explosions is drop-shaped ("Pele's tears") and hair-like ("Pele's hair") fragments. It is possible to eject crystals (crystallapilli) in the form of prepared plagioclase individuals up to 3-5 cm in diameter. The temperature of the lava is 1200–1100°C, 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 South BTTI rupture (Kamchatka).

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1.3. The Vulcan type of eruption is widespread and usually combined with the Strombolian type. The composition of volcanic products is andesitic and dacitic, less often basaltic andesite and rhyolitic. In this type of eruptions, heated, but not plastic, explosive material of various sizes is ejected, and lava flows are rare. Lava flows are usually short with a blocky surface. The blocks are much larger than in the basaltic and basaltic andesite flows of the Strombolian eruptions. Peculiar volcanic bombs are characteristic - such as "breadcrust", having a smooth, highly fractured surface. Explosive index 60-80 or more. The shape of the fragments is angular, their dimension is from silty (0.01 mm) to blocks with a diameter of 1 m or more, but ash (less than 2.0 mm) particles predominate, which are most often represented by angular (acute-angled) fragments of volcanic glass. Slags are usually absent. The admixture of alien and resurgent material is more than 10%. 1.3. The Vulcan type of eruption is widespread and usually combined with the Strombolian type. The composition of volcanic products is andesitic and dacitic, less often basaltic andesite and rhyolitic. In this type of eruptions, heated, but not plastic, explosive material of various sizes is ejected, and lava flows are rare. Lava flows are usually short with a blocky surface. The blocks are much larger than in the basaltic and basaltic andesite flows of the Strombolian eruptions. Peculiar volcanic bombs are characteristic - such as "breadcrust", having a smooth, highly fractured surface. Explosive index 60-80 or more. The shape of the fragments is angular, their dimension is from silty (0.01 mm) to blocks with a diameter of 1 m or more, but ash (less than 2.0 mm) particles predominate, which are most often represented by angular (acute-angled) fragments of volcanic glass. Slags are usually absent. The admixture of alien 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 large areas near the volcano. The finest material (10-15%), mainly vitroclastic, belongs outside the volcanic edifice and is included in the soil-pyroclastic covers and volcano-terrigenous deposits. The ashes of Vulcanian eruptions are not characterized by a porous, droplet-like, melted form of debris. So for fragments of the ashes of the Karymsky volcano eruptions in 1966, 1979. a shape close to isometric with angular protrusions of crystals was noted, but sharply angular forms were not observed. According to E.F.Maleev (1982), the mineral composition of ashes changes with increasing particle size. 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. The ashes contain about 10% of resurgent and retroclastic fragments, which, after weak explosions, again fell into the crater and, being subjected to repeated heating, acquired a red color. The temperature of the lava is 1050–950 °C, the viscosity coefficient is 105–106 poise. The prototype is described on the island of Vulcano in the group of the Aeolian Islands. The volcanic type of eruption is characteristic of the Avachinsky and Karymsky volcanoes (Kamchatka), and was widely manifested in combination with the Strombolian type at the Northern rupture of the GTFE (Kamchatka).

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1.7. The phreatic (bandaisan, ultravolcanic) type of eruption yields only explosive material in a cold and rarely hot state. A large amount of rock fragments from the basement of the volcano (75-100%) in the absence of juvenile material is typical. Phreatic eruptions can partially destroy the volcanic structure, 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. Explosivity index 100. Rock fragments are ejected by steam due to the contact of overheated (thermal) waters with groundwater or when lava sinks in the volcano channel below the groundwater level. 1.7. The phreatic (bandaisan, ultravolcanic) type of eruption yields only explosive material in a cold and rarely hot state. A large amount of rock fragments from the basement of the volcano (75-100%) in the absence of juvenile material is typical. Phreatic eruptions can partially destroy the volcanic structure, 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. Explosivity index 100. Rock fragments are ejected by steam due to the contact of overheated (thermal) waters with groundwater or when lava sinks in the volcano channel below the groundwater level. A feature 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 beginning to end (more than 30 minutes) on the Soufrière volcano (Guadeloupe Island), thirteen of which eruptions were phreatic. The best-known example of this type is the eruption of the Bandai-San volcano (Japan, 1888). Phreatic explosions are also possible when lava flows intrude into glaciers covering the slopes of stratovolcanoes. Thus, in July 1993, during the eruption of Klyuchevskoy volcano, the intrusion of a lava flow into the Erman Glacier was accompanied by a series of powerful phreatic explosions that reached a height of 2–3 km (Fedotov et al., 1995). The above classification is illustrative, but applies mainly to simple eruptions. Complex eruptions can be characterized simultaneously by several types of activity. At the same time, they are so intertwined with each other that it is 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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Description of the slide:

• 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 explore this element.

• Volcano formation

• When a magma chamber forms in the bowels of the Earth, molten liquid magma presses down on the tectonic plate with such force that it begins to crack. Magma rushes upward along cracks and faults, melting through the rock and expanding the cracks. This is how the exit channel is formed. It passes in the center of the volcano, along it molten magma pours out from the vent of the volcano outward 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 is a depression - a crater. At the bottom of the crater, you can see the vent 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 the lava solidifies in the vent, then a solid plug is formed, which can only be broken by a strong volcanic eruption, and a powerful explosion occurs.

• Types of volcanoes

• active volcanoes

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

• Those volcanoes are also considered active, the eruptions of which have been preserved any evidence in the history of mankind.

• Extinct volcanoes

• Extinct volcanoes were active only in prehistoric times. The hearth beneath them has long been extinguished, and they themselves are so badly destroyed that only geologists' studies reveal traces of ancient volcanic activity.

• dormant volcanoes

• Sleeping volcanoes have not erupted in historical time, but at any moment their catastrophic eruption may begin, because the magma chamber under them has not died out. Sleeping volcanoes show signs of life: they can smoke, smoke comes out of their crater, gases and steam are released from cracks in the mountain, hot springs beat. The longer a dormant volcano is at rest, the more dangerous it is: the power of its explosive awakening can be catastrophic.

• Eruption types

• explosive eruptions

• A volcano 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.

• Effusive eruptions

• During an effusive volcanic eruption, liquid lava spreads freely with the formation of lava flows and covers

• extrusive eruptions

• A huge amount of burning gases and red-hot lava dust are ejected from the crater of the volcano. Spreading around the volcano with great speed, this scorching cloud instantly burns everything over a very large area.

• 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 the eruption include lava.

• Lava is magma that has erupted onto the surface of the earth

• Types of lava flow.

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

• It has an uneven surface with cracks. Such 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 red-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"

• Lava flow "pa-hoe-hoe"

• pyroclasts

• Fragments of rocks that are scattered 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, the gases are released unhindered and do not threaten to explode. Gases can foam even viscous magma, forming porous pumice, spray 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 mouth of a volcano.

• Volcanoes in Kamchatka

• Volcano Nameless

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

• A powerful jet of hot gas, volcanic sand and ash escaped from the vent, 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 the fury of the eruption, no one died - not a single living soul was during the hours of the eruption within a radius of 45 km from the volcano.

• Tolbachinskaya Sopka

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

• In a very short time, many cracks more than a kilometer long were formed. All this was accompanied by flooding and gushing of lava. During the Tolbachik eruption, two cubic kilometers of volcanic products were ejected from the depths of the Earth to the surface. This is the largest known volcanic eruptions in Kamchatka and the Kuril Islands.

• Volcano in the Philippines

• Mayon Volcano, the most active on the island of Luzon. On October 23, 1776, he caused the death of 2,000 people when a huge amount of lava was thrown out of his crater.

• Volcano Mayon

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

• Volcanoes of the Mediterranean

• Volcano Stromboli

• In southern Italy, near the island of Vulcano. The volcano island of Stromboli is located. It has a very restless character, and it has been operating for several millennia almost without 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 powerful eruptions of Stromboli was noted in 1930, and in the beginning of the fifteenth century there were already seven of them.

• Volcanoes of the Atlantic

• In the south of Iceland there is a volcanic mountain range Lucky, in which 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 Vatnajo-kull in the southeast of Iceland began powerful eruption volcano Laki. It lasted 8 months, the length of the flow of lava erupted into the light was almost 70 kilometers, and the volume of this mass, moving at a speed of over 45 km / h, was 12,000 cubic meters and occupied an area of ​​579 square kilometers.

• Volcano Lucky

• Volcanoes of Africa

• Mount Kilimanjaro

• Kilimanjaro is a volcanic mountain range in east africa
• The array consists of three peaks - Kibo, Mawenzi and Shira. The Mawenzi and Shira volcanoes have long gone extinct, and Kibo continues to smoke with volcanic gases through holes in the slopes.

• Volcanoes of the Pacific

• Volcano St. Helens

• AT 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, Tolbachinskaya Sopka, Mayon, Stromboli, Lucky, Kilimanjaro, St. Helens
• Show on the map the volcanoes that have erupted in the past year

• Questions about the material covered

• 1. What are volcanoes?

• 3. What types of eruptions do you know?

• 5. What are the products of an eruption?

• 2.How are volcanoes formed?

• 4. Give brief description each type of eruptions.