Presentation "Volcanoes". Presentation on the topic of volcanoes Volcanoes and types of volcanic eruptions presentation

geological formation that occurs above channels and cracks in the earth's crust, through which molten rocks (lava), hot gases, ash, water vapor and rock fragments erupt onto the earth's surface

The main parts of the volcano

At the top of the volcano is deep depression- crater. A vent enters the crater - a channel through which liquid magma rises from the bowels of the Earth.

Types of volcanoes:

Active

• central type volcanoes

• linear volcanoes

• Active Mount Etna

• Dormant Volcano Parinacota

Volcanoes are: active, dormant, extinct .

• Extinct Mount Fuji

• There are about 500 volcanoes on Earth. Approximately 370 of them are located on the shores and island arcs of the Pacific Ocean (Aleutian, Kuril, Japanese, Philippine, Sunda Islands) and on the outskirts of the continents North America, Central America, in the Andes in the west South America. 9 active volcanoes are located in Antarctica. Some volcanic islands are located in the Indian Ocean. AT Atlantic Ocean there are only 45 of them.

Volcanoes in Russia.

In Russia, Kamchatka, the Kuriles, and Sakhalin are exposed to the danger of volcanic eruptions. There are extinct volcanoes in the Caucasus.

• Hot lava flows (their flow speed is up to 100 km / h)
• Scorching avalanches (consist of blocks, sand, ash and volcanic gases with a temperature of 700 degrees C)
• Clouds of ash and gases (thrown to a height of 15-20 km)
• Blast wave and debris spread
• Water and mud-stone streams (speed up to 90-100 km/h)
• Sharp fluctuations in climate (may create a greenhouse effect)

Actions in the event of a volcanic eruption.

In the event of a volcanic eruption: 1 )Protect sensitive devices; 2) close the drinking water tanks; 3) follow the shelter; 4) periodically it is necessary to go out and sweep the ashes from the roofs and shake it off the trees.

Actions in the event of a volcanic eruption in its immediate vicinity

• Name the types of volcano
• List the parts of a volcano
• Actions in the event of a volcanic eruption

Knowledge check

1) Tremors and vibrations of the earth's surface resulting from sudden displacements and breaks in the earth's crust are called ...

Knowledge check

2. Of the following consequences, indicate which of them are related to earthquakes:

a) scorching avalanches;

b) dips and rise of the earth's surface;

d) accidents at industrial enterprises;

f) sharp fluctuations in climate;

Knowledge check

3 . Of the following consequences, indicate which of them relate to volcanoes:

a) dips and rise of the earth's surface;

b) scorching avalanches;

c) destruction of buildings and structures;

d) clouds of ash and gases;

e) blast wave and scatter of debris;

f) sharp fluctuations in climate;

g) vibrations, shocks and cracks in the soil.

Knowledge check

4. What not to do during an earthquake:

a) stand near the windows

b) stand in the doorway;

c) hide in a cast-iron bath;

d) use the elevator;

e) light matches, candles, use open fire;

f) approach dilapidated houses.

Knowledge check

5. Determine the types of earthquakes by origin:

a) tectonic;

b) active;

c) induced;

d) sleeping;

e) seaquake;

e) collapse.

Knowledge check

6. A geological formation that occurs above channels and cracks in the earth's crust, through which molten rocks (lava), hot gases, ash, water vapor and rock fragments are erupted onto the earth's surface is called ...

Knowledge check

7. Determine the types of volcanoes:

a) collapse;

b) active;

c) induced;

d) sleeping;

e) tectonic.

Examination

answers

Grading Criteria

1) Earthquake

20 points - 19 points - "5"

18 points - 15 points - "4"

14 points - 10 points - "3"

Less than 10 points - "2"

• b, d, e, f
• And where

• In the event of a volcanic eruption in the immediate vicinity, protect your respiratory organs and follow for cover.

• In 79 AD e. the volcano Vesuvius suddenly awakened, which had not been active in historical times before. A terrible catastrophe wiped out the cities of Pompeii, Herculaneum and Stabia, almost all of their inhabitants died.

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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, disc, ribbon, 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, disc, ribbon, 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 characteristic. 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 characteristic. 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 well-known 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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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.
A large amount of rock fragments from the basement of the volcano (75–100%) is characteristic, 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.

History of the name About 20 centuries ago, a mountainous island in the Mediterranean Sea near Sicily began to spew smoke and fire. Explaining it strange phenomenon, people believed that the forge of the Roman god Vulcan was located in the mountain. The ash clouds, they argued, were the smoke from his forge, and the lava splashes were sparks from the anvil. They called this island "Vulcano" - from the Latin word "Volcano".

Volcano (Greek - Hephaestus). In Greek and Roman mythology, the god of fire and the blacksmith who forged weapons for many gods and heroes. He was an educator 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 pharynx opened the smoke gushed a club of flames 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 inflamed ashes, Under stone rain, run away from the city. A.S. Pushkin VOLCANOES are silent extinct volcanoes, ash falls to the bottom of them. There the giants rest after the deed of evil. B. Akhmadulina Volcanoes are blown up. Defeated Ocean... Arthur Rimbaud

The structure of a volcano A typical volcano is a hill with a pipe passing through its thickness, called a volcano vent, and with a magma chamber (magma accumulation area), from which the vent rises. When 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 - the smallest volcanic product, which has the form of a powdery mass. During explosive eruptions, it is ejected to the surface of the earth, often with a volume of many cubic kilometers and rises in the form of a cloud cloud to a height of up to several tens of kilometers. Powerful deposits of ash, covering the slopes and foot of volcanoes in many meters, destroy large woodlands and even cities. Ash - the smallest volcanic product, which has the form of a powdery mass. During explosive eruptions, it is ejected to the surface of the earth, often with a volume of many cubic kilometers and rises in the form of a cloud cloud to a height of up to several tens of kilometers. Powerful deposits of ash, covering the slopes and foot of volcanoes in many meters, destroy large forests and even cities.

Left, right - breadcrust bombs, in the middle - in the form of a spindle. Volcanic bombs have an unusually large variety of shapes and sizes among detrital material. They are formed from pieces of lava raised to a certain height by gases that are intensively released from a hot melt.

Volcanoes are divided into: Active Active - these are volcanoes that currently have an eruption or it is observed periodically, at some intervals. If magma does not erupt, and the volcano "smokes" or "smokes", then it is also considered active. Dormant Volcanoes are considered to be dormant if they have been active in a historical period of time and have retained their shape; weak tremors and earthquakes periodically occur in their depths. Extinct Extinct - volcanoes that were active sometime in the distant past; they have blurred and destroyed cones

Hawaiian type Mauna Loa volcano is located on the main island of Hawaii. Its characteristic feature is that basaltic melts pour out here relatively calmly, without explosions. The melt is slightly saturated with gases and has a low viscosity, although unusually spectacular lava fountains sometimes appear. 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, ie, has a basic composition, it has some viscosity. Therefore, there is an alternation of outpourings of lava flows and explosions. Explosions eject bombs, lapilli, ash and basalt slag. Stromboli - the volcano of the Aeolian Islands - is notable for the fact that it is constantly active, being a kind of unusually bright lighthouse mediterranean sea

Type Vulcano The volcano of the island of Vulcano, located in the Aeolian Islands, is also quite famous. It is characterized by the eruption of relatively acidic volcanic products (andesite-dacites). Due to the high viscosity of the melt, the volcanic vent becomes blocked. The accumulated vapors and gases explode this cork and, together with other finely crushed particles of various shapes and sizes, throw them to a great height. So often they say: explosive eruptions of the Vulcan type.

Vesuvian type Named for 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 eruptions 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 continuously fell on the streets and houses. Herculaneum was flooded with red-hot lava and boiling mud. Stabia was also almost completely destroyed. Only on August 27, three days after the start of the eruption, the sun peeped out for the first time, illuminating the three dead cities. On August 24, 1979, people paid with their lives for their carelessness: suddenly in the blue sky above Gulf of Naples a lava plug shot up, which for many millennia tightly clogged the mouth of the crater of Vesuvius.

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

Pele type Volcano Mont Pele (Bald Mountain), which gave the name to the following type of eruptions, is located on the island of Martinique (group of Small Antilles 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 noted here, covering a large area.

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

The large fissure Tolbachik eruption is one of the largest known basalt 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 Tolbachinsky 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 have not had time to cool down to the end, so standing 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 - apparatuses for the outpouring of liquid lavas; volcanic ridges that arose when the centers of the outpouring moved along cracks; volcanic ridges that arose when the centers of the outpouring moved along the cracks; caldera caldera volcanoes; somma volcanoessoma volcanoes that have arisen within calderas after their renewal; dome volcanoes.

Underwater volcanic activity of Guyot Guyot [named after the discoverer of the American geographer and geologist A. Guyot (Guyot; A. Guyot;)], isolated flat-topped volcanic seamounts. Occur in groups or as solitary uplifts, predominantly in pacific ocean. Separate G. are also available in the Atlantic and Indian Oceans. The peaks of the mountain are located at depths from 200 to 2000 m. It is believed that the alignment of the peaks of the mountain is the result of abrasion. Since abrasion affects only to a depth of the order of m, it is assumed that most of the G. experienced subsidence along with the ocean floor that forms their base.

Volcanoes are very dangerous, but they also bring benefits to man. Various igneous rocks are used as building materials and abrasives. The sulfur emitted by the volcano is part of many useful chemicals. Volcanic material - pumice - is part of 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 An unnamed volcano near the north pole of Io (satellite of Jupiter). Galileo (an artificial probe) photographed the eruption of this volcano, the column of dust rose to a height of about 430 km. An even higher column of ash and dust was also seen - it rose to a height of more than 480 km. With the help of equipment installed on Galileo, it was possible to determine the composition of the volcanic ejecta. They were particles resembling snowflakes, made up of molecules of sulfur dioxide.

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

Structure: hearth, vent, crater. A focus 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 on the top of a mountain-volcano.

Volcanoes are classified by location, shape and activity.

By activity: extinct, dormant, active. Such a classification is rather conditional. The extinct ones have not erupted for more than 1000 years: they retain their general shape, the crater and slopes undergo changes. Sometimes they are active. Example: Mont Pele on Martinique, the Valley of Volcanoes in Buryatia, Kalara volcanoes.

Sleeping volcanoes are volcanoes in which the probability of an eruption is higher than that of extinct ones. Some of them are called supervolcanoes - Toba in Sumatra, Taulo in New Zealand, 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. Most active volcanism: South and Central America, Hawaii, Japan, Sunda Islands.

Classified by location: subglacial, terrestrial, underwater. According to the shape, types are distinguished: domed, cinder cone, thyroid, stratovolcano, complex view.

On the basis of the general design, formations of the central and linear types are distinguished. The former have a central channel through which lava comes to the surface. The second type is fissure, the channels through which lava rises have an elongated shape. Scientists distinguish an areal type, but such types have not been recorded on Earth, at least in our time. It is believed that they existed when the planet was forming.

The eruption is considered an emergency, a catastrophe. It can happen an hour, a month, a year, several years. The consequences of the eruption: the formation of depressions-calderas, geysers, fumaroles. There may be low mountains, islands. Lakes form in craters.

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

A mud-type volcano is a formation, as a result of which mud, gases, and not magma, come to the surface. They are found on the territory of Russia, Central Asia.

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

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