There are no volcanoes. How does a volcano erupt? Volcanic bombs are also part of the structure of the Earth's volcanoes

In this lesson, we will learn what volcanoes are, how they form, get acquainted with the types of volcanoes and their internal structure.

Theme: Earth

Volcanism- a set of phenomena caused by the penetration of magma from the depths of the Earth to its surface.

The word "volcano" comes from the name of one of the ancient Roman gods - the god of fire and blacksmithing - Vulcan. The ancient Romans believed that this god had a forge underground. As Vulcan begins to work at his forge, smoke and flames burst out through the crater. In honor of this god, the Romans named the island and the mountain on the island in the Tyrrhenian Sea - Vulcano. And later, all fire-breathing mountains began to be called volcanoes.

The globe is arranged in such a way that under the solid earth's crust there is a layer of molten rocks (magma), moreover, under great pressure. When cracks appear in the Earth's crust (and hills form on the earth's surface in this place), the magma under pressure in them rushes and exits to the earth's surface, breaking up into red-hot lava (500-1200 ° C), caustic volcanic gases and ash. The spreading lava hardens, and the volcanic mountain increases in size.

The formed volcano becomes a vulnerable place in the earth's crust, even after the end of the eruption inside it (in the crater), gases constantly come out of the earth's interior to the surface (the volcano "smokes"), and with any slightest shifts or shocks of the earth's crust, such a "sleeping" volcano can wake up at any time. Sometimes the awakening of the volcano occurs without obvious reasons. Such volcanoes are called active.

Rice. 2. The structure of the volcano ()

volcano crater- a cup-shaped or funnel-shaped depression on the top or slope of a volcanic cone. The diameter of the crater can be from tens of meters to several kilometers and the depth from several meters to hundreds of meters. At the bottom of the crater there are one or more vents through which lava and other volcanic products rise to the surface from the magma chamber through the outlet channel. Sometimes the bottom of the crater is blocked by a lava lake or a small newly formed volcanic cone.

volcano mouth- a vertical or almost vertical channel connecting the source of the volcano with the surface of the earth, where the vent ends with a crater. The shape of the vents of lava volcanoes is close to cylindrical.

magma chamber- a place under the earth's crust where magma collects.

Lava- erupted magma.

Types of volcanoes (according to the degree of their activity).

Active - which erupt, and information about this is in the memory of mankind. There are 800 of them.

Extinct - no information has been preserved about the eruption.

Asleep - those that are extinguished, and suddenly begin to act.

Volcanoes are classified according to their shape. conical and shield.

The slopes of the conical volcano are steep, the lava is thick, viscous, and cools down quite quickly. The mountain has the shape of a cone.

Rice. 3. Conical Volcano ()

The slopes of the shield volcano are gentle, very hot and liquid lava spreads quickly over considerable distances, and cools slowly.

Rice. 4. Shield volcano ()

A geyser is a source that periodically ejects a fountain of hot water and steam. Geysers are one of the manifestations of the late stages of volcanism and are common in areas of modern volcanic activity.

A mud volcano is a geological formation that is a hole or depression on the surface of the earth, or a cone-shaped elevation with a crater, from which mud masses and gases are constantly or periodically erupted onto the surface of the Earth, often accompanied by water and oil.

Rice. 6. Mud volcano ()

- a lump or piece of lava thrown out during a volcanic eruption in a liquid or plastic state from a crater and received a specific shape during squeezing, during flight and solidification in air.

Rice. 7. Volcanic bomb ()

An underwater volcano is a type of volcano. These volcanoes are located at the bottom of the ocean.

Most modern volcanoes are located within the three main volcanic belts: Pacific, Mediterranean-Indonesian and Atlantic. As evidenced by the results of studying the geological past of our planet, submarine volcanoes in terms of their scale and volume of ejecta products coming from the bowels of the Earth significantly exceed volcanoes on land. Scientists believe that this is the main source of tsunamis on Earth.

Rice. 8. Underwater volcano ()

Klyuchevskaya Sopka (Klyuchevskoy volcano) is an active stratovolcano in the east of Kamchatka. With a height of 4850 m, it is the highest active volcano on the Eurasian continent. The age of the volcano is approximately 7000 years.

Rice. 9. Volcano Klyuchevskaya Sopka ()

1. Melchakov L.F., Skatnik M.N. Natural history: textbook. for 3.5 cells. avg. school - 8th ed. - M.: Enlightenment, 1992. - 240 p.: ill.

2. Bakhchieva O.A., Klyuchnikova N.M., Pyatunina S.K. and others. Natural history 5. - M .: Educational literature.

3. Eskov K.Yu. et al. Natural History 5 / Ed. Vakhrusheva A.A. - M.: Balass.

3. The most famous volcanoes of the Earth ().

1. Tell us about the structure of the volcano.

2. How are volcanoes formed?

3. How is lava different from magma?

4. * Prepare a short message about one of the volcanoes in our country.

Volcanic eruptions are dangerous primarily due to their direct impact - the release of tons of burning lava, under which entire cities can die. But, in addition to this, such side factors as the suffocating effect of volcanic gases, the threat of a tsunami, isolation from sunlight, distortion of the terrain and local climatic changes are also dangerous.

Merapi, Indonesia

Merapi is one of the largest volcanoes on the islands of Indonesia. He is one of the most active: large eruptions occur once every seven to eight years, and small ones - once every two years. At the same time, smoke from the top of the volcano appears almost daily, preventing the locals from forgetting about the threat. Merapi is also famous for the fact that in 1006 the whole medieval Javanese-Indian state of Mataram was seriously affected by his activities. The special danger of the volcano is that it is located near the large Indonesian city of Yogyakarta, which is home to about 400 thousand people.

Sakurajima, Japan

Sakurajima has been in constant volcanic activity since 1955, with the last eruption occurring in early 2009. Until 1914, the volcano was located on a separate island of the same name, but frozen lava flows connected the island with the Osumi Peninsula. Residents of Kagoshima City have become accustomed to the erratic behavior of the volcano and are constantly ready to take refuge in shelters.

Aso Volcano, Japan

The last time the volcanic activity of the volcano was recorded quite recently, in 2011. Then the ash cloud spread over a territory of more than 100 km. From that time to the present, about 2,500 tremors have been recorded, which indicates the activity of the volcano and its readiness for an eruption. Despite the direct danger, about 50 thousand people live in the immediate vicinity of it, and the crater is a popular tourist attraction for daredevils. In winter, the slopes are covered with snow and people go skiing and tobogganing in the valley.

Popocatepetl, Mexico

One of the largest volcanoes in Mexico is located literally fifty kilometers from. This is a city with a population of 20 million people who are in constant readiness for evacuation. In addition to Mexico City, major cities such as Puebla and Tlaxcala de Jicotencatl are located in the neighborhood. Popocatepetl also gives them a reason to be nervous: emissions of gas, sulfur, dust and stones occur literally every month. Over the past decades, the volcano has erupted in 2000, 2005 and 2012. Many climbers strive to climb to its summit. Popocatepetl is famous for being conquered by Ernesto Che Guevara in 1955.

Etna, Italy

This Sicilian volcano is interesting in that it has not only one main wide crater, but also many small craters on the slopes. Etna is in constant activity, and small eruptions occur at intervals of several months. This does not prevent the Sicilians from densely populating the slopes of the volcano, since the presence of minerals and trace elements makes the soil very fertile. The last major eruption was in May 2011, and small ash and dust emissions were in April 2013. By the way, Etna is the largest volcano in: it is two and a half times larger than Vesuvius.

Vesuvius, Italy

Vesuvius is one of three active volcanoes in Italy along with Etna and Stromboli. They are even jokingly called the "hot Italian family." In 79, the eruption of Vesuvius destroyed the city of Pompeii with all the inhabitants who were buried under layers of lava, pumice and mud. During one of the last strong eruptions, which occurred in 1944, about 60 people died and the nearby cities of San Sebastiano and Massa were almost completely destroyed. According to scientists, Vesuvius destroyed nearby cities about 80 times! By the way, this volcano has set many records. Firstly, this is the only active volcano in the mainland, secondly, it is the most studied and predictable, and thirdly, the territory of the volcano is a reserve and a national park where excursions are held. You can only go up on foot, as the lift and funicular have not yet been restored.

Colima, Mexico

The volcanic mountain consists of two peaks: the already extinct Nevado de Colima, which is covered with snow most of the time, and the active volcano Colima. Colima is particularly active: since 1576, it has erupted more than 40 times. A strong eruption happened in the summer of 2005, when the authorities had to evacuate people from nearby villages. Then a column of ash was thrown to a height of about 5 km, spreading a cloud of smoke and dust behind it. Now the volcano is fraught with danger not only for local residents, but for the whole country.

Mauna Loa, Hawaii, USA

Scientists have been observing the volcano since 1912 - there is a volcanological station on its slopes, as well as solar and atmospheric observatories. The height of the volcano reaches 4169 m. The last strong eruption of Mauna Loa destroyed several villages in 1950. Until 2002, the seismic activity of the volcano was low, until its increase was recorded, which indicates the possibility of eruptions in the near future.

Galeras, Colombia

The Galeras volcano is very powerful: its diameter at the base exceeds 20 km, and the width of the crater is about 320 m. The volcano is very dangerous - every few years, due to its activity, the population of the nearby town of Pasto has to be evacuated. The last such evacuation took place in 2010, when about 9 thousand people found themselves in shelters due to the threat of a strong eruption. Thus, the restless Galeras keeps the locals in constant tension.

Nyiragongo, Republic of the Congo

Volcano Nyiragongo is considered the most dangerous in all: it accounts for about half of all cases of volcanic activity recorded on the continent. There have been 34 eruptions since 1882. Lava Nyiragongo has a special chemical composition, so it is unusually liquid and fluid. The speed of erupting lava can reach 100 km/h. There is a lava lake in the main crater of the volcano, the temperature of which heats up to 982 Cº, and bursts reach a height of 7 to 30 m. The last largest eruption occurred in 2002, when 147 people died, 14 thousand buildings were destroyed, and 350 thousand people left homeless.

It is worth noting that scientists have been studying the activity of volcanoes for many years and modern technology recognizes the beginning of their seismic activity. Many volcanoes are equipped with webcams, with the help of which you can follow what is happening in real time. People living nearby are already accustomed to this behavior of volcanoes and know what to do when an eruption begins, and emergency services have the means to evacuate local residents. So every year the probability of victims from volcanic eruptions becomes less and less.

It is difficult to find a person who at least once would not take an interest in volcanoes. Most of them read books about them, with bated breath watched footage from the sites of eruptions, at the same time admiring the power and splendor of the elements and rejoicing that this does not happen next to them. Volcanoes are something that leaves no one indifferent. So what is it?

The structure of the volcano

Volcanoes are special geological formations that arise when the hot substance of the mantle rises from the depths and comes to the surface. Magma rises up the cracks and faults in the earth's crust. Where it breaks out, active volcanoes form. This occurs at the boundaries of lithospheric plates, where faults arise due to their separation or collision. And the plates themselves are involved in movement when the mantle substance moves.

Most often, volcanoes look like conical mountains or hills. In their structure, a vent is clearly distinguished - a channel through which magma rises, and a crater - a depression at the top through which an outpouring of lava occurs. The volcanic cone itself consists of many layers of products of activity: solidified lava, and ash.

Since the eruption is accompanied by the release of hot gases, glowing even during the day, and ash, volcanoes are often called "fire-breathing mountains." In ancient times, they were considered gates to the underworld. And they got the name in honor of the ancient Roman It was believed that fire and smoke fly from his underground forge. Such interesting facts about volcanoes fuel the curiosity of a variety of people.

Types of volcanoes

The existing division into active and extinct is very conditional. Active volcanoes are those that have erupted in human memory. There are eyewitness accounts of these events. There are a lot of active volcanoes in the areas of modern mountain building. These are, for example, Kamchatka, the island of Iceland, East Africa, the Andes, the Cordillera.

Extinct volcanoes are those that have not erupted for thousands of years. In the memory of people, information about their activity was not preserved. But there are many cases when a volcano, which was considered inactive for a long time, suddenly woke up and brought a lot of troubles. The most famous of them is the famous eruption of Vesuvius in 79, glorified by Bryullov's painting The Last Day of Pompeii. 5 years before this catastrophe, rebels hid on its top. And the mountain was covered with lush vegetation.

The extinct volcanoes include Mount Elbrus - the highest peak in Russia. Its two-headed top consists of two cones merged at the bases.

Volcanic eruption as a geological process

An eruption is the process of ejection to the earth's surface of incandescent magmatic products in a solid, liquid and gaseous state. For each volcano it is individual. Sometimes the eruption is quite calm, liquid lava pours out in streams and flows down the slopes. It does not interfere with the gradual release of gases, so strong explosions do not occur.

This type of eruption is typical for Kilauea. This volcano in Hawaii is considered one of the most active in the world. With a diameter of about 4.5 km, its crater is also the largest in the world.

If the lava is thick, it plugs up the crater from time to time. As a result, the released gases, finding no way out, accumulate in the vent of the volcano. When the pressure of the gases becomes very high, a powerful explosion occurs. It lifts large volumes of lava into the air, which subsequently falls to the ground in the form of volcanic bombs, sand and ash.

The most famous explosive volcanoes are the already mentioned Vesuvius, Katmai in North America.

But the most powerful explosion, which led to a cooling around the world due to volcanic clouds, through which the sun's rays could hardly break through, occurred in 1883. Then I lost most of it. A column of gas and ash rose up to 70 km in the air. The contact of ocean water with red-hot magma led to the formation of a tsunami up to 30 m high. In general, about 37 thousand people became victims of the eruption.

Modern volcanoes

It is believed that now in the world there are more than 500 active volcanoes. Most of them belong to the zone of the Pacific "ring of fire", located along the boundaries of the lithospheric plate of the same name. Every year there are about 50 eruptions. At least half a billion people live in their zone of activity.

Volcanoes of Kamchatka

One of the most famous areas of modern volcanism is located in the Russian Far East. This is an area of ​​modern mountain building, belonging to the Pacific Ring of Fire. The volcanoes of Kamchatka are included in the UNESCO World Heritage List. They are of great interest not only as objects of scientific research, but also as natural monuments.

It is here that the highest active volcano in Eurasia is located - Klyuchevskaya Sopka. Its height is 4750 m. Plosky Tolbachik, Mutnovskaya Sopka, Gorely, Vilyuchinsky, Gorny Tooth, Avachinsky Sopka and others are also widely known for their activity. In total, there are 28 active volcanoes in Kamchatka and about half a thousand extinct ones. But here are some interesting facts. Much is known about the volcanoes of Kamchatka. But along with this, the region is known for a much rarer phenomenon - geysers.

These are sources that periodically throw out fountains of boiling water and steam. Their activity is connected with magma that has risen along cracks in the earth's crust close to the earth's surface and heats groundwater.

The famous Valley of Geysers, located here, was discovered in 1941 by T. I. Ustinova. It is considered to be one of the wonders of nature. The area of ​​the Valley of Geysers is no more than 7 sq. km, but there are 20 large geysers and dozens of springs with boiling water. The largest geyser, the Giant, throws out a column of water and steam to a height of about 30 m!

Which volcano is the tallest?

It is not so easy to determine this. Firstly, the height of active volcanoes can increase with each eruption due to the growth of a new layer of rocks or decrease due to explosions destroying the cone.

Secondly, a volcano that was considered extinct may wake up. If it is high enough, it can push back the already existing leader.

Thirdly, where to calculate the height of the volcano - from the base or from sea level? This gives completely different numbers. After all, the cone, which has the highest absolute height, may not be the largest in comparison with the surrounding area, and vice versa.

Currently, among the active volcanoes, Lluillaillaco in South America is considered the largest. Its height is 6723 m. But many volcanologists believe that Cotopaxi, located on the same mainland, can claim the title of the greatest. Let it have a lower height - “only” 5897 m, but on the other hand, its last eruption was in 1942, and at Lluillaillaco - already in 1877.

The Hawaiian Mauna Loa can also be considered the highest volcano on Earth. Although its absolute height is 4169 m, this is less than half of its true value. The cone of Mauna Loa starts from the very ocean floor and rises more than 9 km. That is, its height from the sole to the top exceeds the dimensions of the Chomolungma!

mud volcanoes

Has anyone heard about the Valley of Volcanoes in Crimea? After all, it is very difficult to imagine this peninsula shrouded in the smoke of eruptions, and the beaches filled with red-hot lava. But do not worry, because we are talking about mud volcanoes.

This is not such a rare occurrence in nature. Mud volcanoes are similar to real ones, but they do not throw out lava, but streams of liquid and semi-liquid mud. The cause of eruptions is the accumulation in underground cavities and cracks of a large amount of gases, most often hydrocarbons. Gas pressure activates the volcano, a high column of mud sometimes rises to several tens of meters, and gas ignition and explosions give the eruption a rather formidable appearance.

The process can continue for several days, accompanied by a local earthquake, underground rumble. As a result, a low cone of solidified mud is formed.

Areas of mud volcanism

In Crimea, such volcanoes are found on the Kerch Peninsula. The most famous of them is Dzhau-Tepe, which greatly frightened the locals with its short eruption (only 14 minutes) in 1914. A column of liquid mud was thrown 60 m up. The length of the mud stream reached 500 m with a width of more than 100 m. But such large eruptions are rather an exception.

The areas of action of mud volcanoes often coincide with oil and gas production sites. In Russia, they are found on the Taman Peninsula, on Sakhalin. Of the neighboring countries, Azerbaijan is "rich" in them.

In 2007, the volcano became more active, flooding a vast territory with its mud, including many buildings. According to the local population, this was due to the drilling of a well that disturbed the deep layers of rocks.

Edinburgh Castle in Scotland is built on top of an extinct volcano. And most Scots don't even know it.

It turns out that volcanoes can be actors! In the film The Last Samurai, Taranaki, considered the most beautiful in New Zealand, played the role of the Japanese sacred mountain Fujiyama. The fact is that the surroundings of Fuji with its urban landscapes were in no way suitable for filming a picture about the events of the late 19th century.

In general, New Zealand volcanoes do not have to complain about the inattention of filmmakers. After all, Ruapehu and Tongariro became famous largely thanks to the film "The Lord of the Rings", in which Orodruin was depicted, in the flame of which the Ring of Omnipotence was created and subsequently destroyed in the same place. The lone mountain in Erebor in The Hobbit movie is also one of the local volcanoes.

And the Kamchatka geysers and waterfalls became the backdrop for the filming of the film "Sannikov Land".

The eruption of Mount St. Helens (USA) in 1980 is considered the most powerful in the entire 20th century. The explosion, in its power equal to 500 bombs dropped on Hiroshima, fell ashes on the territory of four states.

Eyyafyadlayokudl became famous for throwing ash and smoke into chaos in the air traffic of European countries in the spring of 2010. And its name has baffled hundreds of radio and television announcers.

The Philippine volcano Pinatubo last erupted in 1991. At the same time, two American military bases were destroyed. And after 20 years, the Pinatubo crater was filled with rainwater, forming an amazingly beautiful lake, the slopes of the volcano were overgrown with tropical vegetation. This made it possible for travel agencies to organize a vacation with swimming in the volcanic lake.

Eruptions often form interesting rocks. For example, the lightest stone is pumice. Numerous air bubbles make it lighter than water. Or "Pele's hair" found in Hawaii. They are long thin strands of rock. Many buildings in the capital of Armenia, Yerevan, are built of pink volcanic tuff, which gives the city a unique flavor.

Volcanoes are a formidable and majestic phenomenon. Interest in them is caused by fear, curiosity, and a thirst for new knowledge. It is not for nothing that they are called windows to the underworld. But there are purely utilitarian interests. For example, volcanic soils are very fertile, which makes people settle near them for centuries, despite the danger.

10 largest and most dangerous volcanoes on Earth.

A volcano is a geological formation that arose due to the movement of tectonic plates, their collision and the formation of faults. As a result of collisions of tectonic plates, faults are formed, and magma comes to the surface of the Earth. As a rule, volcanoes are a mountain, at the tip of which there is a crater, which is the place where the lava comes out.

Volcanoes are divided into:

- operating;
- sleeping;
- extinct;

Active volcanoes are those that have erupted in the short term (approximately 12,000 years)
Dormant volcanoes are called volcanoes that have not erupted in the near historical perspective, but their eruption is practically possible.
Extinct volcanoes include those that have not erupted in the near historical future, however, the top has the shape of a crater, but such volcanoes are unlikely to erupt.

List of the 10 most dangerous volcanoes in the world:

1. (Hawaii, USA)

2. Taal Volcano (Philippines)

3. Merapi Volcano (Java Island)

4. Santa Maria Volcano (Guatemala)

It is one of the most active volcanoes of the 20th century.
It is located at a distance of 130 kilometers from the city of Guatemala, and is located in the so-called Pacific. Ring of Fire. The Santa Maria crater was formed after it erupted in 1902. About 6,000 people died then. The last eruption occurred in March 2011.

5. Volcano Ulawun (Papua New Guinea)

Ulawun volcano, located in the region of New Guinea, began to erupt from the beginning of the 18th century. Since then, eruptions have been recorded 22 times.
In 1980, the largest volcanic eruption occurred. The ejected ash covered an area of ​​more than 20 square kilometers.
Now this volcano is the highest peak in the region.
The last volcanic eruption occurred in the year 2010.

6. Volcano Galeras (Colombia)

7. Volcano Sakurajima (Japan)

8. Nyiragongo (DR Congo)

One of the most amazing and mysterious geological formations on Earth are volcanoes. However, many of us have only a superficial understanding of them. What is the nature of volcanism? Where and how does a volcano form?

Before considering the question of how a volcano is formed, one should delve into the etymology and meaning of this term. In ancient Roman myths, Vulcan is mentioned by name, whose house was underground. If he was angry, the earth began to tremble, and smoke and flames erupted from the depths. This is where the name of these mountains comes from.

The word "volcano" comes from the Latin "vulcanus", which literally means fire. Volcanoes are geological formations that arise directly above cracks in the earth's crust. It is through these cracks that lava, ash, a mixture of gases with water vapor and rocks erupt to the surface of the earth. The sciences of geomorphology and volcanology are engaged in the study of this mysterious phenomenon.

Classification and structure

According to the nature of activity, all volcanoes are active, dormant and extinct. And by location - terrestrial, underwater and subglacial.

To understand how a volcano forms, you must first consider its structure in detail. Each volcano consists of the following elements:

1. The vent (the main channel in the center of the geological formation).
2. Dike (channel with erupted lava).
3. Crater (a large hole on top in the form of a bowl).
4. (solidified pieces of erupted magma).
5. Volcanic chamber (an area below the earth's surface where magma is concentrated).
6. Cone (the so-called "mountain", formed by erupted lava, ash).

Despite the fact that the volcano looks like a huge mountain, its underground part is much larger than the one on the surface. Craters are often filled with water.

Why do volcanoes form?

The process of volcano formation begins with the formation of a magma chamber underground. Gradually, liquid hot magma heats up in it, which puts pressure on the earth's crust from below. It is for this reason that the earth begins to crack. Through cracks and faults, magma erupts upward, and in the process of its movement, it melts through rocks and significantly expands cracks. This is how a volcanic vent is formed. How is a volcano formed? During the eruption, various rocks come to the surface, which subsequently settle on the slope, as a result of which a cone is formed.

Where are volcanoes located?

Where do volcanoes form? These geological formations are distributed on Earth extremely unevenly. If we talk about the patterns of their distribution, then a large number of them are located near the equator. There are far fewer of them in the southern hemisphere than in the northern. In the European part of Russia, Scandinavia, Australia and Brazil, they are completely absent.

But if we talk about Kamchatka, Iceland, the Mediterranean, the western coast of North and South America, the Indian and Pacific Oceans, Central Asia and Central Africa, then there are plenty of them. They are mainly located near islands, archipelagos, coastal zones of continents. The dependence of their activity and processes associated with the movement of the earth's crust is generally recognized.

How is a volcanic eruption formed?

How and why the processes are hidden in the bowels of the Earth. In the process of magma accumulation, a large amount of thermal energy is generated. The temperature of the magma is quite high, but it is not able to melt because the crust presses on it from above. If the layers of the earth's crust put less pressure on the magma, the red-hot magma becomes liquid. It is gradually saturated with gases, melts rocks on its way and in this way makes its way to the surface of the earth.

If the volcanic vent is already filled with solidified and hardened lava, then the eruption will not occur until the magnitude of the magma pressure is sufficient to push out this plug. always accompanied by an earthquake. Ashes can be thrown to a height of up to several tens of kilometers.

Volcanoes are mountain-shaped formations from which hot magma erupts. How is a volcano formed? In the presence of cracks in the earth's crust, red-hot magma erupts to its surface under pressure. The slopes of the volcano are formed as a result of subsidence of rocks, lava, ash near the vent.