The very word "volcano" itself began to be used in everyday life in Ancient Rome, since that was the name of the ancient god of fire - Vulcan. The ancient Romans believed that every volcano that spouted smoke or lava was the chimney of a god's forge.
You can understand the structure of the volcano, since its principle is quite simple. In fact, a volcano is essentially a hole in the Earth's crust, and through this hole a mixture of molten rocks (lava), ash, steam and gases is ejected to the surface under high pressure. When volcanoes erupt, a large amount of volcanic ash rises into the air, which then covers everything in the area.
In most cases, a volcano is a single mountain or hill, which consists of those materials that are ejected during the eruption. Almost always, the top of a volcano is its crater; in fact, it is a hearth, the vent from which, during the eruption, all those substances about which it is written above are ejected. The crater necessarily has a connection with the vent, although sometimes this connection is blocked by frozen rock.
In 1943, on the territory of Mexico in one of its regions, local residents were eyewitnesses of a unique phenomenon that not everyone can see. At one point, in the center of the field where the corn grew, smoke appeared from the ground, and then lava began to appear. Literally in 90 days, on the site of a flat field, a cone-shaped mountain was formed, the height of which was about 300 meters. From the action of this new volcano, two nearby towns fell into desolation, and an even larger area of \u200b\u200bthe land around was simply killed by a large layer of volcanic ash, and part was scorched by burning lava.
How are volcanoes formed in general, according to what principle and algorithm? You need to start with the fact that in the depths of our planet the temperatures are quite high, and the closer you get to the center of the Earth, the hotter it gets. If you find yourself at a depth of about 40 kilometers, then you can see that everything around is in a molten state, these are various rocks that we are used to seeing in solid.
The fact is that as soon as minerals pass from a solid to a liquid state, their volume increases dramatically, so they need to look for a way out from time to time. It is for this reason that new mountain ranges are formed from time to time in different parts of the globe.
Due to this uplift of the earth's crust and the formation of solid rocks from igneous masses, pressure is reduced at great depths of the earth's crust. True, under the so-called "young" mountains, real lakes are formed, which consist of hot magma.
This very magma is essentially molten minerals and they rise up, while filling the cracks that appeared during the formation of mountain ranges. Day by day, the pressure in the underground burning lakes increases, and at some point it becomes critical. It is at such moments that the stone vault does not withstand great pressure, cracks and lava bursts through them. Here is an algorithm for the appearance of new volcanoes on our planet.
On Earth, the largest number of volcanoes are concentrated in places of tectonic regions and large faults; they are also present on island arcs and on the ocean floor.
In 98 percent of cases, volcanoes have the correct conical shape:
- if lava of a viscous consistency is squeezed out, then the volcano becomes domed;
- if liquid lava pours out of the crater, then a shield-shaped volcano is formed.
To date, there are such types of volcanoes:
- extinct, dormant and active;
- volcanoes with a central outlet;
- fissure volcanoes, which consist of several cones or look like gaping cracks
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The ancient Romans, watching black smoke and fire bursting from the top of the mountain into the sky, believed that they had an entrance to hell or to the possessions of Vulcan, the god of blacksmithing and fire. In honor of him, fire-breathing mountains are still called volcanoes.
In this article, we will figure out what the structure of the volcano is and look into its crater.
Active and extinct volcanoes
There are many volcanoes on Earth, both dormant and active. The eruption of each of them can last days, months, or even years (for example, the Kilauea volcano located on the Hawaiian archipelago woke up back in 1983 and still does not stop its work). After that, the craters of volcanoes are able to freeze for several decades, in order to then again remind themselves of themselves with a new ejection.
Although, of course, there are also such geological formations, the work of which was completed in the distant past. At the same time, many of them have still retained the shape of a cone, but there is no information about exactly how their eruption took place. Such volcanoes are considered extinct. As an example, Kazbek can be cited, since ancient times covered with shining glaciers. And in the Crimea and Transbaikalia there are heavily eroded and destroyed volcanoes that have completely lost their original shape.
What are volcanoes
Depending on the structure, activity and location, in geomorphology (the so-called science that studies the described geological formations), separate types of volcanoes are distinguished.
In general, they are divided into two main groups: linear and central. Although, of course, such a division is very approximate, since most of them are attributed to linear tectonic faults in the earth's crust.
In addition, there is also a shield-like and domed structure of volcanoes, as well as the so-called cinder cones and stratovolcanoes. By activity, they are defined as active, dormant or extinct, and by location - as terrestrial, underwater and subglacial.
What is the difference between linear volcanoes and central volcanoes?
Linear (fissure) volcanoes, as a rule, do not rise high above the earth's surface - they look like cracks. The structure of volcanoes of this type includes long supply channels associated with deep cracks in the earth's crust, from which liquid magma, which has a basalt composition, flows out. It spreads in all directions and, while solidifying, forms lava covers that erase forests, fill depressions, and destroy rivers and villages.
In addition, during the explosion of a linear volcano, explosive ditches may appear on the earth's surface, having a length of several tens of kilometers. In addition, the structure of volcanoes along the fissures is decorated with gently sloping ridges, lava fields, splashes and flat wide cones that radically change the landscape. By the way, the main component of the relief of Iceland is the lava plateaus that arose in this way.
If the composition of the magma turns out to be more acidic (increased content of silicon dioxide), then extrusive (ie squeezed out) swells with a loose composition grow around the mouth of the volcano.
The structure of volcanoes of the central type
A volcano of the central type is a cone-shaped geological formation that crowns a crater on top - a depression shaped like a funnel or bowl. By the way, it gradually moves up as the volcanic structure itself grows, and its size can be completely different and be measured both in meters and in kilometers.
Deep into the vent leads, along which magma rises up into the crater. Magma is a molten fiery mass that has a predominantly silicate composition. It is born in the earth's crust, where its hearth is located, and having risen upward, in the form of lava, it pours onto the surface of the earth.
An eruption is typically accompanied by the ejection of fine magma spurts that form ash and gases, which, interestingly, are 98% water. They are joined by various impurities in the form of flakes of volcanic ash and dust.
What determines the shape of volcanoes
The shape of a volcano largely depends on the composition and viscosity of the magma. Easily mobile basaltic magma forms shield (or shield-like) volcanoes. They are usually flat and have a large circumference. An example of such types of volcanoes is the geological formation located on the Hawaiian Islands and called Mauna Loa.
Cinder cones are the most common type of volcano. They are formed during the eruption of large fragments of porous slag, which, piling up, build a cone around the crater, and their small parts form sloping slopes. Such a volcano becomes higher with each eruption. An example is the Plosky Tolbachik volcano that exploded in December 2012 in Kamchatka.
Features of the structure of domed and stratovolcanoes
And the famous Etna, Mount Fuji and Vesuvius are examples of stratovolcanoes. They are also called layered, since they are formed by periodically erupting lava (viscous and quickly solidifying) and pyroclastic substance, which is a mixture of hot gas, hot stones and ash.
As a result of such ejections, these types of volcanoes have sharp cones with concave slopes, in which these deposits alternate. And the lava flows from them not only through the main crater, but also from cracks, while solidifying on the slopes and forming ribbed corridors that serve as a support for this geological formation.
Dome volcanoes are formed with the help of viscous granite magma, which does not flow down the slopes, but solidifies at the top, forming a dome, which, like a cork, clogs the vent and is kicked out by the gases accumulated under it over time. An example of such a phenomenon is the dome that forms over Mount St. Helens in the northwestern United States (it formed in 1980).
What is a caldera
The central volcanoes described above have, as a rule, the shape of a cone. But sometimes, during an eruption, the walls of such a volcanic structure collapse, and calderas are formed - huge depressions that can reach a depth of thousands of meters and a diameter of up to 16 km.
From what was said earlier, you remember that the structure of volcanoes includes a huge vent, along which molten magma rises during an eruption. When all the magma is on top, a huge void appears inside the volcano. It is precisely in it that the top and walls of a volcanic mountain can fall, forming on the earth's surface vast cauldron-shaped depressions with a relatively flat bottom, bordered by the remnants of the crash.
The largest to date is the Toba caldera, located on (Indonesia) and completely covered with water. The lake formed in this way has a very impressive size: 100/30 km and a depth of 500 m.
What are fumaroles
The craters of volcanoes, their slopes, foot, as well as the crust of cooled lava flows are often covered with cracks or holes, from which hot gases dissolved in magma burst out. They are called fumaroles.
As a rule, thick white steam swirls over large holes, because magma, as already mentioned, contains a lot of water. But besides it, fumaroles also serve as a source of emissions for carbon dioxide, all kinds of sulfur oxides, hydrogen sulfide, hydrogen halide and other chemical compounds that can be very dangerous for humans.
By the way, volcanologists believe that the fumaroles that make up the structure of the volcano make it safer, since the gases find a way out and do not accumulate in the depths of the mountain to form a bubble that will eventually push the lava to the surface.
The famous volcano, which is located near Petropavlovsk-Kamchatsky, can be attributed to such a volcano. The smoke swirling above it is visible in clear weather for tens of kilometers.
Volcanic bombs are also part of the structure of the Earth's volcanoes
If a long-dormant volcano explodes, then during the eruption, the so-called They fly out of its mouth. They consist of fused rocks or fragments of lava frozen in the air and can weigh several tons. Their shape depends on the composition of the lava.
For example, if the lava is liquid and does not have time to cool enough in the air, a volcanic bomb that has fallen to the ground turns into a cake. And basalt low-viscosity lavas rotate in the air, taking on this twisted shape or becoming like a spindle or a pear. Viscous - andesitic - pieces of lava become after falling like a bread crust (they are rounded or multifaceted and covered with a network of cracks).
The diameter of a volcanic bomb can reach seven meters, and these formations are found on the slopes of almost all volcanoes.
Types of volcanic eruptions
As Koronovsky N.V. pointed out in the book “Fundamentals of Geology”, which considers the structure of volcanoes and types of eruptions, all types of volcanic structures are formed as a result of various eruptions. Among them, 6 types stand out in particular.
When did the most famous volcanic eruptions occur?
The years of volcanic eruptions can, perhaps, be attributed to serious milestones in the history of mankind, because at that time the weather changed, a huge number of people died, and even entire civilizations were erased from the Earth (for example, as a result of the eruption of a giant volcano, the Minoan civilization died in 15 or 16 century BC e).
In 79 A.D. e. near Naples, Vesuvius erupted, burying the cities of Pompeii, Herculaneum, Stabia and Oplontius under a seven-meter layer of ash, leading to the death of thousands of inhabitants.
In 1669, several eruptions of the Etna volcano, as well as in 1766 - the Mayon volcano (Philippines) led to terrible destruction and death under lava flows of many thousands of people.
In 1783, the volcano Laki, which exploded in Iceland, caused a drop in temperature, which led in 1784 to crop failure and famine in Europe.
And on the island of Sumbawa, who woke up in 1815, the next year he left the whole Earth without summer, lowering the temperature in the world by 2.5 ° C.
In 1991, a volcano from the Philippines, with its explosion, also temporarily lowered it, however, already by 0.5 ° C.
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 comes out to the earth's surface, disintegrating 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, which 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 constantly or periodically erupt 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, underwater volcanoes in terms of their scale and volume of ejecta 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.
In February 1943, in one of the regions of Mexico, people witnessed a rare and amazing sight: a new volcano was born in the middle of a corn field! In just three months, a cone-shaped mountain 300 meters high was formed. As a result, two cities were destroyed, and a vast territory was buried under a layer of ash and lava.
How does the formation of volcanoes proceed? First of all, it should be remembered that the temperature in the depths of the Earth rises as it approaches the center of the Earth. At a depth of 35-40 km, most of the rocks are in a molten state.
When minerals change from solid to liquid, they increase in volume. As a result, new mountain ranges rise at various points on the earth's surface. This leads to a decrease in pressure in the thickness of the earth's crust, and huge lakes of magma - molten minerals - can appear under the newly formed mountains.
Magma rises up, filling the cracks that appeared in the process of mountain building. When the pressure in the underground lakes becomes too great, the stone vaults, unable to withstand it, bend upwards, and a new volcano is formed.
During the eruption that has begun, a mixture of hot gases, molten rocks and solid debris is pushed to the surface from the depths. Cooling, they form a cone-shaped top of the volcano, in the center of which there is a depression called a crater. In the middle of the crater there is a hole - a vent leading into the thickness of the earth's crust.
The material ejected through the vent to the surface is mainly a mixture of gases, however, along with them, a large amount of lava and solid particles that look like ash and cinders are also erupted.
Lava is actually magma flowing out of a volcano, but differs from the latter in its physical and chemical properties. Changes occur when magma rises to the surface and its temperature and pressure decrease dramatically.
Why are volcanoes located in certain places?
In the area of cities such as New York, London or Paris, there are no volcanoes, and they are unlikely to appear there in the future. However, in some areas of the globe, several volcanoes are located in one place at once.
The Pacific coast of Central America is one of the most active places of volcanic activity in the world. And in fact, more than two-thirds of the active volcanoes are located in this place, as well as many of those that have ceased their activity relatively recently.
And the reason is this: in these places the earth's crust is very weak compared to other regions of the globe. Where there is a weak section of the earth's crust, a volcano appears there.
Here is how it is formed. As we already know, the Earth's core is very hot. As the depth increases, so does the temperature. At a depth of 25 km, the temperature is so high that all rocks (here the temperature reaches 1000-1100 ° C) are in a molten state.
When rock melts, it expands in volume - it needs more space. In some regions of the Earth, new mountain systems were formed not so long ago (that means several thousand years ago). Under them and in this area, the pressure is lower than in other areas. This is a kind of weak spot in the earth's crust.
Molten rock, called "magma", infiltrates these areas, creating reservoirs of molten rock. Magma rises through cracks formed by the uplift of the earth's rocks. When the pressure in such a reservoir exceeds the forces that hold the magma underground, the molten rock breaks out, forming a volcano. The eruption stops with the end of the release of associated gas.
During the eruption, gaseous substances are mainly released, as well as a large amount of molten rock "lava", solid particles in the form of ash. An eruption is an explosion of gases, but part of the lava turns into dust, and during the eruption we observe a cloud of black smoke.
Volcanoes are geological formations on the Earth's surface where magma comes out in the form of lava. These mountains are not only on Earth, but also on other planets. So, the Olympus volcano on Mars reaches a height of several tens of kilometers. Such formations are dangerous not only with lava, but also with the release of a large amount of dust and ash into the atmosphere.
The eruption of the Icelandic volcano Eyjafjallajökull in 2010 made a lot of noise. Although it was not the most destructive in terms of strength, its proximity to Europe led to the impact of emissions on the transport system of the mainland. However, history knows many other cases of the destructive effects of volcanoes. Let's talk about the ten most famous and large-scale of them.
Vesuvius, Italy. On August 24, 79, the volcano Vesuvius erupted, which destroyed not only the well-known city of Pompeii, but also the cities of Stabiae and Herculaneum. Ashes even reached Egypt and Syria. It would be a mistake to assume that the catastrophe destroyed Pompeii alive, out of 20 thousand people, only 2 thousand died. Among the victims was the famous scientist Pliny the Elder, who approached the volcano on a ship in order to explore it and thus found himself practically at the epicenter of the disaster. During the excavations of Pompeii, it was found that under a multi-meter layer of ash, the life of the city froze at the time of the disaster - objects remained in their places, houses with furnishings, people and animals were found. Today, Vesuvius remains the only active volcano in the continental part of Europe, more than 80 of its eruptions are known in total, the very first one supposedly happened 9 thousand years ago, and the last one took place in 1944. Then the cities of Massa and San Sebastiano were destroyed, and 57 people died. Naples is located 15 kilometers from Vesuvius, the height of the mountain is 1281 meters.
Tambora, Sumbawa Island. The cataclysm on this Indonesian island happened on April 5, 1815. This is the largest eruption in modern history in terms of the number of people killed and the volume of ejected material. The catastrophe associated with the eruption and the ensuing famine killed 92,000 people. In addition, the Tambora culture, which Europeans had only met shortly before, completely disappeared from the face of the earth. The volcano lived for 10 days, decreasing during this time in height by 1400 meters. Ashes for 3 days hid the territory within a radius of 500 kilometers from the sun. According to the testimony of the British authorities in those days in Indonesia, it was impossible to see anything at arm's length. Most of the island of Sumbawa was covered with a meter layer of ash, under the weight of which even stone houses crumbled. 150-180 cubic kilometers of gases and pyroclassics were thrown into the atmosphere. The volcano therefore had a strong impact on the climate of the entire planet - ash clouds poorly transmitted the rays of the Sun, which led to a noticeable decrease in temperature. 1816 became known as "the year without summer", in Europe and America the snow melted only in June, and the first frosts appeared already in August. The result was massive crop failures and famine.
Taupo, New Zealand. 27 thousand years ago, a strong volcanic eruption occurred on one of the islands, surpassing even Tamboru in strength. Geologists consider this cataclysm the last such force in the history of the planet. As a result of the work of the supervolcano, Lake Taupo was formed, which today is the object of attention of tourists, as it is very beautiful. The last eruption of the giant took place in 180 AD. The ash and the blast destroyed half of all life on the North Island, about 100 cubic kilometers of tectonic matter fell into the atmosphere. The speed of the rock eruption was 700 km/h. The ash that rose into the sky painted sunsets and sunrises all over the world with purple, which was reflected in the ancient Roman and Chinese chronicles.
Krakatau, Indonesia. The volcano, located between the islands of Sumatra and Java, produced on August 27, 1883 the largest explosion of its kind in modern history. During the cataclysm, a tsunami up to 30 meters high appeared, which simply washed away 295 villages and cities, while about 37 thousand people died. The roar from the explosion was heard on 8% of the entire surface of the planet, and pieces of lava were thrown into the air to an unprecedented height of 55 kilometers. The wind carried the volcanic ash so much that after 10 days it was found at a distance of 5330 kilometers from the scene. The mountain-island then split into 3 small parts. The wave from the explosion circled the earth from 7 to 11 times, geologists believe that the explosion was 200 thousand times stronger than the nuclear strike on Hiroshima. Krakatau woke up before, so, in 535, his activity significantly changed the climate of the planet, perhaps then the islands of Java and Sumatra were divided. On the site of the volcano destroyed in 1883 during an underwater eruption in 1927, a new volcano appeared, Anak Krakatau, which is still quite active today. Its height is now 300 meters due to new activities.
Santorini, Greece. Approximately one and a half thousand years BC, a volcanic eruption occurred on the island of Thera, which put an end to the entire Cretan civilization. Sulfur covered all the fields, which made further farming unthinkable. According to some versions, it is Thera that is the very Atlantis described by Plato. Someone also believes that the eruption of Santorini entered the annals, like a pillar of fire seen by Moses, and the parted sea is nothing more than the consequences of the disappearance of the island of Thera under water. However, the Volcano continued its activity, in 1886 its eruption lasted a whole year, while pieces of lava flew straight out of the sea and rose to a height of 500 meters. As a result - several new islands nearby.
Etna, Sicily. About 200 eruptions of this Italian volcano are known. Among them were quite powerful ones, so, in 1169, about 15 thousand people died during the cataclysm. Today, Etna remains an active volcano with a height of 3329 meters, waking up about once every 150 years and destroying one of the nearby villages. Why don't people leave the slopes of the mountain? The fact is that the frozen lava helps the soil to become more fertile, which is why the Sicilians settle here. In 1928, besides, a miracle happened - the flow of red-hot lava stopped in front of the Catholic procession. This inspired the believers so much that in 1930 a chapel was erected on this site, 30 years later the lava stopped in front of it. The Italians protect these places, so in 1981 the local government created a reserve around Etna. It is curious that a blues music festival is even arranged on a calm volcano. Etna is quite large, exceeding the size of Vesuvius by 2.5 times. The volcano has from 200 to 400 side craters, lava erupts from one of them every three months.
Montagne Pele, Martinique island. The volcanic eruption on the island began in April 1902, and on May 8 a whole cloud of vapors, gases and red-hot lava hit the city of Saint-Pierre, located 8 kilometers away. A few minutes later he was gone, and of the 17 ships that were in the harbor at that moment, only one managed to survive. The ship "Roddam" escaped from the clutches of the elements with broken masts, smoking and littered with ashes. Of the 28 thousand inhabitants of the city, two escaped, one of them was called Opost Siparis, and he was sentenced to death. He was saved by the thick stone walls of the prison. Subsequently, the prisoner was pardoned by the governor, spending the rest of his life traveling the world with stories about what happened. The force of the blow was such that the monument on the square, weighing several tons, was thrown aside, and the heat was such that even the bottles melted. It is interesting that the outpouring of liquid lava did not directly occur, the impact was caused by vapors, gases and pulverized lava. Later, a sharp lava plug 375 meters high came out of the crater of the volcano. It also turned out that the bottom of the sea near Martinique had sunk several hundred meters. The city of Saint-Pierre, by the way, became famous for the birth of Napoleon's wife, Josephine Beauharnais, in it.
Nevado del Ruiz, Colombia. A volcano 5400 meters high, located in the Andes, splashed out lava flows on November 13, 1985, and the main blow fell on the city of Armero, located 50 kilometers away. It took only 10 minutes for the lava to destroy it. The death toll exceeded 21 thousand people, and in total at that time about 29 thousand lived in Armero. Sadly, no one listened to the volcanologists' information about the impending eruption, since the specialists' information was repeatedly not confirmed.
Pinatubo, Philippines. Until June 12, 1991, the volcano was considered extinct for 611 years. The first signs of activity appeared in April and the Philippine authorities managed to evacuate all residents within a radius of 20 kilometers. The eruption itself claimed the lives of 875 people, while the US naval base and the American strategic air base, located 18 kilometers from Pinatubo, were destroyed. The ejected ash covered an area of 125,000 km2 of the sky. The consequences of the disaster were a general decrease in temperature by half a degree and a reduction in the ozone layer, due to which a very large ozone hole formed over Antarctica. The height of the volcano before the eruption was 1486 meters, and after - 1745 meters. At the site of Pinatubo, a crater with a diameter of 2.5 kilometers was formed. Today, earthquakes regularly occur in this area, preventing any construction within a radius of tens of kilometers.
Katmai, Alaska. The eruption of this volcano on June 6, 1912 was one of the largest in the 20th century. The height of the ash column was 20 kilometers, and the sound reached the capital of Alaska, the city of Juneau, located 1200 kilometers away. At a distance of 4 kilometers from the epicenter, the ash layer reached 20 meters. Summer in Alaska turned out to be very cold, as the rays could not break through the cloud. After all, thirty billion tons of rocks were taken into the air! In the crater itself, a lake with a diameter of 1.5 kilometers formed, and it became the main attraction of the Katmai National Park and Reserve formed here in 1980. Today, the height of this active volcano is 2047 meters, and the last known eruption occurred in 1921.
