It's hard to find a person who hasn't taken an interest in volcanoes at least once. 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 does not leave anyone 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 exits 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 lava flows. The volcanic cone itself consists of many layers of products of activity: solidified lava, volcanic bombs and ash.
Becausethe 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 their name in honor of the ancient Roman god Vulcan. It was believed that fire and smoke were flying from his underground forge. Such interesting facts about volcanoes fuel the curiosity of all kinds 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, the rebellious gladiators of Spartacus were hiding on its top. And the mountain was covered with lush vegetation.
Mount Elbrus, the highest peak in Russia, belongs to extinct volcanoes. Its two-headed apex consists of two cones merged at their bases.
Volcanic eruption as a geological process
An eruption is the process of ejection of red-hotmagmatic products in solid, liquid and gaseous states. 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 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 the Krakatoa volcano lost most of its part. 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 areaPacific "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.
This is where the highest active volcano in Eurasia - Klyuchevskaya Sopka is located. 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 springs that periodically eject fountains of boiling water and steam. Their activity is connected with magma that has risen through 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 is the Giant Geyser -throws out a column of water and steam to a height of about 30 m!
Which volcano is the tallest?
Determining this is not so easy. 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 with 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 him have a lower height - “only” 5897 m, but then his last eruption was in 1942, and at Lluillaillaco - already in 1877
Also, the highest volcano on Earth can be considered the Hawaiian Mauna Loa. 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
Have anyone heard about the Valley of Volcanoes in the Crimea? After all, veryit is hard 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 sets the volcano in motion, 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 last for several days, accompanied by a local earthquake, underground rumble. The result is a low cone of hardened mud.
Regions 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, a volcano intensified on the island of Java, flooding a vast territory with its mud, including many buildings. According to the local population, this was due to drillingwell that disturbed deep rock layers.
Interesting facts about volcanoes
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 there. 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. An explosion equivalent to 500 bombs dropped on Hiroshima fell ashes across four states.
The Icelandic volcano Eyjafällajökull became famous for throwing ash and smoke into chaos in European air traffic in the spring of 2010. And its name has baffled hundreds of radio and television announcers.
Philippine volcano Pinatubo last erupted in 1991. At the same time there weretwo 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 produce 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 Armenian capital 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.
