Volcanoes are. Volcanoes

Translated from Latin "volcano" means "flame, fire." In the depths of the planet due to a very high temperature, rocks melt to form magma. When this occurs, the release of a huge amount of gaseous substances, which increases the volume of the melt and its pressure on the surrounding solid rocks. Magma rushes into an area with less pressure up towards the surface of the Earth. Cracks in the earth's crust are filled with heated liquid rocks, layers of the earth's crust are broken and rise. Partially, the magma solidifies in the earth's crust with the formation of igneous veins and laccoliths. The rest of the hot magma comes to the surface during volcanic eruptions, in the form of lava, volcanic ash, gases, frozen lava ingots, fragments of rocks. The term "volcanism" refers to the movement of molten magma from the deep layers of the Earth to the surface of the earth or the ocean floor.

In the structure of each volcano, a channel through which lava moves is distinguished. This so-called vent usually ends in a crater - a funnel-shaped extension. The diameter of the craters varies, ranging from hundreds of meters to several kilometers. For example, the diameter of the crater of Vesuvius is more than 0.5 km. Overly large craters are called calderas. Thus, the caldera of the Uzon volcano, which is located in Kamchatka, has a diameter of 30 km.

Lava and eruptions

The height and shape of volcanoes determines the viscosity of the lava. If the lava is liquid and quickly flows down, a cone-shaped mountain does not form, for example, the Kilauza volcano in the Hawaiian Islands. The crater of this volcano looks like a lake of round shape with a diameter of about 1 km. The crater is filled with hot liquid lava, and its level rises at times, then descends, sometimes spilling over the edge.

Most of the volcanoes are characterized by viscous lava, which when cooled and forms a volcanic cone. The structure of such a cone is usually layered. On this basis it is possible to judge that the eruptions were carried out repeatedly, so that the volcano grew gradually with each emission of lava.

The height of volcanic cones is different and can range from tens of meters to several kilometers.  Widely known for a very high volcano in the Andes - Aconcagua (6960 m).

There are about 1500 volcanoes throughout the Earth, among them there are both active and extinct. For example, Klyuchevskaya Sopka in Kamchatka, Elbrus in the Caucasus, Kilimanjaro in Africa, Fujiyama in Japan, etc.

The vast majority of active volcanoes are located around the perimeter of the Pacific Ocean. They make up the Pacific Ring of Fire. Also the zone of active volcanism is considered the Mediterranean-Indonesian belt. For example, there are 28 volcanoes in Kamchatka, and there are more than 600 in total. There is a certain pattern in the location of active volcanoes. They are localized in the moving areas of the earth's crust - in seismic belts.

In the ancient geological epoch of our planet, volcanism was more active than at present. In addition to typical (central) eruptions, fissure ones were also noted. From the huge faults in the crust stretching tens and hundreds of kilometers, the bubbling lava was thrown to the surface. When this occurred, the formation of lava covers, both continuous and intermittent. These covers lined the terrain. The thickness of the lava layer could reach 2 km. Such processes led to the formation of lava plains. These include some areas of the Central Siberian Plateau, the Armenian Highlands, the Deccan Plateau in India, the Columbia Plateau.

Related materials:

Volcanoes are geological formations on the surface of the earth's crust or the crust of another planet, where magma comes to the surface, forming lava, volcanic gases, stones (volcanic bombs) and pyroclastic flows.

The word "volcano" comes from the name of the ancient Roman god of fire Vulcan.

The science that studies volcanoes is volcanology, geomorphology.

Volcanoes are classified according to the form (thyroid, stratovolcanoes, slag cones, dome), activities (active, dormant, extinct), location (terrestrial, submarine, subglacial), etc.

Volcanic activity [edit]
Depending on the degree of volcanic activity, volcanoes are divided into active, dormant and extinct. The active volcano is considered to be a volcano that erupted in a historical period of time or in the Holocene. The concept of "active" is quite inaccurate, as the volcano, having active fumaroles, some scientists refer to active, and some - to extinct. Inactive dormant volcanoes are considered to be sleeping, where eruptions are possible, and extinct volcanoes are considered to be unlikely.

However, among volcanologists there is no consensus on how to identify an active volcano. The period of activity of a volcano can last from several months to several million years. Many volcanoes showed volcanic activity several tens of thousands of years ago, but at the present time are not considered active.

Astrophysicists, in the historical aspect, believe that volcanic activity, caused in turn by the tidal influence of other celestial bodies, may contribute to the emergence of life. In particular, volcanoes contributed to the formation of the Earth's atmosphere and hydrosphere, throwing out a significant amount of carbon dioxide and water vapor. Scientists also note that too active volcanism, such as on the satellite of Jupiter Io, can make the surface of the planet uninhabitable. At the same time, weak tectonic activity leads to the disappearance of carbon dioxide and sterilization of the planet. “These two cases are potential limits of the habitability of the planets and exist along with the traditional parameters of the life zones for systems of low-mass main sequence stars,” the scientists write
facts Edit
In 1963 Surtsey Island was formed as a result of an eruption of an underwater volcano in the south of Iceland.
The eruption of the volcano Krakatau in Indonesia in 1883 caused the loudest roar ever heard in history; the sound was heard at a distance of more than 4,800 km from the volcano. Atmospheric shock waves circled the Earth seven times and were still visible for 5 days. The volcano claimed the lives of more than 36,000 people, demolished 165 villages and damaged 132 more (mostly with the help of the tsunami that followed the eruption). After 1927, volcanic eruptions formed a new volcanic island called Anak-Krakatau (“Child Krakatau”).
Kilauea Volcano, located in the Hawaiian archipelago - the most active volcano at the moment. The volcano rises only 1.2 km above sea level, but its last long eruption began in 1983 and is still ongoing. Lava flows into the ocean for 11-12 km.
An active volcano has been discovered in Taipei (Taiwan). It was previously believed that the last activity of the volcano in this area was more than 200 thousand years ago, but it turned out that the last activity was only 5,000 years ago.
In 2010, a volcanic eruption near the Eyjafjallajökull glacier caused the cancellation of more than 60 thousand flights throughout Europe.
Perhaps the largest flow of basaltic lava on Earth is a volcanogenic plateau in the valleys of the Hi-Gol and John-Bolok rivers with access to the valley of the Oka Sayan river in Eastern Siberia in the mountains of the Eastern Sayan; the length of the L-shaped narrow basalt plateau formed in the post-glacial period 10-12 thousand years ago as a result of fissure outpouring of lava is about 75 km. On the plateau are the volcanoes Peretolchina, Kropotkin and Stary.