How long does lava take to cool? What is lava? Types of lava

In today's article we will look at the types of lava based on temperature and viscosity.

As you probably know, lava is molten rock that erupts from active volcano to the surface of the earth.

Outer shell globe– the earth’s crust, underneath it hides a hot, liquid layer called the mantle. Hot magma makes its way to the top through cracks in the earth's crust.

The entry points of hot magma into the earth's surface are called "hot spots", which means hot spots

(pictured left). This usually occurs within the boundaries between tectonic plates and gives rise to entire volcanic chains.

What is the temperature of the lava?

Lava has a temperature of 700 to 1200C. Depending on the temperature and composition, lava is divided into three types of fluidity.

Liquid lava has the highest temperature, more than 950C, and its main component is basalt. With such a high temperature and fluidity, lava can flow for several tens of kilometers before it stops and hardens. Volcanoes that erupt this type of lava are often very gentle, since it does not linger at the vent, but spreads around.

Lava with a temperature of 750-950C is andesitic. It can be recognized by its frozen round blocks with a broken crust.

Lava with the lowest temperature of 650-750C is acidic and very rich in silica. A characteristic feature This lava has slow speed and high viscosity. Very often, during an eruption, this type of lava forms a crust over the crater (pictured on the right). Volcanoes with this temperature and type of lava often have steep slopes.

Below we will show you some photos of hot lava.

Volcanic eruptions are an undeniably fascinating, albeit deadly, spectacle. These mountains of fire can kill you in many ways - pyroclastic flows, super-velocity mud flows, radioactive ash fallout, lava bombs. They kill everyone indiscriminately, and the one who happens to be in their path is unhappy.

Have you ever wondered what it's like when a person falls into lava? Thanks to scientific experiments and several accidents involving people, we know the answer to this question.

If the lava flow is large enough, a person can drown in the molten rock, the heat from which can even melt internal organs. If the person who falls into the flow does not die due to stress, the lava will flow in and physically eat away all the organs. Of course, there are many more nuances here, but these are considered the main ones.

Types of lava

First, it's worth noting that there are different varieties of lava. Some are hotter, others have more low temperature, and still others are sticky. It is the properties of the lava that will determine how fast or slow your untimely death will be.

Generally speaking, most lava temperatures are around 1000°C and are incredibly sticky or viscous. It's more like very hot oil than water, so if you get caught in one, the lava will stick to you like glue. Since the average density of lava is 3-4 times greater than our body, a person will slowly sink into it, perhaps over several minutes.

What happens to the human body in a lava flow

Thus, a person caught in this fatal bath will be stuck on the surface for several minutes, while the lava will lead to extensive burns. This type of injury not only destroys upper layer skin (epidermis), but also nerve endings, and also disconnects blood vessels in the dermis.
Subcutaneous fat will also evaporate. The skin itself will not even have a chance to become dehydrated. The skeleton will not be able to withstand such extreme temperatures, and therefore will begin to melt too quickly, there will literally be nothing left of it.

But don't worry. Thanks to the mixture of highly toxic acidic and hot gases inside the lava lake, you are likely to suffocate, faint, and die long before your body melts.

"Safe Lava"

The safest lava to fall can be found near a strange volcano in Tanzania called Ol Doinyo Lengai. It sits atop the East African Rift Line, along which the continent is tearing itself apart. The lava temperature of this volcano never exceeds 510 °C, which means that if you fall into it, you still have a chance to survive. A similar thing happened to a local Maasai tribesman several years ago.

Flow speed

But the problem is that this lava, according to some evidence, is 10 times more liquid than water. This means that she will literally chase you if you try to run away from her down the slope.

Although this is nothing compared to the fastest lava in the world, which erupts from Nyiragongo, a stratovolcano in the Democratic Republic of the Congo. During the 1977 eruption, lava flows with a temperature of 1200 °C moved at a speed of 60 kilometers per hour.

Unexpected danger

There is always a cooled crust at the top of a lava flow, so if something or someone gets caught in it, it breaks through. This disturbs the lava lake, causing it to explode and release a lot of gas. As a result, flames appear around the unfortunate man who is splashing in the center, which, of course, does not contribute in any way to the hope of salvation.

Origin of lava

Lava is formed when a volcano erupts magma onto the Earth's surface. Due to cooling and interaction with gases included in the atmosphere, magma changes its properties, forming lava. Many volcanic island arcs are associated with deep fault systems. Earthquake centers are located approximately at a depth of up to 700 km from the level earth's surface, that is, the volcanic material comes from the upper mantle. On island arcs it often has an andesitic composition, and since andesites are similar in composition to the continental crust, many geologists believe that the continental crust in these areas builds up due to the influx of mantle material.

Volcanoes that operate along oceanic ridges (such as the Hawaiian ridge) erupt predominantly basaltic material, such as Aa lava. These volcanoes are probably associated with shallow earthquakes, the depth of which does not exceed 70 km. Because basaltic lavas are found both on continents and along ocean ridges, geologists hypothesize that there is a layer just below the Earth's crust from which basaltic lavas come.

However, it is unclear why in some areas both andesites and basalts are formed from mantle material, while in others only basalts are formed. If, as is now believed, the mantle is indeed ultramafic (enriched in iron and magnesium), then lavas derived from the mantle should have a basaltic rather than andesitic composition, since andesite minerals are absent in ultramafic rocks. This contradiction is resolved by the theory of plate tectonics, according to which the oceanic crust moves under island arcs and melts at a certain depth. These molten rocks erupt in the form of andesite lavas.

Types of lava

Lava varies from volcano to volcano. It differs in composition, color, temperature, impurities, etc.

Carbonate lava

Half consists of sodium and potassium carbonates. This is the coldest and most liquid lava on earth; it flows along the ground like water. The temperature of carbonate lava is only 510-600 °C. The color of hot lava is black or dark brown, but as it cools it becomes lighter, and after a few months it becomes almost white. Solidified carbonate lavas are soft and brittle and easily dissolve in water. Carbonate lava flows only from the Oldoinyo Lengai volcano in Tanzania.

Silicon lava

Silicon lava is most typical for the volcanoes of the Pacific Ring of Fire; such lava is usually very viscous and sometimes solidifies in the crater of the volcano even before the end of the eruption, thereby stopping it. A plugged volcano may swell a little, and then the eruption resumes, usually with a powerful explosion. Lava contains 53-62% silicon dioxide. It has average speed flow (several meters per day), temperature 800-900 °C. If the silica content reaches 65%, then the lava becomes very viscous and clumsy. The color of hot lava is dark or black-red. Solidified silicon lavas can form black volcanic glass. Such glass is obtained when the melt cools quickly without having time to crystallize.

Basalt lava

The main type of lava erupted from the mantle is characteristic of oceanic shield volcanoes. Half consists of silicon dioxide (quartz), half - from aluminum oxide, iron, magnesium and other metals. This lava is very mobile and can flow at a speed of 2 m/s (the speed of a fast walking person). It has a high temperature of 1200-1300 °C. Basaltic lava flows are characterized by a small thickness (a few meters) and a large length (tens of kilometers). The color of hot lava is yellow or yellow-red.

Literature

Natela Yaroshenko Fiery youth of volcanoes // Encyclopedia of natural wonders. - London, New York, Sydney, Moscow: Reader's Digest, 2000. - pp. 415-417. - 456 s. - ISBN 5-89355-014-5

Notes

Links

Metamorphoses of lava on the website of the magazine “Around the World”

Wikimedia Foundation. 2010.

Synonyms:

See what "Lava" is in other dictionaries:

Lavash, oh, I eat... Russian word stress

Dictionary Dahl

Women a different mixture of molten rocks flowing from the mouth of the fire mountains; swimmer II. LAVA female a bench, a blank, fixed bench, a board for a seat along the wall; sometimes a bench, a portable board with legs; | south., nov., yarosl.... ... Dahl's Explanatory Dictionary

- (Spanish lava flowing rain stream). Molten material erupted by volcanoes. Dictionary of foreign words included in the Russian language. Chudinov A.N., 1910. LAVA is a substance ejected from a vent by a volcano. A complete dictionary of foreign words... Dictionary of foreign words of the Russian language

Production, mass, face, reach, structure, attack, magma Dictionary of Russian synonyms. lava noun, number of synonyms: 20 aa lava (2) at... Synonym dictionary

LAVA, molten rock, or MAGMA, reaching the surface of the Earth and flowing through volcanic vents in streams or sheets. There are three main types of lava: bubbly, like pumice; glassy, like obsidian; Equal-grained. By… … Scientific and technical encyclopedic dictionary

Ushakov's Explanatory Dictionary

1. LAVA1, lava, female. (Italian lava). 1. Molten fiery liquid mass ejected by a volcano during an eruption. 2. transfer Something grandiose, fast, steadily moving, sweeping away everything along the way. “We are marching on a revolutionary path.” Mayakovsky... Ushakov's Explanatory Dictionary

1. LAVA, s; and. [ital. lava] 1. Molten mineral mass erupted by a volcano. 2. whom what or what. An uncontrollably moving mass (people, animals, etc.). ◁ Lava, in the sign. adv. Spread like lava (in a continuous stream). Lava, oh, oh; (1 digit... encyclopedic Dictionary

Everything about everything. Volume 5 Likum Arkady

Why is lava hot?

The earth in the center is a very hot place. If we could get 48 km closer to the center of the Earth, the temperature there would be 1200 degrees Celsius. At the core, or center, of the Earth, temperatures reach 5,500 degrees Celsius. At this temperature, the stone exists in a molten state. Lava is molten stone mixed with steam and gas, which forcefully erupts from the bowels of the Earth. It breaks out from the center of the Earth through cracks in the crust.

Sometimes the cracks are circular. Then the lava comes out through them, spreads into a round puddle and freezes in the shape of a mountain. If lava erupts again, it builds on top of the first eruption and makes the mountain taller. If eruptions are repeated, layer after layer is added, forming a mountain called a volcano. When lava erupts and spreads across the Earth, it destroys everything in its path.

This happens because the rapid flow of molten stone has a temperature of 1090 to 1640 degrees Celsius. Cities that are located close to volcanoes are always in danger of being destroyed if lava erupts. Sometimes this does not happen for a long time and people think that they are safe forever. And then suddenly the eruptions start again. This happened two thousand years ago with the Italian city of Pompeii. It was completely buried under a lava flow and a layer of ash from Mount Vesuvius.

From the book Big Soviet Encyclopedia(GO) of the author TSB

From the book Great Soviet Encyclopedia (LA) by the author TSB

From the book Great Soviet Encyclopedia (PI) by the author TSB

From the book Great Soviet Encyclopedia (SHA) by the author TSB

From the book Everything about everything. Volume 2 author Likum Arkady

From the book Everything about everything. Volume 3 author Likum Arkady

From the book Soviet satirical press 1917-1963 author Stykalin Sergey Ilyich

From the book Man in the Water author Konovalov Evgeniy Dmitrievich

From the book Who's Who in the Natural World author Sitnikov Vitaly Pavlovich

From the author's book

Why is the water in the geyser hot? Even if a huge stream of water did not shoot into the air from the geyser, it would still remain one of the most interesting wonders nature. The geyser really is hot spring, and a hot spring is in itself

From the author's book

Why is the earth hot inside? Outer thickness earth's crust in different places it ranges from 15 to 50 km, and its temperature increases as it approaches the center of the Earth. Approximately every 40 m it increases by one degree. It's so hot at a depth of three kilometers

From the author's book

HOT WASH A bi-weekly magazine of satire and humor. The only issue was published on October 31, 1934 in Gorky. Publication of the newspaper “On the Rails of Ilyich” of the political department of the 4th branch of the Moscow-Kursk Railway. Responsible editor - A. V. Shuklin. Printed on 8 pages, with

From the author's book

Chapter Six REAL DANGERS OF WATER In previous chapters, some objectively difficult and potentially dangerous situations have already been mentioned: jumping into water in an unfamiliar place; the fatal role of alcohol in accidents on the water; jellyfish - "cross-shaped" jellyfish that live in Pacific Ocean;

From the author's book

Why is the water in the geyser hot? Even if a huge stream of water did not shoot into the air from the geyser, it would still remain one of the most interesting wonders of nature. A geyser is truly a hot spring, and a hot spring is itself

Types of volcanoes and lava have fundamental differences that make it possible to distinguish several main types from them.

Types of volcanoes

Hawaiian type of volcanoes. These volcanoes do not exhibit significant release of vapors and gases; their lava is liquid.
Strombolian type of volcanoes. These volcanoes also have liquid lava, but they emit a lot of vapors and gases, but do not emit ash; As the lava cools, it becomes wavy.
Volcanoes like Vesuvius characterized by more viscous lava, vapors, gases, volcanic ash and other solid eruption products are released abundantly. As lava cools, it becomes blocky.
Peleian type of volcanoes. Very viscous lava causes strong explosions with the release of hot gases, ash and other products in the form of scorching clouds, destroying everything in its path, etc.

Hawaiian type of volcanoes

Hawaiian-type volcanoes During an eruption, they calmly and abundantly pour out only liquid lava. These are the volcanoes of the Hawaiian Islands. The Hawaiian volcanoes, whose bases lie on the ocean floor at a depth of approximately 4,600 meters, were undoubtedly the result of powerful underwater eruptions. The strength of these eruptions can be judged by the fact that the absolute height of the extinct volcano Mauna Kea (i.e., the “white mountain”) reaches from the ocean floor 8828 meters (relative height of the volcano 4228 meters). The most famous are Mauna Loa, otherwise “high mountain” (4168 meters), and Kilauea (1231 meters). Kilauea has a huge crater - 5.6 kilometers long and 2 kilometers wide. At the bottom, at a depth of 300 meters, lies a seething lava lake. During eruptions, powerful lava fountains are formed on it, up to 280 meters high, with a diameter of approximately 30 meters. Kilauea Volcano. Droplets of liquid lava thrown to such a height are stretched in the air into thin threads, called by the indigenous population “the hair of Pele” - the goddess of fire of the ancient inhabitants of the Hawaiian Islands. Lava flows during the Kilauea eruption sometimes reached enormous sizes - up to 60 kilometers in length, 25 kilometers in width and 10 meters in thickness.

Strombolian type of volcanoes

Strombolian type of volcanoes emitting mainly only gaseous products. For example, the Stromboli volcano (900 meters high), on one of the Aeolian Islands (north of the Strait of Messina, between the island of Sicily and the Apennine Peninsula).

Volcano Stromboli on the island of the same name. At night, the reflection of its fiery vent in a column of vapors and gases, clearly visible at a distance of up to 150 kilometers, serves as a natural beacon for sailors. Another natural lighthouse is widely known among sailors all over the world, in Central America off the coast of El Salvador is the Tsalko volcano. Gently every 8 minutes it emits a column of smoke and ash, rising 300 meters. Against a dark tropical sky, it is effectively illuminated by the crimson glow of lava.

Volcanoes like Vesuvius

The most complete picture of an eruption is provided by volcanoes of the type. A volcanic eruption is usually preceded by a strong underground rumble that accompanies the impacts and tremors of earthquakes. Choking gases begin to be released from cracks on the slopes of the volcano. The release of gaseous products - water vapor and various gases (carbon dioxide, sulfur dioxide, hydrochloride, hydrogen sulfide and many others) increases. They are released not only through the crater, but also from fumaroles (fumarole is a derivative of the Italian word "fumo" - smoke). Plumes of steam along with volcanic ash rise several kilometers into the atmosphere. Masses of light gray or black volcanic ash, representing tiny pieces of solidified lava, are carried for thousands of kilometers. The ashes of Vesuvius, for example, reach Constantinople and North America. Black clouds of ash obscure the sun, turning the bright day into dark night. Strong electrical voltage from the friction of ash particles and vapors manifests itself in electrical discharges and thunderclaps. Vapors raised to a considerable height condense into clouds, from which streams of mud pour out instead of rain. Volcanic sand, stones of various sizes, as well as volcanic bombs - rounded pieces of lava frozen in the air - are thrown out of the volcano's mouth. Finally, lava appears from the crater of the volcano, which rushes down the mountainside like a fiery stream.

A volcano of the same type - Klyuchevskaya Sopka

This is how the picture of the eruption of a volcano of this type - Klyuchevskaya Sopka on October 6, 1737, is conveyed (more details:), the first Russian explorer of Kamchatka, Acad. S. P. Krasheninnikov (1713-1755). He took part in the Kamchatka expedition while still a student at the Russian Academy of Sciences in 1737-1741.

The whole mountain seemed like a hot stone. The flames, which were visible inside it through the crevices, sometimes rushed down like rivers of fire, with a terrible noise. In the mountain one could hear thunder, crashing and swelling, as if by strong bellows, from which all nearby places trembled.

A modern observer gives an unforgettable picture of the eruption of the same volcano on the night of New Year 1945:

A sharp orange-yellow cone of flame, one and a half kilometers high, seemed to pierce the clouds of gases that rose in a huge mass from the crater of the volcano to approximately 7000 meters. From the top of the fiery cone, hot volcanic bombs fell in a continuous stream. There were so many of them that they gave the impression of a fabulous fiery blizzard.

The figure shows samples of various volcanic bombs - these are clumps of lava that have taken a certain shape. They acquire a round or spindle-shaped shape by rotating during flight.

Volcanic bomb of spherical shape - a sample from Vesuvius;
Trass - porous trachytic tuff - specimen from Eichel, Germany;
Volcanic fusiform bomb sample forms from Vesuvius;
Lapilli - small volcanic bombs;
Encrusted volcanic bomb - specimen from Southern France.

Peleian type of volcanoes

Peleian type of volcanoes presents an even more terrible picture. As a result terrible explosion a significant part of the cone suddenly sprays into the air, covering it with an impenetrable haze sunlight. This was the eruption.

The Japanese volcano Bandai-San also belongs to this type. For more than a thousand years it was considered extinct, and suddenly, in 1888, a significant part of its 670-meter-high cone flies into the air.

Volcano Bandai-san. The awakening of the volcano from a long rest was terrible:

the blast wave uprooted trees and caused terrible destruction. The atomized rocks remained in the atmosphere in a dense veil for 8 hours, blocking out the sun, and the bright day gave way to a dark night... There was no release of liquid lava.

This type of volcanic eruption of the Peleian type is explained by presence of very viscous lava, preventing the release of vapors and gases accumulated under it.

Rudimentary forms of volcanoes

In addition to the listed types, there are rudimentary forms of volcanoes, when the eruption was limited to the breakthrough of only vapors and gases to the surface of the earth. These rudimentary volcanoes, called “maars,” are found in Western Germany near the Eifel. Their craters are usually filled with water and in this respect the maars are similar to lakes, surrounded by a low rampart of rock fragments ejected by a volcanic explosion. Rock fragments also fill the bottom of the maar, and deeper the ancient lava begins. The richest diamond deposits in South Africa, located in ancient volcanic channels, are, by their nature, apparently formations similar to maars.

Lava type

Based on silica content, they are classified acidic and basic lavas. In the former, its amount reaches 76%, and in the latter it does not exceed 52%. Acidic lavas They are distinguished by their light color and low specific gravity. They are rich in vapors and gases, viscous and inactive. When cooled, they form so-called block lava.

Basic lavas, on the contrary, are dark in color, fusible, low in gases, have high mobility and significant specific gravity. When cooled, they are called "wavy lavas."

Lava of Vesuvius volcano

By chemical composition lava is different not only at volcanoes various types, but also at the same volcano depending on the periods of eruptions. For example, Vesuvius in modern times it pours out light (acidic) trachyte lavas, while the more ancient part of the volcano, the so-called Somma, is composed of heavy basaltic lavas.

Lava movement speed

Average lava movement speed- five kilometers per hour, but in some cases the liquid lava moved at a speed of 30 kilometers per hour. The spilled lava soon cools and a dense slag-like crust forms on it. Due to the poor thermal conductivity of lava, it is quite possible to walk on it, like on the ice of a frozen river, even while the lava flow is moving. However, inside the lava remains at a high temperature for a long time: metal rods lowered into cracks of the cooling lava flow quickly melt. Under the outer crust, the slow movement of lava continues for a long time - it was noted in a flow 65 years ago, while traces of heat were detected in one case even 87 years after the eruption.

Lava flow temperature

Seven years after the 1858 eruption, the lava of Vesuvius still contained temperature at 72°. The initial temperature of the lava was determined for Vesuvius to be 800-1000°, and the lava of the Kilauea crater (Hawaii Islands) was 1200°. In this regard, it is interesting to see how two researchers from the Kamchatka volcanological station measured the temperature of the lava flow.

In order to carry out the necessary research, they jumped onto the moving crust of the lava flow at the risk of their lives. They had asbestos boots on their feet, which did not conduct heat well. Although it was cold November and it was blowing strong wind, however, even in asbestos boots, the feet still became so hot that one had to alternately stand on one foot or the other so that the sole would cool down at least a little. The temperature of the lava crust reached 300°. Brave researchers continued to work. Finally, they managed to break through the crust and measure the temperature of the lava: at a depth of 40 centimeters from the surface it was 870°. After measuring the temperature of the lava and taking a gas sample, they safely jumped onto the frozen side of the lava flow.

Due to the poor thermal conductivity of the lava crust, the air temperature above lava flow changes so little that trees continue to grow and bloom even on small islands bordered by branches of a fresh lava flow. Lava outpouring occurs not only through volcanoes, but also through deep cracks in the earth's crust. In Iceland there are lava flows frozen between layers of snow or ice. Lava, filling cracks and voids in the earth's crust, can maintain its temperature for many hundreds of years, which explains the presence hot springs in volcanic areas.

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