Contained in volcanic gases. What does "volcanic gases" mean?

Gases Gastroenterology deals directly with this phenomenon. The gases formed in the intestines are methane, hydrogen sulfide. Methane is produced due to the presence of certain bacteria. Exhaust gases are the winds that our body emits. They are always connected with our

During a volcanic eruption, products of volcanic activity are released, which can be liquid, gaseous and solid.
Gaseous - fumaroles and sophioni, play an important role in volcanic activity. During the crystallization of magma at depth, the released gases raise the pressure to critical values ​​​​and cause explosions, throwing clots of red-hot liquid lava to the surface. Also, during volcanic eruption, a powerful release of gas jets occurs, creating huge mushroom clouds in the atmosphere. Such a gas cloud, consisting of droplets of molten (over 7000c) ash and gases, formed from the cracks of the Mont Pele volcano, in 1902, destroyed the city of Saint-Pierre and 28,000 of its inhabitants.
The composition of gas emissions largely depends on temperature. The following types of fumaroles are distinguished:

a) Dry - temperature about 5000C, contains almost no water vapor; saturated with chloride compounds.
b) Acidic, or hydrochloric-hydrogen-sulphurous - the temperature is approximately equal to 300-4000C.
c) Alkaline, or ammonia - the temperature is not more than 1800C.
d) Sulphurous, or solfatars - temperature is about 1000C, mainly consists of water vapor and hydrogen sulfide.
e) Carbon dioxide, or mophers - the temperature is less than 1000C, mainly carbon dioxide.

Liquid - characterized by temperatures in the range of 600-12000C. Represented by lava.

The viscosity of lava is determined by its composition and depends mainly on the content of silica or silicon dioxide. With its high value (more than 65%), the lavas are called acid, they are relatively light, viscous, inactive, contain a large amount of gases, and cool slowly. A lower content of silica (60-52%) is characteristic of medium lavas; they, like acidic ones, are more viscous, but they are usually heated more strongly (up to 1000-12000s) compared to acidic ones (800-9000s). Basic lavas contain less than 52% silica and are therefore more fluid, mobile, and free-flowing. When they solidify, a crust forms on the surface, under which further movement of the liquid occurs.

Solid products include volcanic bombs, lapilli, volcanic sand and ash. At the time of the eruption, they fly out of the crater at a speed of 500-600 m / s.

Volcanic bombs are large pieces of hardened lava with a diameter ranging from a few centimeters to 1 m or more, and in mass they reach several tons (during the eruption of Vesuvius in 79 AD, volcanic bombs "tears of Vesuvius" reached tens of tons). They are formed during an explosive eruption, which occurs when the gases contained in the magma are rapidly released from the magma. Volcanic bombs come in 2 categories: 1st, arising from more viscous and less gas-saturated lava; they retain their correct shape even when they hit the ground due to the hardening crust formed when they cool. 2nd, formed from more liquid lava, during the flight they take on the most bizarre shapes, further complicated by impact. Lapilli are relatively small fragments of slag 1.5-3 cm in size, having a variety of shapes. Volcanic sand - consists of relatively small particles of lava (і 0.5 cm). Even smaller fragments, ranging in size from 1 mm or less, form volcanic ash, which, settling on the slopes of the volcano or at some distance from it, forms volcanic tuff.

Volcanic eruptions

Volcanoes - (named after the god of fire Vulcan), a geological formation that occurs above channels and cracks in the earth's crust through which lava, hot gases and rock fragments erupt onto the earth's surface from the depths of magmatic sources. Volcanoes usually represent individual mountains composed of eruptions.

Volcanoes are divided into active, dormant and extinct. The former include volcanoes that are currently erupting constantly or periodically. Dormant volcanoes are those whose eruptions are not known, but they have retained their shape and local earthquakes occur under them. Extinct volcanoes are called heavily destroyed and eroded volcanoes without any manifestations of volcanic activity.

Depending on the shape of the supply channels, volcanoes are divided into central and fissure volcanoes.

Deep magma chambers can be located in the upper mantle at a depth of about 50-70 km (Klyuchevskaya Sopka volcano in Kamchatka) or the earth's crust at a depth of 5-6 km (Vesuvius volcano, Italy) and deeper.

Volcanic phenomena

Eruptions are long-term (for several years, decades and centuries) and short-term (measured by hours). The precursors of eruptions include volcanic earthquakes, acoustic phenomena, changes in the magnetic properties and composition of fumarole gases, and other phenomena.

Beginning of the eruption

Eruptions usually begin with an increase in gas emissions, first along with dark, cold fragments of fishing, and then with red-hot ones. These emissions are in some cases accompanied by an outpouring of lava. The height of the rise of gases, water vapor saturated with heat and debris, depending on the strength of the explosions, ranges from 1 to 5 km (during the eruption of the Bezymyanny volcano in Kamchatka in 1956, it reached 45 km.). The ejected material is transported over distances from several to tens of thousands of kilometers. The volume of ejected clastic material sometimes reaches several km3. With some eruptions, the concentration of volcanic ash in the atmosphere is so great that darkness occurs, similar to darkness in an enclosed space. This took place in 1956 in the village of Klyuchi, located 40 km from Bezymyanny volcano.

The eruption is an alternation of weak and strong explosions and lava outpourings. Explosions of maximum force are called climactic paroxysms. After them, there is a decrease in the strength of explosions and a gradual cessation of eruptions. The volume of the erupted lava is up to tens of km3.

Eruption types

Volcanic eruptions are not always the same. Depending on the amount of products (gaseous, liquid and solid) and the viscosity of lavas, 4 main types of eruptions have been distinguished: effusive, mixed, extrusive and explosive, or, as they are more commonly called, respectively, Hawaiian, Strombolian, dome and Vulcan.

The Hawaiian type of eruption, which most often creates shield volcanoes, is distinguished by a relatively calm outpouring of liquid (basalt) lava, which forms fiery liquid lakes and lava flows in craters. The gases, contained in a small amount, form fountains, throwing out lumps and drops of liquid lava, which are drawn out in flight into thin glass threads.

In the Strombolian type of eruptions, which usually create stratovolcanoes, along with fairly abundant outpourings of liquid lavas of basaltic and basaltic andesite composition (sometimes form very long flows), small explosions are predominant, which throw out pieces of slag and various twisted and spindle-shaped bombs.

For the dome type, gaseous substances play an important role, producing explosions and ejections of huge black clouds overflowing with a large number of lava fragments. Lavas of viscous andesitic composition form small flows.

Eruption Products

The products of volcanic eruptions are gaseous, liquid and solid.

VOLCANIC GASES, gases emitted by volcanoes both during eruption - eruptive, and during periods of its calm activity - fumarolic from the crater, from cracks located on the slopes of the volcano, from lava flows and pyroclastic rocks. They contain pairs of H2O, H2, HCl, HF, H2S, CO, CO2, etc. Passing through the groundwater zone, they form hot springs.

LAVA (Italian lava), a hot liquid or very viscous, mostly silicate mass, pouring out onto the Earth's surface during volcanic eruptions. When lava solidifies, effusive rocks are formed.

VOLCANIC ROCKS (volcanites), rocks formed as a result of volcanic eruptions. Depending on the nature of the eruption, erupted, or effusive (basalts, andesites, trachytes, liparites, diabases, etc.), volcanogenic-clastic, or pyroclastic (tuffs, volcanic breccias), volcanic rocks are distinguished.

TECTONIC GAP (tectonic fault), discontinuity of rocks as a result of movements of the earth's crust (faults, shifts, reverse faults, overthrusts, etc.).

Depending on the nature of the eruptions and the composition of the magma, structures of various shapes and heights are formed on the surface. They are volcanic apparatuses consisting of a pipe-shaped or fissure channel, a vent (the uppermost part of the channel), powerful accumulations of lavas and volcano-detrital products surrounding the channel from different sides, and a crater (a cup-shaped or funnel-shaped depression on the top or slope of a volcano with a diameter of several meters to several km.). The most common forms of structures are cone-shaped (with the predominance of ejections of clastic material), dome-shaped (when squeezing out viscous lava).

Reasons for the activity of volcanoes

The geographic distribution of volcanoes indicates a close connection between the belts of volcanic activity and the dislocated mobile zones of the earth's crust. Faults formed in these zones are channels through which magma moves to the earth's surface, apparently under the influence of tectonic processes. At a depth, when the pressure of the gases dissolved in the magma becomes greater than the pressure of the overlying ones, because the gases begin to move rapidly and entrain the magma to the earth's surface. It is possible that gas pressure is created during the process of magma crystallization, when its liquid part is enriched with residual gases and steam. The magma boils, as it were, and due to the intense release of gaseous substances, high pressure is created in the focus, which can also be one of the causes of the eruption.

Eruption of Mount Etna. The Etna volcano on the Italian island of Sicily, known for its sudden eruptions, has been haunting residents of cities located on its slopes since mid-July this year (2001). In total, 5 craters were opened, from which magma, volcanic ash and hydrogen sulfide smoke, heated up to several thousand degrees, whips. The highest emission point is at an altitude of 2950 meters. But from there the stream goes into the deserted valley of Beauvais, already repeatedly burned by the volcano, without threatening anyone. Other hearths are lower, at around 2700, and hot lava slowly flows down a hundred meters below. Worst of all is the crater at 2100 meters - the most inexhaustible for emissions, which threatens to cover the village of Nicolosi. Around the village, bulldozers erected two barriers to the path of the lava. But if the mountain, where another crack opened, explodes, it will be very difficult to escape from the town.

Let me remind you: not only Vesuvius was to blame for the infamous death of Pompeii, but also the unwillingness of the inhabitants to leave everything in time and flee the city.

Clever pompeians "evacuated" in time, and the greedy, lazy people remained in the city, where they accepted a painful death.

This story is very instructive, so do not neglect the danger and try to save your life despite the material losses that will never pay off your life.

Photos of volcanoes

Volcanic gases

The lion's share of everything gas emitted by volcanoes accounts for water vapor, but other gases are released along with it in various proportions; chief among them: carbon dioxide. All these gases at a significant concentration are harmful to plants and animals. Some gases are harmful even at very low levels.

Sulfurous and sulfuric anhydrides combine with water to form sulfurous and sulfuric acids, respectively.. Downwind of smoking vents, a mist often forms, consisting of an aerosol of acids.
gases may be emitted through the main vent (or through several vents) of the volcano, but often they also exit through relatively narrow openings through which neither lava nor ash has ever erupted. Openings through which only gas is released are called fumaroles, and the very process of gas escaping without eruption of lava or tephra is often referred to as fumarole activity. Typically, fumarolic activity continues for several weeks, months, or years after lava or tephra eruptions have ended. Fumaroles that emit sulfur gases are called solfataras, and low-temperature fumaroles that emit a lot of CO2 (sometimes C) are called mofettes. Gases are emitted by lava and either over their entire surface, or in the form of clearly localized fumaroles.
Acid gases are harmful to both vegetation and metals. When the wind blows such gases away from the volcano, the foliage is damaged and the fruits fall off; this can cause complete denudation and death of plants. Where sulfuric gases predominate among harmful gases, their effect on foliage is very similar to how smoke from metallurgical plants or heavy urban smog act on it.

Masaya Nindiri Volcano in Nicaragua- a complex double cone with several craters. Over the past century, there have been several periods, each of several years, when one of the vents in the Santiago crater released a lot of water vapor and sulfuric gases, which kept above the crater in the form of a large cloud. located in the central depression of Nicaragua, its height is only about 700 m. To the west of it is a hill, and coffee plantations rise along it to a height slightly greater than the top of the volcano. The winds carried the gas cloud to the west, and it captured a strip 5-8 km wide, inside which, on an area of ​​approximately 150 km2, damage was caused to plantations in the amount of tens of millions of dollars; crops of wheat and other grain crops as far as the Pacific Ocean also suffered. Wire fences, telephone wires and metal equipment on plantations and in a cement factory off the coast were damaged by acids. Exactly the same damage was done to coffee plantations and other crops west of the Irazu volcano in Costa Rica.

The most insidious of volcanic gases - CO2 and CO because they are invisible and odorless. Carbon monoxide causes leaves to turn white and fall off, and poisons animals. Carbon dioxide does not have a serious effect on plants, but can cause suffocation in animals, since carbon dioxide is heavier than air and sometimes forms accumulations in low relief. If there is a mofetta in a small valley, then in certain wind directions carbon dioxide can accumulate, and animals and even people that get there can suffocate. Such "gorges of death" are known on the slopes of some Indonesian volcanoes, and one such gorge used to exist in the Absaroka Mountains in Wyoming. During the eruption of Hekla in 1947, carbon dioxide formed such gas "lakes" in the hollows, and the sheep that got there died from suffocation; people were not injured, since their heads were above the surface of the CO2 layer. During the recent eruption of the Eldafell volcano, carbon dioxide and partly carbon monoxide (CO) and sulfuric gases accumulated in the basements of the houses of Vestmannaeyjar, and one person died from the gases. This is the only victim of the eruption. Countless other examples of the damage caused by gases to plants and people can be cited. What can be done to reduce or eliminate the harmful effects of gases? Various methods of chemical treatment of affected plants, neutralizing the effect of gases, have been proposed; some of them have been tested experimentally. The most promising so far is the method of spraying lime, which creates a protective layer on the leaves. Whether this method will be practically applicable is not yet clear. Areas such as the western highlands of Nicaragua often experience heavy rainfall that will wash the lime off the leaves; frequent spraying will be required and the cost will be high, though perhaps not excessive. Ordinary gas masks, such as those found in many industrial plants, can probably provide adequate protection for people who are briefly exposed to a volcanic gas cloud. In most cases, such a cloud contains enough breathable air, provided that harmful gases are removed or neutralized. In the absence of masks, a rag pressed to the face, moistened with water, and preferably with a weak acid, such as vinegar or urine, provides some protection. When heavy gases accumulate in hollows or cellars, there is no longer enough air for breathing, and the gas mask is useless unless it is provided with an autonomous supply of air. Knowing about the possibility of heavy gas accumulation in one place or another, it is possible to warn people about this and thereby avoid many accidents.

The period when there was no gas release lasted 19 years, but in 1946 a new vent opened, and again the volcano began to smoke, damaging the coffee trees. Again, various solutions to this problem were proposed, including the construction of a large chimney 250 m high to carry the gas high enough into the air and direct it over high ground where it could no longer cause harm. Another proposal was to drop an atomic bomb into the crater and thereby close the crater. On the other hand, by making a small explosion or dropping ordinary bombs into the crater, one could close the vent and stop the gas from escaping, as was done in 1927, and although after some time the vent would almost certainly reopen, one could count on temporary relief. In 1953, two medium-sized bombs were dropped into the crater, but without any noticeable result.
Further great efforts are required to develop general problems of exposure to volcanic gases and to reduce their harmful effects.

In the section on the question of volcanic gases, why are they dangerous and how to avoid them? given by the author Kirik Vasily the best answer is VOLCANIC GASES - gases released during and after an eruption from a crater, fissures located on the slopes of volcanoes, from lava flows and pyroclastic rocks.
The composition of gases is different and depends on the type and duration of volcanic activity. The main component of almost all volcanic gases is water vapor and carbon dioxide. In various percentages, the following are added here. substances: hydrogen sulfide, sulfur dioxide, ammonia, hydrogen, etc.

Volcanic gases are poisonous - volcanic sulfur dioxide in combination with rainwater constitutes sulfuric acid. Fluorine contained in gases poisons water. Carbon dioxide was the cause of the largest volcanic gas disaster.
Volcanic gases affect the climate and cause significant damage to the environment. Or they directly affect a person, such as August 21, 1986 at Lake Nyos in Cameroon. In the deeper layers of the crater lake Nyos, approximately 1 km3 of CO2 of magmatic origin has accumulated. This gas, originally dissolved in water, flowed due to the release of pressure by a deadly, invisible cloud that was heavier than air, over the rim of the crater into valleys and depressions. As a result, more than 1700 people and countless animals suffocated.
The most commonly encountered volcanic gases are water vapor (H2O), carbon dioxide (CO2), and sulfur dioxide (SO2). Minor quantities produced: carbon monoxide (CO), hydrogen sulfide (H2S), carbonyl sulfide (COS), hydrochloric acid (HCl), hydrogen (H2), methane (CH4), hydrofluoric acid (HF), boron, bromic acid (HBr ), mercury vapor, as well as a small amount of noble metals, metals and semimetals.