Questions. Natural phenomena in the lithosphere

Signs of pregnancy after embryo implantation

Volcano- the place where the red-hot substance of the earth's interior - magma - breaks out to the surface.

The interior of the Earth is constantly in a heated state. Molten rocks or magma accumulate at depths of 10 to 30 km. During tectonic processes, cracks form in the earth's crust. Magma rushes along them to the surface under the pressure of water and gas vapors, when it comes out to the surface, magma pours out in the form of lava. From the vapors and gases released into the atmosphere, sediments of volcanic rock, called tephra, settle to the ground.

Solid volcanic ash and volcanic ash, as well as thicker materials, lapil and volcanic bombs. Volcanic ash consists of: pulverized lava, airborne particles or rock dust crushed by the force of an explosion. Volcanic ash is so large that it covers large areas in thick layers, and when the wind explodes during an explosion, it can be transmitted over very long distances. The colors of the sky at dusk were especially beautiful, in which yellow and purple hues prevailed.

The twilight lasted longer than usual. These phenomena have been observed for more than two years, as dust rises in the air. Volcanic bombs are lavas in the air. Conical rotation, they are usually oblong and slightly twisted. Small pieces of peas or nuts are called lapels, small particles form volcanic sand. Sometimes large-scale rocks crushed from the crater walls are thrown out. For example, Vesuvius threw stone blocks weighing up to 60 tons.

According to the degree of activity, volcanoes are classified into active, dormant and extinct. The active ones include those that erupted in historical time. The extinct ones, on the contrary, did not erupt. Dormant ones are characterized by the fact that they periodically manifest themselves, but it does not come to an eruption.

Several hundred active volcanoes are currently known around the globe. Most of them are located on the shores of the Pacific Ocean, including in Russia in Kamchatka and the Kuril Islands.

The gases produced from volcanoes are mainly composed of water vapor, hydrogen sulfide, chlorine, sulfur dioxide, hydrogen chloride, carbon dioxide, methane and hydrogen. Gases, including volcanic dust, are generated over a volcano during an eruption, as if a tall pillar rose up in the shape of a tree crown.

Volcanoes are generally conical. At their top, there is a crater connected by a chimney with magma fire. The cone is made of volcanic eruptions, so its shape, steepness and inclination depend on the type and amount of material thrown. Alkaline lands form flat, vast volcanic volcanoes with very sloping slopes. Their craters reach very large sizes, and although the volcano is active, they are filled with liquid lava, forming the so-called. "Lake of Fire".

The most dangerous phenomena accompanying volcanic eruptions:

 lava flows,

 fallout of tephra,

 volcanic mud flows,

 volcanic floods,

 scorching volcanic cloud,

 volcanic gases,

 volcanic ash ejection.

Lava flows - these are molten rocks with a temperature of about 1000 0C. The flow rate usually does not exceed 1 km / h.

These volcanoes are located in the Hawaiian Islands and have a Hawaiian type name for volcanoes that release lava at the same time as solid explosives. The spilled lava strengthens and compacts the bulk material. The shape of the cone changes after the explosions increase as a result of the throwing of new materials, but sometimes it can be destroyed during a strong explosion.

The course of a volcanic eruption depends on whether the magma that underlies the volcanic event contains many gases, whether rare or dense, regardless of whether the gases evaporate easily or are difficult to eject. The longer the period of peace precedes the outbreak, the more dangerous it can be. The most cruel and dangerous for people are volcanic eruptions, where lava does not splash out at all, but only gases and ash are thrown out. Such was the unexpected outbreak of Vesuvius in 79 AD. Before the explosion, Vesuvius made a small cone with a large crater.

Tephra consists of fragments of solidified lava. Its loss leads to the destruction of animals, plants, and in some cases to the death of people.

Mud streams - These are thick layers of ash on the slopes of the volcano, which are in an unstable position. When new portions of ash fall on them, they slide down the slope. In some cases, ash becomes saturated with water, resulting in volcanic mud flows. Their speed can reach several tens of kilometers per hour. Due to the high speed of movement, it is difficult to carry out rescue operations and evacuate the population.

The hill was overgrown with forests and vineyards and was considered a volcano. The activity of Vesuvius began with a strong earthquake, and a huge dark cloud of dust and huge volcanic ash came out of the crater, and the volcano began to throw stones and ash. Heavy rain fell from steam condensation. Rainwater mixed with ash formed a stream of mud. The swamp flooded the nearest city of Herculaneum, and the more distant ones, Pompeii and Stabia, flooded the ash. In a few hours, these three cities ceased to exist. On the other side of the Gulf of Naples, at a distance of about 30 km from Misenne, during the explosion of Vesuvius, a cloud of ash plunged into the sky so dark that it was dark.

Volcanic floods ... When glaciers melt during volcanic eruptions, huge amounts of water can form very quickly, leading to floods. For example, the height of the summit, where the main crater of the Klyuchevskaya Sopka volcano in Kamchatka is located, is 4750 m.At this height, powerful glaciers are formed, which at strong eruptions melt, and then rushing streams of water rush from the mountain.

The mass of the thrown material was so great that a new thin volcanic cone formed in the old crater. The edge of the old crater, depending on the time of destruction, remained in the form of a semicircular arch. Since then, Vesuvius has been active. Weak explosions are common. The gases escaping from the crater create fiery smoke smoke on it, and sometimes an explosion of ash and lava occurs, usually preceding underground masses and earthquakes. Sometimes on the slopes of such volcanoes, parasitic craters are formed, through which lava is extracted, flows with streams, sometimes reaching considerable length.

Scorching volcanic cloud ... It is a mixture of hot gases and tephra. Its damaging effect is due to the appearance of a shock wave (strong wind), propagating at a speed of up to 40 km / h, and a heat roll with a temperature of up to 1000 0С.

Volcanic gases ... Eruptions are always accompanied by the release of gases mixed with water vapor - a mixture of sulphurous and sulfuric oxides, hydrogen sulphide, hydrochloric and hydrofluoric acids in a gaseous state, as well as carbon dioxide and carbon monoxide in high concentrations that are fatal to humans. The release of these gases can continue for a very long time, even after the volcano has stopped ejecting lava and ash.

Volcanoes hawaiian type totally different. The explosions are peaceful, they consist in an ascent into a lava crater, which, when filling the crater, quickly flows along the slopes or flows out of channels on the slopes of volcanoes. The movement speed of this rare lava can be up to 30 km per hour. Basically, lava does not pour out of the crater, but rises and falls inside.

The Stromboli volcano is still active in Europe. The flares are repeated regularly every few or several minutes, these are gases, lapels and bombs coming from the surface of the lava. The Stromboli volcano is called a "lighthouse" because it has served sailors for a sign from the earliest times, illuminating the horizon with its brightness at night.

An intense release of volcanic ash impairs visibility, creates a great danger for aviation flights (ash ingress into the engine), in large quantities ash accumulates on rooftops.

Protective measures:

 Choosing a place of residence at a distance from active volcanoes.

 Evacuation of the population.

 Impact on the lava flow: deflection of the flow, dividing it into several small ones, cooling, creating barriers.

Volcanoes were formed not only in the past, but also in the present. Within a few months, a volcanic cone appeared in the place of the crop fields. The explosive material consisted mainly of ash, dust, water vapor, and finally lava flows. Parikutin did not stop his activity. Geographic distribution volcanoes. Active volcanoes are currently found in land areas. Most of them are located on islands or continents, close to the coast. The most numerous volcanoes are on the islands and coasts of the Pacific Ocean; They travel along the eastern shores of Asia from the Aleuts through Kamchatka, the Japanese Islands, New Zealand to Antarctica, and along the western coasts of America from Alaska to Mexico, the Antilles and Andy.

 Breaking the crater wall (by bombardment) and directing the lava flow in a safe direction.

 Deviation in a safe direction of mud flows.

 Dumping volcanic ash from rooftops.

Question. Landslides, landslides, mudflows, avalanches.

Mud - a rapid, turbulent mud or mud-stone stream, consisting of a mixture of water, sand, clay and rock debris, which suddenly appears in the basins of small mountain rivers. The reason for its occurrence is intense and prolonged downpours, rapid melting of snow or glaciers, breakthrough of water bodies, less often earthquakes, volcanic eruptions.

Numerous volcanoes are found on the islands of the Sunda archipelago, where there are about 120, only in Java, of which 28 are active. In Europe active volcanoes are located on the Mediterranean - the most famous are Vesuvius, Etna, Stromboli, Santorini and Iceland - Hekla. In the Atlantic Ocean, volcanoes leave Iceland through the Azores, the Canary Islands to the island of Santos. Volcanoes exist where the earth's crust has not yet been formed - in these places there is a weaker concentration of mountain masses, cracks are formed through which magma more easily penetrates to the Earth's surface.

Possessing a large mass and high speed of movement (up to 40 km / h), mudflows destroy buildings, roads, power lines, lead to the death of people and animals. A steep front of a mudflow wave with a height of 5 to 15 m forms the "head" of a mudflow (the maximum height of a mud flow shaft can reach 25 m), the length of mudflow channels ranges from several tens of meters to several tens of kilometers.

Volcanic activity on the ocean floor is associated with deep fracture zones in the underwater part crust... Due to the geological structure of the ocean floor, oceanic volcanism is characterized by basaltic lava and a relatively small proportion of hemostatic explosives. On the other hand, in the area of \u200b\u200btidal ridges and in the transition zone, there is a significant variability of the law and a high prevalence of volcanic volcanic products.

With the characteristics of the ocean floor, there has been talk about how many bottom forms are associated with underwater volcanism. Archipelagos of islands as well as isolated islands are part of volcanic cones. The ridge valleys of the middle tribe geologists also belong to the forms formed by the fissure of volcanism.

Mudflows are especially active in the North Caucasus. Due to the negative role of the anthropogenic factor (destruction of vegetation, development of quarries, etc.), mudflows began to develop on the Black Sea coast of the North Caucasus (Novorossiysk region, Dzhubga - Tuapse - Sochi section).

Protective measures:

Not only oceanic islands, but terrestrial volcanism is largely associated with young oceanic structures that run through continental blocks. Contemporary underwater volcanism can be seen in examples of the periodic emergence and disappearance of new islands. For example, three islands appeared and disappeared in the Aleutian archipelago. Modern Icelandic volcanism, like the Azores, occurs in the Central Atlantic Ridge.

There are traces of an ancient volcanic activity in different regions of the Earth. Visible cones are often visible, although over time they are subject to deterioration from water and atmospheric activity. Sometimes volcanic cones are completely destroyed, and the first eruptions are attested only by volcanic rocks. The most famous of Europe - extinct volcanoes Auvergne in France and the Eiffel mountains on the Rhine. Also in our country we can find solidified lava, for example, in Krakow, in the Swietokrzyskie Mountains, in the Pieniny Mountains, in the northwestern Beskids and in many places in the Sudetenland.

 Strengthening mountain slopes (planting forests);

 Anti-mudflow dams, dams, ditches;

 Periodic descent of water from mountain reservoirs;

 Construction of protective walls along river beds;

 Reducing the rate of snow melting in the mountains by creating smoke screens.

 Catching mud flows into special pits located in river beds.

Anna south of Opole also belongs to volcanic origin... In earlier geologic periods, volcanic activity was more intense than today. Over time, volcanic activity ceases, and it is believed that volcanoes that do not explode in human memory have expired. Sometimes, however, the volcano is considered extinct, resuming its activity, as happened with Vesuvius.

The extinction of volcanic activity in some areas can take a long time, with characteristic phenomena occurring at that time. From craters, as well as areas covered with solid lava, which in the depth can remain for a very long time after a volcanic eruption, a very high temperature is released - water vapor and other gases. Fumaric gases include water vapor, carbon dioxide, hydrogen chloride, chlorine compounds and sulfur anhydride and others. The chemical composition varies with the temperature of the fumaroles.

 Effective warning and warning system.

Collapse - this is a rapid separation (separation) and a fall in the mass of rocks (earth, sand, clay stones) on a steep slope due to the loss of stability of the slope, weakening of the connectivity, integrity of rocks.

The collapse occurs under the influence of weathering processes, movement of ground and surface water, washout or dissolution of rocks, soil vibrations. landslides most often occur during rains, melting snow, during blasting and construction work.

Fumaroles are mainly ferric chloride and copper chloride. In the further phase of volcanic activity, the stage of solaphrate occurs. This name comes from one of the extinct Italian volcanoes called Solfatara. During this period, water vapor, hydrogen sulfide, carbonic anhydride and some other gases are released.

As the volcanic symptoms subside, the temperature drops and the saline phase becomes what is called. in the second stage. Then carbon dioxide and hydrocarbons are separated. Long-standing volcanic activity is symbolized by hot springs or termites. Over time, even the faintest signs of volcanic activity cease, denudation factors destroy volcanic cones, and the only consequence of previous eruptions is volcanic rock.

The striking factors of the collapse are the fall of heavy masses of rocks that can damage, crush even strong structures or fill them with soil, blocking access to them. Another danger of landslides is the possible damming of rivers and the collapse of the shores of lakes, the waters of which, in the event of a breakthrough, could cause floods or mud flows.

Iceland is one of the world's most popular tourist destinations in Mecca. The unusual nature and landscape, the way of life of non-traditional people, the far north and remoteness from all continents to Iceland attract travelers from all over the world. In summer it is even difficult to get by with the abundance of tourists in Iceland, and in winter it is cold, constant darkness and winds. Besides, it is a really expensive country and for the usual services and goods you really need to bring a lot of money here. To make the most of your Iceland trip, here are 10 things to really do when you arrive.

Signs of a possible collapse are numerous cracks in sheer rocks, overhanging blocks, the appearance of individual fragments of rocks, blocks, separated from the main rock.

Landslide - sliding displacement of rock masses down the slope under the influence of gravity; arises, as a rule, due to slope washout, waterlogging, seismic shocks and other factors.

The causes of landslides can be the following factors.

1. Natural:

    earthquakes;

    waterlogging of slopes with precipitation;

    increase in slope steepness as a result of water washout;

    weakening of the strength of hard rocks during weathering, leaching or leaching

    the presence of softened clays, quicksands, fossil ice in the soil:

2. Anthropogenic:

    deforestation and shrubs on the slopes. Moreover, deforestation can occur much higher than the place of the future landslide, but the water will not be retained by the plants at the top, as a result of which the soil becomes waterlogged far below;

    blasting operations, which are, in fact, a local earthquake and contribute to the development of cracks in the rocks;

    plowing slopes, excessive watering of orchards and vegetable gardens on the slopes;

    destruction of slopes by foundation pits, trenches, road cuts,

    clogging, clogging, blockage of groundwater outlets;

    construction of housing and industrial facilities on the slopes, which leads to destruction of the slopes, an increase in gravity directed down the slope.

The damaging factor of landslides are heavy masses of soil, filling or destroying everything in its path. Therefore, the main indicator of a landslide is its volume, measured in cubic meters.

Unlike landslides, landslides develop much more slowly, and there are many signs that allow early detection of an incipient landslide.

Signs of an incipient landslide:

    breaks and cracks in the ground, on the roads;

    violation and destruction of underground and ground communications;

    displacement, deviation from the vertical of trees, poles, supports, uneven tension or wire breakage;

    curvature of the walls of buildings and structures, the appearance of cracks on them;

    change in water level in wells, wells, in any water bodies.

Landslide prevention measures include: monitoring the condition of slopes; analysis and forecasting of the possibility of landslides; carrying out complex engineering protective works; training of people living, working and having a rest in the danger zone, the rules of life safety.

Snow avalanches arise as a result of the accumulation of snow on mountain peaks during heavy snowfalls, strong blizzards with a sharp drop in air temperature. Avalanches can also descend during the formation of deep rime, when a loose layer (snow-quicksand) appears in the thickness of the snow.

Snow avalanches are annually observed in the mountainous regions of the North Caucasus, Sakhalin, Kamchatka, Magadan region, in the Khibiny, in the Urals.

Most avalanches descend along specific trays - narrow hollows on steep mountain slopes. Along these hollows, 200–300, and sometimes up to 500 thousand tons of snow can simultaneously fall.

In addition to trough avalanches, there are main and jumping avalanches. The main avalanches slide off the mountain slopes in undefined places, as a rule, they are small and do not pose a particular danger. Jumping avalanches are trough avalanches that meet “springboards” on their way and “jump” over them with great force, acquiring an increasing speed of movement, and as a result, the force of destruction increases.

Quite often, avalanches occur suddenly and begin their initial movement silently. When avalanches move in narrow mountain gorges, an air wave growing in strength moves ahead of them, bringing even greater destruction in comparison with the falling mass of snow. The repeated avalanches leave deep footprints in the mountainous landscape. Often, avalanches fall into river beds and block them, forming on long time dams.

Avalanche danger is caused by abrupt weather changes, heavy snowfalls, heavy blizzards, and rains. To prevent avalanche danger, there is a special mountain avalanche service.

Catastrophic snow avalanches in the world occur on average at least once every two years, and in some mountainous regions - at least once every 10–12 years.

When people get caught in an avalanche, it should be remembered that a person, being covered with avalanche snow, can stay alive for only a few hours, and the chance of survival is higher, the thinner the layer of snow above him. Among people who have been in an avalanche for no more than 1 hour, up to 50% can survive, after 3 hours the probability of surviving does not exceed 10%. Therefore, work to rescue people caught in an avalanche should begin even before the arrival of the rescue team.

When a covered one is found, first of all, the head is freed, the mouth, nose, ears are cleared of snow; then, carefully (taking into account the possibility of fractures), they remove it from under the snow, transfer it to a place protected from the wind, wrap it in dry clothes, give a hot drink, and in the absence of signs of life, proceed to artificial ventilation and other resuscitation measures.

D actions of the population under the threat of landslides, landslides, mudflows

The population living in landslide, mudflow and landslide-prone zones should know the foci, possible directions of movement and the main characteristics of these dangerous phenomena. The population of mountainous regions is obliged to strengthen their homes and territories on which they were built, as well as to participate in the construction of protective hydraulic engineering and other protective engineering structures.

The population is alerted about natural disasters through sirens, radio and television broadcasting, as well as through local warning systems that directly connect the hydrometeorological service unit with settlements in hazardous areas.

Before leaving the house or apartment during the evacuation, it is necessary to remove the property from the yard or balcony into the house, the most valuable property that cannot be taken with you, the doors, windows, ventilation and other openings must be tightly closed from the effects of moisture and dirt, the electricity must be turned off , gas and water.

Flammable and toxic substances should be taken out of the house and, if possible, buried in a hole or hidden in a cellar.

In all other respects, citizens must act in accordance with the procedure established for an organized evacuation.

If there was no warning of the danger or it was made just before the natural disaster, then residents, not caring about property, should quickly go to a safe place. Natural places for salvation from mudflows or landslides are mountain slopes and hills that are not prone to landslide, landslide process or flooding by mudflows. When climbing safe slopes, it is impossible to use valleys, gorges and excavations, since side channels of the main mudflow can form in them.In the case when people, buildings and structures find themselves on the surface of a moving landslide area, leave the premises and move upwards as much as possible, being careful when braking a landslide of stones, fragments of structures, an earthen rampart, and talus rolling down from its rear part. When a fast moving landslide is stopped, a strong shock is possible. This poses a great danger to people on the landslide.

Question. Wind speed classification. Definition of the concept of "storm". Types of storms. Definitions of the concepts "hurricane", "cyclone" and "tornado". Types of hurricanes

Wind is the movement of air parallel to the earth's surface, resulting from an uneven distribution of heat and atmospheric pressure and directed from a high to a low pressure zone.

Many words are used to denote the movement of the wind: tornado, storm, hurricane, storm, typhoon, cyclone and many local names. To systematize them all over the world, they use the Beaufort scale, which makes it possible to very accurately assess the strength of the wind in points (from 0 to 12) by its effect on ground objects or by the roughness at sea. This scale is also convenient in that it allows, according to the features described in it, to fairly accurately determine the wind speed without instruments.

From the group of meteorological and agrometeorological phenomena of natural origin, extremely dangerous natural disasters are storms (storms), hurricanes (typhoons), tornadoes (tornadoes), cyclones, which are extremely fast and strong, often catastrophic air movement that causes the destruction of buildings, death of people and animals.

Wind speed is distinguished: weak wind - up to 5 m / s, strong - up to 10 m / s, very strong 15-18 m / s, storm (storm) - 18-29 m / s, hurricane (typhoon) - over 29 m / s, sometimes reaching 120-210 m / s.

Storm - very strong and prolonged wind, causing great destruction on land and roughness at sea (storm). Depending on the season and the involvement of various particles in the air flow, dust, dust-free, snow and squall storms are distinguished.

Dust (sand) storms accompanied by the transfer of large quantities of soil and sand particles. They arise in deserts, semi-desert and plowed steppes and are capable of transferring millions of tons of dust over hundreds of kilometers and covering territories of several thousand kilometers.

In Russia, the border of the spread of such storms goes through the Saratov and Samara regions, the cities of Ufa and Orenburg, the foothills of Altai.

Dustless storms are characterized by the absence of dust entrainment into the air flow and a relatively smaller scale of destruction and damage.

Snow storms occur in winter and move huge masses of snow through the air. Their duration is from several hours to several days. They have a relatively narrow band of action. They are more often in Siberia.

Squall storm characterized by an almost sudden onset, the same quick end, a short duration of action and a huge destructive force.

Hurricane is a vortex with a huge speed of movement of air masses and low atmospheric air pressure in the central part. Air speed can exceed 120 m / s in an area with a diameter of 500–1000 km and a height of up to 10–12 km. Hurricanes occur in areas of contact between warm and cold air masses with the most pronounced temperature contrasts and are accompanied by strong cloudiness, heavy rains, thunderstorms and hail. Hurricanes have different names: in the Philippines, begvis; in Australia - willy-willy; hurricanes in North America.

Most often hurricanes occur in regions with tropical climates, where they are most destructive. Powerful hurricanes destructive force in some cases can be equated with earthquakes. In Russia, the most likely region for hurricanes is the Pacific coast. At the same time, hurricane winds and heavy torrential rains are often observed in the coastal regions of the Arctic seas, the seas of the Far East, the Black Sea, as well as in the regions of the Volga region and the republics of the North Caucasus. Hurricanes often cause floods as a result of intense rainfall, which took place in the Primorsky Territory. As a result of hurricanes, structures are destroyed, fires break out, people die, a huge number of the population needs medical care.

Cyclone- a giant atmospheric vortex, in which the pressure decreases towards the center, air currents circulate around the center counterclockwise (in the Northern Hemisphere) or clockwise - in the Southern Hemisphere.

Cloudy weather prevails during the cyclone. The most dangerous are tropical cyclones with storm and hurricane winds and air force 9 and 12 points on the Beaufort scale, respectively. The wind speed with a strong upward movement sometimes reaches 70 m / s, and its individual gusts - 100 m / s, dense continuous clouds develop with abundant rainfall (up to 1000 mm per day or more) and thunderstorms.

In Southeast Asia, tropical cyclones are called typhoons, and in the Caribbean, hurricanes. During thunderstorms, atmospheric vortices often arise, spreading down to the very surface of the earth. Their diameter can be tens of meters above the sea and hundreds - above land. Such a whirlwind is called a tornado (thrombus in Western Europe, tornado in the USA).

Tornadois the most destructive atmospheric phenomenon. It is a huge vortex with a vertically directed axis of rotation, reminiscent of a funnel with a "trunk" extended upward. The air in a tornado rotates at a speed of several tens of meters per second, simultaneously rising in a spiral to an altitude of 800-1500 m. The tornado travels 40-60 km, moving with the cloud, accompanied by a thunderstorm, downpour, hail, is capable of causing great destruction.

Tornadoes are formed when the atmosphere is unstable, when the air in its lower layers is very warm, and in the upper layers it is cold, while a powerful vertical movement of air masses occurs. Inside the vortex flow, a low atmospheric pressure is formed, so the tornado draws in dust, water and all objects on the way of its movement like a giant vacuum cleaner, lifting them high up and carrying them over long distances.

Protective measures after receiving a "storm warning":

 Alerting the population about the time of the hurricane approach.

 Transition to safe modes of operation of various industries.

 Reduction of stocks of hazardous substances at enterprises, increasing the reliability of their storage.

 Preparation of shelters, basements to protect the population.

 Partial evacuation of the population.

 Increasing the security of buildings, structures and other human habitats (close windows, doors, ventilation openings, cover glass, windows and shop windows, protect with shutters and shields).

 Fix fragile structures and objects or remove, free the balconies from things.

 Creation of stocks of food and water, items for life support.

Plinian type named after the Roman scientist Pliny the Elder, who died in the eruption of Vesuvius in 79 AD. Eruptions of this type are characterized by the highest intensity (into the atmosphere at an altitude of 20-50 km, a large number of ash) and occur continuously for several hours and even days. Pumice of dacite or rhyolite composition is formed from viscous lava. Products of volcanic emissions cover a large area, and their volume ranges from 0.1 to 50 km 3 and more. The eruption can end with the collapse of a volcanic structure and the formation of a caldera. Sometimes, during the eruption, scorching clouds appear, but lava flows are not always formed. Fine ash is carried over long distances by strong winds at speeds up to 100 km / h.

Peleus type... Eruptions of this type are characterized by very viscous lava, which solidifies before exiting the vent with the formation of one or more extrusive domes, squeezing an obelisk over it, and ejection of scorching clouds. This type included the eruption in 1902 of the Montagne Pele volcano on the island. Martinique.

Vulcan type (the name comes from the island of Vulcano in the Mediterranean Sea). Eruptions of this type are short-lived - from several minutes to several hours, but they resume every few days or weeks for several months. The height of the eruptive column reaches 20 km. Fluid magma, basaltic or andesite composition. The formation of lava flows is characteristic, and ash emissions and extrusion domes do not always occur. Volcanic structures are built from lava and pyroclastic material (stratovolcanoes). The volume of such volcanic structures is quite large - from 10 to 100 km 3. The age of stratovolcanoes is from 10,000
up to 100,000 years. The frequency of eruptions of individual volcanoes has not been established. This type includes the Fuego volcano in Guatemala, which erupts every few years, ejections of basaltic ash sometimes reach the stratosphere, and their volume in one of the eruptions was 0.1 km 3.

Strombolian type. This type is named after the volcanic island. Stromboli in the Mediterranean. The Strombolian eruption is characterized by continuous eruptive activity for several months or even years and a not very high eruptive column (rarely higher than 10 km). Cases are known when lava was splashed within a radius of 300 m, but almost all of it returned to the crater. Lava flows are characteristic. Ash covers have a smaller area than in volcanic eruptions. The composition of the eruption products is usually basaltic, less often andesite. The volcano Stromboli has been in a state of activity for over 400 years.


Hawaiian type eruptions are characterized by outpourings of liquid basaltic lava. Fountains of lava ejected from cracks or faults can reach heights of 1000 and sometimes 2000 m. There are few pyroclastic products emitted, most of them are splashes falling near the source of the eruption. Lavas pour out from cracks, holes (vents) along the crack, or craters sometimes containing lava lakes. When there is only one vent, lava spreads radially, forming a shield volcano with very gentle (up to 10º) slopes (stratovolcanoes have cinder cones and a steepness of slopes of about 30º). Shield volcanoes are composed of layers of relatively thin lava flows and do not contain ash (for example, famous volcanoes on about. Hawaii, Mauna Loa and Kilauea).

Other types of eruptions are known, but they are much less common. An example is the underwater eruption of the Surtsey volcano in Iceland in 1965, which formed the island.

With the attenuation of volcanic activity, a number of characteristic phenomena are observed for a long time, indicating active processes continuing in the depths. These include: gas evolution (fumaroles), geysers, mud volcanoes, terms. Fumaroles (volcanic gases). After volcanic eruptions, for a long time, gaseous products are released from the craters themselves, various cracks, from hot tuff-lava flows and cones. The composition of postvolcanic gases contains the same gases of the group of halogens, sulfur, carbon, water vapor, and others that are released during volcanic eruptions... However, it is impossible to outline a single scheme for the composition of gases for all volcanoes. For example, in Alaska, thousands of gas jets with a temperature of
600–650 ºС, which contain a large amount of halogens (HCl and HF), boric acid, hydrogen sulfide and carbon dioxide. Geysers - one of the manifestations of the late stages of volcanism, common in areas of modern volcanic activity. The geyser is a source that periodically throws out fountains of hot water and steam to a height of 30-60 m. They got their fame and name in Iceland, where they were observed for the first time. Geysers are found in the USA, New Zealand, Russian Federation (in Kamchatka). The geyser water has a temperature of 80–100 ºС, chlorides, bicarbonates and a significant amount of silica are dissolved in it, which is often deposited around the geyser in the form of scale (siliceous tuff).

Mud volcanoes(salsa) - holes or depressions on the surface of the land or cone-shaped hills with a crater (mud hill), constantly or periodically spewing mud and gases onto the Earth's surface. The crater of a mud volcano is filled with clay or sandy (cold) mud, through which gas bubbles are released. If the dirt is thick enough, its lumps fly upward when gas bubbles explode and are deposited around the hole, forming a salsa roll or a gradually growing cone of a hill. The relative height of the ridges reaches 30–50 m, and of the cones, 400–500 m.

Mud volcanoes are often associated with oil and gas basins (Sakhalin, Apsheron, Taman and Kerch peninsulas), while the products of the eruption contain oil, and the emitted gases can ignite spontaneously, forming flares.

Consequences of volcanic activityActive volcanoes, along with earthquakes, pose a formidable danger to nearby settlements... The moments of their eruptions often bring irreparable natural disasters, expressed not only in huge material damage, but sometimes in mass death of the population. However, volcanic activity brings only disasters, some useful aspects should be noted: - huge ejected masses of volcanic ash renew the soil and make it more fertile; - water vapor and gases released in volcanic areas, steam-water mixtures and hot springs became sources of geothermal energy; - volcanic activity associated with many mineral springs, which are used for balneological purposes; - products of direct volcanic activity - individual lava, pumice, perlite, etc. are used in construction and chemical industry; - the formation of certain minerals, such as sulfur, cinnabar, etc., is associated with fumarolic and hydrothermal activity; - volcanic products of underwater eruptions are sources of accumulation of minerals such as iron, manganese, phosphorus, etc.

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