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Natural disasters: occurrence, consequences and forecasting

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Natural disasters - these are dangerous natural phenomena of geophysical, geological, atmospheric or biospheric origin, which are characterized by a sudden disruption of the life of the population, destruction, destruction of material values, injuries and casualties among people. Such phenomena can cause numerous accidents and catastrophes, the appearance of secondary damaging factors. The list of the main types of natural disasters is presented in Table. 2.1.

Table 2.1. List of main types of natural disasters

Earthquakes in terms of damage, casualties and destructive action, there is no equal. They are tectonic, volcanic, landslide, may be the result of the fall of meteorites or occur under the thickness of sea waters. In the CIS, an average of 500 earthquakes are recorded annually, in Japan - 7500. An earthquake is a sudden tremors or vibrations of the earth's surface caused by faults and displacements occurring in the thickness of the earth's crust, during which energy of enormous force is released. Seismic waves from the center of an earthquake propagate over considerable distances, producing destruction and creating centers of combined damage. The area where an earthquake occurs is called the focus of an earthquake. In the center of the focus is a point (hypocenter), the projection of which on the surface of the earth is called the epicenter.

In case of strong earthquakes, the integrity of the soil is violated, buildings are destroyed, communications, energy facilities fail, fires occur, and human casualties are possible. Earthquakes are usually accompanied by characteristic sounds of varying intensity, reminiscent of thunder, rumble, and the roar of explosions. At the same time, a few tens of initial seconds can be saving for a trained person. In residential areas and forests, blockages appear, soil sinks over vast areas, roads and railways are displaced or deformed. The disaster area is often cut off from the rest of the region.

If an earthquake occurs under water, then huge waves arise - tsunamis, causing severe destruction and flooding in coastal areas. Earthquakes can lead to mountain collapses, landslides, floods, and cause avalanches.

The number of sanitary (temporary) and irretrievable losses depends on:

• seismic and geological activity of the region;
• design features of the building;
• population density and its gender and age composition;
• features of the settlement of residents of the settlement;
• time of day when an earthquake occurs;
• the location of citizens (in or out of buildings) at the time of the strikes.

As an example, we can compare the results of earthquakes in Nicaragua (Managua, 1972, 420 thousand inhabitants) and in the USA (San Fernando, 1971, 7 million inhabitants). The force of the tremors was 5,6 and 6,6, respectively, on the Richter scale, and the duration of both earthquakes was about 10 s. But if in Managua 6000 people died and 20 thousand people were injured, then in San Fernando 60 people died and 2450 people were injured. In San Fernando, the earthquake hit early in the morning (when there are few cars on the roads), and the buildings of the city met the requirements of earthquake resistance. In Managua, an earthquake occurred at dawn, the buildings did not meet the seismic resistance requirements, and 5 cracks crossed the city, which caused the destruction of 50 thousand residential buildings (915 residential buildings were damaged in San Fernando).

During earthquakes, the ratio of the dead and the wounded is on average 1:3, and the seriously and lightly wounded are approximately 1:10, and up to 70% of the wounded receive soft tissue injuries; up to 21% - fractures, up to 37% - craniocerebral injuries, as well as injuries of the spine (up to 12%), gas (up to 8%), chest (up to 12%). Many victims have multiple injuries, prolonged compression syndrome, burns, reactive psychoses and psychoneuroses. Most of the victims of earthquakes are women and children. For example:

Ashgabat (1948), among the dead - 47% of women, 35% of children;

Tashkent (1966), among the sanitary losses of women there were 25% more than men, and among the irretrievable losses, children aged from one to 10 years predominated;

Tokyo (1923), up to 65% of the dead women and children had burns.

To assess the strength and nature of an earthquake, certain parameters are used. Intensity is a measure of ground shaking. It is determined by the degree of destruction, the degree of change in the earth's surface and the sensations of people. It is measured according to the 12-point international scale MZK-64 (Table 2.2).

The magnitude, or strength, of an earthquake is a measure of the cumulative effect of an earthquake as recorded by seismographs. This is a conditional value that characterizes the total energy of elastic vibrations caused by an earthquake or explosion. It is proportional to the decimal logarithm of the amplitude of the strongest wave recorded by a seismograph at a distance of 100 km from the epicenter. The measurement scale is from 0 to 8,8 units (an earthquake with a magnitude of 6 units is strong). The earthquake sources in different regions lie at different depths (from 0 to 750 km).

In areas with high seismic activity, the population must be prepared to act in an earthquake. First of all, you need to think over the order of your actions at home, at work, on the street, in public places and determine the safest in each of these places. These are openings of the main walls, corners, places at the columns and under the beams of the building frame. It is necessary to strengthen cabinets, shelves, racks and furniture so that when they fall, they do not block the exit. Heavy things and glass should be positioned so that they do not cause injury if they fall, especially near sleeping places. Sleeping places should be located as far as possible from large windows and glass partitions. It is advisable to have a supply of food, water, a first aid kit, documents and money ready for take-out. You need to know how to turn off the electricity, water and gas supply. It is advisable to prepare a garden house for temporary residence. The radio broadcast must be on at all times.

At the first sign of an earthquake, you should run out of the building to an open place without using the elevator and without creating a crush on the doors, or hide in the apartment in a pre-selected place (open the door to the stairwell and stand in the opening, covering your face from fragments, or hide under table). After the earthquake, provide assistance to the victims (stop the bleeding, ensure the immobility of the limbs in case of fractures, help free themselves from the blockage). Take all measures to restore the radio broadcast to listen to the messages of the civil defense authorities. Check for leaks in communication networks. Do not use open fire. Do not enter dilapidated buildings. Remember that after the first aftershocks may follow. The list of a number of large earthquakes is given in Table. 2.3.

Table 2.2. Characteristics of earthquake damage

Table 2.3. Some major earthquakes

Volcanic eruptions. In the modern world, there are about 760 active volcanoes, during the eruptions of which over 400 thousand people have died over the past 300 years (Table 2.4).

Table 2.4. The number of human casualties in the eruption of a number of volcanoes

In Russia, all volcanoes are located in Kamchatka and the Kuril Islands. Volcanic eruptions occur less frequently than earthquakes, but also become giant cataclysms with planetary consequences. Explosion of a volcano on about. Santorini (Aegean Sea, 1470 BC) was the cause of the decline of a civilization that flourished in the Eastern Mediterranean. The eruption of Vesuvius (79 AD) led to the death of Pompeii. The eruption of the Krakatau volcano (1883, Indonesia) caused a tsunami - waves up to 36 m high, which even reached the English Channel, but already at a height of about 90 cm. The sound of a volcano explosion was heard at a distance of 5000 km, on about. Sumatra (40 km from the volcano) burned hundreds of people alive, about 20 km were thrown into the stratosphere³ ash (volcanic dust flew around the Earth almost twice).

The main damaging factors during volcanic eruptions are air-blast, flying fragments (stones, trees, parts of structures), ash, volcanic gases (carbon dioxide, sulfur dioxide, hydrogen, nitrogen, methane, hydrogen sulfide, sometimes fluorine, which poisons water sources), thermal radiation, lava, moving along a slope at a speed of up to 80 km / h at temperatures up to 1000 ° C and burning everything in its path. Secondary damaging factors are tsunamis, fires, explosions, blockages, floods, landslides. The most common causes of death of people and animals in areas of volcanic eruptions are injuries, burns (often of the upper respiratory tract), asphyxia (oxygen starvation), eye damage. For a considerable period of time after the volcanic eruption, there has been an increase in the incidence of bronchial asthma, bronchitis, exacerbation of a number of chronic diseases among the population. Epidemiological surveillance is established in areas of volcanic eruptions.

Mud (in Arabic "turbulent stream") is a temporary mud-stone stream that suddenly forms in the beds of mountain rivers. Such a mixture of water, mud, stones weighing up to 10 tons, trees and other objects rushes at a speed of up to 15 km / h, sweeping away, flooding or carrying away bridges, buildings, destroying dams, dams, flooding villages. The volume of rock moved is millions of cubic meters. The duration of mudflows reaches 10 hours with a wave height of up to 15 m. Mudflows are formed due to prolonged downpours, intense melting of snow (glaciers), breakthrough of dams, and illiterate blasting. According to their power, mudflows are divided into groups: powerful - with a removal of more than 100 thousand m³ mixtures of rocks and materials (average frequency of repetition once in 10 ... 10 years); medium power - with offset from 100 thousand to XNUMX thousand m³ mixtures (every 2 ... 3 years); weak power - with a removal of less than 10 thousand m³ mixtures.

The main areas of mudflow occurrence in Russia are located in Transbaikalia (the frequency of powerful mudflows is 6...12 years), in the BAM zone (once every 20 years), in the Far East and the Urals.

An example of devastating consequences is the result of a mudflow in Uzbekistan (May 4, 1927), when an hour and a half after a hailstorm in the mountains, a noise resembling an artillery cannonade was heard. 30 minutes after that, a mud-stone stream up to 15 m high poured into the gorge, which swallowed up more than 100 carts with loads and pilgrims who were in the village. After 10 hours, the already weakened mudflow reached Ferghana (then more than 800 heads of cattle died in the city).

Mudflows in May 1998 in Tajikistan destroyed 130 schools and preschool institutions, 12 clinics and hospitals, 520 km of roads, 115 bridges, 60 km of power lines. Cotton crops on an area of ​​112 hectares were damaged, orchards and vineyards were swept away by mudflows, and a significant number of livestock died.

Landslides - this is the separation and sliding of the upper layers of the soil down the slope under the influence of gravity. Most often, landslides occur due to an increase in the steepness of the slopes of mountains, river valleys, high shores of the seas, lakes, reservoirs and rivers when they are washed away by water. The main reason for the occurrence of landslides is excessive saturation of clay rocks with groundwater to a fluid state, the impact of seismic shocks, and unreasonable economic activity without taking into account local geological conditions. According to international statistics, up to 80% of landslides are currently associated with human activities. At the same time, huge masses of soil slide down the slope along with buildings, trees and everything that is on the surface of the earth. The consequences of landslides are victims (Table 2.5.), blockages, dams, deforestation, floods.

Table 2.5. Number of deaths from avalanches and landslides

By power, landslides are divided into groups: very large - with a removal of more than 1 million m³ mixtures of rocks and materials; large - with removal from 100 thousand to 1 million m³ mixtures; medium - with offset from 10 thousand to 100 thousand m³ mixtures; small - with an offset of less than 10 thousand m³ mixtures.

In Russia, landslides occur on the Black Sea coast, along the banks of the Oka, Volga, Yenisei, and in the North Caucasus. Most landslides can be prevented by regulating water flows (melt and storm water), runoffs and drainages, and greening slopes. An example of the results of a landslide is the tragedy of June 6, 1997 in the Dnepropetrovsk residential area. Suddenly, the earth swallowed up a kindergarten and a 9-story residential building that stood at the edges of a deep ravine. The rescuers who arrived on the first signals managed to expel the residents of the house in conditions of pandemonium and panic (this could not be called an evacuation). Policemen and soldiers did not stand on ceremony - the seconds gained saved many lives. Half-dressed tenants were pushed back from the dangerous place. At 6.40 in the morning, a nine-story panel building exploded, fell apart, and 72 apartments went underground. In place of the collapsed house, a funnel 150 m wide and 30 m deep was formed, at the bottom of which a mass of wet, greasy clay was bubbling mixed with the remains of the house. Down went the secondary school, the children's factory, small buildings, trees, garages.

Preventive measures to combat landslides, mudflows and avalanches are monitoring the condition of slopes, performing strengthening measures on them (driving piles, afforestation, erecting walls, dams), building drainage systems and dams (a dam built near Alma-Ata 100 high and 400 wide m prevented the approach to the city of a mudflow in 1973, stopping a stream 30 m high at a speed of about 10 m / s. As a result, Lake Medeo appeared with a volume of 6,5 million m³).

Storm - This is an atmospheric phenomenon in which strong electrical discharges - lightning - occur between powerful cumulonimbus clouds and the earth. Such discharges reach a voltage of millions of volts, and the total power of the Earth's "lightning machine" is 2 million kilowatts (with one thunderstorm, so much energy is consumed that it would be enough to meet the needs of a small city for electricity during the year). The discharge speed reaches 100 thousand km / s, and the current strength - 180 thousand amperes. The temperature in the lightning channel - due to the huge current flowing there - is 6 times higher than on the surface of the Sun, so almost every object penetrated by lightning burns out. The width of the discharge channel of lightning reaches 70 cm. Due to the rapid expansion of the air heated in the channel, thunder is heard. 33

Every year there are up to 44 thousand thunderstorms on the globe. Their duration is within an hour. Lightning usually strikes high places, isolated trees, and equipment. It is dangerous to be in or near water, you can not put up tents near the water itself. Sometimes, after a strong discharge of linear lightning, a ball lightning appears - a luminous ball with a diameter of 5 to 30 cm, the path of movement of which is unpredictable.

It is noteworthy that already in ancient times people tried to protect themselves from lightning. The ancient Jews surrounded the Temple of Jerusalem with high masts studded with copper (for a thousand-year history, it has never been damaged by lightning, although it was located in one of the most thunder-prone areas of the planet).

Thunderstorms lead to the most dangerous manifestations of the elements - fires. A fire is an arbitrary spread of combustion that has gotten out of control. Peat and forest fires are especially dangerous. In this case, people and animals die, and huge material damage is caused.

Forest fires are divided into zones by area coverage:

• individual fires that occur in small quantities and are dispersed in time and area;
• mass fires, that is, individual fires that occur simultaneously;
• continuous fires, characterized by the rapid development and spread of fire, the presence of high temperature, smoke and gas pollution;
• a fire storm, or a particularly intense fire in a continuous fire zone, in the center of which an ascending column appears in the form of a fiery vortex column, where strong wind currents rush. It is almost impossible to put out a firestorm.

Forest fires can be of different types:

• grassroots, when dry peat cover, forest litter, fallen trees, shrubs, young forest burn;
• riding, when the forest is burning from top to bottom or tree crowns. Fire moves fast, sparks fly far. A crown fire develops from a lightning discharge or a ground fire;
• peat (subsoil), when peat burns flamelessly at a depth. In the fire area, there are blockages from fallen trees due to the burning of their roots and the appearance of voids under the soil layer. Equipment and people fall into these voids, which makes it difficult to extinguish fires and makes them especially dangerous.

Ways to extinguish forest fires

Flooding the edge of a fire is the simplest and most effective way to extinguish fires of medium intensity. Using bundles of wires or rods (in the form of a broom), young hardwood trees up to 2 m long, a group of four people is able to knock down the flames of a fire on the edge up to 1 km in an hour.

Throwing the edge of the fire with soil.

Installation of barrier strips and ditches by removing forest plantations and combustible materials to the mineral soil layer. In strong winds, the width of the lane can exceed 100 m (created using machinery, corded demolition charges or annealing).

When extinguishing fires, water or solutions of fire-extinguishing chemicals are most often used. Sometimes it is required to lay temporary conduits, deliver water containers by air and anneal (early launch of oncoming fire on the ground cover). Annealing is carried out by trained firefighters. They start from support bands (rivers, roads, streams) or artificially created mineralized bands.

Lightning discharges of atmospheric electricity are dangerous for people's lives, and when they enter a building, they can destroy it and cause a fire. For fire prevention and damage reduction on the OE is carried out:

• construction of reservoirs, pools and other water reservoirs;
• maintenance of fire retardant strips;
• ensuring the readiness of communications, warning systems, reconnaissance equipment;
• control of readiness of fire extinguishing means.

For protection, lightning rods of various designs are used: a) rod, b) antenna, c) mesh (Fig. 2.1). Any lightning rod consists of three elements: a lightning rod, a down conductor and a ground electrode. Particular attention is drawn to the fact that there is no contact between the ground loop in the building and the lightning protection ground loop. An example of lightning protection calculation is shown in fig. 2.2.

Ways to eliminate the danger from static electricity:

• reliable grounding of equipment, communications, vessels;
• reduction of specific (volume) resistance by increasing humidity, the use of antistatic impurities;
• ionization of air or environment;
• preventing the creation of explosive concentrations, reducing the speed of liquid movement and the length of product pipelines, the use of less flammable and explosive substances.

For electrical protection of equipment are used:

• fuse-links (melt or burn out when the current in the circuit is higher than the permissible value);
• circuit breakers, electromagnetic, thermal or combined circuit breakers (provide a break in the electrical circuit when the permissible value of the current passing through it is exceeded);
• thermal relays for protection of electric motors (based on bimetallic plates).

Rice. 2.1. Lightning protection structures

Fig2.2. Determining the height of a single lightning rod

At present, no one doubts the harmful effects on humans of electromagnetic fields (EMF) even of low intensity from high-voltage power lines, power distribution systems, contact networks of railway and urban electric transport, metro and even household electrical appliances. The consequences of such exposures can be increased fatigue, the appearance of heart pain, impaired functioning of the immune, reproductive, central nervous and endocrine systems, the risk of developing malignant tumors (especially the brain, breast), leukemia and the appearance of other serious diseases. EMF exposure is especially dangerous for children.

The foregoing is confirmed by studies conducted in the United States and, more carefully, in Sweden (1958-1977). It turned out that within a radius of 150 m from substations, transformers, near power lines, contact networks, the magnetic field induction exceeds 0,3 μT. In people living near such structures, tumors and leukemia occur twice as often (induction under power lines-200 is 0,2 μT). Then in Sweden, in-depth studies were carried out on these issues using the example of the population living in 800-meter corridors along the TL-200 and TL-400 routes. Statistical processing of the obtained results by 1992 confirmed that with an increase in the magnetic field inductance above 0,1 μT, the risk of disease increases by 24 times. Similar results were obtained in Finland and Denmark. By 1991, the US published the results of a survey that revealed an increased risk of leukemia in children who regularly use video games, electric blankets, heating pads and electric heaters.

A sanitary protection zone should be allocated along the power line route, the size of which depends on the type of radiation source and voltage of the power line (Table 2.6).

Table 2.6

Outside the sanitary protection zone, the electric field strength level should not exceed E = 0,5 kV / m, and the magnetic field induction - 0,1 μT. Calculations show that maintenance personnel are allowed to be under the power transmission line-400 at E = 10 kV/m for no more than 3 hours, and at E = 20 kV/m - no more than 10 minutes per day. Ignoring the dangers of EMF exposure can lead to changes in the production of melanin by the pineal gland of the brain, which in turn causes molecular changes in tissues and can lead to coronary disease and Parkinson's disease.

No less dangerous is the effect of EMF on biological objects near radio, television and location stations, power plants, and such an effect is a disaster for large cities. The number of such radiation sources is enormous, and their frequency range is distributed from a few hertz to hundreds of gigahertz. The share of means of communication is especially high (cellular, satellite, mobile, police traffic radars). Studies conducted by employees of the Research Institute of Occupational Medicine of the Russian Academy of Medical Sciences (Moscow, 1), the Center for Electromagnetic Safety (Moscow, 1992), the St. Petersburg branch of the Institute of Terrestrial Magnetism showed that the intensity of EMF in cities is ten times greater than the country background (Table 1996). And in electric trains, the EMF level exceeds the natural background by thousands of times, reaching a magnetic field induction value of up to 2.7 mT.

Table 2.7. Home sources of electromagnetic field

Even your own apartment is not a safe haven from EMF. There are enough sources with exceeding the conditional safety limit of 0,2 μT, as evidenced by studies conducted by employees of the Center for Electromagnetic Safety. It turned out that our apartments are entangled in electrical cables, the contents of electrical panels, cable lines, power supply systems for elevators and other products of civilization. Inside the apartment, EMF sources include all working electrical appliances (grills, irons, hoods, refrigerators, washing machines, TVs, computers).

Urahan (cyclone, typhoon - from whale. "big wind") is a wind with a force of up to 12 points. Its speed reaches 300 m/s, the front of the hurricane reaches a length of up to 500 km. A hurricane can travel hundreds of kilometers. It devastates everything in its path: it breaks trees, destroys buildings, creates waves up to 30 m high on the coast, can cause showers, and later cause an epidemic. In 1988, a hurricane in the Odessa region disabled 6000 km of power lines, leaving more than 130 settlements without power, as well as the city's water intake. Hurricanes, cyclones have seasonal dynamics.

Storm - a type of hurricane, but has a lower wind speed. The main causes of casualties during hurricanes and storms are the defeat of people by flying fragments, falling trees and building elements. The immediate cause of death in many cases is asphyxia from pressure, severe injuries. Among the survivors, there are multiple soft tissue injuries, closed or open fractures, craniocerebral injuries, spinal injuries. Wounds often contain deeply penetrated foreign bodies (soil, pieces of asphalt, glass fragments), which leads to septic complications and even gas gangrene. Dust storms are especially dangerous in the southern arid regions of Siberia and the European part of the country, as they cause erosion and weathering of the soil, removal or backfilling of crops, and exposure of roots.

Tornado (tornado) - a whirlwind movement of air propagating in the form of a giant black column with a diameter of up to hundreds of meters, inside which rarefaction of the air is observed, where various objects are drawn. The speed of air rotation in the dust column reaches 500 m/s. The air in the column rises in a spiral and draws in dust, water, objects, people. A tornado sometimes destroys entire villages. During its existence, it can travel up to 600 km, moving at a speed of up to 20 m/s. Buildings caught in a tornado due to rarefaction in the air column are destroyed from the pressure of air from the inside. Sometimes a tornado moves at a speed exceeding the speed of sound. It uproots trees, overturns cars, trains, lifts houses or their elements (roofs, individual parts) into the air, and transports people for several kilometers. The dead showed devastation of the body, broken empty skulls, compressed chests.

Tornadoes happen in many regions of Russia. So, in 1984, a tornado swept over the Ivanovo, Yaroslavl and Kostroma regions. Only in the Ivanovo region, four settlements were completely destroyed, a number of objects in the regional center, more than 70 people died and about 300 people were injured.

Hurricanes, storms and tornadoes are quite accurately predicted, and if timely notification is provided, serious material and human losses can be avoided (Table 2.8).

Table 2.8. Impact of some hurricanes

Having received a storm warning, it is necessary to immediately strengthen insufficiently strong structures and elements of equipment, close the doors of buildings, attics, and ventilation openings. Sheathe showcases and windows with boards, stick strips of paper or fabric on the glass. From roofs, balconies and loggias, remove objects that, if dropped, can cause injury. You should take care of emergency sources of lighting (lanterns, lamps), supplies of water, food, medicines, have efficient broadcasting facilities to receive information from the civil defense authorities.

Heavy snowfall, drifts, icing, avalanches - examples of the manifestation of the forces of nature in the winter. Snowfalls can last up to several days, covering roads, settlements, causing casualties and cutting off supplies. These natural phenomena are accurately predicted, and usually a warning is issued in a timely manner to areas of possible disaster.

In mountainous areas, the accumulation of snow leads to the formation of avalanches, the descent of which leads to the movement of significant masses of snow and stones. The moving mass sweeps away everything in its path, which leads to casualties, power line breaks, and destruction of communications. Cases have been recorded when settlements that existed for hundreds of years were buried under avalanches (Switzerland, the Caucasus). The volume of an avalanche can reach 2,5 million m³, and the speed - up to 100 m / s at a pressure at the moment of impact 60 ... 100 t / m² (dry avalanche) or up to 20 m/s at impact pressure up to 200 t/m² (an avalanche of dense, wet snow). The air shock wave that occurs during an avalanche also poses a serious danger (there was a case of transferring a railway car to a distance of 80 m, and in Japan in 1938, air-blast, formed during a large dry avalanche, tore off the second floor of a residential building, moved it to a distance of 800 m and smashed against the rocks).

Sharp temperature changes during snowfall lead to the appearance of ice and sticking of wet snow, which is especially dangerous for power lines and the urban electric transport network. To eliminate the consequences, the maximum number of trucks and means of loading snow is involved. Measures are being taken to clean up the main highways and establish the uninterrupted operation of the main life support enterprises (bakery, water supply, sewerage).

Flood - temporary flooding of a significant part of the land with water as a result of the action of natural forces. Depending on the causing causes, they can be divided into groups.

Floods caused by heavy rainfall or heavy melting of snow, glaciers. This leads to a sharp rise in the level of rivers, lakes, and the formation of congestion. The breakthrough of congestion and dams can lead to the formation of a breakthrough wave, characterized by the rapid movement of huge masses of water and a significant height. The flood in August 1989 in Primorye demolished a significant number of bridges and buildings, killing a huge number of livestock, damaging power lines, communications, roads destroyed, and thousands of people were left homeless.

Floods caused by surge winds. They are typical for coastal regions, where there are mouths of large rivers flowing into the sea. The surging wind delays the movement of water into the sea, which sharply raises the water level in the river. The coasts of the Baltic, Caspian and Azov seas are under constant threat of such flooding. So, St. Petersburg has experienced more than 240 such floods during its existence. At the same time, cases of the appearance of heavy ships were observed on the streets, which caused the destruction of urban buildings. In November 1824, the water level in the Neva rose 4 m above the norm; in 1924 - by 3,69 m, when water flooded half of the city; in December 1973 - by 2,29 m; January 1984 - by 2,25 m. And as a result of the floods - huge material losses and victims.

Flooding caused by underwater earthquakes. They are characterized by the appearance of giant waves of great length - tsunamis (in Japanese - "big wave in the harbor"). Tsunami propagation speed up to 1000 km/h. The height of the wave in the area of ​​its origin does not exceed 5 m. But when approaching the shore, the steepness of the tsunami increases sharply, and the waves crash on the coast with great force. At flat coasts, the wave height does not exceed 50 m, and in narrow bays it reaches 3 m (tunnel effect). The duration of a tsunami is up to 1000 hours, and the coastline affected by them reaches a length of 1952 km. In XNUMX, the waves almost washed away Yuzhno-Kurilsk.

The structure of sanitary losses during floods is dominated by injuries (fractures, damage to the joints, spine, soft tissues). Cases of diseases as a result of hypothermia (pneumonia, acute respiratory infections, rheumatism, worsening of the course of chronic diseases), the appearance of victims from burns (due to flammable liquids spilled and ignited on the surface of the water) have been recorded. The consequences of floods from the point of view of medicine can be judged from the data in Table. 2.9.

In the structure of sanitary losses, children occupy a significant place, and the most common consequences among the population are psychoneuroses, intestinal infections, malaria, and yellow fever. Human casualties are especially high on the coasts during hurricanes and tsunamis, as well as during the destruction of dams and dams (more than 93% drowned). As an example, the consequences of the 1970 flood in Bangladesh can be cited: on most of the coastal islands, the entire population died; out of 72 thousand fishermen in coastal waters, 46 thousand died. More than half of the dead were children under 10 years old, although they accounted for only 30% of the population of the disaster zone. Mortality among the population older than 50 years, among women and patients was also high.

Frequent companions of floods are large-scale poisoning. Due to the destruction of treatment facilities, warehouses with AHOV and other harmful substances, drinking water sources are poisoned. The development of extensive fires is not ruled out when flammable liquids spill over the surface of the water (gasoline and other combustible liquids are lighter than water).

Floods are successfully predicted, and the relevant services give warnings to dangerous areas, which reduces damage. In places of floods, dams, dams, hydraulic structures are built to regulate the flow of water. In the winding places of the rivers, work is carried out to expand and straighten their channels. During the threatened period, duty and maintenance of readiness of civil defense formations are organized. Early evacuation of the population, cattle theft, and removal of equipment are being carried out.

Rescue work in flooded areas often takes place in difficult weather conditions (rain showers, fogs, squally winds). Work to save people begins with reconnaissance, using boats and helicopters equipped with communications equipment.

Places of congestion of people are established, and funds are sent there to ensure their salvation. Work on hydraulic structures is carried out by the formation of engineering and emergency technical services of the Civil Defense and Emergency Service: this is the strengthening of dams, dams, embankments or their construction.

Table 2.9. Consequences of a number of floods

Flooding. Up to 75% of all cities are flooded, about 9 million hectares of agricultural land. The area of ​​flooding over the past 15 years has increased by 50%. There are two types of flooding: man-made (as a result of human activities) and natural (manifestation of natural processes).

Technogenic flooding has a latent (hidden) character and therefore is the most dangerous, it can lead to the emergence and development of hazardous processes (landslides, karst phenomena). It is provoked by the illiterate activity of people:

• leakage from water-bearing communications, tanks, constructed reservoirs and technological water storage tanks;
• violation of the natural conditions of surface water runoff during the development of the urban economy, especially storm sewers;
• elimination of natural drainage systems, destruction of groundwater flow paths by buried structures, screening of the evaporating surface of the territory with impermeable coatings;
• backwater groundwater by raising the water level in reservoirs.

Natural flooding is the result of floods, spills, surge phenomena. The consequences of flooding can be:

• deterioration of the sanitary and epidemiological situation;
• groundwater pollution, water supply source;
• soil destruction, deterioration of land quality;
• suppression and change in the species composition of flora and fauna;
• flooding of basements and technical undergrounds, which leads to the appearance of dampness, mosquitoes and fungal formations in residential premises, the destruction of communications and increased morbidity of people;
• deformation of buildings, failures, swelling and subsidence of the soil;
• pollution of underground waters with heavy metals, oil products and other chemical elements;
• destruction of tanks, product pipelines and other buried structures due to increased corrosion processes;
• unacceptable moisture, swamping and salinization of territories in the area of ​​flooding;
• the degeneration of vegetation and forests with all the negative consequences for the animal world;
• violation of the tightness of animal burial grounds, landfills.

Authors: Grinin A.S., Novikov V.N.

 We recommend interesting articles Section Basics of safe life:

▪ Protection against toxic emissions

▪ Natural and man-made emergencies, their possible consequences

▪ Distribution of duties between officials involved in the elimination of emergencies

See other articles Section Basics of safe life.

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Machine for thinning flowers in gardens 02.05.2024

In modern agriculture, technological progress is developing aimed at increasing the efficiency of plant care processes. The innovative Florix flower thinning machine was presented in Italy, designed to optimize the harvesting stage. This tool is equipped with mobile arms, allowing it to be easily adapted to the needs of the garden. The operator can adjust the speed of the thin wires by controlling them from the tractor cab using a joystick. This approach significantly increases the efficiency of the flower thinning process, providing the possibility of individual adjustment to the specific conditions of the garden, as well as the variety and type of fruit grown in it. After testing the Florix machine for two years on various types of fruit, the results were very encouraging. Farmers such as Filiberto Montanari, who has used a Florix machine for several years, have reported a significant reduction in the time and labor required to thin flowers. ... >>

Advanced Infrared Microscope 02.05.2024

Microscopes play an important role in scientific research, allowing scientists to delve into structures and processes invisible to the eye. However, various microscopy methods have their limitations, and among them was the limitation of resolution when using the infrared range. But the latest achievements of Japanese researchers from the University of Tokyo open up new prospects for studying the microworld. Scientists from the University of Tokyo have unveiled a new microscope that will revolutionize the capabilities of infrared microscopy. This advanced instrument allows you to see the internal structures of living bacteria with amazing clarity on the nanometer scale. Typically, mid-infrared microscopes are limited by low resolution, but the latest development from Japanese researchers overcomes these limitations. According to scientists, the developed microscope allows creating images with a resolution of up to 120 nanometers, which is 30 times higher than the resolution of traditional microscopes. ... >>

Air trap for insects 01.05.2024

Agriculture is one of the key sectors of the economy, and pest control is an integral part of this process. A team of scientists from the Indian Council of Agricultural Research-Central Potato Research Institute (ICAR-CPRI), Shimla, has come up with an innovative solution to this problem - a wind-powered insect air trap. This device addresses the shortcomings of traditional pest control methods by providing real-time insect population data. The trap is powered entirely by wind energy, making it an environmentally friendly solution that requires no power. Its unique design allows monitoring of both harmful and beneficial insects, providing a complete overview of the population in any agricultural area. “By assessing target pests at the right time, we can take necessary measures to control both pests and diseases,” says Kapil ... >>

Random news from the Archive Duracell Powercheck technology detects battery charge 14.10.2015 Duracell has developed Powercheck technology to help you accurately determine battery charge. This will allow you not to throw away seemingly discharged batteries, but to use the residual charge in devices with low power consumption. Usually, if a battery-powered device stops showing signs of life, we simply replace the batteries and the problem is solved. But hardly anyone thought that the batteries that are sent to the scrap were not used up by at least a third. According to a European study by Battery Back, the European Recycling Platform, the Energy Saving Trust and the Duracell brand, one in three batteries has up to 40% charge left. To prevent people from losing money by throwing half the cost of a battery into the trash, Duracell has developed Powercheck technology, which is already implemented in Duracell TurboMax batteries. This innovation allows you to accurately determine the remaining charge, so that batteries with residual energy can be used in more energy-intensive devices (for example, in remote controls or children's toys). Devices with a higher power consumption (for example, a digital camera or an electric shaver) can turn off even when a third of the capacity is left in the battery. When using Duracell TurboMax batteries, you will always know how much energy is left in the power cell. To do this, simply click on the white circles of the Powercheck indicator.

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