Hazardous natural phenomena mean extreme climatic or meteorological phenomena that occur naturally at one point or another on the planet. In some regions, such hazardous events may occur with greater frequency and destructive force than in others. Dangerous natural phenomena develop into natural disasters when the infrastructure created by civilization is destroyed and the people themselves die.

1.Earthquakes

Among all natural hazards, earthquakes should take first place. In places where the earth's crust breaks, tremors occur, which cause vibrations of the earth's surface with the release of gigantic energy. The resulting seismic waves are transmitted over very long distances, although these waves have the greatest destructive power at the epicenter of the earthquake. Due to strong vibrations of the earth's surface, massive destruction of buildings occurs.
Since quite a lot of earthquakes occur, and the surface of the earth is quite densely built up, the total number of people throughout history who died as a result of earthquakes exceeds the number of all victims of other natural disasters and is estimated in many millions. For example, over the past decade, about 700 thousand people have died from earthquakes around the world. Entire settlements instantly collapsed from the most destructive shocks. Japan is the country most affected by earthquakes, and one of the most catastrophic earthquakes occurred there in 2011. The epicenter of this earthquake was in the ocean near the island of Honshu; on the Richter scale, the force of the tremors reached 9.1. Powerful tremors and the subsequent destructive tsunami disabled the Fukushima nuclear power plant, destroying three out of four power units. Radiation covered a significant area around the station, making densely populated areas, so valuable in Japanese conditions, uninhabitable. The colossal tsunami wave turned into mush what the earthquake could not destroy. Only officially over 16 thousand people died, to which we can safely include another 2.5 thousand who are considered missing. Only in this century destructive earthquakes occurred in the Indian Ocean, Iran, Chile, Haiti, Italy, Nepal.

2.Tsunami waves

A specific water disaster in the form of tsunami waves often results in numerous casualties and catastrophic destruction. As a result of underwater earthquakes or shifts of tectonic plates in the ocean, very fast but subtle waves arise, which grow into huge ones as they approach the shores and reach shallow waters. Most often, tsunamis occur in areas with increased seismic activity. A huge mass of water, quickly approaching the shore, destroys everything in its path, picks it up and carries it deep into the coast, and then carries it into the ocean with a reverse current. People, unable to sense danger like animals, often do not notice the approach of a deadly wave, and when they do, it is too late.
Usually killed by a tsunami more people than from the earthquake that caused it (the latest case in Japan). In 1971, the most powerful tsunami ever observed occurred there, the wave of which rose 85 meters at a speed of about 700 km/h. But the most catastrophic was the tsunami observed in the Indian Ocean (source - an earthquake off the coast of Indonesia), which claimed the lives of about 300 thousand people along a large part of the Indian Ocean coast.

3. Volcanic eruption

Throughout its history, humanity has remembered many catastrophic volcanic eruptions. When the pressure of magma exceeds the strength of the earth's crust at the weakest points, which are volcanoes, it ends in an explosion and outpouring of lava. But the lava itself, from which you can simply walk away, is not so dangerous as the hot pyroclastic gases rushing from the mountain, penetrated here and there by lightning, as well as the noticeable influence of the strongest eruptions on the climate.
Volcanologists count about half a thousand dangerous active volcanoes, several dormant supervolcanoes, not counting thousands of extinct ones. Thus, during the eruption of Mount Tambora in Indonesia, the surrounding lands were plunged into darkness for two days, 92 thousand inhabitants died, and cold temperatures were felt even in Europe and America.
List of some major volcanic eruptions:

• Volcano Laki (Iceland, 1783). As a result of that eruption, a third of the island's population died - 20 thousand inhabitants. The eruption lasted for 8 months, during which streams of lava and liquid mud erupted from volcanic fissures. Geysers have become more active than ever. Living on the island at this time was almost impossible. The crops were destroyed and even the fish disappeared, leaving the survivors hungry and suffering from unbearable living conditions. This may be the longest eruption in human history.
• Volcano Tambora (Indonesia, Sumbawa Island, 1815). When the volcano exploded, the sound of the explosion spread over 2 thousand kilometers. Even the remote islands of the archipelago were covered with ash, and 70 thousand people died from the eruption. But even today, Tambora is one of the highest mountains in Indonesia that remains volcanically active.
• Volcano Krakatoa (Indonesia, 1883). 100 years after Tambora, another catastrophic eruption occurred in Indonesia, this time “blowing the roof off” (literally) the Krakatoa volcano. After the catastrophic explosion that destroyed the volcano itself, frightening rumbles were heard for another two months. A gigantic amount of rock, ash and hot gases were thrown into the atmosphere. The eruption was followed by a powerful tsunami with wave heights of up to 40 meters. These two natural disasters together destroyed 34 thousand islanders along with the island itself.
• Volcano Santa Maria (Guatemala, 1902). After a 500-year hibernation, this volcano woke up again in 1902, beginning the 20th century with the most catastrophic eruption, which resulted in the formation of a one and a half kilometer crater. In 1922, Santa Maria reminded itself again - this time the eruption itself was not too strong, but the cloud of hot gases and ash brought the death of 5 thousand people.

4.Tornadoes

A tornado is a very impressive natural phenomenon, especially in the United States, where it is called a tornado. This is an air flow twisted in a spiral into a funnel. Small tornadoes resemble slender, narrow pillars, and giant tornadoes can resemble a mighty carousel reaching towards the sky. The closer you are to the funnel, the stronger the wind speed is; it begins to drag along increasingly larger objects, up to cars, carriages and light buildings. In the “tornado alley” of the United States, entire city blocks are often destroyed and people die. The most powerful vortices of the F5 category reach a speed of about 500 km/h at the center. The state that suffers the most from tornadoes every year is Alabama.

There is a type of fire tornado that sometimes occurs in areas of massive fires. There, from the heat of the flame, powerful upward currents are formed, which begin to twist into a spiral, like an ordinary tornado, only this one is filled with flame. As a result, a powerful draft is formed near the surface of the earth, from which the flame grows even stronger and incinerates everything around. When a catastrophic earthquake occurred in Tokyo in 1923, it caused massive fires that led to the formation of a fire tornado that rose 60 meters. The column of fire moved towards the square with frightened people and burned 38 thousand people in a few minutes.

5.Sandstorms

This phenomenon occurs in sandy deserts when strong winds rise. Sand, dust and soil particles rise to a fairly high altitude, forming a cloud that sharply reduces visibility. If an unprepared traveler gets caught in such a storm, he may die from grains of sand falling into his lungs. Herodotus described the story as 525 BC. e. In the Sahara, a 50,000-strong army was buried alive by a sandstorm. In Mongolia in 2008, 46 people died as a result of this natural phenomenon, and a year earlier two hundred people suffered the same fate.

6.Avalanches

Avalanches periodically fall from snow-capped mountain peaks. Climbers especially often suffer from them. During the First World War, up to 80 thousand people died from avalanches in the Tyrolean Alps. In 1679, half a thousand people died from snow melting in Norway. In 1886 it happened major disaster, as a result of which the “white death” claimed 161 lives. The records of Bulgarian monasteries also mention human casualties from avalanches.

7.Hurricanes

In the Atlantic they are called hurricanes, and in Pacific Ocean typhoons. These are huge atmospheric vortices, in the center of which the strongest winds and sharply reduced pressure are observed. Several years ago, the devastating Hurricane Katrina swept over the United States, which particularly affected the state of Louisiana and the densely populated city of New Orleans, located at the mouth of the Mississippi. 80% of the city's territory was flooded, and 1,836 people died. Other famous destructive hurricanes include:

• Hurricane Ike (2008). The diameter of the vortex was over 900 km, and in its center the wind blew at a speed of 135 km/h. In the 14 hours that the cyclone moved across the United States, it managed to cause $30 billion worth of destruction.
• Hurricane Wilma (2005). This is the largest Atlantic cyclone in the entire history of weather observations. The cyclone, which originated in the Atlantic, made landfall several times. The damage it caused amounted to $20 billion, killing 62 people.
• Typhoon Nina (1975). This typhoon was able to breach China's Bangqiao Dam, causing the destruction of the dams below and causing catastrophic flooding. The typhoon killed up to 230 thousand Chinese.

8.Tropical cyclones

These are the same hurricanes, but in tropical and subtropical waters, representing huge low-pressure atmospheric systems with winds and thunderstorms, often exceeding a thousand kilometers in diameter. Near the surface of the earth, winds at the center of the cyclone can reach speeds of more than 200 km/h. Low pressure and wind cause the formation of a coastal storm surge - when colossal masses of water are thrown ashore at high speed, washing away everything in its path.

9.Landslide

Prolonged rains can cause landslides. The soil swells, loses stability and slides down, taking with it everything that is on the surface of the earth. Most often, landslides occur in the mountains. In 1920, the most devastating landslide occurred in China, under which 180 thousand people were buried. Other examples:

• Bududa (Uganda, 2010). Due to mudflows, 400 people died, and 200 thousand had to be evacuated.
• Sichuan (China, 2008). Avalanches, landslides and mudflows caused by an 8-magnitude earthquake claimed 20 thousand lives.
• Leyte (Philippines, 2006). The downpour caused a mudslide and landslide that killed 1,100 people.
• Vargas (Venezuela, 1999). Mudflows and landslides after heavy rains (almost 1000 mm of precipitation fell in 3 days) on the northern coast led to the death of almost 30 thousand people.

10. Ball lightning

We are accustomed to ordinary linear lightning accompanied by thunder, but ball lightning is much rarer and more mysterious. The nature of this phenomenon is electrical, but scientists cannot yet give a more accurate description of ball lightning. It is known that it can have different sizes and shapes, most often they are yellowish or reddish luminous spheres. For unknown reasons, ball lightning often defies the laws of mechanics. Most often they occur before a thunderstorm, although they can also appear in absolutely clear weather, as well as indoors or in an airplane cabin. The luminous ball hovers in the air with a slight hiss, then can begin to move in any direction. Over time, it seems to shrink until it disappears completely or explodes with a roar. But the damage ball lightning can cause is very limited.

Natural disasters are very diverse in nature. Despite this, natural disasters have some common patterns. Here are some of them.

The first rule of natural hazards is that they can never be completely eliminated. This is due to the fact that humanity constantly uses environment as the source of its existence and development.

The second pattern of natural hazards is revealed when analyzing the development of a geographical system: the total number of extreme events leading to the occurrence natural Disasters, is constantly increasing (thus, the increase in emergencies of natural origin in the Russian Federation in 1997 compared to 1996 was 29.7%). At the same time, the destructive power and intensity of most natural disasters are growing, as well as the number of victims, moral and material damage caused by them (Table 3.1). As can be seen from the table, in the north of Eurasia the greatest danger is posed by

floods (746 cities affected), landslides and collapses (725), earthquakes (103), tornadoes (500).

The total annual socio-economic damage from the development of the 21 most dangerous processes in Russia, according to expert estimates, is about 15-19 billion rubles.

The third pattern is related to the second and is manifested in the ever-increasing general sensitivity of the world community to natural disasters. Increasing “sensitivity” implies that the community is devoting an increasing number of resources to the preparation and implementation of various global organizational and technical activities, as well as to the manufacture of protective devices and the construction of protective structures.

The fourth pattern allows us to identify the main general factors without which it is impossible to reliably predict material damage and the number of victims in any natural disaster. These include historical and social conditions in society that had developed at the time of the forecast; the level of economic development and geographical location of disaster areas; determining land use conditions and their prospects; the possibility of a negative combination with other natural processes, etc.

The fifth regularity is that for any type of natural disaster a spatial location can be established.

The sixth pattern allows us to connect the strength and intensity of a natural disaster with its frequency and recurrence: the greater the intensity of a natural disaster, the less often it is repeated with the same force.

These patterns are confirmed by the dynamics of growth of hazardous natural phenomena over the past 5 years (Table 3.29.

As can be seen from the table, while the number of hazardous natural phenomena characteristic of the territory of Russia fluctuates from 300 to 500 per year, there has been a steady tendency to increase in the last five years the number of emergency situations (from 123 to 360) resulting from hazardous natural phenomena .

A dangerous natural phenomenon should be understood as a spontaneous event of natural origin, which, due to its intensity, scale of distribution and duration, can cause negative consequences for the life of people, as well as the economy and the natural environment.

A natural disaster is a catastrophic natural phenomenon (or process) that can cause numerous casualties, significant property damage and other severe consequences.

3.2, Classification of natural emergencies

Depending on the mechanism and nature of origin, hazardous natural phenomena are divided into the following groups (classes):

Geophysical hazards:

E) earthquakes;

E) volcanic eruptions;

E) tsunami.

Geological hazards (exogenous geological phenomena):

E) landslides, axles; E) avalanches;

ts inclined flush;

q subsidence (failure) of the earth's surface as a result of carriage;

c abrasion, arosion;

ts kuruma;

dust storms.

Meteorological and agrometeorological hazards:

si storms (9-11 points);

c hurricanes (12-15 points);

c tornadoes (tornado);

c squalls;

q vertical vortices (flows);

Ei large hail;

c heavy rain (rain);

c heavy snowfall;

c heavy ice;

O severe frost;

About a strong snowstorm;

O intense heat;

O strong fog;

O drought;

About dry winds;

c freezing.

Marine hydrological hazards:

c tropical cyclones (typhoon);

C strong excitement (5 points or more);

C strong fluctuations in sea level;

- strong draft in ports;

O early ice cover or fast ice;

O ice pressure, intense ice drift;

O impassable (difficult to pass) ice;

About icing of ships;

c separation of coastal ice.

Hydrological hazards:

c high water level:

About the flood;

About rain floods;

O low water level;

rising groundwater levels (flooding).

Natural fires:

O extreme fire danger;

About forest fires;

About fires of steppe and grain massifs;

About peat fires;

About underground fossil fuel fires.

Not every dangerous natural phenomenon leads to an emergency, especially if there is no threat to human life at the place where it occurs. For example, an annual flood is not counted as a flood if it does not threaten anyone. There is no reason to consider storms, storms, avalanches, freeze-ups, and volcanic eruptions as emergencies in places where people do not live or do any work. An emergency occurs only when, as a result of a dangerous natural phenomenon, a real threat arises to people and their environment.

Many dangerous natural phenomena are closely related to each other. Earthquake

can cause landslides, landslides, mudflows, floods, tsunamis, avalanches, and increased volcanic activity. Many storms, hurricanes, and tornadoes are accompanied by showers, thunderstorms, and hail. Extreme heat is accompanied by drought, low groundwater, fires, epidemics, and pest infestations. Try to trace these connections and the mechanisms of their formation when studying individual topics.

About congestion and gluttons; About wind surge;

d early freeze-up and the appearance of ice on navigable reservoirs and rivers;

It is known that the earth’s crust, together with part of the upper mantle, is not a monolithic shell of the planet, but consists of several large blocks (plates) with a thickness of 60 to 200 km. In total there are 7 huge slabs and dozens of smaller slabs. The upper part of most plates is both continental and oceanic crust, that is, on these plates there are continents, seas and oceans.

The plates lie on a relatively soft, plastic layer of the upper mantle, along which they slowly move at a speed of 1 to 6 cm per year. Neighboring plates move closer together, diverge, or slide relative to each other. They “float” on the surface of the plastic layer of the upper mantle, like pieces of ice on the surface of water.

As a result of the movement of plates, complex processes constantly occur in the bowels of the Earth and on its surface. For example, when plates collide with the oceanic crust, deep-sea depressions (trenches) can appear, and when plates that form the base of the continental crust collide, mountains can form. When two plates approach the continental crust, their edges, along with all the sedimentary rocks accumulated on them, are crushed into folds, forming mountain ranges. With the onset of critical overloads, the folds shift and tear. The ruptures occur instantly, accompanied by a shock or a series of shocks that have the nature of impacts. The energy released during the rupture is transmitted through the earth's crust in the form of elastic seismic waves and leads to earthquakes.

The boundary areas between lithospheric plates are called seismic belts. These are the most restless, mobile areas of the planet. The majority of active volcanoes are concentrated here and at least 95% of all earthquakes occur.

Thus, geological natural phenomena are associated with the movement of lithospheric plates and changes occurring in the lithosphere.

Dangerous geological phenomenon- an event of geological origin or the result of geological processes occurring in the earth’s crust under the influence of various natural or geodynamic factors or their combinations, which have or may have a damaging effect on people, farm animals and plants, economic objects and the environment.

Dangerous geological natural phenomena include earthquakes, volcanic eruptions, landslides, and landslides.

Meteorological natural phenomena

Dangerous meteorological phenomenon- natural processes and phenomena that occur in the atmosphere under the influence of various natural factors or their combinations, which have or may have a damaging effect on people, farm animals and plants, economic objects and the natural environment.

These processes and phenomena are associated with various atmospheric processes, and primarily with processes occurring in the lower layer of the atmosphere - the troposphere. The troposphere contains about 9/10 of the total air mass. Under the influence of solar heat entering the earth's surface and the force of gravity, clouds, rain, snow, and wind are formed in the troposphere.

Air in the troposphere moves in horizontal and vertical directions. Strongly heated air near the equator expands, becomes lighter and rises. There is an upward movement of air. For this reason, a belt of low atmospheric pressure forms near the Earth's surface near the equator. At the poles, due to low temperatures, the air cools, becomes heavier and sinks. There is a downward movement of air. For this reason, the pressure at the Earth's surface near the poles is high.

In the upper troposphere, on the contrary, above the equator, where ascending air currents predominate, the pressure is high, and above the poles it is low. Air constantly moves from an area of ​​high pressure to an area of ​​low pressure. Therefore, the air rising above the equator spreads towards the poles. But due to the rotation of the Earth around its axis, the moving air does not reach the poles. As it cools, it becomes heavier and sinks at about 30° north and south latitudes, forming areas of high pressure in both hemispheres.

Large volumes of air in the troposphere with homogeneous properties are called air masses. Depending on the place of formation of air masses, four types are distinguished: equatorial air mass, or equatorial air; tropical air mass, or tropical air; moderate air mass, or temperate air; Arctic (Antarctic) air mass, or Arctic (Antarctic) air.

The properties of these air masses depend on the territories over which they formed. As air masses move, they retain their properties for a long time, and when they meet, they interact with each other. The movement of air masses and their interaction determine the weather in the places where these air masses arrive. The interaction of various air masses leads to the formation of moving atmospheric vortices in the troposphere - cyclones and anticyclones.

Cyclone is a flat rising vortex with low atmospheric pressure at the center. The diameter of a cyclone can be several thousand kilometers. The weather during a cyclone is predominantly cloudy with strong winds.

Anticyclone is a flat downward vortex with high atmospheric pressure with a maximum in the center. In an area of ​​high pressure, the air does not rise, but falls. The air spiral unwinds clockwise in the northern hemisphere. The weather during the anticyclone is partly cloudy, without precipitation, and the wind is weak.

The movement of air masses and their interaction is associated with the emergence of dangerous meteorological phenomena that can cause natural disasters. These are typhoons and hurricanes, storms, blizzards, tornadoes, thunderstorms, drought, severe frosts and fogs.

Hydrological natural phenomena

Water on the surface of the Earth is found in oceans and seas, in rivers and lakes, in the atmosphere in a gaseous state and in glaciers in a solid state.

All water on Earth that is not part of rocks is united by the concept of “hydrosphere”. The volume of all water on Earth is so large that it is measured in cubic kilometers. A cubic kilometer is a cube with each edge measuring 1 km, completely filled with water. The weight of 1 km 3 of water is equal to 1 billion tons. The Earth contains 1.5 billion km 3 of water, 97% of which is the World Ocean. Currently, it is customary to divide the World Ocean into 4 separate oceans and 75 seas with bays and straits.

Water is in a constant cycle, and closely interacts with the air shell of the Earth and with the land.

The driving force behind the water cycle is solar energy and gravity.

Under the influence sun rays water evaporates from the surface of the ocean and land (from rivers, reservoirs, soil and plants) and enters the atmosphere. Some of the water immediately returns with rain back to the ocean, while some is transported by winds to land, where it falls to the surface in the form of rain or snow. Once on the soil, water is partially absorbed into it, replenishing the reserves of soil moisture and groundwater, and partially flows into rivers and reservoirs. Soil moisture partly passes into plants, which evaporate it into the atmosphere, and partly flows into rivers. Rivers fed by surface and underground waters carry water to the World Ocean, replenishing its loss. Water, evaporating from the surface of the World Ocean, again ends up in the atmosphere, and the cycle closes.

This movement of water between the constituent parts of nature and all parts of the earth's surface occurs constantly and uninterruptedly for many millions of years.

The water cycle in nature, like a closed chain, consists of several links. There are eight such links: atmospheric, oceanic, underground, river, soil, lake, biological and economic. Water constantly moves from one link to another, connecting them into a single whole. In the process of the water cycle in nature, dangerous natural phenomena constantly arise that affect the safety of human life and can lead to catastrophic consequences.

Dangerous hydrological phenomenon- an event of hydrological origin or the result of hydrological processes arising under the influence of various natural or hydrodynamic factors or their combinations, which have a damaging effect on people, farm animals and plants, economic objects and the environment.

Hazardous natural phenomena of a hydrological nature include floods, tsunamis and mudflows.

Biological hazards

Living organisms, including humans, interact with each other and the surrounding inanimate nature. During this interaction, the exchange of substances and energy occurs, there is continuous reproduction, growth of living organisms and their movement.

Among the most dangerous natural phenomena of a biological nature that have a significant impact on the safety of human life are:

• natural fires(forest fires, fires of steppe and grain massifs, peat fires and underground fires of fossil fuels);
• infectious diseases of people (single cases of exotic and especially dangerous infectious diseases, group cases of dangerous infectious diseases, epidemic outbreak of dangerous infectious diseases, epidemic, pandemic, infectious diseases of people of unknown etiology);
• infectious diseases of animals (single outbreaks of exotic and especially dangerous infectious diseases, enzootics, epizootics, panzootics, infectious diseases of farm animals of unknown etiology);
• damage to agricultural plants by diseases and pests (epiphytoty, panphytoty, disease of agricultural plants of unknown etiology, mass spread of plant pests).

Wildfires include forest fires, fires of steppe and grain massifs, and peat fires. The most common are forest fires, which occur annually, causing enormous losses and resulting in casualties.

Forest fires are uncontrolled burning of vegetation that spontaneously spreads throughout the forest area. In dry weather and wind, forest fires cover large areas.

In hot weather, if there is no rain for 15-20 days, the forest becomes a fire hazard. Statistics show that in 90-97% of cases, the cause of forest fires is human activity.

Epidemic- widespread spread of an infectious disease among people, significantly exceeding the incidence rate usually recorded in a given territory. The usual (minimal) morbidity rate for a given area is most often isolated cases of diseases that have no connection with each other.

Epizootics- widespread infectious diseases of animals.

Epiphytoty- widespread plant diseases.

The massive spread of infectious diseases among people, farm animals or plants poses a direct threat to the safety of human life and can lead to emergency situations.

Infectious diseases is a group of diseases that are caused by specific pathogens (bacteria, viruses, fungi). Characteristic Features infectious diseases are: contagiousness, i.e. the ability to transmit pathogens from a sick organism to a healthy one; stages of development (infection, incubation period, course of the disease, recovery).

Space hazards

The Earth is a cosmic body, a small particle of the Universe. Other cosmic bodies can have a strong influence on earthly life.

Everyone has seen “shooting stars” appear and disappear in the night sky. This meteors- small celestial bodies. We are observing a short-term flash of hot glowing gas in the atmosphere at an altitude of 70-125 km. It occurs when a meteor enters the atmosphere at high speed.

Consequences of the fall of the Tunguska meteorite. Photo 1953

If, during its movement in the atmosphere, the solid particles of the meteor do not have time to completely collapse and burn, then their remains fall to the Earth. This meteorites.

There are also larger celestial bodies that planet Earth can encounter. These are comets and asteroids.

Comets- these are fast moving starry sky bodies of the solar system moving in highly elongated orbits. As they approach the Sun, they begin to glow and a “head” and a “tail” appear. The central part of the “head” is called the nucleus. The diameter of the core can be from 0.5 to 20 km. The core is an icy body of frozen gases and dust particles. The “tail” of a comet consists of gas molecules and dust particles evaporated from the nucleus under the influence of sunlight. The length of the “tail” can reach tens of millions of kilometers.

Asteroids- these are small planets, the diameter of which ranges from 1 to 1000 km.

Currently, about 300 cosmic bodies are known that can cross the Earth's orbit. In total, according to astronomers, there are approximately 300 thousand asteroids and comets in space.

Fall of the Sikhote-Alin meteorite

The meeting of our planet with large celestial bodies poses a serious threat to the entire biosphere.

The natural world around us is constantly changing, metabolic and energy processes take place in it, and all this, taken together, gives rise to various natural phenomena. Depending on the intensity of manifestation and the power of the processes occurring, these natural phenomena can create a threat to human life and create an emergency situation natural character.

Test yourself

1. Name the main groups of natural hazards.
2. List the main natural phenomena of a geological nature and explain the reasons for their occurrence.
3. What main natural phenomena of a meteorological and hydrological nature do you know? Indicate their interdependence.
4. Tell us about dangerous natural phenomena of a biological nature. State the reasons for their appearance.

After lessons

Ask an adult, look online and keep a safety diary for the main natural phenomena of geological, meteorological, hydrological and biological origin in your area.

Subject: General concepts about dangerous and emergency situations of a natural nature.

Lesson topic: Natural phenomena and their classification.

The purpose of the lesson: To introduce students to natural phenomena and their diversity.

Lesson objectives:

I. Educational objectives:

• Recall and consolidate knowledge about the shells of the Earth.
• To develop students’ knowledge that the formation of any natural phenomenon is associated with processes occurring in the Earth’s shells.
• To give students a general idea of ​​the types of natural phenomena at the place of their occurrence.

II. Developmental tasks.

• To develop in students the ability and ability to foresee natural phenomena in their area that can lead to serious consequences, as well as ways to protect against them.

III. Educational tasks.

• To instill in students the belief that any natural phenomenon of destructive force brings enormous damage to the state various types, primarily material and loss of life. Therefore, the state needs to allocate funds to scientific institutions so that they can deal with this problem and be able to predict them in the future.

During the classes

Teacher: Today, children, we will talk about natural phenomena and their diversity. Some you know, of course, some you learned from a course in natural history and geography, and if someone is interested in the media, then from there. If you turn on the TV, radio or use the Internet, you can say with confidence that natural phenomena of destructive force are occurring more and more often, and their strength is becoming greater. Therefore, we need to know what natural phenomena occur, where they most often occur and how to protect ourselves from them.

Teacher: And so let's remember from the geography course what shells of the Earth exist.

In total, there are 4 shells of the Earth:

1. Lithosphere - it includes the earth's crust and the upper part of the mantle.
2. The hydrosphere is a shell of water that contains all the water in different states.
3. The atmosphere is a gas shell, the lightest and most mobile.
4. The biosphere is the sphere of life, this is the area of ​​existence of all living organisms.

Teacher: All these shells have their own specific processes, as a result of which natural phenomena arise. Therefore, various natural phenomena can be divided according to the place of their occurrence:

Teacher: From this diagram we see how many natural phenomena there are. Now let's look at each of them and find out what they are. (Children must take an active part in this part.)

Geological.

1. An earthquake is a natural phenomenon associated with geological processes occurring in the Earth’s lithosphere; it manifests itself in the form of tremors and vibrations of the earth’s surface, resulting from sudden displacements and ruptures in the earth’s crust or in the upper part of the mantle.

Picture 1.

2. A volcano is a conical mountain from which hot material – magma – erupts from time to time.

A volcanic eruption is the release of molten matter from the Earth’s crust and mantle, called magma, onto the surface of the planet.

Figure 2.

3. A landslide is a sliding downward displacement of soil masses under the influence of gravity, which occurs on slopes when the stability of the soil or rocks is disrupted.

The formation of landslides depends on various factors, such as:

• what rocks make up this slope;
• slope steepness;
• groundwater, etc.

Landslides can occur either naturally (for example, earthquakes, heavy rainfall) or artificially (for example, human activities: deforestation, soil excavation).

Figure 3.

4. A landslide is the separation and fall of large masses of rocks, their overturning, crushing and rolling down on steep and steep slopes.

Causes of landslides in mountains can be:

• the rocks that make up the mountains are layered or broken by cracks;
• water activity;
• geological processes(earthquake), etc.

The causes of landslides on the coasts of seas and rivers are the erosion and dissolution of underlying rocks.

Figure 4.

5. A snow avalanche is a collapse of a mass of snow on mountain slopes; the angle of inclination must be at least 15°.

The causes of an avalanche are:

• earthquake;
• intense snow melting;
• prolonged snowfall;
• human activity.

Figure 5.

Meteorological.

1. A hurricane is a wind whose speed exceeds 30 m/s, leading to enormous destruction.

Figure 6.

2. A storm is wind, but at a lower speed than in a hurricane and is no more than 20 m/s.

Figure 7.

3. A tornado is an atmospheric vortex that forms in a thundercloud and descends downwards; it has the shape of a funnel or sleeve.

A tornado consists of a core and a wall. There is an upward movement of air around the core, the speed of which can reach 200 m/s.

Figure 8.

Hydrological.

1. Flood is a significant inundation of an area as a result of rising water levels in a lake, river, etc.

Causes of flooding:

• intensive snow melting in spring;
• heavy rainfall;
• obstruction of river beds with rocks during an earthquake, landslide, etc., as well as with ice during congestion;
• wind activity (water surge from the sea, bay to the mouth of the river).

Types of floods:

Figure 9.

2. A mudflow is a stormy stream in the mountains that is temporary in nature, consisting of water and a large amount of rock fragments.

The formation of mudflows is associated with heavy precipitation in the form of rain or intense snow melting. As a result, loose rocks are washed away and move along the river bed at high speed, which picks up everything in its path: boulders, trees, etc.

Figure 10.

3. Tsunamis are a type of sea waves that arise as a result of vertical displacement of large sections of the seabed.

A tsunami occurs as a result of:

• earthquakes;
• underwater volcanic eruptions;
• landslides, etc.

Figure 11.

Biological.

1. A forest fire is an uncontrolled burning of vegetation that spontaneously spreads through a forest area.

A forest fire can be ground fire or crown fire.

An underground fire is the burning of peat in marshy and swampy soils.

Figure 12.

2. An epidemic is the spread of an infectious disease among a large population and significantly exceeds the incidence rate usually recorded in a given area.

Figure 13.

3. Epizootic is a widespread infectious disease among animals (for example: foot and mouth disease, swine fever, cattle brucellosis).

Figure 14.

4. Epiphytoty is a massive spread of an infectious disease among plants (for example: late blight, wheat rust).

Figure 15.

Teacher: As you can see, in the world there are a huge number of phenomena that surround us. So let's remember them and be extremely careful when they occur.

Some of you may say: “Why do we need to know all of them if most of them are not typical for our area?” From one point of view you are right, but from another you are wrong. Each of you tomorrow, the day after tomorrow or in the future will probably be going on a trip to other parts of the Motherland and the country. And there, as we know, there may be completely different phenomena that are not typical for our area. And then your knowledge will help you in critical situation survive and avoid negative consequences. As they say: “God protects those who are careful.”

Literature.

1. Smirnov A.T. Fundamentals of life safety. 7th grade.
2. Shemanaev V.A. Teaching practice in the system of training a modern teacher.
3. Smirnov A.T. Program of general education institutions basics of life safety for grades 5-11.

Grishin Denis

Natural disasters have threatened the inhabitants of our planet since the beginning of civilization. Somewhere more, somewhere less. One hundred percent security does not exist anywhere. Natural disasters can cause enormous damage. In recent years, the number of earthquakes, floods, landslides and other natural disasters has been constantly increasing. In my essay I want to consider dangerous natural processes in Russia.

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ADMINISTRATION OF THE CITY OF NIZHNY NOVGOROD

Municipal budgetary educational institution

average comprehensive school № 148

Students' Scientific Society

Natural hazards in Russia

Completed by: Grishin Denis,

6a grade student

Supervisor:

Sinyagina Marina Evgenievna,

geography teacher

Nizhny Novgorod

27.12.2011

PLAN

Page

Introduction

Chapter 1. Natural hazards (natural emergencies).

1.1. The concept of emergency situations.

1.2. Natural disasters of a geographical nature.

1.3. Natural disasters of a meteorological nature.

1.4. Natural disasters of a hydrological nature.

1.5. Natural fires.

Chapter 2. Natural disasters in the Nizhny Novgorod region.

Chapter 3. Measures to combat natural disasters.

Conclusion

Literature

Applications

Introduction

In my essay I want to consider dangerous natural processes.

Natural disasters have threatened the inhabitants of our planet since the beginning of civilization. Somewhere more, somewhere less. One hundred percent security does not exist anywhere. Natural disasters can cause enormous damage.

Emergencies Natural disasters (natural disasters) have tended to increase in recent years. The activities of volcanoes are intensifying (Kamchatka), earthquakes are becoming more frequent (Kamchatka, Sakhalin, Kuril Islands, Transbaikalia, North Caucasus), and their destructive power is increasing. Floods have become almost regular ( Far East, Caspian lowland, Southern Urals, Siberia), landslides along rivers and in mountainous areas are common. Ice, snow drifts, storms, hurricanes and tornadoes visit Russia every year.

Unfortunately, in areas of periodic flooding, the construction of multi-storey buildings continues, which increases the concentration of the population, underground communications are laid, and dangerous industries operate. All this leads to the fact that the usualFloods in these places are causing more and more catastrophic consequences.

In recent years, the number of earthquakes, floods, landslides and other natural disasters has been constantly increasing.

The purpose of my essay is to study natural emergencies.

The purpose of my work is to study hazardous natural processes (natural emergencies) and measures to protect against natural disasters.

1. Concept of natural emergencies

1.1.Natural emergencies –the situation in a certain territory or water area as a result of the occurrence of a source of natural emergencies that can or will result in human casualties, damage to human health or the natural environment, significant losses and disruption of people’s living conditions.

Natural emergencies are distinguished by the nature of their source and scale.

Natural emergencies themselves are very diverse. Therefore, based on the reasons (conditions) of their occurrence, they are divided into groups:

1) dangerous geophysical phenomena;

2) dangerous geological phenomena;

3) dangerous meteorological phenomena;

4) marine hazardous hydrometeorological phenomena;

5) dangerous hydrological phenomena;

6) natural fires.

Below I want to take a closer look at these types of natural emergencies.

1.2. Natural disasters of a geophysical nature

Natural disasters associated with geological natural phenomena are divided into disasters caused by earthquakes and volcanic eruptions.

EARTHQUAKES - These are tremors and vibrations of the earth's surface, caused mainly by geophysical reasons.

Complex processes are constantly taking place in the bowels of the earth. Under the influence of deep tectonic forces, stress arises, layers of earth rocks are deformed, compressed into folds and, with the onset of critical overloads, they shift and tear, forming faults in the earth's crust. The rupture is accomplished by an instantaneous shock or a series of shocks that have the nature of a blow. During an earthquake, the energy accumulated in the depths is discharged. The energy released at depth is transmitted through elastic waves in the thickness of the earth's crust and reaches the surface of the Earth, where destruction occurs.

There are two main seismic belts: the Mediterranean-Asian and the Pacific.

The main parameters characterizing an earthquake are their intensity and focal depth. The intensity of an earthquake on the Earth's surface is assessed in points (see. Table 1 in the Appendices).

Earthquakes are also classified by the reason they occur. They can arise as a result of tectonic and volcanic manifestations, landslides (rockbursts, landslides) and, finally, as a result of human activity (filling reservoirs, pumping water into wells).

Of considerable interest is the classification of earthquakes not only by severity, but also by number (recurrence frequency) during the year on our planet.

Volcanic activity

arises as a result of constant active processes occurring in the depths of the Earth. After all, the inside is constantly in a heated state. During tectonic processes, cracks form in the earth's crust. Magma rushes along them to the surface. The process is accompanied by the release of water vapor and gases, which create enormous pressure, eliminating obstacles in its path. When reaching the surface, part of the magma turns into slag, and the other part flows out in the form of lava. From the vapors and gases released into the atmosphere, volcanic rocks called tephra precipitate onto the ground.

According to the degree of activity, volcanoes are classified into active, dormant and extinct. Active ones include those that erupted in historical time. 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 the point of eruption.

The most dangerous phenomena that accompany volcanic eruptions are lava flows, tephra fallout, volcanic mud flows, volcanic floods, scorching volcanic clouds and volcanic gases.

Lava flows - these are molten rocks with a temperature of 900 - 1000 °. The flow speed depends on the slope of the volcano cone, the degree of viscosity of the lava and its quantity. The speed range is quite wide: from a few centimeters to several kilometers per hour. In some and the most dangerous cases it reaches 100 km, but most often it does not exceed 1 km/h.

Tephra consists of fragments of solidified lava. The largest ones are called volcanic bombs, the smaller ones are called volcanic sand, and the smallest ones are called ash.

Mud flows - 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

Volcanic floods. When glaciers melt during eruptions, huge amounts of water can form very quickly, which leads to floods.

A scorching volcanic cloud is a mixture of hot gases and tephra. Its damaging effect is caused by the appearance of a shock wave (strong wind), spreading at a speed of up to 40 km/h, and a wave of heat with a temperature of up to 1000°.

Volcanic gases. An eruption is always accompanied by the release of gases mixed with water vapor - a mixture of sulfur dioxide and sulfur oxides, hydrogen sulfide, hydrochloric and hydrofluoric acids in a gaseous state, as well as carbon dioxide and carbon monoxide in high concentrations, deadly to humans.

Classification of volcanoesis carried out according to the conditions of their occurrence and the nature of the activity. According to the first sign, four types are distinguished.

1) Volcanoes in subduction zones or zones of subduction of the oceanic plate under the continental plate. Due to thermal concentration in the depths.

2) Volcanoes in rift zones. They arise due to weakening of the Earth's crust and bulging of the boundary between the Earth's crust and mantle. The formation of volcanoes here is associated with tectonic phenomena.

3) Volcanoes in zones of large faults. In many places in the earth's crust there are ruptures (faults). There is a slow accumulation of tectonic forces that can turn into a sudden seismic explosion with volcanic manifestations.

4) Volcanoes of “hot spot” zones. In certain areas under the ocean floor, “hot spots” are formed in the earth’s crust, where particularly high thermal energy is concentrated. In these places, rocks melt and come to the surface in the form of basaltic lava.

According to the nature of activity, volcanoes are divided into five types (see. Table 2)

1.3. Natural disasters of a geological nature

Natural disasters of a geological nature include landslides, mudflows, avalanches, landslides, and subsidence of the earth's surface as a result of karst phenomena.

Landslides is a sliding displacement of rock masses down a slope under the influence of gravity. They are formed in various rocks as a result of an imbalance or weakening of their strength. Caused by both natural and artificial (anthropogenic) reasons. Natural ones include: increasing the steepness of slopes, eroding their bases with sea and river waters, seismic tremors. Artificial causes include the destruction of slopes by road cuttings, excessive removal of soil, deforestation, and unwise farming on slopes. According to international statistics, up to 80% of modern landslides are associated with human activity. They occur at any time of the year, but mostly in the spring and summer.

Landslides are classifiedby the scale of the phenomenon, speed of movement and activity, mechanism of the process, power and place of formation.

Based on their scale, landslides are classified into large, medium and small-scale.

Large ones are usually caused by natural causes and form along slopes for hundreds of meters. Their thickness reaches 10 - 20 meters or more. The landslide body often retains its solidity.

Medium and small-scale ones are smaller in size and are characteristic of anthropogenic processes.

Scale is often characterized by the area involved. The speed of movement is very varied.

Based on activity, landslides are divided into active and inactive. The main factors here are the rocks of the slopes and the presence of moisture. Depending on the amount of moisture, they are divided into dry, slightly wet, wet and very wet.

According to the mechanism of the process, they are divided into: shear landslides, extrusion landslides, viscoplastic landslides, hydrodynamic landslides, and sudden liquefaction landslides. Often have signs of a combined mechanism.

According to the place of formation, they are divided into mountain, underwater, adjacent and artificial earthen structures (pits, canals, rock dumps).

Mudflow (mudflow)

A rapid mud or mud-stone flow, consisting of a mixture of water and rock fragments, suddenly appearing in the basins of small mountain rivers. It is characterized by a sharp rise in water level, wave movement, short duration of action (on average from one to three hours), and a significant erosion-accumulative destructive effect.

The immediate causes of the formation of gray lakes are rainfall, intense snow melting, outburst of reservoirs, and, less commonly, earthquakes and volcanic eruptions.

All mudflows, according to the mechanism of their origin, are divided into three types: erosion, breakthrough and landslide.

With erosion, the water flow is first saturated with debris due to the washout and erosion of the adjacent soil, and then a mudflow wave is formed.

During a landslide, the mass is torn down to saturated rocks (including snow and ice). The flow saturation in this case is close to maximum.

In recent years, to natural reasons In the formation of mudflows, man-made factors were added: violation of the rules and regulations of mining enterprises, explosions during the construction of roads and the construction of other structures, forest cutting, improper agricultural work and disturbance of soil and vegetation cover.

When moving, a mudflow is a continuous stream of mud, stones and water. Based on the main factors of occurrence, mudflows are classified as follows;

Zonal manifestation. The main formation factor is climatic conditions (precipitation). They are zonal in nature. The convergence occurs systematically. The paths of movement are relatively constant;

Regional manifestation. The main formation factor is geological processes. The descent occurs sporadically, and the paths of movement are not constant;

Anthropogenic. This is the result of human economic activity. Occur where there is the greatest load on the mountain landscape. New mudflow basins are formed. The gathering is episodic.

Snow avalanches - snow masses falling from mountain slopes under the influence of gravity.

Snow accumulating on mountain slopes, under the influence of gravity and weakening of structural bonds within the snow column, slides or crumbles down the slope. Having started its movement, it quickly picks up speed, capturing more and more snow masses, stones and other objects along the way. The movement continues to flatter areas or the bottom of the valley, where it slows down and stops.

Avalanches form within the avalanche source. An avalanche source is a section of a slope and its foot within which an avalanche moves. Each source consists of 3 zones: origin (avalanche collection), transit (trough), and stopping of the avalanche (alluvial cone).

Avalanche-forming factors include: the height of old snow, the condition of the underlying surface, the increase in freshly fallen snow, snow density, snowfall intensity, subsidence of snow cover, snowstorm redistribution of snow cover, air and snow cover temperatures.

The ejection range is important for assessing the possibility of hitting objects located in avalanche zones. A distinction is made between the maximum emission range and the most probable, or long-term average. The most probable ejection range is determined directly on the ground. It is assessed if it is necessary to place structures in the avalanche zone for a long period. It coincides with the boundary of the avalanche fan.

The frequency of avalanches is an important temporal characteristic of avalanche activity. A distinction is made between average long-term and intra-annual recurrence rates. The density of avalanche snow is one of the most important physical parameters, which determines the impact force of the snow mass, the labor costs for clearing it, or the ability to move on it.

How are they classified?

According to the nature of the movement and depending on the structure of the avalanche source, the following three types are distinguished: flume (moves along a specific drainage channel or avalanche chute), wasp (snow landslide, does not have a specific drainage channel and slides across the entire width of the area), jumping (arising from flume where the drainage channel has steep walls or areas with sharply increasing steepness).

According to the degree of repeatability, they are divided into two classes - systematic and sporadic. Systematic ones go every year or once every 2-3 years. Sporadic - 1-2 times per 100 years. It is quite difficult to determine their location in advance.

1.4. Natural disasters of a meteorological nature

All of them are divided into disasters caused by:

by the wind, including a storm, hurricane, tornado (at a speed of 25 m/s or more, for the Arctic and Far Eastern seas - 30 m/s or more);

Heavy rain (with precipitation of 50 mm or more in 12 hours or less, and in mountainous, mudflow and storm-prone areas - 30 mm or more in 12 hours or less);

Large hail (for hailstones with a diameter of 20 mm or more);

Heavy snowfall (with precipitation of 20 mm or more in 12 hours or less);

- strong snowstorms(wind speed 15 m/s or more);

Dust storms;

frosts (when the air temperature drops during the growing season on the soil surface below 0°C);

- severe frost or extreme heat.

These natural phenomena, in addition to tornadoes, hail and squalls, lead to natural disasters, as a rule, in three cases: when they occur in one third of the territory of the region (region, republic), cover several administrative districts and last for at least 6 hours.

Hurricanes and storms

In the narrow sense of the word, a hurricane is defined as a wind of great destructive force and significant duration, the speed of which is approximately 32 m/s or more (12 points on the Beaufort scale).

A storm is a wind whose speed is less than the speed of a hurricane. Losses and destruction from storms are significantly less than from hurricanes. Sometimes a strong storm is called a storm.

The most important characteristic of a hurricane is wind speed.

The average duration of a hurricane is 9 - 12 days.

A storm is characterized by a wind speed lower than that of a hurricane (15 -31 m/s). Duration of storms- from several hours to several days, width - from tens to several hundred kilometers. Both are often accompanied by fairly significant precipitation.

Hurricanes and stormy winds in winter often lead to snow storms, when huge masses of snow move from one place to another at high speed. Their duration can be from several hours to several days. Snowstorms that occur simultaneously with snowfall, at low temperatures or with sudden changes in temperature are especially dangerous.

Classification of hurricanes and storms.Hurricanes are usually divided into tropical and extratropical. In addition, tropical hurricanes are often divided into hurricanes that originate over the Atlantic Ocean and over the Pacific Ocean. The latter are usually called typhoons.

There is no generally accepted, established classification of storms. Most often they are divided into two groups: vortex and flow. Vortex formations are complex vortex formations caused by cyclonic activity and spreading over large areas. Streams are local phenomena of small distribution.

Vortex storms are divided into dust, snow and squall. In winter they turn into snow. In Russia, such storms are often called blizzards, blizzards, and blizzards.

Tornado is an ascending vortex consisting of extremely rapidly rotating air mixed with particles of moisture, sand, dust and other suspended matter. It is a rapidly rotating air funnel hanging from a cloud and falling to the ground in the form of a trunk.

They occur both over the water surface and over land. Most often - during hot weather and high humidity, when air instability in the lower layers of the atmosphere appears especially sharply.

A funnel is the main component of a tornado. It is a spiral vortex. Its internal cavity is from tens to hundreds of meters in diameter.

It is extremely difficult to predict the location and time of a tornado.Classification of tornadoes.

Most often they are divided according to their structure: dense (sharply limited) and vague (vaguely limited). In addition, tornadoes are divided into 4 groups: dust devils, small short-acting ones, small long-acting ones, hurricane whirlwinds.

Small short-acting tornadoes have a path length of no more than a kilometer, but have significant destructive power. They are relatively rare. The path length of small long-acting tornadoes is several kilometers. Hurricane vortices are larger tornadoes and travel several tens of kilometers during their movement.

Dust (sand) stormsaccompanied by the transfer of large quantities of soil and sand particles. They occur in desert, semi-desert and plowed steppes and are capable of transporting millions of tons of dust over hundreds and even thousands of kilometers, covering an area of ​​several hundred thousand square kilometers.

Dustless storms. They are characterized by the absence of dust entrainment into the air and a relatively smaller scale of destruction and damage. However, with further movement they can turn into a dust or snow storm, depending on the composition and condition of the earth's surface and the presence of snow cover.

Blizzards characterized by significant wind speeds, which contributes to the movement of huge masses of snow through the air in winter. Their duration ranges from several hours to several days. They have a relatively narrow range (up to several tens of kilometers).

1.5. Natural disasters of a hydrological nature and marine hazardous hydrometeorological phenomena

These natural phenomena are divided into disasters caused by:

High water levels - floods, which cause flooding of low-lying parts of cities and other populated areas, agricultural crops, damage to industrial and transport facilities;

Low water levels, when navigation, water supply to cities and national economic facilities, and irrigation systems are disrupted;

Mudflows (during the breakthrough of dammed and moraine lakes that threaten populated areas, roads and other structures);

Snow avalanches (if there is a threat to populated areas, automobile and railways, power lines, industrial and agricultural facilities);

Early freeze-up and the appearance of ice on navigable bodies of water.

Marine hydrological phenomena: tsunamis, strong waves on the seas and oceans, tropical cyclones (typhoons), ice pressure and intense drift.

Floods - is the flooding of water adjacent to a river, lake or reservoir, which causes material damage, damages public health or leads to death. If flooding is not accompanied by damage, it is a flood of a river, lake, or reservoir.

Particularly dangerous floods are observed on rivers fed by rain and glaciers, or by a combination of these two factors.

Flood is a significant and rather prolonged rise in the water level in the river that occurs annually in the same season. Typically, floods are caused by spring melting of snow on the plains or by rainfall.

A flood is an intense, relatively short-term rise in water level. Formed by heavy rains, sometimes by melting snow during winter thaws.

The most important basic characteristics are the maximum level and maximum flow of water during a flood. WITH The maximum level is related to the area, layer and duration of flooding of the area. One of the main characteristics is the rate of rise of the water level.

For large river basins, an important factor is one or another combination of flood waves of individual tributaries.

For cases of flood, the factors influencing the values ​​of the main characteristics include: the amount of precipitation, its intensity, duration, coverage area preceding precipitation, basin moisture, soil permeability, basin topography, river slopes, the presence and depth of permafrost.

Ice jams and jams on rivers

Congestion - This is an accumulation of ice in the riverbed that limits the flow of the river. As a result, water rises and spills.

Jams usually form at the end of winter and in spring when rivers open up during the destruction of the ice cover. It consists of large and small ice floes.

Zazhor - a phenomenon similar to ice jam. However, firstly, a jam consists of an accumulation of loose ice (slush, small pieces of ice), while a jam is an accumulation of large and, to a lesser extent, small ice floes. Secondly, ice jams are observed at the beginning of winter, while ice jams occur at the end of winter and spring.

The main reason for the formation of ice jams is the delay in the opening of ice on those rivers where the edge of the ice cover in the spring moves from top to bottom downstream. In this case, the crushed ice moving from above encounters an undisturbed ice cover on its way. The sequence of river opening from top to bottom downstream is a necessary but not sufficient condition for the occurrence of a jam. The main condition is created only when the surface velocity of the water flow at the opening is quite significant.

Ice jams form on rivers during the formation of ice cover. A necessary condition formation is the appearance of inland ice in the channel and its involvement under the edge of the ice cover. The surface velocity of the current, as well as the air temperature during the freezing period, are of decisive importance.

Surges is a rise in water level caused by the influence of wind on the water surface. Such phenomena occur at the mouths of large rivers, as well as on large lakes and reservoirs.

The main condition for its occurrence is strong and prolonged wind, which is typical for deep cyclones.

Tsunami - These are long waves resulting from underwater earthquakes, as well as volcanic eruptions or landslides on the seabed.

Their source is at the bottom of the ocean,

In 90% of cases, tsunamis are caused by underwater earthquakes.

Often before a tsunami begins, the water recedes far from the shore, exposing the seabed. Then the approaching one becomes visible. At the same time, thunderous sounds are heard created by the air wave that the water mass carries in front of it.

Possible scales of consequences are classified by points:

1 point - the tsunami is very weak (the wave is recorded only by instruments);

2 points - weak (can flood a flat coast. Only specialists notice it);

3 points - average (noted by everyone. The flat coast is flooded. Light ships may be washed ashore. Port facilities may receive minor damage);

4 points - strong (the coast is flooded. Coastal buildings are damaged. Large sailing and small motor vessels can be washed ashore and then washed back into the sea. Human casualties are possible);

5 points - very strong (coastal areas are flooded. Breakwaters and jetties are severely damaged, Large ships are thrown ashore. There are casualties. There is great material damage).

1.6. Wildfires

This concept includes forest fires, fires of steppe and grain massifs, peat and underground fires of fossil fuels. We will focus only on forest fires, as the most common phenomenon, causing colossal losses and sometimes leading to human casualties.

Forest fires is an uncontrolled burning of vegetation that spontaneously spreads throughout the forest area.

In hot weather, if there is no rain for 15 to 18 days, the forest becomes so dry that any careless handling of fire causes a fire that quickly spreads throughout the forest area. A negligible number of fires occur from lightning discharges and spontaneous combustion of peat crumbs. The possibility of forest fires is determined by the degree of fire danger. For this purpose, a “Scale for assessing forest areas according to the degree of fire danger in them” has been developed (see. Table 3)

Classification of forest fires

Depending on the nature of the fire and the composition of the forest, fires are divided into ground fires, crown fires, and soil fires. Almost all of them at the beginning of their development have a grassroots character and, if certain conditions are created, they turn into upland or soil ones.

The most important characteristics are the speed of spread of ground and crown fires and the depth of underground burning. Therefore, they are divided into weak, medium and strong. Based on the speed of fire spread, ground and top fires are divided into stable and fugitive. The intensity of combustion depends on the condition and supply of combustible materials, the slope of the terrain, the time of day and especially the strength of the wind.

2. Natural emergencies in the Nizhny Novgorod region.

The region's territory has a fairly wide variety of climatic, landscape and geological conditions, which causes the occurrence of various natural phenomena. The most dangerous of them are those that can cause significant material damage and lead to death.

- hazardous meteorological processes:squally and hurricane winds, heavy rain and snow, downpours, large hail, severe snowstorm, severe frost, ice and frost deposits on wires, extreme heat (high fire danger due to weather conditions);agrometeorological,such as frost, drought;

- hazardous hydrological processes,such as floods (in the spring, rivers in the region are characterized by high water levels, coastal ice floes may break off, ice jams are possible), rain floods, low water levels (in summer, autumn and winter, water levels are likely to decrease to unfavorable and dangerous levels);hydrometeorological(separation of coastal ice floes with people);

- natural fires(forest, peat, steppe and fires in wetlands);

- hazardous geological phenomena and processes:(landslides, karsts, subsidence of loess rocks, erosion and abrasion processes, slope washouts).

Over the past thirteen years, of all registered natural phenomena that had a negative impact on the livelihoods of the population and the operation of economic facilities, the share of meteorological (agrometeorological) hazards amounted to 54%, exogenous-geological - 18%, hydrometeorological - 5%, hydrological - 3%, large forest fires - 20%.

The frequency of occurrence and area of ​​distribution of the above natural phenomena in the region are not the same. Actual data from 1998 to 2010 make it possible to classify meteorological phenomena (harmful squally winds, the passage of thunderstorm fronts with hail, ice and frost deposits on wires) as the most common and frequently observed - an average of 10 - 12 cases are recorded annually.

At the end of winter and spring of each year, events are carried out to rescue people from broken coastal ice floes.

Natural fires occur every year and water levels rise during flood periods. Adverse consequences of forest fires and high water levels are recorded quite rarely, which is due to pre-planned preparations for floods and fire hazard periods.

Spring flood

The passage of floods in the region is observed from the end of March to May. In terms of the degree of danger, floods in the region are of the moderately dangerous type, when the maximum levels of water rise are 0.8 - 1.5 m higher than the levels at which flooding begins, flooding of coastal areas (emergency situations at the municipal level). The flood area of ​​the river floodplain is 40 - 60%. Settled areas are usually subject to partial flooding. Repeatability of water level exceeding critical level- every 10 - 20 years. Excesses of critical levels on most rivers in the region were recorded in 1994 and 2005. To one degree or another, 38 districts of the region are exposed to hydrological processes during the spring flood period. The results of the processes are flooding and flooding of residential buildings, livestock and agricultural complexes, destruction of sections of roads, bridges, dams, dams, damage to power lines, and increased landslides. According to recent data, the areas most susceptible to flood phenomena were Arzamas, Bolsheboldinsky, Buturlinsky, Vorotynsky, Gaginsky, Kstovsky, Perevozsky, Pavlovsky, Pochinkovsky, Pilninsky, Semenovsky, Sosnovsky, Urensky and Shatkovsky.

Increased ice thickness can cause congestion on rivers during the break-up period. The number of ice jams on the region's rivers averages 3-4 per year. The flooding (flooding) caused by them is most likely in populated areas located along the banks of rivers flowing from south to north, the opening of which occurs in the direction from the source to the mouth.

Forest fires

In total, there are 304 settlements in the region in 2 urban districts and 39 municipal areas that may be subject to the negative impact of forest-peat fires.

Wildfire hazards involve the occurrence of large wildfires. Fires whose area reaches 50 hectares account for 14% of the total number of large forest fires, fires from 50 to 100 hectares occupy 6% of the total, fires from 100 to 500 hectares - 13%; the share of large forest fires exceeding 500 hectares is small – 3%. This ratio changed significantly in 2010, when the bulk (42%) of large forest fires reached an area of ​​more than 500 hectares.

The number and area of ​​natural fires vary significantly from year to year, because they directly depend on weather conditions and anthropogenic factors (visitation of forests, preparation for the fire season, etc.).

It should be noted that almost throughout the entire territory of Russia in the period up to 2015. One should expect an increase in the number of days with high air temperatures in summer. At the same time, the likelihood of extremely long periods with critical air temperatures will increase significantly. In this regard, by 2015 Compared to current values, an increase in the number of days with fire danger is predicted.

1. MEASURES FOR PROTECTION AGAINST NATURAL DISASTERS.

Over many centuries, humanity has developed a fairly coherent system of measures to protect against natural disasters, the implementation of which in various parts of the world could significantly reduce the number of human casualties and the amount of material damage. But until today we, unfortunately, can only talk about individual examples successful resistance to the elements. Nevertheless, it is advisable to once again list the main principles of protection against natural disasters and compensation for their consequences. Clear and timely forecasting of the time, location and intensity of a natural disaster is necessary. This makes it possible to promptly notify the population about the expected impact of the elements. A correctly understood warning allows people to prepare for a dangerous phenomenon by either temporary evacuation, or the construction of protective engineering structures, or strengthening their own homes, livestock premises, etc. The experience of the past must be taken into account, and its hard lessons must be brought to the attention of the population with an explanation that such a disaster can happen again. In some countries, the state buys land in areas of potential natural disasters and organizes subsidized travel from hazardous areas. Insurance is important to reduce losses due to natural disasters.

An important role in preventing damage from natural disasters belongs to the engineering-geographical zoning of potential disaster zones, as well as the development of building codes and regulations that strictly regulate the type and nature of construction.

Various countries have developed fairly flexible legislation on economic activities in disaster zones. If a natural disaster occurs in a populated area and the population was not evacuated in advance, rescue operations are carried out, followed by repair and restoration work.

Conclusion

So I studied natural emergencies.

I have come to realize that there is a wide variety of natural disasters. These are dangerous geophysical phenomena; hazardous geological phenomena; hazardous meteorological phenomena; marine hazardous hydrometeorological phenomena; hazardous hydrological phenomena; natural fires. There are 6 types and 31 species in total.

Natural emergencies can result in loss of life, damage to human health or the environment, significant losses and disruption of people's living conditions.

From the point of view of the possibility of carrying out preventive measures, hazardous natural processes, as a source of emergency situations, can be predicted with very little advance notice.

In recent years, the number of earthquakes, floods, landslides and other natural disasters has been constantly increasing. This cannot go unnoticed.

List of used literature

1. V.Yu. Mikryukov “Ensuring life safety” Moscow - 2000.

2. Hwang T.A., Hwang P.A. Life safety. - Rostov n/d: “Phoenix”, 2003. - 416 p.

3. Reference data on emergencies of man-made, natural and environmental origin: In 3 hours - M.: GO USSR, 1990.

4. Emergency situations: Brief description and classification: Textbook. allowance / Author. benefits A.P. Zaitsev. - 2nd ed., rev. and additional - M.: Journal "Military knowledge", 2000.