Why earthquakes are particularly dangerous in the mountains and cities?

Seismically hazardous zones of Russia

Despite, that our country has a moderate dangerous in terms of occurrence of large earthquakes, yet 1/3 its territory is included in the zone of seismic activity (110 cities).

1. Far East

On Sakhalin Island (g. Neftegorsk) 28 May 1995 года произошло самое разрушительное землетрясение за всю историю России. Most of the houses were destroyed, since during their construction the safety standards for such earthquake-prone regions were not observed. The population of the city at that time was about 3000 human. 2040 the person was the victim of a tragedy.

Today the entire territory of the Far East, including the island of Sakhalin and the Kuril-Kamchatka region is classified as earthquake-prone areas. Камчатский полуостров входит в так называемый Тихоокеанский пояс, which accounts for 2/3 largest earthquakes in the world. Scientists predict that there will be 10 years, catastrophic earthquakes are possible.

2. Регионы Северного Кавказа

Until the 20th century, many lands of the Caucasus, especially in mountainous areas have not been developed, they were not studied for seismic activity, therefore earthquakes were not recorded there. IN 2008 in the territory of the Chechen Republic, an earthquake occurred in 6 points, which killed 13 human. Since most of the cities in this region are in the highlands, then seismologists predict the occurrence of catastrophic earthquakes.

3. Полуостров Крым

The territory of Crimea has been known as earthquake-prone since the V century. BC. e. Последствия мощных землетрясений в прошлом мы наблюдаем сегодня в виде грязевых вулканов. The famous mountain Kara-Dag is the result of a powerful volcanic eruption during an earthquake. Many earthquakes in Crimea can lead to a tsunami, since their foci will lie on the seabed. So,in the last century (1927) during a strong earthquake in Crimea, residents have already observed very high waves on the Black Sea. by the way, именно это землетрясение послужило началом создания в России первых норм для постройки зданий в сейсмоопасных регионах.

4. Юг Сибири, Altai, Sayany, Baikal and Transbaikalia

Altai is classified as earthquake-prone, since strong earthquakes happen here once in 10 years. The most destructive tremors in 7.3 балла произошли в 2003 year.

In March 2016 tremors were recorded at the focus of this earthquake. Very strong earthquakes also occur off the shores of Lake Baikal. 9 points and even a tsunami of 3 meters height. The consequence of such tremors is the lowering of the lake bottom by 15-20 m, which leads to land flooding and the appearance of bays and sinkholes.

5. Регионы центральной России также не могут чувствовать себя в полной безопасности, хотя ученые и не относят их к сейсмически опасным. for instance, in Moscow, even in the annals, a strong earthquake was recorded in 1445 year, as a result of which the central part of the city around the Kremlin was shaken. Сегодня сейсмологи подсчитали, what's next 50 years in Moscow, earthquakes are possible for about 5 points with 10% probability.

Life triangle

Douglas conducted his first rescue operation at a Mexican school after the disastrous earthquake in 1985 year. Even then he was surprised, that all the dead schoolchildren were under their desks. In fact, they were crushed by desks, также как это случилось в Армении. Выжившие же дети свернулись на полу между столами и были спасены.
According to Douglas, today there is the only real opportunity to survive in a strong earthquake - to escape in the so-called "triangle of life". The thing is, that when a building collapses, then the upper floors fall on furniture or other large objects. A free space or a small hole is formed around these objects due to the resistance to compression., which is called the "triangle of life". It is this space that must be used in the event of an earthquake. Such buffer zones save a person from crushing..

What is an earthquake?

An earthquake is a tremor in the earth's crust.. They are perceived by a person the more strongly, the more powerful the vibration of the earth's surface. This natural phenomenon is not uncommon: it is celebrated every day in different parts of the world. The vast majority of large aftershocks are recorded in the oceans. If the phenomenon were more typical for sushi, then the number of human victims and destroyed objects would increase many times.

An earthquake can be called the completion of the process of movement of earth rocks. The movement of parts of the earth's crust is limited by the force of friction. When the voltage reaches its maximum, rocks shift abruptly with rupture, frictional force transforms into motion energy, as a result, the earth vibrations diverge radially. The breaking point is called focus, point on the surface of the earth above focus - epicenter. Moving away from the epicenter, fluctuations gradually weaken. An underground wave can move at speeds up to 8 km per second.

Signs of an earthquake can be not only readings of seismic instruments, but also specific changes in the environment. The main harbingers of earthquakes are:

  • restless behavior of domestic and wild animals (many animals are able to sense the approach of disaster, they try to leave the epicenter and the surrounding area, heading to safety);
  • the appearance of special clouds in the sky, like long stripes;
  • change in water level in water sources;
  • problems in the operation of mobile and electrical devices.

Not all areas of the globe are earthquake zones. Oscillations of the earth's crust are only possible in areas, called seismic belts. Two main belts: Pacific and Mediterranean. Also distinguish the Arctic, West Indian, East African belt. The last three account for 5% of all tremors recorded on the planet.

In the Pacific, ringing the Pacific coast, observed about 80% earthquakes. Moreover, every 100 – 150 years, catastrophic seismic processes occur. The Mediterranean belt accounts for 15% aftershocks, disasters are noted every 250 – 300 years.

Australia is the only continent, which is not in the zone of lithospheric junctions. There are no mountainous areas or active volcanoes on the mainland, Consequently, earthquakes are impossible. Also, weak seismic activity is characteristic of Antarctica and Greenland.. These land areas have a thick layer of ice., which does not allow underground vibrations to manifest themselves on the surface.

Russia also has seismically safe, and dangerous areas. The following mountainous areas are considered dangerous:

  • Altai;
  • Caucasus (especially the northern part);
  • Far East;
  • Mountainous regions of Siberia (mostly eastern part);
  • Sakhalin;
  • Kuril and Commander Islands.

The strength of earthquakes

The magnitude scale and the intensity scale are used to assess the strength of an earthquake..

The first distinguishes earthquakes by magnitude - the energy characteristics of an earthquake (measures of its energy). Most popular scale, earthquake energy estimator, - Richter magnitude scale.

The magnitude value ranges from 1 to 9. This scale is often confused with the 12-point earthquake intensity scale., which evaluates the external manifestations of an earthquake (impact on buildings, people, natural objects). When an earthquake happens, then at first its magnitude becomes known, determined from seismograms, and the intensity can be found out only after a time after receiving sufficiently complete information about the consequences.

Damaged city after the Sichuan earthquake (China)

9,5 - the maximum magnitude recorded to date, although theoretically it could be higher.

The intensity of earthquakes depends both on the depth of the source, and from the magnitude. She is the more, the closer the focus is to the surface. For example, if the source of an earthquake with a magnitude 8,0 located at depth 10 km, then on the surface of the earth its intensity will be 11-12 points. And with the same magnitude, but in the hearth, located at a depth of 40-50 km, the impact on the surface will be equal to 9-10 points.

At the moment, several intensity scales are used in the world.. In Europe since 1996 g. apply the European macroseismic scale (EMS). Japan uses the Japan Meteorological Agency scale (Shindo), in Russia and the United States - a modified Mercalli scale (MM).

So, a moderate 4-point earthquake on the Mercalli scale is already noted by many people; a 6-point may cause minor damage to buildings.

Earthquake intensity point scale:

  • 1 ball - Not felt. Marked only with special devices
  • 2 ball - Very weak, observed only by pets and some people in the upper floors of buildings
  • 3 ball - Weak. Felt only inside some buildings, like a concussion while driving a truck
  • 4 ball - Moderate. The creak of the floorboards is heard, beams, clinking dishes, furniture shake. Inside a building, shaking is felt by most people
  • 5 ball - Pretty strong. In the rooms, shocks are felt as from falling heavy objects. Window panes burst, swinging chandeliers and furniture
  • 6 ball - Strong. Heavy furniture sways, the dishes are beating, books fall from the shelves, only very dilapidated houses are destroyed
  • 7 ball - Very strong. Old houses are crumbling. Cracks appear in strong buildings, plaster crumbles. Water becomes cloudy in rivers and lakes
  • 8 ball - Destructive. The trees are swaying hard, strong fences break. Many strong buildings collapse. Cracks appear in the soil
  • 9 ball - Devastating. Strong structures collapse. Significant cracks appear in the soil
  • 10 ball - Destructive. Even strong buildings and bridges are destroyed. Landslides and landslides occur, cracks and bends in the soil
  • 11 ball - Disaster. Almost all stone buildings are destroyed, roads, dams, bridges. Shear cracks form on the earth's surface
  • 12 ball - Strong disaster. All structures are destroyed, the whole area is devastated. River beds change

A.S. Pushkin. I erected a monument to myself…

I like

Musina Fagiya

05.02.201017:08

I erected a monument not made by hands,The folk path will not grow to it,Вознесся выше он главою непокорной Александрийского столпа.Нет, all I will not die - the soul in the cherished lyre My ashes will survive and decay will run away - and I will be glorious, доколь в подлунном мире Жив будет хоть один пиит.Слух обо мне пройдет по всей Руси великой,And every language in her will call me,And the proud grandson of the Slavs, and finn, и ныне дикой Тунгус, and a friend of the Kalmyk steppes, and for a long time I will be so kind to the people,That good feelings I awakened with my lyre,Что в мой жестокий век восславил я Свободу И милость к падшим призывал.Веленью божию, about the muse, be obedient,Not fearing resentment, requiring no crown,Хвалу и клевету приемли равнодушно И не оспоривай глупца.

Why earthquakes are especially dangerous in cities

Town – this is primarily a high population density, building, structures and communications. They create the following dangers:

  1. Collapse of buildings and structures. Even if a small country house collapses, there is a chance to die under the rubble. Multi-storey buildings are collapsing rapidly, therefore, many residents do not have time to descend from the upper floors. The huge amount of debris makes rescue operations very difficult.
  2. Damage to communications. If the electrical cable or gas pipeline is damaged, fire and even explosion may occur.. This greatly reduces the chances of rescuing people under the rubble..
  3. Large number of people. Sometimes panic, in the crowd, can be more dangerous than the earthquake itself. Trying to escape, not everyone understands, that you need to act consistently and clearly.

Can an earthquake pump the Earth?

In the middle of May 1960 g. Chile experienced one of the most significant and destructive earthquakes - the Great Chilean Earthquake. Despite, that the main earth vibrations occurred in the southwestern part of South America - the epicenter of the earthquake was located near the city of Valdivia - their “echoes” reached other territories of our planet: in particular, Hawaii and Japan. Phenomenon, in which the earthquake, what happened in one part of the earth, makes other parts of it throb and tremble, even located thousands of kilometers from the epicenter, called “rocking” or “vibration” land.

Consequences of earthquakes

Earthquakes are one of the most dangerous natural phenomena. They bring great destruction and disaster, destroying not only material values, but all living things, including people.

After strong earthquakes, the landscape changes, new lakes and mountains may appear

Areas of the earth's crust at the site of a fault can be displaced vertically or even crawl over each other. In those places, where the earth sinks to one side of the fault right at the intersection of the river bed, waterfalls are formed. Often, after an earthquake, significant areas of land sink and are flooded with water. Besides, tremors can displace loose upper soil layers from slopes, initiating landslides and landslides. The abrupt movement of significant masses of the earth's crust in the focus is accompanied by an impact of colossal force. Throughout the year, the inhabitants of the planet in different parts of it feel the order 10 thousand. earthquakes, of which about 100 more or less destructive.

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References, creation

References, creation

Types of earthquakes

Factors, disclosing, why earthquakes happen, there may be tectonic phenomena (movement or deformation of the earth's crust, processes in the planetary mantle), volcanic activity, landslides and other rock movements, engineering and military activities on the territory. The causes of earthquakes are as natural, and artificial.

More details below, what kind of earthquakes are by origin.

Tectonic

This category includes the largest part of recorded underground processes.. Tectonic earthquakes occur, when, due to the movement of tectonic plates, rocks are sharply displaced. This is either a collision of thick continental plates, or about the diving of a thin oceanic plate under a thick continental.

The movement of lithospheric plates is insignificant, usually does not exceed a couple of centimeters, but it provokes the movement of the rocks above the focus, resulting in a lot of energy. Moving rocks creates cracks in the ground. Earth blocks, adjacent to these cracks, fall apart, deformed, and objects located on their surface are destroyed.

Technogenic

Due to vigorous human activity, man-made earthquakes occur, and their number is increasing every year following the increasing destructive impact of man on the planet. Seismologists note, that the number of aftershocks in the territories, surrounding large reservoirs, mining areas, active and depleted mines and quarries and other engineering structures.

The frequent occurrence of underground processes in the area of ​​the location of reservoirs is due to the fact, that a significant mass of water presses on the earth's crust, erodes rocks.

Volcanic

This type of earthquake is characterized by a weak manifestation, but the duration of existence. Earth vibrations do not cause much destruction, catastrophic consequences are rare.

The most powerful shift of the earth's crust as a result of volcanic activity happened in 19 century in Indonesia. The erupting volcano Krakatoa split into three parts the Indonesian island of the same name. The tremors were so powerful, that the volcano is half destroyed, and two parts of the island went into the water. Further tsunami struck the coast, destroyed the entire population, not having time to leave the ill-fated island.

Landslide

Large rock falls and landslides can cause underground vibrations.. Such earthquakes are also not intense, but the danger lies in the descent of huge soil layers.

The worst landslide earthquake is considered to have occurred in Peru in January 1062 of the year. Giant avalanche, composed of mud and melted snow, descended from Mount Huascaran, provoked vibrations of the earth's crust, demolished several settlements. More than 18 thousands of people.

Underwater

When tectonic plates collide, forming an ocean bed, underwater earthquakes occur. When the focus is shallow, and with a magnitude higher 7 points seismic process is extremely dangerous, as a tsunami provocateur. When the oceanic crust moves, some parts of the bottom rise, others are omitted, as a result, water mass, trying to return to its original position, starts to move vertically. So giant are born, waves directed towards the coast - tsunami.

Earthquakes, tsunami-weighted, often disastrous. So, a few years ago in the Indian Ocean there was a tectonic plate shift, leading to the formation of a huge wave. Tsunami hits Indian and Indonesian shores, killed more than 200 thousand local residents.

Artificial

We are talking about seismic processes, provoked by human engineering and military activities. Artificial earthquakes are the result of missile launches, well drilling, development of oil-bearing and gas-bearing underground formations. So, during the demonstration launch of North Korean nuclear missiles in different parts of the planet, seismographs recorded shocks of moderate intensity.

From the impact of cosmic bodies

When a large space object, breaking through the earth's atmosphere, crashes into the surface of the planet, it explodes, what causes the shock wave, spreading in the ground, and in the air for considerable distances.

Minor seismic belts

Not a secret, that during earthquakes, waves from vibrations of the earth's crust can reach remote areas, which are considered to be safe in relation to seismic activity. In some places, the echoes of earthquakes are not felt at all, and in some they reach several points on the Richter scale.

Fig. 4. Earth seismic activity map.

Basically these zones, sensitive to vibrations of the earth's crust, are under the water column of the World Ocean. The planet's minor seismic belts are located in the waters of the Atlantic, Pacific, Indian Ocean and Arctic. Most of the minor belts are in the eastern part of the planet, So, these belts stretch from the Philippines, gradually descending towards Antarctica. The echoes of the tremors can still be felt in the Pacific Ocean, but in the Atlantic there is almost always a seismically quiet zone.

What have we learned?

so, earthquakes on Earth do not occur in random places. Seismic activity of the earth's crust can be predicted, since the main part of earthquakes occurs in special zones, which are called the earth's seismic belts. There are only two of them on our planet: Latitudinal Mediterranean-Trans-Asian seismic belt, which stretches parallel to the Equator and the meridional Pacific seismic belt, perpendicular to latitudinal.

How to escape in case of an earthquake

Today, there are many official guidelines in the event of an earthquake.. However, many years of experience shows, что при очень сильных землетрясениях подобные рекомендации иногда не приносят пользы, but rather the opposite. So with an earthquake, what happened in Armenia 1988 year, there were many victims among schoolchildren, who took refuge under the desks - so, how they were taught. Only a few survived, who jumped out of windows, contrary to recommendations. Even then they started talking, that it is common practice to hide under a table or bed in an earthquake, as well as in the doorway - is incorrect. There is plenty of evidence for this today.. American lifeguard, recognized UN expert on saving human life, Douglas Kopp developed his theory of earthquake survival. He was one of those, who single-handedly saved people from the Twin Towers in America 11 September. Today Douglas is the founder and leader of the AmericanRescueTeam international rescue team..

За время своей работы Дуглас участвовал при ликвидации наиболее разрушительных землетрясений в 60 countries. Based on his observations, he drew up rules of conduct for severe destructions, which increase a person's chances of survival.

Geography of the phenomenon

The distribution of earthquakes on the planet is rather uneven. It is determined mainly by the interaction and movement of lithospheric plates.

The location of the earthquake foci practically coincides with the boundaries of the lithospheric plates

Main seismic belt, where about 80% all seismic energy, located in the pacific ocean. Here, in areas of deep-sea trenches, there are shifts of lithospheric plates under the continent. The rest of the energy is released in the Eurasian fold belt. This occurs at the collision points of the Eurasian plate with the Indian and African plates., as well as in areas of mid-oceanic ridges.

Earthquake in messina 1908 g.

The strongest earthquake in the history of Europe happened 28 December 1908 g. in 5:20 in the Strait of Messina between the Apennines and Sicily. Several tremors with a magnitude 7,5 caused tremendous destruction in more than 20 settlements in the coastal strip of Sicily. After that, three tsunami waves hit the coast, completing the deed with an earthquake.

Russian sailors from the battleship Slava help carry out rescue operations after the earthquake in Messina (Italy). 28 December 1908 g.

The death toll during this tragedy exceeded 123 thousand. human. According to some researchers, the number of victims was 200 thousand. human. The city of Messina suffered the most, where about 60 thousand. inhabitants with a population 150 thousand. human.

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