What is an earthquake and why does it happen? Earthquakes

It seems that natural disasters happen once every hundred years, and our vacation in one or another exotic country lasts only a few days.

Frequency of earthquakes of different magnitudes in the world per year

• 1 earthquake with a magnitude of 8.0 or higher
• 10 – with a magnitude of 7.0 – 7.9 points
• 100 – with a magnitude of 6.0 – 6.9 points
• 1000 - with a magnitude of 5.0 - 5.9 points

Earthquake intensity scale

Richter scale, points	Force	Description
	Not felt	Not felt
	Very weak tremors	Sensible only to very sensitive people
		Only felt inside some buildings
	Intensive	Feels like slight vibration of objects
	Quite strong	Sensible to sensitive people on the street
		Felt by everyone on the street
	Very strong	Cracks may appear in the walls of stone houses
	Destructive	Monuments are moved from their places, houses are severely damaged
	Devastating	Severe damage or destruction of houses
	Destructive	Cracks in the ground can be up to 1m wide
	Catastrophe	Cracks in the ground can reach more than a meter. Houses are almost completely destroyed
	Catastrophe	Numerous cracks in the ground, collapses, landslides. The appearance of waterfalls, deviation of river flows. No structure can withstand

Mexico City, Mexico

One of the world's most populous cities is known for its insecurity. In the 20th century, this part of Mexico felt the force of more than forty earthquakes, the magnitude of which exceeded 7 points on the Richter scale. In addition, the soil under the city is saturated with water, which makes high-rise buildings vulnerable in the event of natural disasters.

The most destructive earthquakes occurred in 1985, when about 10,000 people died. In 2012, the epicenter of the earthquake was in the southeastern part of Mexico, but vibrations were well felt in Mexico City and Guatemala, about 200 houses were destroyed.

The years 2013 and 2014 were also marked by high seismic activity in different parts of the country. Despite all this, Mexico City is still attractive to tourists due to its picturesque landscapes and numerous monuments of ancient culture.

Concepcion, Chile

Chile's second largest city, Concepción, located in the heart of the country near Santiago, regularly falls victim to tremors. In 1960, the famous Great Chilean earthquake with the highest magnitude in history, magnitude 9.5, destroyed this popular Chilean resort, as well as Valdivia, Puerto Montt, etc.

In 2010, the epicenter was again located near Concepción, about one and a half thousand houses were destroyed, and in 2013 the outbreak sank to a depth of 10 km off the coast of central Chile (magnitude 6.6 points). However, today Concepcion does not lose popularity among both seismologists and tourists.

Interestingly, the elements have haunted Concepcion for a long time. At the beginning of its history, it was located in Penko, but due to a series of destructive tsunamis in 1570, 1657, 1687, 1730, the city was moved just south of its previous location.

Ambato, Ecuador

Today, Ambato attracts travelers with its mild climate, beautiful landscapes, parks and gardens, and massive fruit and vegetable fairs. Ancient buildings from the colonial era are intricately combined here with new buildings.

Several times this young city, located in central Ecuador, two and a half hours from the capital Quito, was destroyed by earthquakes. The most powerful tremors were in 1949, which leveled many buildings and claimed more than 5,000 lives.

Recently, seismic activity in Ecuador has continued: in 2010, an earthquake with a magnitude of 7.2 occurred southeast of the capital and was felt throughout the country; in 2014, the epicenter moved to the Pacific coast of Colombia and Ecuador, however, in these two cases there were no casualties .

Los Angeles, USA

Predicting destructive earthquakes in Southern California is a favorite pastime of geological survey specialists. The fears are fair: the seismic activity in this area is associated with the San Andreas Fault, which runs along the Pacific coast across the state.

History remembers the powerful earthquake of 1906, which claimed 1,500 lives. In 2014, the sun twice survived tremors (magnitude 6.9 and 5.1), which affected the city with minor destruction of houses and severe headaches for residents.

True, no matter how much seismologists frighten with their warnings, the “city of angels” Los Angeles is always full of visitors, and the tourist infrastructure here is incredibly developed.

Tokyo, Japan

It is no coincidence that a Japanese proverb says: “Earthquakes, fires and father are the most terrible punishments.” As you know, Japan is located at the junction of two tectonic layers, the friction of which often causes both small and extremely destructive tremors.

For example, in 2011, the Sendai earthquake and tsunami near the island of Honshu (magnitude 9) led to the death of more than 15,000 Japanese. At the same time, Tokyo residents are already accustomed to the fact that several earthquakes of minor magnitude occur every year. Regular fluctuations only impress visitors.

Despite the fact that most buildings in the capital were built taking into account possible shocks, residents are defenseless in the face of powerful disasters.

Repeatedly throughout its history, Tokyo disappeared from the face of the earth and was rebuilt again. The Great Kanto Earthquake of 1923 turned the city into ruins, and 20 years later, rebuilt, it was destroyed by large-scale bombing by American air forces.

Wellington, New Zealand

The capital of New Zealand, Wellington, seems to be created for tourists: it has many cozy parks and squares, miniature bridges and tunnels, architectural monuments and unusual museums. People come here to take part in the grandiose Summer City Program festivals and admire the panoramas that became the film set for the Hollywood trilogy The Lord of the Rings.

Meanwhile, the city was and remains a seismically active zone, experiencing tremors of varying strength from year to year. In 2013, just 60 kilometers away, a magnitude 6.5 earthquake struck, causing power outages in many parts of the country.

In 2014, Wellington residents felt tremors in the northern part of the country (magnitude 6.3).

Cebu, Philippines

Earthquakes in the Philippines are a fairly common occurrence, which, of course, does not frighten those who like to lie on the white sand or snorkel in clear sea water. On average, more than 35 earthquakes with a magnitude of 5.0-5.9 points and one with a magnitude of 6.0-7.9 occur here per year.

Most of them are echoes of vibrations, the epicenters of which are located deep under water, which creates the danger of a tsunami. The 2013 earthquakes claimed more than 200 lives and caused serious damage in one of the most popular resorts in Cebu and other cities (magnitude 7.2).

Employees of the Philippine Institute of Volcanology and Seismology are constantly monitoring this seismic zone, trying to predict future disasters.

Sumatra Island, Indonesia

Indonesia is rightfully considered the most seismically active region in the world. The westernmost one in the archipelago has become especially dangerous in recent years. It is located at the site of a powerful tectonic fault, the so-called “Pacific Ring of Fire.”

The plate that forms the floor of the Indian Ocean is being squeezed under the Asian plate here as quickly as a human fingernail grows. The accumulated tension is released from time to time in the form of tremors.

Medan is the largest city on the island and the third most populous in the country. Two major earthquakes in 2013 seriously injured more than 300 local residents and damaged nearly 4,000 homes.

Tehran, Iran

Scientists have been predicting a catastrophic earthquake in Iran for a long time - the entire country is located in one of the most seismically active zones in the world. For this reason, the capital Tehran, home to more than 8 million people, was repeatedly planned to be moved.

The city is located on the territory of several seismic faults. An earthquake of magnitude 7 would destroy 90% of Tehran, whose buildings are not designed for such violent elements. In 2003, another Iranian city, Bam, was destroyed by a 6.8 magnitude earthquake.

Today Tehran is familiar to tourists as the largest Asian metropolis with many rich museums and majestic palaces. The climate allows you to visit it at any time of the year, which is not typical for all Iranian cities.

Chengdu, China

Chengdu is an ancient city, the center of the southwestern Chinese province of Sichuan. Here they enjoy a comfortable climate, see numerous sights, and become immersed in the unique culture of China. From here they travel along tourist routes to the gorges of the Yangtze River, as well as to Jiuzhaigou, Huanglong and.

Recent events have reduced the number of visitors to the area. In 2013, the province experienced a powerful earthquake with a magnitude of 7.0, when more than 2 million people were affected and about 186 thousand houses were damaged.

Residents of Chengdu annually feel the effects of thousands of tremors of varying strength. In recent years, the western part of China has become especially dangerous in terms of seismic activity of the earth.

What to do in case of an earthquake

• If an earthquake catches you on the street, do not go near the eaves and walls of buildings that may fall. Stay away from dams, river valleys and beaches.
• If an earthquake strikes you in a hotel, open the doors to freely leave the building after the first series of tremors.
• During an earthquake, you should not run outside. Many deaths are caused by falling building debris.
• In case of a possible earthquake, it is worth preparing a backpack with everything you need for several days in advance. A first aid kit, drinking water, canned food, crackers, warm clothes, and washing supplies should be at hand.
• As a rule, in countries where earthquakes are a common occurrence, all local cellular operators have a system for alerting customers about an approaching disaster. While on vacation, be careful and observe the reaction of the local population.
• After the first shock there may be a lull. Therefore, all actions after it must be thoughtful and careful.

Recently I helped my son with a short report on this topic. Despite the fact that I know enough about this phenomenon, the information I discovered turned out to be extremely interesting. I will try to accurately convey the essence of the topic and talk about How are earthquakes classified?. By the way, my son proudly brought an A from school. :)

Where do earthquakes occur?

First you need to understand what is commonly called an earthquake. So, scientifically speaking, these are strong vibrations on the surface of our planet, caused by processes that occur in the lithosphere. Areas where high mountains are located are places where this phenomenon occurs most often. The thing is that the surfaces in these areas are at the stage of formation, and the cortex is most mobile. Such areas are called places rapidly changing terrain, however, many earthquakes were also observed on the plains.

What types of earthquakes are there?

Science identifies several types of this phenomenon:

• tectonic;
• landslide;
• volcanic.

Tectonic earthquake- a consequence of the displacement of mountain plates, which is caused by the collision of two platforms: continental and oceanic. This species is characterized by formation of mountains or depressions, as well as surface vibrations.

Regarding earthquakes volcanic type, then they are caused by the pressure of gases and magma on the surface from below. Usually the shocks are not very strong, however can last quite a long time. Typically, this species is a harbinger of a more destructive and dangerous phenomenon - volcano eruptionA.

Landslide earthquake occurs as a result of the formation of voids that can be formed by the movement of groundwater. In this case the surface just collapses, which is accompanied by small tremors.

Intensity measurement

According to Richter scale it is possible to classify an earthquake based on the energy it carries seismic waves. It was proposed in 1937 and over time became widespread throughout the world. So:

1. not felt- shocks are absolutely not detected;
2. very weak- is registered only by devices, a person does not feel it;
3. weak- can be felt while in the building;
4. intense- accompanied by slight displacement of objects;
5. almost strong- felt in open spaces by sensitive people;
6. strong- felt by all people;
7. very strong- small cracks appear in the brickwork;
8. destructive- serious damage to buildings;
9. devastating- huge destruction;
10. destructive- gaps up to 1 meter are formed in the ground;
11. catastrophic- buildings are destroyed to the foundation. Cracks more than 2 meters;
12. catastrophe- the entire surface is cut with cracks, the rivers change their channels.

According to seismologists - scientists who study this phenomenon, about 400 thousand happen per year earthquakes of varying strengths.

An earthquake is a physical vibration of the lithosphere - the solid shell of the earth's crust, which is in constant motion. Often such phenomena occur in mountainous areas. It is there that underground rocks continue to form, causing the Earth's crust to be especially mobile.

Causes of the disaster

The causes of earthquakes can be different. One of them is the displacement and collision of oceanic or continental plates. During such phenomena, the surface of the Earth vibrates noticeably and often leads to the destruction of buildings. Such earthquakes are called tectonic. They may form new depressions or mountains.

Volcanic earthquakes occur due to the constant pressure of hot lava and all kinds of gases on the earth's crust. Such earthquakes can last for weeks, but, as a rule, they do not cause massive destruction. In addition, such a phenomenon often serves as a prerequisite for a volcanic eruption, the consequences of which can be much more dangerous for people than the disaster itself.

There is another type of earthquake - landslide, which occurs for a completely different reason. Groundwater sometimes forms underground voids. Under the pressure of the earth's surface, huge sections of the Earth fall down with a roar, causing small vibrations that can be felt many kilometers from the epicenter.

Earthquake scores

To determine the strength of an earthquake, they generally resort to either a ten- or twelve-point scale. The 10-point Richter scale determines the amount of energy released. The 12-point Medvedev-Sponheuer-Karnik system describes the impact of vibrations on the Earth's surface.

The Richter scale and the 12-point scale are not comparable. For example: scientists detonate a bomb underground twice. One at a depth of 100 m, the other at a depth of 200 m. The energy expended is the same, which leads to the same Richter rating. But the consequence of the explosion - displacement of the crust - has varying degrees of severity and has different effects on the infrastructure.

Degree of destruction

What is an earthquake from the point of view of seismic instruments? A one-point phenomenon is determined only by the equipment. 2 points can be sensitive animals, and also, in rare cases, especially sensitive people located on the upper floors. A score of 3 feels like the vibration of a building caused by a passing truck. A magnitude 4 earthquake causes slight rattling of glass. With a score of five, the phenomenon is felt by everyone, and it does not matter where the person is, on the street or in a building. An earthquake of magnitude 6 is called strong. It terrifies many: people run out into the street, and mother-in-laws form on some walls of houses. A score of 7 leads to cracks in almost all houses. 8 points: architectural monuments, factory chimneys, towers are knocked over, and cracks appear in the soil. 9 points lead to severe damage to houses. Wooden buildings either topple over or sag heavily. Magnitude 10 earthquakes lead to cracks in the ground up to 1 meter thick. 11 points is a disaster. Stone houses and bridges are collapsing. Landslides occur. No building can withstand 12 points. With such a catastrophe, the topography of the Earth changes, the flow of rivers is diverted and waterfalls appear.

Japanese earthquake

A destructive earthquake occurred in the Pacific Ocean, 373 km from the capital of Japan, Tokyo. This happened on March 11, 2011 at 14:46 local time.

A magnitude 9 earthquake in Japan led to massive destruction. The tsunami that hit the country's east coast flooded large parts of the coastline, destroying houses, yachts and cars. The height of the waves reached 30-40 m. The immediate reaction of people prepared for such tests saved their lives. Only those who left home in time and found themselves in a safe place were able to avoid death.

Japan earthquake victims

Unfortunately, there were no casualties. The Great East Japan Earthquake, as the event became officially known, claimed 16,000 lives. 350,000 people in Japan were left homeless, leading to internal migration. Many settlements were wiped off the face of the Earth, and there was no electricity even in large cities.

The earthquake in Japan radically changed the habitual way of life of the population and greatly undermined the economy of the state. The authorities estimated the losses caused by this disaster at $300 billion.

What is an earthquake from the point of view of a Japanese resident? It is a natural disaster that keeps the country in constant turmoil. The looming threat forces scientists to invent more accurate instruments for detecting earthquakes and more durable materials for building buildings.

Affected Nepal

On April 25, 2015, at 12:35 p.m., an almost 8-magnitude earthquake that lasted 20 seconds occurred in central Nepal. The following happened at 13:00. Aftershocks lasted until May 12. The reason was a geological fault on the line where the Hindustan plate meets the Eurasian plate. As a result of these tremors, the capital of Nepal, Kathmandu, moved to the south by three meters.

Soon the whole earth learned about the destruction caused by the earthquake in Nepal. Cameras installed directly on the street recorded the moment of the tremors and their consequences.

26 districts of the country, as well as Bangladesh and India, felt what an earthquake was like. Authorities are still receiving reports of missing people and collapsed buildings. 8.5 thousand Nepalese lost their lives, 17.5 thousand were injured, and about 500 thousand were left homeless.

The earthquake in Nepal caused real panic among the population. And it is not surprising, because people lost their relatives and saw how quickly what was dear to their hearts collapsed. But problems, as we know, unite, as was proven by the people of Nepal, who worked side by side to restore the former appearance of city streets.

Recent earthquake

On June 8, 2015, an earthquake of magnitude 5.2 occurred in Kyrgyzstan. This is the last earthquake to exceed magnitude 5.

Speaking about a terrible natural disaster, one cannot fail to mention the earthquake on the island of Haiti, which occurred on January 12, 2010. A series of tremors ranging from magnitude 5 to 7 claimed 300,000 lives. The world will remember this and other similar tragedies for a long time.

In March, the shores of Panama experienced a magnitude 5.6 earthquake. In March 2014, Romania and southwestern Ukraine learned the hard way what an earthquake is. Fortunately, there were no casualties, but many experienced anxiety before the disaster. In recent years, earthquake scores have not crossed the brink of catastrophe.

Earthquake Frequency

So, the movement of the earth's crust has various natural causes. Earthquakes, according to seismologists, occur up to 500,000 annually in different parts of the Earth. Of these, approximately 100,000 are felt by people, and 1,000 cause serious damage: they destroy buildings, highways and railways, break power lines, and sometimes carry entire cities underground.

An earthquake is a natural phenomenon with destructive power; it is an unpredictable natural disaster that occurs suddenly and unexpectedly. An earthquake is an underground tremors caused by tectonic processes occurring inside the earth; these are vibrations of the earth's surface that arise as a result of sudden ruptures and displacements of sections of the earth's crust. Earthquakes occur anywhere on the globe, at any time of the year; it is virtually impossible to determine where and when, and what strength an earthquake will be.

They not only destroy our homes and change the natural landscape, but also raze cities and destroy entire civilizations; they bring fear, grief and death to people.

How is the strength of an earthquake measured?

The intensity of tremors is measured by points. Earthquakes with a magnitude of 1-2 are detected only by special devices - seismographs.

With an earthquake strength of 3-4 points, vibrations are already detected not only by seismographs, but also by people - objects around us sway, chandeliers, flower pots, dishes clink, cabinet doors open, trees and buildings sway, and the person himself sways.

At 5 points, it shakes even more strongly, wall clocks stop, cracks appear on buildings, and plaster crumbles.

At 6-7 points, the vibrations are strong, objects fall, paintings hanging on the walls, cracks appear on window glass and on the walls of stone houses.

Earthquakes of magnitude 8-9 lead to the collapse of walls and the destruction of buildings and bridges, even stone houses are destroyed, and cracks form on the surface of the earth.

A magnitude 10 earthquake is more destructive - buildings collapse, pipelines and railway tracks break, landslides and collapses occur.

But the most catastrophic in terms of the force of destruction are earthquakes of 11-12 points.
In a matter of seconds, the natural landscape changes, mountains are destroyed, cities turn into ruins, huge holes form in the ground, lakes disappear, and new islands may appear in the sea. But the most terrible and irreparable thing during such earthquakes is that people die.

There is also another more accurate objective way of assessing the strength of an earthquake - by the magnitude of the vibrations caused by the earthquake. This quantity is called magnitude and determines the strength, that is, the energy of the earthquake, the highest value being magnitude-9.

The source and epicenter of the earthquake

The force of destruction also depends on the depth of the earthquake source; the deeper the earthquake source occurs from the surface of the earth, the less destructive force the seismic waves carry.

The source occurs at the site of displacement of giant rock masses and can be located at any depth from eight to eight hundred kilometers. It doesn’t matter at all whether the displacement is large or not, vibrations of the earth’s surface still occur and how far these vibrations will spread depends on their energy and strength.

The greater depth of the earthquake source reduces destruction on the earth's surface. The destructiveness of an earthquake also depends on the size of the source. If the vibrations of the earth's crust are strong and sharp, then catastrophic destruction occurs on the surface of the Earth.

The epicenter of an earthquake should be considered the point above the source, located on the surface of the earth. Seismic or shock waves diverge from the source in all directions; the further away from the source, the less intense the earthquake. The speed of shock waves can reach eight kilometers per second.

Where do earthquakes most often occur?

Which corners of our planet are more earthquake-prone?

There are two zones where earthquakes occur most often. One belt begins at the Sunda Islands and ends at the Isthmus of Panama. This is the Mediterranean belt - it stretches from east to west, passes through mountains such as the Himalayas, Tibet, Altai, Pamir, Caucasus, Balkans, Apennines, Pyrenees and passes through the Atlantic.

The second belt is called the Pacific. This is Japan, the Philippines, and also covers the Hawaiian and Kuril Islands, Kamchatka, Alaska, and Iceland. It runs along the western coasts of North and South America, through the mountains of California, Peru, Chile, Tierra del Fuego and Antarctica.

There are also seismically active zones on the territory of our country. These are the North Caucasus, Altai and Sayan Mountains, the Kuril Islands and Kamchatka, Chukotka and the Koryak Highlands, Sakhalin, Primorye and the Amur Region, and the Baikal zone.

Earthquakes also often occur in our neighbors - in Kazakhstan, Kyrgyzstan, Tajikistan, Uzbekistan, Armenia and other countries. And in other areas that are distinguished by seismic stability, tremors periodically occur.

The seismic instability of these belts is associated with tectonic processes in the earth's crust. Those territories where there are active smoking volcanoes, where there are mountain ranges and the formation of mountains continues, the foci of earthquakes are most often located there and tremors often occur in those places.

Why do earthquakes happen?

Earthquakes are a consequence of tectonic movement occurring in the depths of our Earth, there are many reasons why these movements occur - these are the external influence of space, the Sun, solar flares and magnetic storms.

These are the so-called earth waves that periodically arise on the surface of our earth. These waves are clearly visible on the sea surface - sea ebbs and flows. They are not noticeable on the earth's surface, but are recorded by instruments. Ground waves cause deformation of the earth's surface.

Some scientists have suggested that the culprit of earthquakes may be the Moon, or rather, the vibrations occurring on the lunar surface also affect the earth's surface. It was observed that strong destructive earthquakes coincided with the full moon.

Scientists also note those natural phenomena that precede earthquakes - these are heavy, prolonged precipitation, large changes in atmospheric pressure, unusual air glow, restless behavior of animals, as well as an increase in gases - argon, radon and helium and uranium and fluorine compounds in groundwater .

Our planet continues its geological development, the growth and formation of young mountain ranges occurs, in connection with human activity, new cities appear, forests are destroyed, swamps are drained, new reservoirs appear, and the changes that occur in the depths of our Earth and on its surface cause all sorts of natural disasters.

Human activities also have a negative impact on the mobility of the earth's crust. A person who imagines himself to be a tamer and creator of nature thoughtlessly interferes with the natural landscape - demolishes mountains, erects dams and hydroelectric power stations on rivers, builds new reservoirs and cities.

And the extraction of minerals - oil, gas, coal, building materials - crushed stone, sand - affects seismic activity. And in those areas where there is a high probability of earthquakes, seismic activity increases even more. With his ill-considered actions, people provoke landslides, landslides and earthquakes. Earthquakes that occur due to human activity are called man-made.

Another type of earthquake occurs with human participation. During underground nuclear explosions, when tectonic weapons are tested, or during the explosion of a large amount of explosives, vibrations of the earth's crust also occur. The intensity of such tremors is not very great, but they can provoke an earthquake. Such earthquakes are called artificial.

There are still some volcanic earthquakes and landslide. Volcanic earthquakes occur due to high tension in the depths of the volcano; the cause of these earthquakes is volcanic gas and lava. The duration of such earthquakes is from several weeks to several months, they are weak and do not pose a danger to people.
Landslide earthquakes are caused by large landslides and landslides.

On our Earth, earthquakes occur every day; about one hundred thousand earthquakes a year are recorded by instruments. This incomplete list of catastrophic earthquakes that occurred on our planet clearly shows the losses humanity suffers from earthquakes.

Catastrophic earthquakes that have occurred in recent years

1923 - Japan epicenter near Tokyo, about 150 thousand people died.
1948 - Turkmenistan, Ashgabat is completely destroyed, about one hundred thousand dead.
1970 in Peru, a landslide caused by an earthquake killed 66 thousand residents of the city of Yungay.
1976 - China, the city of Tianshan is destroyed, 250 thousand dead.

1988 - Armenia, the city of Spitak was destroyed - 25 thousand people died.
1990 - Iran, Gilan province, 40 thousand dead.
1995 - Sakhalin Island, 2 thousand people died.
1999 - Türkiye, the cities of Istanbul and Izmir - 17 thousand dead.

1999 - Taiwan, 2.5 thousand people died.
2001 - India, Gujarat - 20 thousand dead.
2003 - Iran, the city of Bam is destroyed, about 30 thousand people died.
2004 - the island of Sumatra - the earthquake and tsunami caused by the earthquake killed 228 thousand people.

2005 - Pakistan, Kashmir region - 76 thousand people died.
2006 - Java island - 5700 people died.
2008 - China, Sichuan province, 87 thousand people died.

2010 - Haiti, -220 thousand people died.
2011 - Japan - an earthquake and tsunami killed more than 28 thousand people, explosions at the Fukushima nuclear plant led to an environmental disaster.

Powerful tremors destroy the infrastructure of cities, buildings, depriving us of housing, causing enormous damage to the residents of those countries where the disaster occurred, but the most terrible and irreparable thing is the death of millions of people. History preserves the memory of destroyed cities, disappeared civilizations, and no matter how terrible the force of the elements, a person, having survived the tragedy, restores his home, builds new cities, erects new gardens and revives the fields on which he grows his own food.

How to behave during an earthquake

At the first tremors of an earthquake, a person experiences fear and confusion, because everything around begins to move, chandeliers sway, dishes clink, cabinet doors open, and sometimes objects fall, the earth disappears from under one’s feet. Many panic and begin to rush around, while others, on the contrary, hesitate and freeze in place.

If you are on the 1-2 floors, the first thing you should do is try to leave the room as quickly as possible and move to a safe distance from buildings, try to find an open place, pay attention to power lines, you should not be under them in case of strong shocks Wires may break and you may receive an electric shock.

If you are above the 2nd floor or did not have time to jump outside, try to leave the corner rooms. It is better to hide under a table or under a bed, stand in the opening of internal doors, in the corner of the room, but away from cabinets and windows, since broken glass and objects in cabinets, as well as cabinets and refrigerators themselves, can hit you and injure you if they fall.

If you still decide to leave the apartment, then be careful, do not enter the elevator; during strong earthquakes, the elevator may turn off or collapse; it is also not recommended to run to the stairs. Flights of stairs may be damaged due to an earthquake, and a crowd of people rushing to the stairs will increase the load on them and the stairs may collapse. Going out onto balconies is just as dangerous; they can also collapse. You should not jump out of windows.

If tremors find you outside, move to an open space, away from buildings, power lines, and trees.

If you are in a car, stop at the side of the road, away from lamps, trees, and billboards. Don't stop in tunnels, under wires and bridges.

If you live in a seismically active area and earthquakes periodically shake your homes, then you should prepare yourself and your family for the possibility of a stronger earthquake. Determine in advance the safest areas in your apartment, take measures to strengthen your home, teach your children how to behave if children are alone at home during earthquakes.

Earthquakes are a natural phenomenon that even today attracts the attention of scientists not only due to their lack of knowledge, but also due to their unpredictability, which can harm humanity.

What is an earthquake?

An earthquake is an underground tremors that can be felt by a person largely depending on the power of vibration of the earth's surface. Earthquakes are not uncommon and occur every day in different parts of the planet. Often, most earthquakes occur at the bottom of the oceans, which avoids catastrophic destruction within densely populated cities.

The principle of earthquakes

What causes earthquakes? Earthquakes can be caused by both natural causes and man-made ones.

Most often, earthquakes occur due to faults in tectonic plates and their rapid displacement. For a person, a fault is not noticeable until the moment when the energy generated from the rupture of rocks begins to break out to the surface.

How do earthquakes occur due to unnatural causes? Quite often, a person, through his carelessness, provokes the appearance of artificial tremors, which in their power are not at all inferior to natural ones. Among these reasons are the following:

• - explosions;
• - overfilling of reservoirs;
• - above-ground (underground) nuclear explosion;
• - collapses in mines.

The location where a tectonic plate breaks is the source of an earthquake. Not only the strength of the potential push, but also its duration will depend on the depth of its location. If the source is located 100 kilometers from the surface, then its strength will be more than noticeable. Most likely, this earthquake will lead to the destruction of houses and buildings. Occurring in the sea, such earthquakes cause tsunamis. However, the source can be located much deeper - 700 and 800 kilometers. Such phenomena are not dangerous and can only be recorded using special instruments - seismographs.

The place where the earthquake is most powerful is called the epicenter. It is this piece of land that is considered the most dangerous for the existence of all living things.

Studying earthquakes

A detailed study of the nature of earthquakes makes it possible to prevent many of them and make the life of the population living in dangerous places more peaceful. To determine the power and measure the strength of an earthquake, two basic concepts are used:

• - magnitude;
• - intensity;

The magnitude of an earthquake is a measure that measures the energy released during release from the source in the form of seismic waves. The magnitude scale allows you to accurately determine the origins of vibrations.

Intensity is measured in points and allows you to determine the ratio of the magnitude of tremors and their seismic activity from 0 to 12 points on the Richter scale.

Features and signs of earthquakes

Regardless of what causes an earthquake and in what area it is localized, its duration will be approximately the same. One push lasts on average 20-30 seconds. But history has recorded cases when a single shock without repetitions could last up to three minutes.

Signs of an approaching earthquake are the anxiety of animals, which, sensing the slightest vibrations on the surface of the earth, try to get away from the ill-fated place. Other signs of an imminent earthquake include:

• - the appearance of characteristic clouds in the form of oblong ribbons;
• - change in water level in wells;
• - malfunctions of electrical equipment and mobile phones.

How to behave during earthquakes?

How to behave during an earthquake to save your life?

• - Maintain reasonableness and calm;
• - When indoors, never hide under fragile furniture, such as a bed. Lie down next to them in the fetal position and cover your head with your hands (or protect your head with something extra). If the roof collapses, it will fall on the furniture and a layer may form, in which you will find yourself. It is important to choose strong furniture whose widest part is on the floor, i.e. this furniture cannot fall;
• - When outside, move away from tall buildings and structures, power lines that may collapse.
• - Cover your mouth and nose with a wet cloth to prevent dust and fumes from entering if any object catches fire.

If you notice an injured person in a building, wait until the tremors end and only then get into the room. Otherwise, both people may be trapped.

Where do earthquakes not occur and why?

Earthquakes occur where tectonic plates break. Therefore, countries and cities located on a solid tectonic plate without faults do not have to worry about their safety.

Australia is the only continent in the world that is not at the junction of lithospheric plates. There are no active volcanoes and high mountains on it and, accordingly, there are no earthquakes. There are also no earthquakes in Antarctica and Greenland. The presence of the enormous weight of the ice shell prevents the spread of tremors across the surface of the earth.

The probability of earthquakes occurring on the territory of the Russian Federation is quite high in rocky areas, where the displacement and movement of rocks is most actively observed. Thus, high seismicity is observed in the North Caucasus, Altai, Siberia and the Far East.