What determines the strength of an earthquake? What is the shadow side of an earthquake? How does an earthquake occur - the strength of the earthquake

In this article we will look at causes of earthquakes. The very concept of an earthquake is known to all people, and even children, but what are the reasons that suddenly the ground under your feet begins to move and everything around collapses?

First of all, it must be said that earthquakes are conventionally divided into several types: tectonic, volcanic, landslide, artificial and man-made. We will briefly look at all of them right now. If you want to know, be sure to read to the end.

1. Tectonic causes of earthquakes

Most often, earthquakes occur due to the fact that they are in constant motion. Upper layer lithospheric plates are called tectonic plates. The platforms themselves move unevenly and constantly press on each other. However, they for a long time remain alone.

Gradually, the pressure increases, as a result of which the tectonic plate makes a sudden push. It is he who produces vibrations in the surrounding rock, which is why an earthquake occurs.

San Andreas Fault

Transform faults are huge cracks in the Earth where plates rub against each other. Many readers will be aware that the San Andreas Fault is one of the most famous and longest transform faults in the world. It is located in the state of California in the USA.

The platforms moving along it cause devastating earthquakes in the cities of San Francisco and Los Angeles. Interesting fact: in 2015, Hollywood released a film called “San Andreas Fault.” He talks about the corresponding disaster.

1. Volcanic causes of earthquakes

One of the causes of earthquakes is volcanoes. Although they do not produce strong vibrations of the earth, they last quite a long time. The reasons for the tremors are related to the fact that deep in the depths of the volcano, tension is growing, formed by lava and volcanic gases. As a rule, volcanic earthquakes last for weeks or even months.

However, history knows cases of tragic earthquakes of this type. An example is the Krakatoa volcano, located in Indonesia, which erupted in 1883.

The force of its explosion was at least 10 thousand times greater than the force of . The mountain itself was almost completely destroyed, and the island split into three small parts. Two-thirds of the land disappeared under water, and the rising tsunami destroyed everyone who still had a chance to escape. More than 36,000 people died.

1. Landslide causes of earthquakes

Earthquakes caused by giant landslides are called landslides. They are local in nature, and their strength is usually small. But there are exceptions here too. For example, in Peru, in 1970, a landslide with a volume of 13 million cubic meters descended from Mount Huascaran at a speed of over 400 km/h. About 20,000 people died.

1. Technogenic causes of earthquakes

Earthquakes of this type are caused by human activity. For example, artificial reservoirs in places not intended for this by nature provoke pressure on the plates with their weight, which serves to increase the number and strength of earthquakes.

The same applies to the oil and gas industry when extraction occurs large quantity natural materials. In a word, man-made earthquakes occur when a person took something from nature from one place and transferred it to another without asking.

1. Artificial causes of earthquakes

From the name of this type of earthquake it is easy to guess that the blame for it lies entirely with man.

For example, North Korea tested a nuclear bomb in 2006, which caused a small earthquake recorded in many countries. That is, any activity of the inhabitants of the earth, which is obviously guaranteed to entail an earthquake, is an artificial cause of this type of disaster.

Is it possible to predict earthquakes?

Indeed it is possible. For example, in 1975, Chinese scientists predicted an earthquake and saved many lives. But this cannot be done with a 100% guarantee, even today. An ultra-sensitive device that records an earthquake is called a seismograph. The vibrations of the earth are recorded on the rotating drum by a recorder.

Animals also feel anxious before earthquakes. Horses begin to rear up for no apparent reason, dogs bark strangely, and snakes crawl out of their holes to the surface.

Earthquake scale

Typically, the strength of earthquakes is measured using the Earthquake Scale. We will present all twelve points so that you have an idea of ​​what it is.

• 1 point (invisible) - the earthquake is recorded exclusively by instruments;
• 2 points (very weak) - can only be noticed by domestic animals;
• 3 points (weak) - noticeable only in some buildings. Feels like driving over bumps in a car;
• 4 points (moderate) - noticed by many people, may cause movement of windows and doors;
• 5 points (quite strong) - glass rattles, hanging objects sway, old whitewash may crumble;
• 6 points (strong) - with this earthquake, slight damage to buildings and cracks in low-quality buildings are noted;
• 7 points (very strong) - at this stage the buildings suffer significant damage;
• 8 points (destructive) - destruction is observed in buildings, chimneys and cornices are falling, cracks of several centimeters can be seen on the mountain slopes;
• 9 points (devastating) - earthquakes cause collapses of some buildings, old walls collapse, and the speed of crack propagation reaches 2 centimeters per second;
• 10 points (destructive) - collapses in many buildings, in most - serious damage. The soil is riddled with cracks up to 1 meter wide, and there are landslides and landslides all around;
• 11 points (catastrophe) - large landslides in mountainous areas, numerous cracks and a picture of general destruction of most buildings;
• 12 points (severe catastrophe) - the relief is changing globally almost before our eyes. Huge collapses and total destruction of all buildings.

In principle, on a twelve-point earthquake scale, any catastrophe caused by tremors of the earth’s surface can be assessed.

Hundreds of thousands of earthquakes occur on our planet every year. Most of them are so small and insignificant that only special sensors can detect them. But there are also more serious fluctuations: twice a month the earth’s crust shakes violently enough to destroy everything around it.

Since most tremors of such force occur at the bottom of the World Ocean, unless they are accompanied by a tsunami, people are not even aware of them. But when the land shudders, the element is so destructive that the number of victims goes into the thousands, as happened in the 16th century in China (during earthquakes of magnitude 8.1, more than 830 thousand people died).

Earthquakes are underground tremors and vibrations. earth's crust caused by natural or artificially created reasons (movement of lithospheric plates, volcanic eruptions, explosions). The consequences of high-intensity tremors are often catastrophic, second only to typhoons in terms of the number of victims.

Unfortunately, at the moment, scientists have not studied the processes that occur in the depths of our planet so well, and therefore the forecast of earthquakes is rather approximate and inaccurate. Among the causes of earthquakes, experts identify tectonic, volcanic, landslide, artificial and man-made vibrations of the earth's crust.

Tectonic

Most of the earthquakes recorded in the world arose as a result of movements tectonic plates when there is a sharp displacement of rocks. This can be either a collision with each other, or a thinner plate being lowered under another.

Although this shift is usually small, amounting to only a few centimeters, the mountains located above the epicenter begin to move, releasing enormous energy. As a result, cracks form on the earth's surface, along the edges of which huge areas of the earth begin to shift, along with everything that is on it - fields, houses, people.

Volcanic

But volcanic vibrations, although weak, continue for a long time. Usually they do not pose any particular danger, but catastrophic consequences have still been recorded. As a result of the powerful eruption of the Krakatoa volcano in late XIX Art. the explosion destroyed half the mountain, and the subsequent tremors were so powerful that they split the island into three parts, plunging two-thirds into the abyss. The tsunami that arose after this destroyed absolutely everyone who had managed to survive before and did not have time to leave the dangerous territory.

Landslide

It is impossible not to mention landslides and large landslides. Usually these tremors are not severe, but in some cases their consequences can be catastrophic. So, it happened once in Peru, when a huge avalanche, causing an earthquake, came down from Mount Ascaran at a speed of 400 km/h, and, having leveled more than one settlement, killed more than eighteen thousand people.

Technogenic

In some cases, the causes and consequences of earthquakes are often related to human activities. Scientists have recorded an increase in the number of tremors in areas of large reservoirs. This is due to the fact that the collected mass of water begins to put pressure on the underlying earth’s crust, and water penetrating through the soil begins to destroy it. In addition, an increase in seismic activity has been noticed in oil and gas production areas, as well as in the area of ​​mines and quarries.

Artificial

Earthquakes can also be caused artificially. For example, after the DPRK tested new nuclear weapons, sensors recorded moderate earthquakes in many places on the planet.

An undersea earthquake occurs when tectonic plates collide on the ocean floor or near the coast. If the source is shallow and the magnitude is 7, an underwater earthquake is extremely dangerous because it causes a tsunami. During the shaking of the sea crust, one part of the bottom falls, the other rises, as a result of which the water, in an attempt to return to its original position, begins to move vertically, generating a series of huge waves moving towards the coast.

Such an earthquake together with a tsunami can often have catastrophic consequences. For example, one of the most powerful seaquakes occurred several years ago in Indian Ocean: As a result of underwater tremors, a large tsunami arose and, hitting the nearby coasts, led to the death of more than two hundred thousand people.

The tremors begin

The source of an earthquake is a rupture, after the formation of which the earth's surface instantly shifts. It should be noted that this gap does not occur immediately. First, the plates collide with each other, resulting in friction and energy that gradually begins to accumulate.

When the stress reaches its maximum and begins to exceed the frictional force, the rocks rupture, after which the released energy is converted into seismic waves moving at a speed of 8 km/s and causing vibrations in the earth.

The characteristics of earthquakes based on the depth of the epicenter are divided into three groups:

1. Normal – epicenter up to 70 km;
2. Intermediate – epicenter up to 300 km;
3. Deep-focus - the epicenter at a depth exceeding 300 km, typical of the Pacific Rim. The deeper the epicenter, the further the seismic waves generated by the energy will reach.

Characteristic

An earthquake consists of several stages. The main, most powerful shock is preceded by warning vibrations (foreshocks), and after it, aftershocks and subsequent tremors begin, and the magnitude of the strongest aftershock is 1.2 less than that of the main shock.

The period from the beginning of foreshocks to the end of aftershocks may well last several years, as, for example, happened at the end of the 19th century on the island of Lissa in the Adriatic Sea: it lasted three years and during this time scientists recorded 86 thousand tremors.

As for the duration of the main shock, it is usually short and rarely lasts more than a minute. For example, the most powerful shock in Haiti, which occurred several years ago, lasted forty seconds - and this was enough to turn the city of Port-au-Prince into ruins. But in Alaska, a series of tremors were recorded that shook the earth for about seven minutes, with three of them leading to significant destruction.

Calculating which shock will be the main one and will have the greatest magnitude is extremely difficult, problematic, and there are no absolute methods. Therefore, strong earthquakes often take the population by surprise. This, for example, happened in 2015 in Nepal, in a country where mild tremors were recorded so often that people simply did not pay much attention to them. Therefore, a ground shaking with a magnitude of 7.9 led to a large number of victims, and the weaker aftershocks with a magnitude of 6.6 that followed it half an hour later and the next day did not improve the situation.

It often happens that the strongest tremors occurring on one side of the planet shake the opposite side. For example, the 2004 magnitude 9.3 earthquake in the Indian Ocean relieved some of the increasing stress on the San Andreas Fault, which lies at the junction of lithospheric plates along the California coast. It turned out to be so powerful that it slightly modified the appearance of our planet, smoothing out its bulge in the middle part and making it more rounded.

What is magnitude

One way to measure the amplitude of oscillations and the amount of energy released is a magnitude scale (Richter scale), containing conventional units from 1 to 9.5 (it is very often confused with a twelve-point intensity scale, measured in points). An increase in the magnitude of earthquakes by just one unit means an increase in the amplitude of vibrations by ten, and energy by thirty-two times.

The calculations showed that the size of the epicenter during weak vibrations of the surface, both in length and vertically, is measured in several meters, when of average strength - in kilometers. But earthquakes that cause disasters have a length of up to 1 thousand kilometers and extend from the rupture point to a depth of up to fifty kilometers. Thus, the maximum recorded size of the epicenter of earthquakes on our planet was 1000 by 100 km.

The magnitude of earthquakes (Richter scale) looks like this:

• 2 – weak, almost imperceptible vibrations;
• 4 - 5 - even though the shocks are weak, they can lead to minor damage;
• 6 – medium damage;
• 8.5 - one of the strongest recorded earthquakes.
• The largest earthquake is considered to be the Great Chilean earthquake with a magnitude of 9.5, which generated a tsunami that, having overcome Pacific Ocean, reached Japan, covering 17 thousand kilometers.

Focusing on the magnitude of earthquakes, scientists claim that out of the tens of thousands of vibrations that occur on our planet per year, only one has a magnitude of 8, ten - from 7 to 7.9, and a hundred - from 6 to 6.9. It must be taken into account that if the earthquake magnitude is 7, the consequences can be catastrophic.

Intensity scale

To understand why earthquakes occur, scientists have developed an intensity scale based on external manifestations, as an impact on people, animals, buildings, nature. The closer the epicenter of earthquakes is to the earth's surface, the greater the intensity (this knowledge makes it possible to give at least an approximate forecast of earthquakes).

For example, if the magnitude of the earthquake was eight and the epicenter was at a depth of ten kilometers, the intensity of the earthquake would be between eleven and twelve. But if the epicenter was located at a depth of fifty kilometers, the intensity will be less and will be measured at 9-10 points.

According to the intensity scale, the first destruction can occur already with magnitude six shocks, when thin cracks appear in the plaster. An earthquake of eleven magnitude is considered catastrophic (the surface of the earth's crust becomes covered with cracks, buildings are destroyed). The strongest earthquakes, capable of significantly changing the appearance of the area, are estimated at twelve points.

What to do during earthquakes

According to rough estimates by scientists, the number of people who have died in the world due to earthquakes over the past half-millennium exceeds five million people. Half of them are in China: it is located in a zone of seismic activity, and a large number of people live on its territory (830 thousand people died in the 16th century, 240 thousand in the middle of the last century).

Such catastrophic consequences could have been prevented if earthquake protection had been well thought out at the state level, and the design of buildings had taken into account the possibility of strong tremors: most people died under the rubble. Often, people living or staying in a seismically active zone do not have the slightest idea of ​​how exactly to act in an emergency situation and how to save their lives.

You need to know that if tremors catch you in a building, you need to do everything possible to get out into the open space as quickly as possible, and you absolutely cannot use elevators.

If it is impossible to leave the building, and the earthquake has already begun, leaving it is extremely dangerous, so you need to stand up or doorway, or in the corner near load-bearing wall, or crawl under a sturdy table, protecting your head with a soft pillow from objects that might fall from above. After the tremors are over, the building must be left.

If a person finds himself on the street during the onset of earthquakes, he must move away from the house by at least one third of its height and, avoiding tall buildings, fences and other buildings, move in the direction of wide streets or parks. It is also necessary to stay as far as possible from tattered electrical wires industrial enterprises, since explosive materials or toxic substances may be stored there.

But if the first tremors caught a person while he was in a car or public transport, he urgently needs to leave vehicle. If the car is in an open area, on the contrary, stop the car and wait out the earthquake.

If it so happens that you are completely covered in debris, the main thing is not to panic: a person can survive without food and water for several days and wait until they find him. After catastrophic earthquakes, rescuers work with specially trained dogs, and they are able to smell life among the rubble and give a sign.

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 happen anywhere globe, at any time of the year, it is virtually impossible to determine where and when, and what strength the 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 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, they stop Wall Clock, cracks appear on buildings, plaster crumbles.

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

Earthquakes of magnitude 8-9 lead to the collapse of walls and 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, and huge failures, 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. Runs along the western shores of the Northern 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, big differences 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.

Yes, and mining - 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 voltage in the depths of a volcano, these earthquakes are caused by 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 1st or 2nd floors, the first thing you should do is try to leave the room as quickly as possible and move to safe distance away from buildings, try to find an open place, pay attention to power lines, you should not be under them, with strong shocks the wires may break and you may receive an electric shock.

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

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.

An earthquake is a strong shaking of the Earth's surface resulting from the sudden release of energy in the earth's crust, which creates seismic waves. It is one of the most deadly natural disasters and often leads to fractures of the earth's surface, shaking and liquefaction of the earth, landslides, tremors or tsunamis.

If we look at the pattern of earthquakes occurring around the world, it becomes clear that most seismic activity is concentrated in a number of different earthquake belts. Earthquakes are unpredictable in terms of when they will strike, but certain areas are most likely to be hit.

The world map of earthquakes shows that most of them lie in precise zones, often along the edges of continents or in the middle of the ocean. The world is divided into seismic zones based on tectonic plates and the magnitude of earthquakes. Here list of the most earthquake-vulnerable countries in the world:

Several cities are also vulnerable to damage from the Indonesia earthquake. Indonesia's capital, Jakarta, is in a difficult situation. Not only does it sit atop the Pacific Ring of Fire, but with slightly less than half the city below sea level, it sits on soft soil that has the potential to liquefy if struck by an earthquake of sufficient magnitude.

But the complications don't end there. Jakarta's altitude also puts the city at risk of flooding. On December 26, 2004, an earthquake occurred in the Indian Ocean with its epicenter on the west coast of Sumatra, Indonesia.

The mega-magnitude undersea earthquake occurred when the Indian Plate subducted under the Burma Plate and triggered a series of devastating tsunamis along much of the Indian Ocean coastline, killing 230,000 people in 14 countries and inundating coastal areas with waves up to 30 meters high.

Indonesia was the worst affected area, with the majority of deaths estimated at around 170,000. This is the third largest earthquake ever recorded on seismographs.

Türkiye lies in a seismic zone between the Arabian, Eurasian and African plates. This geographical location assumes that an earthquake can occur in the country at any time. Türkiye has a long history of large earthquakes, which often occur in progressive contiguous earthquakes.

The magnitude 7.6 earthquake that struck western Turkey on August 17, 1999 is one of the world's longest and best-studied strike-slip faults: the East-West strike North Anatolian Fault.

The incident lasted only 37 seconds and killed approximately 17,000 people. More than 50,000 people were injured and more than 5,000,000 people were left homeless, making it one of the most destructive earthquakes of the 20th century.

Mexico is another earthquake-prone country and has experienced several high magnitude earthquakes in the past. Situated on three large tectonic plates, namely the Cocos Plate, the Pacific Plate and the North American Plate, which make up the earth's surface, Mexico is one of the most seismically active areas on earth.

The movement of these plates causes earthquakes and volcanic activity. Mexico has an extensive history of devastating earthquakes and volcanic eruptions. In September 1985, an earthquake measuring 8.1 on the Richter scale was centered on a 300-kilometer subduction zone off Acapulco, killing 4,000 people in Mexico City.

One of the most recent earthquakes occurred in 2014 in the state of Guerrero with a magnitude of 7.2, causing numerous casualties in the region.

El Salvador is another seismically active country that has suffered massive damage due to earthquakes. The small Central American Republic of El Salvador has experienced an average of one devastating earthquake per decade over the past hundred years. Two large earthquakes occurred on January 13 and February 13, 2001, with magnitudes of 7.7 and 6.6, respectively.

These two events, which have different tectonic origins, reveal patterns of seismicity in the region, although neither event has a known precedent in the earthquake catalog in terms of size and location. The earthquakes have damaged thousands of traditionally built houses and caused hundreds of landslides, which are the leading causes of deaths.

The earthquakes have clearly demonstrated the increasing trends in seismic risk in El Salvador due to rapid population growth in areas of increased risk of tremors and landslides, a situation aggravated by deforestation and uncontrolled urbanization. The institutional mechanisms needed to control land use and construction practices are very weak and pose a major obstacle to risk reduction.

Another earthquake-prone country is Pakistan, which is geologically located in the Indus-Tsangpo suture zone, which is approximately 200 km north of the front Himalayas and is defined by an ophiolite chain along the southern margin. This region has the highest rates of seismic activity and the largest earthquakes in the Himalayan region, caused mainly by fault movement.

A magnitude 7.6 earthquake struck Pakistan's Kashmir in October 2005, killing more than 73,000 people, many in remote parts of the country, in sparsely populated urban centers such as Islamabad. More recently, in September 2013, a powerful earthquake measuring 7.7 on the Richter scale occurred, causing enormous damage to lives and property, killing at least 825 people and injuring hundreds.

The Philippines lies on the edge of the Pacific Plate, which is traditionally considered a seismically hot zone that surrounds the state. The risk of earthquakes in Manila is three times higher. The city is comfortably adjacent to the Pacific Ring of Fire, which, of course, makes it especially sensitive not only to earthquakes, but also to volcanic eruptions.

The threat to Manila is worsened by soft soil, which poses a risk of liquefaction. On October 15, 2013, an earthquake measuring 7.1 on the Richter scale struck the central Philippines. According to official statistics from the National Disaster Risk Reduction and Management Council (NDRRMC), 222 people were killed, 8 were missing, and 976 people were injured.

Overall, more than 73,000 buildings and structures were damaged, of which more than 14,500 were completely destroyed. It was the deadliest earthquake to hit the Philippines in 23 years. The power released by the earthquake was equivalent to 32 Hiroshima bombs.

Ecuador has several active volcanoes, making the country extremely vulnerable to large magnitude earthquakes and tremors. The country is located in the seismic zone between the South American plate and the Nazca plate. Earthquakes that affect Ecuador can be divided into those that result from movement along a subduction junction along a plate boundary, those that result from deformation within the South American and Nazca plates, and those that are associated with active volcanoes.

On August 12, 2014, an earthquake measuring 5.1 on the Richter scale rocked Quito, followed by an aftershock measuring 4.3. 2 people were killed and 8 were injured.

India has also experienced a number of several deadly earthquakes due to the movement of the Indian tectonic plate at a rate of 47 mm every year. Due to the movement of tectonic plates, India is prone to earthquakes. India has been divided into five zones based on peak ground acceleration.

On December 26, 2004, an earthquake created the third deadliest tsunami in the history of the world, killing 15,000 people in India. The earthquake in Gujarat occurred on January 26, 2001, on the occasion of the 52nd Republic Day of India.

It lasted more than 2 minutes and amounted to 7.7 points on the Kanamori scale, according to statistics, from 13,805 to 20,023 people were killed, another 167,000 people were injured and about 400,000 houses were destroyed.

If the calculations are correct, then a citizen in Nepal will be more likely to die from an earthquake than any citizen in the world. Nepal is a disaster-prone country. Floods, landslides, epidemics and fires cause significant property damage in Nepal every year. This is one of the most seismically active regions in the world.

Mountains are built due to the movement of Indian tectonic plates under Central Asia. These two large crustal plates are moving closer together at a relative rate of 4-5 cm per year. The peaks on Everest and its sister mountains are subject to numerous tremors. In addition, the remains of a prehistoric lake, in a 300-meter deep layer of black clay, lie in the lowlands of the Kathmandu Valley. This increases the damage from large earthquakes.

Thus, the region becomes susceptible to soil liquefaction. During strong earthquakes, solid soil turns into something like quicksand, swallowing everything above the ground. In April 2015, an earthquake in Nepal killed more than 8,000 people and injured more than 21,000. The earthquake triggered an avalanche on Everest, killing 21 people, making April 25, 2015 the deadliest day on the mountain in history.

Japan tops the list of earthquake-prone areas. Japan's physiographic location along the Pacific Ring of Fire makes the country very susceptible to earthquakes and tsunamis. The Ring of Fire are tectonic plates in the Pacific Basin that are responsible for 90% of the world's earthquakes and 81% of the world's largest earthquakes.

At the height of its prolific tectonic activity, Japan is also home to 452 volcanoes, making it the most destructive geographical location from the point of view of natural disasters. The powerful earthquake that occurred in Japan on March 11, 2011 caused swipe and became one of the five largest earthquakes in the world since the beginning of seismological recording.

It was followed by a tsunami with waves up to 10 m high. The disaster killed thousands of people and caused extensive property damage to buildings and infrastructure, leading to significant accidents at four major nuclear power plants.

You will see the consequences of the most powerful earthquakes in the world and understand why this phenomenon is considered so dangerous.

The danger of such natural phenomenon, like an earthquake, is estimated by most seismologists in points. There are several scales by which the strength of seismic shocks is assessed. The scale, adopted in Russia, Europe and the CIS countries, was developed in 1964. According to data from a 12-point scale, the greatest destructive force is typical for an earthquake of 12 points, and such strong tremors are classified as a “severe catastrophe.” There are also other methods for measuring the strength of shocks, which take into account fundamentally different aspects - the area where the shocks occurred, the time of “shaking” and other factors. However, no matter what yardstick one uses to measure the strength of tremors, there is natural disasters, which are among the most terrible.

The strength of earthquakes: has there ever been a magnitude 12?

Since the Kamori scale was adopted, and this made it possible to evaluate natural disasters that have not yet disappeared into the dust of centuries, at least 3 earthquakes with a magnitude of 12 have occurred.

1. Tragedy in Chile, 1960.
2. Destruction in Mongolia, 1957.
3. Tremors in the Himalayas, 1950.

In first place in the ranking, which contains the most powerful earthquakes in the world, is the 1960 cataclysm known as the “Great Chilean Earthquake.” The scale of destruction is estimated at the maximum known 12 points, while the magnitude of the ground vibrations exceeded 9.5 points. The most powerful earthquake in history occurred in May 1960 in Chile, near several cities. The epicenter was Valdivia, where the fluctuations reached a maximum, but the population was warned of the impending danger, since the tremors were felt in nearby provinces of Chile the day before. 10 thousand people are considered dead in this terrible disaster; a lot of people were carried away by the tsunami that began, but experts say that without prior notification there could have been many more victims. By the way, many people were saved due to the fact that the mass of people went to church for Sunday services. At the moment the shaking began, people were in churches that stood.

The most destructive earthquakes in the world include the Gobi-Altai disaster, which swept through Mongolia on December 4, 1957. As a result of the tragedy, the earth was literally turned inside out: fractures formed, demonstrating geological processes that would not be visible under normal circumstances. The high mountains in the mountain ranges ceased to exist, the peaks collapsed, and the usual pattern of the mountains was disrupted.

The tremors in populated areas were increasing and continued for quite a long time until they reached 11-12 points. People managed to leave their houses seconds before complete destruction. Dust flying from the mountains covered the cities of southern Mongolia for 48 hours, visibility did not exceed several tens of meters.

Another terrible cataclysm, estimated by seismologists at 11-12 points, occurred in the Himalayas, in the highlands of Tibet, in 1950. The terrible aftermath of the earthquake in the form of mudflows and landslides changed the relief of the mountains beyond recognition. With a terrible roar, the mountains folded like paper, and dust clouds spread from the epicenter to a radius of up to 2000 km.

Tremors from the depths of centuries: what do we know about ancient earthquakes?

The largest earthquakes that occurred in modern times, discussed and well covered in the media.

Thus, they are still widely known, the memory of them, of the victims and destruction, is still fresh. But what about earthquakes that occurred a long time ago - a hundred, two hundred or three hundred years ago? Traces of destruction have long been eliminated, and witnesses either survived the incident or died. Nevertheless, historical literature contains traces of the most terrible earthquakes in the world, which occurred a long time ago. Thus, in the chronicles recording the largest earthquakes in the world, it is written that in ancient times tremors occurred much more often than now, and were much stronger. According to one such source, in 365 BC, tremors occurred that affected the entire Mediterranean territory, as a result of which the seabed was exposed before the eyes of eyewitnesses.

Deadly earthquake for one of the Wonders of the World

One of the most famous ancient earthquakes is the destruction of 244 BC. In those days, according to scientists, tremors occurred much more often, but this particular earthquake is especially famous: as a result of the tremors, the statue of the legendary Colossus of Rhodes collapsed. This statue, according to ancient sources, was one of the Eight Wonders of the World. It was a giant beacon in the form of a statue of a man with a torch in his hand. The statue was so huge that a flotilla could sail between its spread legs. The size played a cruel joke on the Colossus: its legs turned out to be too fragile to withstand seismological activity, and the Colossus collapsed.

Iranian earthquake of 856

The death of hundreds of thousands of people as a result of even not very strong earthquakes was common: there were no systems for predicting seismic activity, no warning, no evacuation. Thus, in 856, more than 200 thousand people became victims of tremors in the north of Iran, and the city of Damkhan was wiped off the face of the earth. By the way, the record number of victims for this one earthquake is comparable to the number of victims of earthquakes in Iran for the rest of the time, until today.

The bloodiest earthquake in the world

The Chinese earthquake of 1565, which destroyed the provinces of Gansu and Shaanxi, killed more than 830 thousand people. This is an absolute record for the number of human casualties, which has not yet been exceeded. It remained in history as the “Great Jiajing Earthquake” (named after the emperor then in power). Historians estimate its power at 7.9 - 8 points, as evidenced by geological surveys.

This is how this phenomenon was described in the chronicles:
“In the winter of 1556, a catastrophic earthquake occurred in Shaanxi and the provinces around it. Our Hua County has suffered numerous troubles and misfortunes. Mountains and rivers changed their location, roads were destroyed. In some places, the ground unexpectedly rose and new hills appeared, or vice versa - parts of the former hills went underground, floated and became new plains. In other places, mudflows constantly occurred, or the ground split and new ravines appeared. Private houses, public buildings, temples and city walls collapsed with lightning speed and completely.”.

Cataclysm for All Saints' Day in Portugal

A terrible tragedy that claimed the lives of more than 80 thousand Portuguese occurred in Lisbon on November 1, 1755. This cataclysm is not included among the most powerful earthquakes in the world either in terms of the number of victims or the strength of seismic activity. But the terrible irony of fate with which this phenomenon broke out is shocking: the tremors began precisely when people went to celebrate the holiday in church. The temples of Lisbon could not stand it and collapsed, burying a huge number of unfortunates, and then the city was covered by a 6-meter tsunami wave, killing the rest of the people on the streets.

The largest earthquakes in the history of the twentieth century

The ten disasters of the 20th century that claimed the greatest number of lives and brought the most terrible destruction are reflected in the summary table:

Tangshan-1976

The Chinese events of 1976 are captured in Feng Xiaogang's film "Disaster". Despite the relative weakness of the magnitude, the disaster claimed a large number of lives; the first shock provoked the destruction of 90% of residential buildings in Tangshan. The hospital building disappeared without a trace; the opening of the earth literally swallowed up the passenger train.

Sumatra 2004, the largest in geographical terms

The 2004 Sumatran earthquake affected several countries: India, Thailand, South Africa, Sri Lanka. The exact number of victims is impossible to calculate, since the main destructive force - the tsunami - carried tens of thousands of people into the ocean. This is the largest earthquake in terms of geography, since its prerequisites were the movement of plates in the Indian Ocean with subsequent tremors over a distance of up to 1600 km. The ocean floor rose as a result of the collision of the Indian and Burmese plates; tsunami waves ran in all directions from the fracture of the plates, which rolled thousands of kilometers and reached the shores.

Haiti 2010, our time

In 2010, Haiti experienced its first major earthquake after almost 260 years of calm. The greatest damage was suffered by the national fund of the republics: the entire center of the capital with its rich cultural heritage, all administrative and government buildings were damaged. More than 232 thousand people died, many of whom were carried away by the tsunami waves. The consequences of the disaster were a surge in the incidence of intestinal diseases and an increase in crime: the tremors destroyed prison buildings, which prisoners immediately took advantage of.

The most powerful earthquakes in Russia

In Russia there are also dangerous seismically active regions where an earthquake can occur. However, most of these Russian territories remote from densely populated areas, which eliminates the possibility of major destruction and casualties.

The largest earthquakes in Russia, however, are also inscribed in the tragic history of the struggle between the elements and man.

Among the most terrible earthquakes in Russia:

• North Kuril destruction of 1952.
• Neftegorsk destruction in 1995.

Kamchatka-1952

Severo-Kurilsk was completely destroyed as a result of tremors and tsunami on November 4, 1952. Unrest in the ocean, 100 km from the coast, brought waves 20 meters high to the city, hour after hour washing the coast and washing away coastal settlements into the ocean. The terrible flood destroyed all buildings and killed more than 2 thousand people.

Sakhalin-1995

On March 27, 1995, the elements took only 17 seconds to wipe out the workers' village of Neftegorsk in the Sakhalin region. More than 2 thousand residents of the village died, accounting for 80% of the residents. Large-scale destruction did not allow the village to be restored, so locality became a ghost: a memorial plaque was installed in it telling about the victims of the tragedy, and the residents themselves were evacuated.

A dangerous area in Russia from the point of view of seismic activity is any region at the junction of tectonic plates:

• Kamchatka and Sakhalin,
• Caucasian republics,
• Altai region.

In any of these regions, the possibility of a natural earthquake remains possible, since the mechanism of the generation of tremors has not yet been studied.