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 of the earth's crust caused by natural or artificially created causes (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 of tectonic plates, when a sharp displacement of rocks occurs. 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 at the end of the 19th century. 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 the 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:
- Normal – epicenter up to 70 km;
- Intermediate – epicenter up to 300 km;
- 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 is located at the junction of lithospheric plates along the California coast. It turned out to be so strong 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 the magnitude scale (Richter scale), containing arbitrary 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 is considered to be the Great Chilean earthquake with a magnitude of 9.5, which generated a tsunami that, having crossed the 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 such as the impact on people, animals, buildings, and 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 magnitude 11 is considered catastrophic (the surface of the earth's crust becomes covered with cracks and 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 either in the doorway, or in a corner near a load-bearing wall, or crawl under a strong table, protecting your head with a soft pillow from objects that may 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 needs to move away from the house by at least one third of its height and, avoiding tall buildings, fences and other buildings, move towards wide streets or parks. It is also necessary to stay as far as possible from downed electrical wires of 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 the 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.
In times of high technology and established rhythms of life, people often forget that they do not control everything until the end. And the manifestations of global events such as earthquakes are only in a few cases truly noticeable. But if this cataclysm does reach civilized corners, this event may remain a scar on people's memories for a long time.
How does an earthquake happen?
Vibrations of the earth's surface, as well as tremors, are the process of an earthquake. Scientists believe that the earth's crust consists of 20 huge plates. They move at a very low speed of about a few centimeters per year through the upper layer of the mantle. The boundaries between plates are often mountains or deep-sea trenches. Where the slabs slide over each other, the edges become folded. And in the crust itself, cracks form - tectonic faults, through which mantle material seeps to the surface. Natural disasters such as earthquakes and volcanic eruptions often occur in these places. The area of shock wave divergence sometimes extends for hundreds of kilometers.
Causes of the earthquake
- Collapses of large masses of rock caused by groundwater often cause earth tremors over a short distance.
- In places of active volcanoes, under the pressure of lava and gases on the upper part of the crust, nearby areas are exposed to weak but prolonged tremors, often on the eve of an eruption.
- Man-made activities of people - the construction of dams, mining activity, nuclear weapons testing, accompanied by powerful underground explosions or redistribution of internal water masses.
How an earthquake occurs - earthquake foci
But not only the cause itself directly affects the power of the earthquake, but also the depth of the source of occurrence. The source or hypocenter itself can be located at any depth, from several kilometers to hundreds of kilometers. And it is a sharp displacement of large massifs of rocks. Even with a slight shift, vibrations of the earth's surface will occur, and the range of their movement will depend only on their strength and sharpness. But the further the surface, the less destructive the consequences of the cataclysm will be. The point above the source in the ground layer will be the epicenter. And it is often subject to the greatest deformation and destruction during the movement of seismic waves. 
How an earthquake occurs - zones of seismic activity
Due to the fact that our planet has not yet stopped its geological formation, there are 2 zones - the Mediterranean and the Pacific. The Mediterranean stretches from the Sunda Islands to the Isthmus of Panama. The Pacific covers Japan, Kamchatka, Alaska, moves further to the California mountains, Peru, Antarctica and many other places. There is constant seismic activity due to the formation of young mountains and volcanic activity.
How does an earthquake occur - the strength of the earthquake
The consequences of such earthly activity can be dangerous. There is a whole science for studying and recording it - seismology. It uses several types of measurements of magnitude - a measure of the energy of seismic waves. The most popular Richter scale with a 10-point system.
- Less than 3 points are recorded only by seismographs due to their weakness.
- From 3 to 4 points a person already feels slight swaying of the surface. The environment begins to react - the movement of dishes, the swaying of chandeliers.
- At 5 points, the effect is enhanced; in old buildings, interior decoration may crumble.
- 6 points can significantly damage old buildings, causing rattling or cracking of glass in new houses, but they are already damaged at 7 points;
- Points 8 and 9 cause significant destruction over large areas and bridge collapses.
- The strongest magnitude 10 earthquakes are also the rarest and cause catastrophic destruction.
- When living in high-rise buildings, you should understand that the lower a person is, the better, but during evacuation you cannot use elevators.
- It is worth leaving buildings and moving away from them to a safe distance (turning off electricity and gas), avoiding large trees and power lines.
- If it is not possible to leave the premises, you need to move away from window openings and tall furniture or hide under a strong table or bed.
- While driving, it is better to stop and avoid high points or bridges.
Humanity cannot yet prevent earthquakes, or even predict in detail the reaction of the earth's crust to seismic shocks. Due to the huge number of variables involved, these are incredibly complex forecasts. A person successfully passively defends himself in the form of strengthening buildings and improving the layout of infrastructure. This allows countries located on the line of constant seismic activity to develop successfully.
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 suggests that an earthquake can occur in the country at any point in 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 high 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. Moreover, 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 geography in terms of natural disasters. The powerful earthquake that struck Japan on March 11, 2011 dealt a powerful blow and became one of the five largest earthquakes in the world since seismological records began.
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.
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 are over 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.
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.