The power of tremors is estimated by the amplitude of the earth's crust from 1 to 10 points. The most seismic areas are considered to be in mountainous areas. We present you the most powerful earthquakes in history.

The worst earthquakes in history

During the earthquake that occurred in Syria in 1202, more than a million people died. Despite the fact that the strength of the shocks did not exceed 7.5 points, underground vibrations were felt along the entire length from the island of Sicily in the Tyrrhenian Sea to Armenia.

A large number of victims is associated not so much with the strength of the shocks, but with their duration. Modern researchers can judge the consequences of the destruction of the earthquake in the II century only by the surviving chronicles, according to which the cities of Catania, Messina and Ragusa in Sicily were practically destroyed, and the coastal cities of Akratiri and Paralimni in Cyprus were also covered by a strong wave.

Earthquake in Haiti

The earthquake in Haiti in 2010 claimed the lives of more than 220 thousand people, 300 thousand were injured, and more than 800 thousand were missing. The material damage as a result of the natural disaster amounted to 5.6 billion euros. For a whole hour, tremors with a power of 5 and 7 points were observed.

Despite the fact that the earthquake occurred in 2010, Haitians are still in need of humanitarian assistance, and are also rebuilding settlements on their own. This is the second most powerful earthquake in Haiti, the first occurred in 1751 - then the cities had to be rebuilt over the next 15 years.

Earthquake in China

About 830 thousand people became victims of an 8-point earthquake in China in 1556. At the very epicenter of the tremors in the Weihe River Valley, near Shaanxi Province, 60% of the population died. A huge number of victims is due to the fact that people in the middle of the 16th century lived in limestone caves, easily destroyed by even minor shocks.

Within 6 months after the main earthquake, the so-called aftershocks were repeatedly felt - repeated seismic shocks with a power of 1-2 points. This catastrophe occurred during the reign of the Jiajing Emperor, which is why it is called the Great Jiajing Earthquake in Chinese history.

The strongest earthquakes in Russia

Almost a fifth of the territory of Russia is located in seismically active regions. These include the Kuril Islands and Sakhalin, Kamchatka, the North Caucasus and the Black Sea coast, Baikal, Altai and Tuva, Yakutia and the Urals. Over the past 25 years, about 30 strong earthquakes with an amplitude of more than 7 points have been registered in the country.

Earthquake on Sakhalin

In 1995, an earthquake of magnitude 7.6 occurred on Sakhalin Island, as a result of which the cities of Okha and Neftegorsk, as well as several nearby villages, were damaged.

The most significant consequences were felt in Neftegorsk, which was 30 kilometers from the epicenter of the earthquake. Within 17 seconds, almost all houses were destroyed. The damage caused amounted to 2 trillion rubles, and the authorities decided not to restore the settlements, so this city is no longer marked on the map of Russia.

More than 1500 rescuers were involved in the liquidation of the consequences. 2040 people died under the rubble. A chapel was built on the site of Neftegorsk and a memorial was erected.

Earthquake in Japan

The movement of the earth's crust is often observed on the territory of Japan, since it is located in the active zone of the volcanic ring of the Pacific Ocean. The strongest earthquake in this country occurred in 2011, the amplitude of oscillations was 9 points. According to a rough estimate of experts, the amount of damage after the destruction reached 309 billion dollars. More than 15,000 people were killed, 6,000 were injured and about 2,500 were missing.

Tremors in the Pacific Ocean caused a powerful tsunami, the wave height of which was 10 meters. As a result of the collapse of a large flow of water on the coast of Japan, a radiation accident occurred at the Fukushima-1 nuclear power plant. Subsequently, for several months, residents of nearby areas were forbidden to drink tap water due to the high content of cesium in it.

In addition, the Japanese government ordered the TEPCO company, which owns the nuclear power plant, to compensate for the moral damage to 80,000 residents who were forced to leave the contaminated areas.

The strongest earthquake in the world

The strongest earthquake caused by the collision of two continental plates occurred in India on August 15, 1950. According to official data, the force of tremors reached 10 points. However, according to the conclusions of the researchers, the vibrations of the earth's crust were much stronger, and the instruments could not establish their exact magnitude.

The strongest tremors were felt in the state of Assam, which was reduced to rubble by the quake, destroying more than 2,000 homes and killing more than 6,000 people. The total area of ​​the territories that ended up in the destruction zone amounted to 390,000 square kilometers.

According to the site, earthquakes also often occur in volcanically active zones. We present you an article about the highest volcanoes in the world.
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The earthly firmament has always been a symbol of security. And today, a person who is afraid of flying on an airplane feels protected only when he feels a flat surface under his feet. Therefore, it becomes the most terrible thing when, literally, the soil leaves from under your feet. Earthquakes, even the weakest ones, undermine the sense of security so much that many of the consequences are not of destruction, but of panic and are psychological, not physical. In addition, this is one of those catastrophes that mankind cannot prevent, and therefore many scientists are studying the causes of earthquakes, developing methods for fixing shocks, forecasting and warning. The amount of knowledge already accumulated by humanity on this issue allows minimizing losses in some cases. At the same time, the examples of earthquakes in recent years clearly indicate that there is still a lot to be learned and done.

The essence of the phenomenon

At the heart of each earthquake is a seismic wave, resulting in It arises as a result of powerful processes of various depths. Quite minor earthquakes occur due to surface drift, often along faults. Deeper in their location, the causes of earthquakes often have devastating consequences. They flow in zones along the edges of shifting plates that are subducting into the mantle. The processes taking place here lead to the most noticeable consequences.

Earthquakes happen every day, but people don't notice most of them. They are only fixed with special devices. In this case, the greatest force of shocks and maximum destruction occur in the epicenter zone, the place above the source that generated seismic waves.

Scales

Today, there are several ways to determine the strength of the phenomenon. They are based on such concepts as the intensity of an earthquake, its energy class and magnitude. The last of these is a value that characterizes the amount of energy released in the form of seismic waves. This method of measuring the strength of a phenomenon was proposed in 1935 by Richter and therefore is popularly called the Richter scale. It is still used today, but, contrary to popular belief, each earthquake is assigned not points, but a certain magnitude.

Earthquake scores, which are always given in the description of the consequences, refer to a different scale. It is based on a change in the amplitude of the wave, or the magnitude of the fluctuations in the epicenter. The values ​​of this scale also describe the intensity of earthquakes:

• 1-2 points: rather weak tremors, recorded only by instruments;
• 3-4 points: noticeable in high-rise buildings, often noticeable by the swinging of a chandelier and the displacement of small objects, a person may feel dizzy;
• 5-7 points: shocks can be felt already on the ground, cracks may appear on the walls of buildings, shedding of plaster;
• 8 points: powerful shocks lead to the appearance of deep cracks in the ground, noticeable damage to buildings;
• 9 points: the walls of houses are destroyed, often underground structures;
• 10-11 points: such an earthquake leads to collapses and landslides, the collapse of buildings and bridges;
• 12 points: leads to the most catastrophic consequences, up to a strong change in the landscape and even the direction of water movement in rivers.

Earthquake scores, which are given in various sources, are determined precisely on this scale.

Classification

The ability to predict any disaster is linked to a clear understanding of what causes it. The main causes of earthquakes can be divided into two large groups: natural and artificial. The former are associated with changes in the bowels, as well as with the influence of some cosmic processes, the latter are caused by human activity. The classification of earthquakes is based on the cause that caused it. Among the natural ones, tectonic, landslide, volcanic and others are distinguished. Let's dwell on them in more detail.

Tectonic earthquakes

The crust of our planet is constantly in motion. This is what causes most earthquakes. The tectonic plates that make up the crust move relative to each other, collide, diverge and converge. In places of faults, where plate boundaries pass and a compression or tension force arises, tectonic stress accumulates. Growing, sooner or later, it leads to the destruction and displacement of rocks, as a result of which seismic waves are born.

Vertical movements lead to the formation of dips or uplift of rocks. Moreover, the displacement of the plates can be insignificant and amount to only a few centimeters, but the amount of energy released in this case is sufficient for serious destruction on the surface. Traces of such processes on earth are very noticeable. These can be, for example, displacements of one part of the field relative to another, deep cracks and dips.

Under the water

The causes of earthquakes at the bottom of the ocean are the same as on land - the movements of lithospheric plates. Their consequences for people are somewhat different. Very often, the displacement of oceanic plates causes a tsunami. Having originated above the epicenter, the wave gradually gains height and often reaches ten meters near the coast, and sometimes fifty.

According to statistics, over 80% of tsunamis hit the shores of the Pacific Ocean. Today, there are many services in seismic zones, working on predicting the occurrence and propagation of destructive waves and alerting the population of danger. However, people are still little protected from such natural disasters. Examples of earthquakes and tsunamis at the beginning of our century are another confirmation of this.

Volcanoes

When it comes to earthquakes, involuntarily, images of the eruption of red-hot magma that were once seen appear in the head. And this is not surprising: two natural phenomena are interconnected. An earthquake can be caused by volcanic activity. The contents of the fiery mountains exert pressure on the surface of the earth. During the sometimes quite long period of preparation for the eruption, periodic explosions of gas and steam occur, which generate seismic waves. The pressure on the surface creates the so-called volcanic tremor (tremor). It is a series of small ground shaking.

Earthquakes are caused by processes occurring in the depths of both active volcanoes and extinct ones. In the latter case, they are a sign that the frozen fiery mountain can still wake up. Volcanic researchers often use micro-earthquakes to predict eruption.

In many cases, it is difficult to unambiguously attribute an earthquake to a tectonic or volcanic group. The signs of the latter are the location of the epicenter in the immediate vicinity of the volcano and a relatively small magnitude.

collapses

An earthquake can also be caused by the collapse of rocks. in the mountains arise as a result of various processes in the bowels and natural phenomena, as well as human activity. Hollows and caves in the ground can collapse and generate seismic waves. The collapse of rocks is facilitated by insufficient drainage of water, which destroys seemingly solid structures. The collapse could also be caused by a tectonic earthquake. The collapse of an impressive mass in this case causes insignificant seismic activity.

Such earthquakes are characterized by a small force. As a rule, the volume of collapsed rock is not enough to cause significant vibrations. Nevertheless, sometimes earthquakes of this type lead to noticeable damage.

Classification by depth of occurrence

The main causes of earthquakes are associated, as already mentioned, with various processes in the bowels of the planet. One of the options for classifying such phenomena is based on the depth of their origin. Earthquakes are divided into three types:

• Surface - the source is located at a depth of no more than 100 km, approximately 51% of earthquakes belong to this type.
• Intermediate - the depth varies in the range from 100 to 300 km, the sources of 36% of earthquakes are located on this segment.
• Deep-focus - below 300 km, this type accounts for about 13% of such disasters.

The most significant marine earthquake of the third type occurred in Indonesia in 1996. Its center was located at a depth of more than 600 km. This event allowed scientists to "enlighten" the bowels of the planet to a considerable depth. In order to study the structure of the subsoil, almost all deep-focus earthquakes that are not dangerous for humans are used. Many data on the structure of the Earth were obtained as a result of studying the so-called Wadati-Benioff zone, which can be represented as a curved inclined line indicating the place where one tectonic plate enters under another.

Anthropogenic factor

The nature of earthquakes has changed somewhat since the beginning of the development of technical knowledge of mankind. In addition to natural causes that cause tremors and seismic waves, artificial ones also appeared. A person, mastering nature and its resources, as well as increasing technical power, by his activity can provoke a natural disaster. The causes of earthquakes are underground explosions, the creation of large reservoirs, the extraction of large volumes of oil and gas, resulting in voids underground.

One of the rather serious problems in this regard is earthquakes arising from the creation and filling of reservoirs. Huge in terms of volume and mass, the water column exerts pressure on the bowels and leads to a change in the hydrostatic equilibrium in the rocks. Moreover, the higher the created dam, the greater the likelihood of the so-called induced seismic activity.

In places where earthquakes occur for natural reasons, often human activity is superimposed on tectonic processes and provokes the occurrence of natural disasters. Such data imposes a certain responsibility on companies involved in the development of oil and gas fields.

Effects

Strong earthquakes cause great destruction over vast areas. The catastrophicity of the consequences decreases with distance from the epicenter. The most dangerous results of destruction are various. The collapse or deformation of industries associated with hazardous chemicals leads to their release into the environment. The same can be said about burial grounds and nuclear waste disposal sites. Seismic activity can cause contamination of vast areas.

In addition to the numerous destruction in cities, earthquakes have consequences of a different nature. Seismic waves, as already noted, can cause collapses, mudflows, floods and tsunamis. Earthquake zones after a natural disaster often change beyond recognition. Deep cracks and sinkholes, soil erosion - these and other "transformations" of the landscape lead to significant environmental changes. They can lead to the death of the flora and fauna of the area. This is facilitated by various gases and metal compounds coming from deep faults, and simply by the destruction of entire sections of the habitat zone.

Strong and Weak

The most impressive destruction remains after mega-earthquakes. They are characterized by a magnitude of over 8.5. Such disasters are, fortunately, extremely rare. As a result of such earthquakes, some lakes and riverbeds were formed in the distant past. A picturesque example of the "activity" of a natural disaster is Lake Gek-Gol in Azerbaijan.

Weak earthquakes are a hidden threat. As a rule, it is very difficult to find out about the probability of their occurrence on the ground, while phenomena of more impressive magnitude always leave identification marks. Therefore, all industrial and residential facilities near seismically active zones are under threat. Such structures include, for example, many nuclear power plants and power plants in the United States, as well as burial sites for radioactive and toxic waste.

Earthquake regions

The uneven distribution of seismically hazardous zones on the world map is also associated with the peculiarities of the causes of a natural disaster. In the Pacific Ocean there is a seismic belt, with which, one way or another, an impressive part of earthquakes is connected. It includes Indonesia, the western coast of Central and South America, Japan, Iceland, Kamchatka, Hawaii, the Philippines, the Kuriles and Alaska. The second most active belt is the Eurasian one: the Pyrenees, the Caucasus, Tibet, the Apennines, the Himalayas, Altai, the Pamirs and the Balkans.

The earthquake map is full of other areas of potential danger. All of them are associated with places of tectonic activity, where there is a high probability of collision of lithospheric plates, or with volcanoes.

The earthquake map of Russia is also full of a sufficient number of potential and active sources. The most dangerous zones in this sense are Kamchatka, Eastern Siberia, the Caucasus, Altai, Sakhalin and the Kuril Islands. The most destructive earthquake in recent years in our country occurred on Sakhalin Island in 1995. Then the intensity of the disaster was almost eight points. The disaster led to the destruction of a large part of Neftegorsk.

The huge danger of a natural disaster and the impossibility of preventing it forces scientists around the world to study earthquakes in detail: the causes and consequences, "identification" signs and forecasting capabilities. It is interesting that technological progress, on the one hand, helps to more accurately predict terrible events, to capture the slightest changes in the internal processes of the Earth, and on the other hand, it also becomes a source of additional danger: accidents at hydroelectric and nuclear power plants, in mining sites, horrendous industrial fires. The earthquake itself is a phenomenon as ambiguous as scientific and technological progress: it is destructive and dangerous, but it indicates that the planet is alive. According to scientists, the complete cessation of volcanic activity and earthquakes will mean the death of the planet in geological terms. The differentiation of the bowels will be completed, the fuel that has been heating the interior of the Earth for several million years will run out. And it is not yet clear whether there will be a place for people on the planet without earthquakes.

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

The frequency of earthquakes of different magnitudes in the world per year

• 1 earthquake with a magnitude of 8 or more
• 10 - with a magnitude of 7.0 - 7.9 points
• 100 - with a magnitude of 6.0 - 6.9 points
• 1000 - with a magnitude of 5.0 - 5.9 points

Earthquake intensity scale

Richter scale, points	Strength	Description
	Not felt	Not felt
	Very weak kicks	Felt only by very sensitive people
		Felt only inside some buildings
	intensive	Perceived by the slight vibration of objects
	Pretty strong	Felt by sensitive people on the street
		Felt by everyone on the street
	Very strong	Cracks may appear in the walls of stone houses
	destructive	Monuments are being moved, houses are badly damaged
	devastating	Severe damage or destruction of houses
	Destroying	Cracks in the ground can be up to 1m wide
	Catastrophe	Cracks in the ground can reach more than a meter. Houses are almost completely destroyed
	Catastrophe	Numerous cracks in the ground, collapses, landslides. The emergence of waterfalls, the deviation of the flow of rivers. No building can withstand

Mexico City, Mexico

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

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

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

Concepcion, Chile

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

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

Interestingly, the elements haunt Concepción for a long time. At the beginning of its history, it was located in Penko, but due to a series of devastating tsunamis in 1570, 1657, 1687, 1730, the city was moved slightly south of its former location.

Ambato, Ecuador

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

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

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

Los Angeles, USA

Predicting devastating earthquakes in Southern California is a favorite pastime for geoscientists. The fears are justified: the seismic activity of this area is associated with the San Andreas Fault, which runs along the Pacific coast through the state.

History remembers the most powerful earthquake of 1906, which claimed 1500 lives. In 2014, the sunny year managed to survive twice the tremors (magnitude 6.9 and 5.1 points), which affected the city with minor destruction of houses and a severe headache for residents.

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

Tokyo, Japan

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

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

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

Repeatedly in its history, Tokyo has disappeared from the face of the earth and rebuilt again. The great Kanto earthquake of 1923 turned the city into ruins, and after 20 years, rebuilt, it was destroyed by a large-scale bombing by American air forces.

Wellington, New Zealand

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

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

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

Cebu, Philippines

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

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

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

Sumatra Island, Indonesia

Indonesia is considered to be the most seismically active region in the world. In recent years, it has managed to become especially dangerous - the westernmost in the archipelago. It is located in the place of a powerful tectonic fault, the so-called "Pacific Ring of Fire".

The plate that forms the bottom of the Indian Ocean "squeezes" under the Asian plate here as fast as a human fingernail grows. The accumulated tension is released from time to time in the form of tremors.

Medan is the largest city on the island and the third most populous in the country. As a result of two strong earthquakes in 2013, more than 300 local residents were seriously affected, and about 4,000 houses were damaged.

Tehran, Iran

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

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

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

Chengdu, China

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

Recent events have reduced the number of visitors to these parts. In 2013, the province experienced a powerful earthquake of magnitude 7, when more than 2 million people were affected and about 186,000 houses were damaged.

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

What to do in case of an earthquake

• If an earthquake caught you outside, stay away from the eaves and walls of buildings that could fall. Stay away from dams, river valleys and beaches.
• If an earthquake caught you in a hotel, open the doors so that you can safely leave the building after the first series of aftershocks.
• During an earthquake, you can not run out into the street. Many deaths are caused by falling debris from buildings.
• In case of a possible earthquake, it is worth preparing a backpack with everything you need for a few days in advance. A first aid kit, drinking water, canned food, crackers, warm clothes, and washing accessories should be at hand.
• As a rule, in countries where earthquakes are frequent, all local cellular operators have a system for alerting customers about an approaching disaster. On vacation, be careful, watch the reaction of the local population.
• After the first push, there may be a lull. Therefore, all actions after it should be thoughtful and cautious.

Hundreds of thousands of earthquakes occur every year on our planet. 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 shudders strongly enough to destroy everything around.

Since most shocks of this magnitude occur at the bottom of the oceans, if they are not accompanied by a tsunami, people are not even aware of them. But when the land shudders, the elements are so destructive that the number of victims goes into the thousands, as happened in the 16th century in China (during earthquakes with a magnitude of 8.1, more than 830 thousand people died).

An earthquake is called 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 shocks of great intensity are often catastrophic, second only to typhoons in the number of victims.

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

Tectonic

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

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

Volcanic

But volcanic fluctuations, although weak, continue for a long time. Usually they do not pose a particular danger, but catastrophic consequences were still recorded. As a result of the most powerful eruption of the Krakatoa volcano at the end of the XIX century. half of the mountain was destroyed by the explosion, and the subsequent tremors were of such force that they split the island into three parts, plunging two thirds into the abyss. The tsunami that rose after that destroyed absolutely everyone who managed to survive before and did not have time to leave the dangerous territory.

landslide

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

man-made

In some cases, the causes and consequences of earthquakes are often associated with human activity. 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 the water penetrating through the soil destroys it. In addition, an increase in seismic activity has been observed 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 a new nuclear weapon, in many places on the planet, sensors recorded earthquakes of moderate strength.

An underwater earthquake occurs when tectonic plates collide on the ocean floor or near the coast. If the focus is shallow, and the magnitude is 7 points, an underwater earthquake is extremely dangerous because it causes a tsunami. During the shudder of the sea crust, one part of the bottom sinks, 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 going towards the coast.

Such an earthquake, together with a tsunami, can often have catastrophic consequences. For example, one of the strongest seaquakes occurred a few years ago in the Indian Ocean: as a result of underwater tremors, a large tsunami rose and, having hit the nearby coasts, led to the death of more than two hundred thousand people.

Start of shocks

The focus of an earthquake is a gap, 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, as a result of which friction occurs and energy is generated, which gradually begins to accumulate.

When the stress reaches its maximum and begins to exceed the force of friction, the rocks are torn apart, after which the released energy is converted into seismic waves moving at a speed of 8 km / s and causing the earth to vibrate.

The characteristics of earthquakes according to 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 for the Pacific Rim. The deeper the epicenter, the farther 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 fluctuations (foreshocks), and after it, aftershocks begin, subsequent shaking, 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 86,000 shocks.

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 a few years ago, lasted forty seconds - and that was enough to reduce the city of Port-au-Prince to ruins. But in Alaska, a series of aftershocks was recorded that shook the earth for about seven minutes, while three of them led to significant destruction.

It is extremely difficult, problematic and there are no 100% ways to calculate what kind of push will be the main one and will have the greatest magnitude. Therefore, strong earthquakes often take the population by surprise. So, for example, it happened in 2015 in Nepal, in a country where mild shaking was recorded so often that people simply did not pay much attention to them. Therefore, a 7.9-magnitude ground tremor resulted in a large number of casualties, and weaker aftershocks of magnitude 6.6 that followed 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, a magnitude 9.3 earthquake in the Indian Ocean in 2004 eased some of the increasing stress on the San Andreas Fault, which lies at the junction of lithospheric plates along the coast of California. It turned out to be of such strength that it slightly changed the appearance of our planet, smoothing out its bulge in the middle part and making it more rounded.

What is magnitude

One of the ways 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 often confused with the twelve-point intensity scale, measured in points). An increase in the magnitude of earthquakes by only one unit means an increase in the amplitude of oscillations by a factor of ten, and an increase in energy by a factor of thirty-two.

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

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

• 2 - weak almost imperceptible fluctuations;
• 4 - 5 - although the shocks are weak, they can lead to minor damage;
• 6 - medium destruction;
• 8.5 is one of the strongest recorded earthquakes.
• The largest is the Great Chilean earthquake with a magnitude of 9.5, which gave rise to a tsunami, which, having overcome the Pacific Ocean, reached Japan, having overcome 17 thousand kilometers.

Focusing on the magnitude of earthquakes, scientists argue that out of tens of thousands of oscillations occurring on our planet per year, only one has a magnitude of 8, ten - from 7 to 7.9 and one hundred - from 6 to 6.9. Keep in mind that if the magnitude of the earthquake is 7, the consequences can be catastrophic.

intensity scale

To understand why earthquakes occur, scientists have developed a scale of intensity based on such external manifestations as the impact on people, animals, buildings, nature. The closer the epicenter of earthquakes 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 will be from eleven to twelve points. 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 scale of intensity, the first destruction can occur already with six-point shocks, when thin cracks appear in the plaster. An earthquake of eleven points is considered catastrophic (the surface of the earth's crust is covered with cracks, buildings are destroyed). The strongest earthquakes that can significantly change the appearance of the area are estimated at twelve points.

What to do in case of earthquakes

According to rough estimates of scientists, the number of people who have died in the world due to earthquakes over the past half a 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 possibility of strong earthquakes was taken into account in the design of buildings: 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 and how you can save your life.

You need to know that if tremors caught you in a building, you need to do everything possible to get out into the open space as soon as possible, while elevators are strictly forbidden to use.

If it is impossible to leave the building, and the earthquake has already begun, it is extremely dangerous to leave it, so you need to stand either in the doorway, or in the corner near the load-bearing wall, or climb 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 during the beginning of earthquakes a person was on the street, you need to move away from the house 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 broken electrical wires in industrial plants, as explosive materials or poisonous substances can be stored there.

But if the first tremors caught a person when he was in a car or public transport, you need to urgently 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 happened that you were completely overwhelmed with 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.

During its history of many thousands of years, mankind has experienced such earthquakes, which, in their destructiveness, can be attributed to catastrophes of a universal scale. The causes of earthquakes are not fully understood and no one can say with certainty why they occur, where the next catastrophe will be and what strength.

In this article, we have collected the most powerful earthquakes in the history of mankind, measured by magnitude. You need to know about this value that it takes into account the amount of energy released during an earthquake, and is distributed from 1 to 9.5.

8.2 points

Although the magnitude of the 1976 Tien Shan earthquake was only 8.2, it can rightfully be considered one of the most destructive earthquakes in human history. According to the official version, this terrible incident claimed the lives of more than 250 thousand people, and according to the unofficial version, the number of deaths is approaching 700 thousand and is quite justified, because 5.6 million houses were completely destroyed. The event formed the basis of the film "Catastrophe", directed by Feng Xiaogang.

Earthquake in Portugal in 1755 8.8 points

The earthquake that occurred in Portugal back in 1755 on All Saints' Day refers to one and h the most powerful and tragic disasters in the history of mankind. Just imagine that in just 5 minutes Lisbon turned into ruins, and almost a hundred thousand people died! But the victims of the earthquake did not end there. The disaster caused a severe fire and tsunami that raged on the coast of Portugal. In general, the earthquake provoked internal unrest, which led to a change in the country's foreign policy. This catastrophe marked the beginning of seismology. The magnitude of the earthquake is estimated at 8.8 points.

9 points

Another devastating earthquake hit Chile in 2010. One of the most destructive and major earthquakes in the history of mankind over the past 50 years brought maximum damage: thousands of victims, millions of people homeless, dozens of destroyed settlements and cities. The Chilean regions of Bio-Bio and Maule suffered the most damage. This catastrophe is significant in that the destruction occurred not only because of, but the earthquake itself brought considerable harm, because. its epicenter was on the mainland.

Earthquake in North America in 1700 9 points

In 1700, strong seismic activity in North America changed the coastline. The disaster occurred in the Cascade Mountains, on the border of the United States and Canada, and according to various estimates was at least 9 points in magnitude. Little is known about the victims of one of the strongest earthquakes in world history. As a result of the disaster, a huge tsunami wave reached the shores of Japan, the destruction of which has been preserved in Japanese literature.

2011 Japan East Coast Earthquake 9 points

Just a few years ago, in 2011, the east coast of Japan shook from the most powerful earthquake in the history of mankind. In 6 minutes of a 9-point catastrophe, more than 100 km of the seabed was raised by 8 meters in height, and the ensuing tsunami hit the northern islands of Japan. The notorious Fukushima nuclear power plant was partially damaged, which provoked a radioactive release, the consequences of which are still felt today. The number of victims is called 15 thousand, but the true figures are not known.

9 points

Residents of Kazakhstan and Kyrgyzstan are difficult to surprise with tremors - these regions are located in the fault zone of the earth's crust. But the most powerful earthquake in the history of Kazakhstan and all mankind happened in 1911, when the city of Almaty was almost completely destroyed. The catastrophe was called the Kemin earthquake, which is recognized as one of the strongest inland earthquakes of the 20th century. The epicenter of events fell on the valley of the Bolshoy Kemin River. In this area, huge breaks in the relief were formed, with a total length of 200 km. In some places, entirely houses that fell into the disaster zone are buried in these gaps.

9 points

Kamchatka and the Kuril Islands are seismically active regions and earthquakes do not surprise them. However, residents still remember the disaster of 1952. One of the most destructive earthquakes that humanity remembers began on November 4 in the Pacific Ocean, 130 km from the coast. Terrible destruction was brought by the tsunami, which was formed after the earthquake. Three huge waves, the height of the largest reached 20 meters, completely destroyed Severo-Kurilsk and damaged many settlements. Waves came with an interval of an hour. The inhabitants knew about the first wave and waited it out on the hills, after which they went down to their villages. The second wave, the largest, which no one expected, brought the greatest damage and claimed the lives of more than 2 thousand people.

9.3 points

On Good Friday, March 27, 1964, all 47 US states were shaken by an earthquake in Alaska. The epicenter of the disaster was in the Gulf of Alaska, where the Pacific and North American plates meet. One of the most powerful natural disasters in human memory, with a magnitude of 9.3, claimed relatively few lives - 9 people died out of 130 victims in Alaska and another 23 lives were claimed by the tsunami that followed the tremors. Of the cities, Anchorage, located 120 kilometers from the epicenter of events, was hit hard. However, destruction swept along the coastline from Japan to California.

9.3 points

Literally 11 years ago, one of the most, perhaps, the strongest recent earthquakes in human history in the Indian Ocean happened. At the very end of 2004, an earthquake of magnitude 9.3 a few kilometers from the coast of the Indonesian city of Sumatra provoked the formation of a monstrous tsunami that wiped part of the city off the face of the earth. 15-meter waves caused damage to the cities of Sri Lanka, Thailand, South Africa and southern India. No one names the exact number of victims, but it is estimated that from 200 to 300 thousand people died, and several million more people were left homeless.

9.5 points

The most powerful earthquake in human history occurred in 1960 in Chile. According to expert estimates, it had a maximum magnitude of 9.5 points. The disaster began in the small town of Valdivia. As a result of the earthquake, a tsunami formed in the Pacific Ocean, its 10-meter waves raged along the coast, causing damage to settlements located by the sea. The scope of the tsunami reached such proportions that residents of the Hawaiian city of Hilo, 10 thousand kilometers from Valdivia, felt its destructive power. Giant waves even reached the shores of Japan and the Philippines.