Where and when there were strong earthquakes. Where do earthquakes most often occur? Tectonic causes of earthquakes

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

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

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

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

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

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

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

Türkiye lies in a seismic zone between the Arabian, Eurasian and African plates. This geographical location 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.

One of the most terrible and unpredictable natural phenomena occurring on planet Earth is an earthquake. The destructive power of this earthly catastrophe can reach colossal proportions and humanity cannot fight it. Due to the fact that earthquakes or tremors occur as a result of sudden and fleeting changes in the very depths of the planet, it is currently almost impossible to prevent their occurrence. And sometimes it is also quite difficult to predict where, when and with what force tremors will occur. Therefore, in order to try to save yourself and the lives of your loved ones during this natural disaster, it is very important to know what to do during an earthquake and be able to provide first aid.

A huge number of earthquakes occur on planet Earth every year. But due to the fact that most of them have a very small impact force or occur at the very bottom of the oceans, many of the tremors do not affect us at all and we are absolutely unaware of their occurrence, and some are not even aware of their existence. Noticeable destruction can only be caused by strong earthquakes or tsunamis that arise in the ocean due to them.

Due to the fact that during earthquakes its energy is produced in many different forms (magnetic, electrical, mechanical), it is impossible to measure the force of its action with absolute accuracy. The greatest part of the destructive power of this natural phenomenon occurs at the epicenter of its occurrence, and the rest of the energy turns into waves, the strength of which decreases with increasing distance.

The strength of an earthquake is usually determined by such concepts as intensity, magnitude and energy class. The most accurate measurement of the amplitude of an earthquake is considered, that is, the magnitude of the vibrations that arise directly at the very epicenter of the disaster, and the concept of intensity or intensity, measured in points, is more often used in everyday life, since it is this that allows us to characterize the strength of the earthquake on the surface of the earth’s crust. The stronger the earthquake and the closer its epicenter, the greater the intensity. Let's consider the impact of this natural disaster depending on the number of points of its intensity:

From 1 to 2 points– insignificant shock force, which can only be determined with the help of special instruments. Earthquakes of magnitude 2 can also sometimes be detected by a person if at that moment he is in a motionless state.
From 3 to 4 points– tremors are felt more strongly in high-rise buildings, chandeliers may sway, slight mixing of objects and a feeling of slight dizziness.
From 5 to 7 points– the tremors begin to be felt quite strongly on the ground, minor destruction of buildings is possible, for example, cracks begin to appear on the walls, windows break, and plaster crumbles.
8 points– an earthquake causes deep cracks to appear on houses, the ground and even slopes.
9 points– the tremors become so strong that they can destroy the walls of houses and even some underground communication structures.
From 10 to 11 points– an earthquake of such strength causes severe destruction of many buildings, bridges, collapses, and landslides.
12 points– the destructive force of such shocks can significantly change the surface of the earth’s crust, practically crumble buildings and even change the movement of water in rivers.

The strength of an earthquake largely depends on how close to the Earth's surface internal changes and movements of the earth's crust occurred. The closer the source, the greater the destructive power of a natural disaster.

Causes of earthquakes

Quite often, many people have the question: “Why do earthquakes happen?” In ancient times, people believed that such disasters were sent to them from above as punishment for bad deeds. Currently, despite the fact that this question has not yet been fully studied, scientists have some answers. In fact, there are quite a lot of reasons for the occurrence of such disasters and they are all divided into the following impacts:

Natural. Natural influences include internal changes of the planet Earth, the influence of cosmic storms, the sun, and some other phenomena of the Cosmos.
Artificial. The artificial influence on the motivation for the occurrence of an earthquake is Man and his influence on the environment. Such actions can be explosions, digging up earth rocks for mining, and the like.

Depending on the cause of occurrence, the following types of earthquakes are distinguished:

Tectonic earthquakes. This type is the most common phenomenon that occurs due to movements, faults and collisions of tectonic plates. Such earthquakes manifest themselves in different ways. This may be the appearance of huge cracks on the surface of the earth, various collapses and landslides, or, with low strength, earthquakes may not reveal themselves at all.
Landslide earthquakes. These earthquakes occur due to the impact of landslides and landslides on the earth's crust. Such phenomena most often occur due to the appearance of voids underground and inside the mountains. Most often, landslide earthquakes are not very powerful.
Volcanic earthquakes caused by a volcanic eruption. Their peculiarity is that they do not cause any significant destruction and can be repeated a number of times.
Artificial earthquakes. This type occurs as a result of a large number of simultaneous explosions, nuclear explosions, as well as underground tests of various types of weapons.
Man-made earthquakes arise from direct human impact on the environment. It can arise as a result of artificial changes in the landscape during the construction of dams or new structures, the search for oil accumulations, the extraction of various types of minerals, or the destruction of mountains and plains by humans.

According to the results of numerous observations, the following natural phenomena occur before the occurrence of many earthquakes:

Heavy and prolonged rain showers.
The appearance in the air of an excess of gases such as uranium compounds, radon, helium, argon.
Severe anxiety and unusual behavior of domestic and wild animals, it is believed that, for example.
An unexpected glow in the air.

Ecological consequences of earthquakes

Depending on the strength of the earthquake, the proximity of the epicenter, and the location of its occurrence, varying degrees of consequences of this phenomenon appear.

Disasters with higher intensity significantly affect the ecology of the environment.

The most common environmental consequences resulting from earthquakes are the occurrence of such natural processes as landslides, landslides, mudflows, destruction of the earth's crust and even floods. With any even slight change in the usual landscape, in any case, great stress arises for the living organisms living in this area. For example, large landslide debris spoils the composition of the soil; flooding caused by an earthquake tsunami can permanently kill the life of organisms in the area.
In the case of deep faults, various heavy metals begin to enter the atmosphere from the bowels of the earth, negatively affecting living organisms.
One of the most dangerous effects of an earthquake is the provocation of man-made disasters. In the event that it arose in an area where there were various structures created to create production technologies, such as, for example, an oil refinery or pharmaceutical enterprise. As a result of violations of such buildings, severe environmental pollution almost always occurs.
If an earthquake occurs in an area where waste was stored, all toxic and unsafe substances can spread over a long distance around the area, which is also detrimental to good environmental conditions.
The destruction of oil and gas pipes is also very dangerous, causing a large accumulation of harmful substances in the air.
The destruction of such energy facilities as a result of an earthquake, such as thermal power plants and state regional power plants, can cause fires of enormous destructive proportions, capable of destroying the area for many kilometers around. The most terrible consequences of earthquakes occur when a nuclear power plant is destroyed.

The area where earthquakes occur does not have a uniform distribution. The main point or seismic belt where earthquakes often occur is in the Pacific Ocean. This belt covers Indonesia, the western coast of Central and South America, Japan, Iceland, Kamchatka, Hawaii, the Philippines, the Kuril Islands and Alaska.

The regions of the Eurasian belt are in second place in terms of seismic activity. It includes such mountain ranges as the Pyrenees, Caucasus, Tibet, Apennines, Himalayas, Altai, Pamir and Balkans.

A large number of earthquakes occur along fault lines and where plate collisions are most likely to occur, as well as in places where volcanoes are active.

Over the past ten years, the most destructive and powerful disasters have occurred in the following countries:

India – more than 20 thousand victims.
Iran - an entire city was razed to the ground and about 30 thousand people died.
O. Sumatra - more than 200 thousand people became victims.
Pakistan - more than 70 thousand dead.
China – more than 80 thousand died
Haiti – more than 200 thousand people became victims.
Japan - the earthquake caused the death of about 30 thousand people and caused the destruction of nuclear power plants, which led to harmful emissions into the atmosphere.

Where do earthquakes occur in Russia?

Russia also has a fairly large number of places where earthquakes periodically occur. The main seismically active points here are mountainous areas such as Kamchatka, Eastern Siberia, the Caucasus, and Altai. Also, quite often, similar catastrophes of fairly large scale were noticed on Sakhalin and the Kuril Islands, where tsunamis are also often formed due to earthquakes.

The most destructive and terrible in terms of the scale of casualties and destruction in recent years in Russia was the earthquake that occurred on the island of Sakhalin in 1995. The intensity of this disaster was almost 8 points, which contributed to the destruction of most of the city of Neftegorsk, where it occurred, and the death of more than two thousand people.

It is very important for every person to know the rules of behavior during an earthquake in order not to get confused at the most crucial moment and to try, if possible, to provide themselves and others with the maximum possible help. First of all, this applies to those people who permanently live or are temporarily located in seismically dangerous zones, who must always be prepared.

In order for an earthquake not to take all important documents and savings by surprise, a first aid kit, as well as a flashlight, must be stored in one place, and always keep in mind an approximate plan of action when you are in any of the possible places where you could be. Also, do not store heavy, sharp or nuclear-containing substances on top shelves and cabinets.

If you receive a message about a strong earthquake and the need to evacuate, if you are not at home and you have a small amount of time, you need to immediately go to your home, collect all the necessary documents and things, turn off the water, electricity and gas and close the doors. After which it is necessary to leave the populated area as soon as possible and go to a safer place.

During an earthquake, it is very important to pull yourself together, suppress panic and confusion, and try to act rationally, as quickly and productively as possible, in order to have a greater chance of saving yourself from damage. First of all, if you are indoors, you should try to get out of the premises as soon as possible, while capturing and, if possible, going to a more open area where there is no electricity, buildings or trees nearby. If you exit from higher floors, it is better to do so by stairs rather than by elevator.

If you cannot leave the premises, you must find the safest place in it. This could be a place near a load-bearing wall that is not overloaded with objects, a doorway, or under a strong table or bed that will be able to protect from falling objects. Under no circumstances should you stand near windows, shelves or heavy objects; you should also not use gas or electricity.

If there are children near you, first of all you need to try to calm them down, find them a secluded place, or, if you are in an open area, under no circumstances let them out of sight and keep them close to you.

If an earthquake finds you in a car, you also need to try to find a more open area, not cluttered with poles, various plantings and billboards intended for advertising, stop the car, open the door and stay in it until the tremors are over.

Earthquakes in Russia are a fairly common phenomenon. Of course, for residents of megacities and the central zone, this is rather an unfamiliar concept, but in other areas, in cities, events are held annually to help people react correctly in the event of such a disaster. For example, an earthquake of magnitude 3.2 occurred in Tuva at the end of 2011, and seismic activity in the area continues to this day.

Residents of the city are familiar with safety precautions firsthand and know perfectly well how to behave in such situations, but this does not diminish the constant stress that the population experiences, fearing for their lives and the safety of their loved ones.

What is an earthquake

In simple terms, these are vibrations of the Earth's surface, which are mainly caused by natural forces of nature. We will not consider such artificial stimuli as large explosions and other technical processes.

Earthquakes occupy a leading position in terms of their destructiveness. In the history of mankind there are many examples of the destructive power of nature. Billions of victims around the world and consequences that completely disrupted the entire infrastructure of cities and even entire countries. Earthquakes usually occur in mountainous areas, at the junction of Kamchatka, Altai, the Caucasus and Eastern Siberia. The leaders in the ranking of those affected by such disasters are undoubtedly Kamchatka, Altai, the Caucasus and Eastern Siberia. Of course, this is not the entire list of settlements prone to tremors. Some cities periodically experience seismic activity, but these phenomena remain invisible to residents.

Types of earthquakes

Today, experts distinguish three types of earthquakes:

Volcanic - volcanic eruptions.
Man-made earthquakes are strong explosions that cause shifts in underground plates.
Technogenic - tremors that are caused by human life processes.

How is an earthquake measured?

Earth tremors are measured by a special device - a seismograph, which with extreme accuracy not only measures the power of tremors, but also predicts how strong the slabs will be.

There is a generally accepted world scale, which consists of 12 points:

1 point. An almost imperceptible earthquake, since the ground vibration is minimal and cannot be felt.

2 points. A rather weak phenomenon that can only be felt when in a calm environment. Only some people are able to sense it.

3 points. A weak earthquake, manifested by vibrations that are more noticeable to others.

4 points. A moderate phenomenon, noticeable to all people.

5 points. A fairly strong earthquake that provokes the movement of objects in the room.

6 points (strong). Fairly strong shocks can cause minor damage to buildings.

7 points. A very strong earthquake, causing more severe destruction of buildings.

8 points. A destructive phenomenon that can destroy even the most powerful structures.

9 points. A devastating earthquake. There are severe landslides in the mountains, and people in cities cannot stand on their feet.

10 points. Destructive earthquakes can lead to the complete destruction of a populated area, turning everything in its path into ruins, including roads and all kinds of communications.

11 points. Catastrophe.

12 points. A severe disaster in which it is impossible to survive. The relief changes completely, strong splits are observed, huge depressions, craters and much more appear.

Causes of earthquakes

Major earthquakes in Russia and other countries of the world occur due to collision. For example, in the Caucasus there is the Arabian Plate, which gradually moves north towards the Eurasian Plate, which, in turn, periodically collides with the Pacific Plate located in Kamchatka. Speaking of the Kamchatka Territory, earthquakes in this area are also influenced by volcanic activity, during which fairly strong tremors are observed.

Signs of earthquakes

Throughout the history of such phenomena, scientists have been able to identify the main signs of an incipient catastrophe. Earthquakes in Russia usually started after the following things:

What earthquakes happened in Russia

Russia has suffered more than once from severe earthquakes. The landscape of our country is large and varied, as are the climatic zones. Seismically active areas are located mainly in Sakhalin and the Kamchatka Territory.

Sakhalin

On May 28, 1995, the village of Neftegorsk was destroyed on Sakhalin. On the scale, the power of the disaster was 7.5 points and 10 points at the epicenter of the earthquake. In a matter of hours, Sakhalin Neftegorsk, which at that time had 3,200 inhabitants, was simply erased from the surface of the earth. Only 400 people survived the disaster, 150 of whom subsequently died in hospitals from their injuries. This is the last earthquake of such magnitude in Russia, which has truly become the most tragic event not only for Sakhalin, but for the entire country.

As eyewitnesses later recalled, the real horror was not during the earthquake itself, but after. Many victims were buried under the ruins of their own homes and gradually suffocated in intense agony.

The surviving residents of the village left for the mainland and tried to start life “after the earthquake.” This disaster was the worst in the last 100 years. In the last century, in 1952, a tsunami occurred on Sakhalin caused by an earthquake in the Pacific Ocean, which wiped out the city of Severo-Kurilsk.

Kamchatka

Earthquakes in Russia mostly occur in the Kamchatka Territory. In the center of the Klyuchevskaya group of volcanoes is the Nameless Sopka with a height of 3085 meters. It was always considered a long-extinct volcano, so the earthquake that began in the morning of 1955 was a complete surprise.

The Klyuchi volcanic station, located 45 kilometers from the volcanoes, recorded huge clouds of white smoke. A few days later, the height of the volcanic emissions was already more than eight kilometers.

Throughout November, residents of the region observed strong lightning strikes, and the surface of the earth was completely covered in ash. In less than 29 days, the volcano's crater expanded by 550 meters. Unfortunately, this was only preparation for the disaster that occurred on March 30, 1956. Such earthquakes were not new in Russia, so no one evacuated in the hope that the awakened volcano would subside, especially after its activity decreased in late November.

In 1956, the pressure in the volcano reached a critical point. Within 15 minutes, the giant erupted a huge pillar of fire, which leaned towards the east at an angle of 30 degrees. Reaching a height of 24 kilometers, this column of fire and black smoke literally covered the sky. 20 kilometers from the volcano, trees were either uprooted or burned at lightning speed. The thickness of hot sand and lava that fell from the sky caused the snow to quickly melt. Powerful mud flows rushed down, carrying with them fragments of rocks and stones, demolishing everything in their path.

The volcanologists' base was literally wiped off the face of the earth; fortunately, there were no scientists there at that time. Professor Gorshkov said that if this flow had rushed in a different direction, the entire populated area would have been destroyed and would have become one of the saddest examples of earthquakes in Russia.

Kamchatka is the most dangerous region not even because there are a large number of volcanoes on its territory, but because in the event of a disaster, most residents will literally remain trapped surrounded by mountains.

Tuva

In 2012, an earthquake with a magnitude of 3.2 was recorded near Kyzyl. This phenomenon began at 7:30 am. Since the disaster was not so strong, there were no casualties.

Earthquake statistics in Russia include a phenomenon that occurred in the same region on December 27, 2011, when its power was 9.5 at the epicenter and 6.7 in other areas. Seismic activity continued until the end of February 2012, when a shock of magnitude 6.5 occurred. Fortunately, the epicenter was located more than 100 kilometers from populated areas. Nevertheless, tremors were felt in Buryatia, the Irkutsk region, as well as in Khakassia and the Krasnoyarsk Territory. The map of earthquakes in Russia contains all the main regions most susceptible to seismic activity, including Kyzyl.

In addition, specialists update all data monthly. Rocks are taken as samples and carefully studied. Based on these studies, volcanologists can roughly predict in which areas such phenomena are possible.

The greenhouse effect has tripped
Vladimir Erashov

In recent decades, the greenhouse effect has become the talk of the town; it is blamed for the increase in all earthly disasters. But here's a sensational surprise - THE GROWTH OF THE GREENHOUSE EFFECT AND THE NUMBER OF EARTHQUAKES COINCIDED ONLY UNTIL 2005, THEN THE PATH diverged, THE GREENHOUSE EFFECT CONTINUED TO GROW, WHILE THE NUMBER OF EARTHQUAKES STARTED TO DROP SHARPLY. Moreover, the statistics of earthquakes are as follows, we will present them below, which does not leave the slightest doubt about the presence of the indicated trends. The number of earthquakes on Earth increased significantly until 2005, and then began to decrease significantly. Earthquakes in modern times are recorded by many tracking stations with great accuracy and very scrupulously. From this side, any error is excluded in principle. Consequently, the indicated trend is an indisputable fact, a fact that allows us to look at the problem of climate warming in a very unconventional way.
First, we present earthquake statistics; these statistics were obtained after processing (summing up) the daily number of earthquakes stored in the archive of the site http://www.moveinfo.ru/data/earth/earthquake/select
Let us clarify that the site stores earthquakes of magnitude four and above, starting in 1974. It has not yet been possible to process all the statistics, it is very labor-intensive, we present statistics for January earthquakes; for other months the picture is similar.
Here are the statistics:
1974 -313, 1975-333, 1976 -539, 1977 – 323, 1978 – 329, 1979 – 325, 1980 – 390, 1981 -367, 1982- 405, 1983 – 507, 1984 – 391, 1985 – 447, 1986 – 496, 1987 – 466, 1988 – 490, 1989 – 490, 1990 – 437, 1991 – 516, 1992 – 465, 1993 – 477, 1994 – 460, 1995 – 709. 1996 – 865, 1997 – 647, 1998 – 747, 1999 – 666, 2000 – 615, 2001 – 692, 2002 – 815, 2003 – 691, 2004 – 915, 2005 – 2127, 2006 – 971, 2007 – 1390, 2008 – 1040, 2009 – 989, 2010 – 823, 2011 – 1211, 2012 – 999, 2013 – 687, 2014 – 468, 2015 – 479, 2016 – 499.
And so in 2005 there was a radical change in the number of recorded earthquakes; if before 2005 the number of earthquakes, albeit with minor stops, only grew, then after 2005 it began to steadily decline.
Main conclusion:
The catastrophic increase in the number of earthquakes that occurred on Earth before 2005 is in no way connected with the greenhouse effect; it occurred for other reasons, these reasons remain to be clarified.
An interesting fact is that in 2005, in parallel with the increase in the number of earthquakes, a radical change occurred in the speed of the Earth’s rotation; the Earth began to slow down its rotation. Now it is still impossible to say unequivocally that these facts are connected with each other, but it is also very unlikely that they coincided by chance. Moreover, short-term surges in the number of earthquakes correlate very well with surges in the Earth’s rotation speed.
From the works of scientist Sidorenkov N.S. It is known that the speed of rotation of the Earth has a very good correlation with the temperature on the Planet; a higher speed of rotation of the Earth also corresponds to a higher average temperature - this has been established experimentally over a fairly long period of observations. Then a completely logical question:
Will a decrease in the Earth's rotation speed be followed not only by a decrease in the number of earthquakes, which has already followed, but also by a decrease in average temperature, that is, do not these factors signal us about the beginning of an era of cooling?
Apparently it is too early to put an end to this issue, but Russian science has no right to leave this issue without attention, the stakes are painfully high. Of course, no scientist will cancel the future cooling of the climate, which may be about to begin, but this cooling should not fall on Russia out of the blue.
In this regard, I ask readers not to be lazy, but also re-read the article “Transparent Climate”.
Isn't it time for Russian science to wake up?
24.05. 2016

NatureAn earthquake refers to underground tremors and vibrations of the earth's surface that are caused by natural or artificial causes. Today, an earthquake is one of the most difficult to predict and dangerous natural phenomena.

Every year about a million earthquakes occur on our planet, but the vast majority of them are so weak that they are recorded only by special instruments (seismographs).

Earthquakes cause rapid displacements of sections of the earth's crust. An earthquake begins with the movement of rocks or a rupture deep in the earth's crust. This place is called the earthquake source. Most often it is located at a depth of up to 100 kilometers, but sometimes the depth reaches 700 kilometers. The area of land that is located above the source of the earthquake is called the epicenter and experiences tremors of maximum strength. From the source of the earthquake, seismic waves propagate in all directions, which gradually attenuate as they move away (this process is similar to the process of propagation of sound waves). The propagation speed of seismic waves can reach 8 kilometers per second.

Most often, earthquakes occur at the bottom of the oceans, which is due to the small thickness of the earth's crust in this area. These earthquakes are completely safe if they do not cause destructive tsunamis.

Currently, work is underway on earthquake forecasting. This issue is most relevant for regions located at the junction of lithospheric plates, since the vast majority of destructive earthquakes occur here.

The cause of an earthquake can be not only nature, but also man. It has been noted that tectonic activity is increasing in areas of the construction of large reservoirs, the extraction of natural gas and oil, the construction of large cities from imported materials and the extraction of large quantities of rocks from quarries and mines. The reason for this is a disruption of the natural balance and changes in pressure in rocks.

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 cause harm to humanity.

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.

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.

Where do earthquakes most often occur?

However, the source can be located much deeper - 700 and 800 kilometers. Such phenomena are not dangerous and can only be recorded with the help of special devices - 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 prudence and calm;
— While indoors, never hide under fragile furniture, for example, under a bed.
Lie down next to them in the fetal position and cover your head with your hands (or protect your head with something extra). If the roof collapses, it will fall on the furniture and a layer may form, in which you will find yourself. It is important to choose strong furniture whose widest part is on the floor, i.e. this furniture cannot fall;
— When outside, move away from tall buildings and structures, power lines that may collapse.
— Cover your mouth and nose with a wet cloth to prevent dust and fumes from entering if any object catches fire.

If you notice an injured person in a building, wait until the tremors end and only then get into the room.

Otherwise, both people may be trapped.

Where do earthquakes not occur and why?

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

Australia is the only continent in the world that is not at the junction of lithospheric plates.

There are no active volcanoes and high mountains on it and, accordingly, there are no earthquakes. There are also no earthquakes in Antarctica and Greenland.

The presence of the enormous weight of the ice shell prevents the spread of tremors across the surface of the earth.

The probability of earthquakes occurring on the territory of the Russian Federation is quite high in rocky areas, where the displacement and movement of rocks is most actively observed.

Thus, high seismicity is observed in the North Caucasus, Altai, Siberia and the Far East.

Report: Earthquakes

An earthquake is an underground tremors and vibrations of the earth's surface that arise as a result of sudden displacements and ruptures in the earth's crust or upper mantle and are transmitted over long distances in the form of vibrations. The intensity of earthquakes is assessed in seismic scores; magnitude is used for the energy classification of earthquakes (see Richter scale). The most famous catastrophic earthquakes: Lisbon 1755, California 1906, Messina 1908, Ashgabat 1948, Chilean 1960, Armenian 1988, Iran 1990.

General information

Strong earthquakes are catastrophic in nature, second only to typhoons in the number of victims and significantly (tens of times) ahead of volcanic eruptions.

The material damage of one devastating earthquake can amount to hundreds of millions of dollars. The number of weak earthquakes is much greater than that of strong ones. Thus, out of hundreds of thousands of earthquakes that occur annually on Earth, only a few are catastrophic. They release about 1020 J of potential seismic energy, which is only 0.01% of the Earth's thermal energy radiated into space.

Where and why do earthquakes occur?

The territorial distribution of earthquakes is uneven.

It is determined by the movement and interaction of lithospheric plates.

Earthquake

The main seismic belt, in which up to 80% of all seismic energy is released, is located in the Pacific Ocean in the region of deep-sea trenches, where cold lithospheric plates move under the continent. The rest of the energy is released in the Eurasian fold belt in places where the Eurasian plate collides with the Indian and African plates and in the areas of mid-ocean ridges under conditions of lithospheric stretching (see Fig.

Rift world system).

Earthquake parameters

The foci of earthquakes are located at depths of up to 700 km, but the majority (3/4) of seismic energy is released in foci located at depths of up to 70 km. The size of the source of catastrophic earthquakes can reach 100×1000 km. Its position and the place where mass movement begins (hypocenter) are determined by recording seismic waves arising during earthquakes (in weak earthquakes, the focus and hypocenter coincide).

The projection of the hypocenter onto the earth's surface is called the epicenter. Around it is the area of greatest destruction (epicentral, or pleistoseist, area).

Earthquake intensity

The intensity of earthquakes on the surface is measured in points and depends on the depth of the source and the magnitude of the earthquake, which serves as a measure of its energy.

The maximum known value of magnitude is close to 9. Magnitude is related to the total energy of an earthquake, but this relationship is not direct, but logarithmic, with an increase in magnitude by one unit, the energy increases 100 times, i.e., with a shock of magnitude 6, 100 times more energy is released than at magnitude 5, and 10,000 more than at magnitude 4. Often in the media reporting on seismic disasters, the magnitude scale (Richter scale) is identified with the seismic intensity scale, measured in seismic points, i.e.

j. journalists reporting 12 points “on the Richter scale” confuse magnitude with intensity. The intensity is greater, the closer the source is to the surface, so, for example, if the source of an earthquake with a magnitude of 8 is located at a depth of 10 km, then on the surface the intensity will be 11-12 points; at the same magnitude, but at a depth of 40-50 km, the impact on the surface decreases to 9-10 points.

Seismic scales

Seismic movements are complex, but can be classified.

There are a large number of seismic scales, which can be reduced to three main groups. In Russia, the 12-point scale MSK-64 (Medvedev-Sponheuer-Karnik), which is the most widely used in the world, is used, dating back to the Mercali-Cancani scale (1902), in Latin American countries the 10-point Rossi-Forel scale (1883) has been adopted, in Japan - 7-point scale.

The assessment of intensity, which is based on the everyday consequences of an earthquake, which are easily distinguishable even by an inexperienced observer, is different on the seismic scales of different countries. For example, in Australia, one of the degrees of shaking is compared to “the way a horse rubs against a veranda post”; in Europe, the same seismic effect is described as “bells begin to ring”; in Japan, “an overturned stone lantern-rick” appears.

In the simplest and most convenient form, sensations and observations are presented in a schematized short descriptive scale (MSK version) that can be used by anyone.

Score - Appearance on the surface

1 - Not felt by anyone, recorded only by seismic instruments

2 - Sometimes felt by people who are in a calm state

3 - Felt by a few, more pronounced in rooms on the upper floors

4 - Felt by many (especially indoors), some wake up at night.

Possible clinking of dishes, rattling of glass, slamming of doors

5 - Felt by almost everyone, many wake up at night. Rocking of hanging objects, cracks in window glass and plaster

6 - Felt by everyone, plaster is crumbling, light damage to buildings

7 - Cracks in the plaster and chipping of individual pieces, thin cracks in the walls. Shocks are felt in cars

8 - Large cracks in the walls, falling pipes, monuments.

Cracks on steep slopes and wet soil

9 - Collapse of walls, roofs in some buildings, ruptures of underground pipelines

10 - Collapses of many buildings, bending of railway rails.

Landslides, landslides, cracks (up to 1 m) in the ground

11 - Numerous wide cracks in the ground, landslides in the mountains, collapsed bridges, only a few stone buildings remain stable

12 - Significant changes in terrain, deviation of river flows, objects thrown into the air, total destruction of structures

How far does the impact of earthquakes extend?

Strong earthquakes can be felt at a distance of a thousand or more kilometers.

Thus, in aseismic Moscow, tremors with an intensity of up to 3 points are observed from time to time, serving as an “echo” of the catastrophic Carpathian earthquakes in the Vrancea Mountains in Romania, the same earthquakes in Moldova, close to Romania, are felt as 7-8 points.

Duration of earthquakes

The duration of earthquakes varies; often the number of tremors forms a swarm of earthquakes, including preceding (foreshocks) and subsequent (aftershocks) tremors.

The distribution of the strongest shock (the main earthquake) within the swarm is random. The magnitude of the strongest aftershock is 1.2 less than that of the main shock; these aftershocks are accompanied by their own secondary series of subsequent shocks.

For example, an earthquake that occurred on the island. Lissa in the Mediterranean lasted three years, the total number of tremors for the period 1870-73 was 86 thousand.

Catastrophic earthquakes

Of the huge number of earthquakes that occur annually, only one has a magnitude equal to or greater than 8, ten - 7-7.9, one hundred - 6-6.9.

Any earthquake with a magnitude of St. 7 could be a major disaster. However, it may go unnoticed if it occurs in a desert area. Thus, the enormous natural disaster - the Gobi-Altai earthquake (1957; magnitude 8.5, intensity 11-12 points) - remains almost unstudied, although due to the enormous force, small depth of the source and lack of vegetation cover, this earthquake left the most a complete and diverse picture (2 lakes appeared, a huge thrust was instantly formed in the form of a stone wave up to 10 m high, the maximum displacement along the fault reached 300 m, etc.)

P.). An area 50-100 km wide and 500 km long (like Denmark or Holland) was completely destroyed. If this earthquake had occurred in a densely populated area, the death toll could be in the millions. The consequences of one of the most powerful earthquakes (magnitude could be 9), which occurred in the oldest region of Europe - Lisbon - in 1755 and covered an area of over 2.5 million km2, were so enormous (50 thousand out of 230 thousand died).

townspeople, a rock grew in the harbor, the coastal bottom became dry land, the outline of the coast of Portugal changed) and so amazed the Europeans that Voltaire responded to it with “The Poem on the Death of Lisbon” (1756, Russian translation 1763). Apparently, the impression of this catastrophe was so strong that Voltaire challenged the doctrine of pre-established world harmony in his poem.

Strong earthquakes, no matter how rare they are, never leave contemporaries indifferent. Thus, in W. Shakespeare’s tragedy “Romeo and Juliet” (1595), the nurse recalls the earthquake of 1580, which, apparently, the author himself survived.

Why do people die in earthquakes

If earthquakes occur at sea, they can cause destructive waves - tsunamis, most often devastating the Pacific coast, as happened in 1933 in Japan and in 1952 in Kamchatka.

The total number of earthquake victims on the planet over the past 500 years has been about 5 million.

people, almost half of them are in China. So in 1556 in the Chinese province. In Shaanxi, an earthquake with a magnitude of 8.1 killed 830 thousand people; in 1976, in the Tangshan region east of Beijing, an earthquake with a magnitude of 7.8 caused the death of 240 thousand people. according to official Chinese data (according to American seismologists, up to 1 million people). Extremely severe consequences are also associated with the earthquakes of 1737 in Calcutta (India), when 300 thousand people died.

people, in 1908 in Messina (Italy) - 120 thousand people, in 1923 in Tokyo - 143 thousand people.

Large earthquake losses are usually associated with high population density, primitive construction methods, especially characteristic of poor areas, and it is not at all necessary that the earthquake be strong (for example, in 1960 as a result of a seismic shock with a magnitude of 5.8 up to 15 thousand died

people in Agadir, Morocco). Natural phenomena - landslides, cracks play a lesser role. The catastrophic consequences of an earthquake can be prevented by improving the quality of buildings, since most people die under their rubble. It is also useful to take advice - during an earthquake, do not run out into the street, but rather take shelter in a doorway or under a strong slab or board (table) that can withstand the weight of the collapsing load.

Forecast and zoning of earthquakes

The problem of predicting earthquakes based on observations of precursors (predicting not only the location, but, most importantly, the time of a seismic event) is far from being solved, i.e.

because none of the precursors can be considered reliable. There are isolated cases of exceptionally successful timely forecasts, for example, in 1975 in China an earthquake with a magnitude of 7.3 was very accurately predicted. In earthquake-prone areas, the construction of earthquake-resistant structures plays an important role (see.

Anti-seismic construction). Dividing the territory according to the degree of potential seismic hazard is part of the task of seismic zoning. It is based on the use of historical data (on the recurrence of seismic events, their strength) and instrumental observations of earthquakes, geological and geographical mapping and information on the movement of the earth’s crust.

The zoning of the territory is also associated with the problem of insurance against earthquakes.

Seismograph

Instrumental observations first appeared in China, where in 132 Chang Hen invented a seismoscope, which was a skillfully made vessel.

On the outside of the vessel, with a pendulum placed inside, the heads of dragons holding balls in their mouths were engraved in a circle. When the pendulum swung due to an earthquake, one or more balls fell into the open mouths of frogs placed at the base of the vessels so that the frogs could swallow them.

A modern seismograph is a set of instruments that record ground vibrations during an earthquake and convert them into an electrical signal, recorded on seismograms in analogue and digital form. However, as before, the main sensitive element is a pendulum with a load.

Seismic service

Constant observations of earthquakes are carried out by the seismic service.

The modern global network includes St. 2000 stationary seismic stations, the data of which is systematically published in seismological bulletins and catalogues.

In addition to stationary stations, expeditionary seismographs are used, including those installed on the ocean floor. Expedition seismographs were also sent to the Moon (where 5 seismographs annually record up to 3000 moonquakes), as well as to Mars and Venus.

Anthropogenic earthquakes

20th century technogenic human activity, which has assumed a planetary scale, has become the cause of induced (artificially caused) seismicity, which occurs, for example, during nuclear explosions (tests at the Nevada test site initiated thousands of seismic tremors), during the construction of reservoirs, the filling of which sometimes provokes strong earthquakes.

This happened in India, when the construction of the Koyna reservoir caused an 8-magnitude earthquake, which killed 177 people.

Studying earthquakes

Seismology studies earthquakes.

Seismic waves arising during earthquakes are also used to study the internal structure of the Earth; advances in this area served as the basis for the development of seismic exploration methods.

Earthquakes have been observed since ancient times. Detailed historical descriptions, reliably indicating earthquakes since mid.

1 thousand BC e., given by the Japanese. Ancient scientists - Aristotle and others - also paid great attention to seismicity. Systematic instrumental observations began in the 2nd half. 19th century, led to the separation of seismology into an independent science (B.

B. Golitsyn, E. Wichert, B. Gutenberg, A. Mohorovicic, F. Omori, etc.).

EARTHQUAKE MAGNITUDE (from Latin magnitudo - magnitude), a conventional value characterizing the total energy of elastic vibrations caused by earthquakes or explosions; allows you to compare vibration sources by their energy.

SEISMIC SCALE, a scale for assessing the intensity of an earthquake on the Earth's surface. In the Russian Federation, the 12-point seismic scale MSK-64 is used.

MIDDLE OCEAN RIDGE, mountain structures that form a single system at the bottom of the World Ocean, encircling the entire globe.

LITHOSPHERIC PLATE, large (several thousand.

km across) a block of the earth's crust, including not only the continental crust, but also the associated oceanic crust; limited on all sides by seismically and tectonically active fault zones.

HYPOCENTER, the point at which mass movement begins (rupture rupture) at the source of the earthquake. Depth up to 700 km.

2017 Directories. Mobile version.

12-point scale of intensity, earthquake strength

Earthquake intensity- a qualitative characteristic of the degree of destruction and other manifestations on the earth’s surface, at a specific point on the earth’s surface.

How does an earthquake happen?

For this, a twelve-point scale is used, in contrast to the nine-point magnitude scale (Richter scale), which quantitatively characterizes the energy at the source of the earthquake.

Gradation of earthquake by strength (intensity, seismic effect):

One point - minimal seismicity, not felt by people.

Two points (very weak) - weak vibrations are noticeable on the upper floors of high-rise buildings.

The reason could also be man-made, from a loaded truck passing under the windows.

Three points. (weak) - the chandeliers are swinging.

Four points (moderate) - shaking is felt inside buildings.

Five points (strong) - vibrations are felt both in the building and on the street.

Six points - furniture moves and falls, dishes bounce, window glass breaks.

People, frightened, run out of buildings into the street.

Seven points (very strong) - it is difficult to stand on your feet, the walls of brick houses crack, flights of stairs and building ceilings fall, landslides and cracks appear on the roads, in winter - ice cracks on rivers and reservoirs.

There is an additional danger - fires, accidents, short circuits.

Eight points. (destructive) - brick buildings collapse, underground communications break.

Nine points (destructive) - cracks form in the soil, there is great excitement in rivers and reservoirs.

Ten points. (destructive) - asphalt on the roads is crushed and broken, cracks in the ground are up to a meter wide, landslides and collapses.

Eleven points (catastrophic) - almost all brick houses are destroyed, roads are badly damaged.

Twelve points (catastrophe) - the earth’s surface is changing; cracks in the earth's crust reach a width of up to 10-15 m, a depth of up to 10 m or more, closing or remaining open during subsequent shocks; the amplitude of vertical soil vibrations reaches half a meter; large areas settle and can be flooded, or rise - with an amplitude of up to several tens of meters or more; displacements occur along faults.

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Navigators, their types and accuracy.
Mobile help

Earthquake are called tremors and vibrations of the surface of the planet that occur in the upper layers of the lithosphere due to a sharp displacement of lithospheric plates. The least dangerous of them are formed in the Earth's mantle (at great depths). But ruptures and displacements of the surface layer can bring with them catastrophic destruction.

This is explained by a decrease in the strength of earthquakes with distance from its source. The deeper the source is, the smaller the vibrations occur on the earth's surface.

Strength of earthquakes in points

The source of an earthquake (the place where it formed) is also called the focus or hypocenter.

They diverge from it in all directions seismic waves, like waves on water arising from a thrown pebble, with the only difference that seismic waves are directed to the sides, and up, and down. But that place on the earth’s surface, which is located directly above the hearth itself, is called epicenter of the earthquake. As a rule, the strongest fluctuations occur precisely there.

The magnitude scale is capable of assessing the strength of this destructive natural phenomenon.

To be more precise, it evaluates the energy that is released in the form of seismic waves. And this value fluctuates from 1 to 9.5(it is usually used by scientists, for example, in the popular film “San Andreas Fault” the magnitude reaches a maximum value of 9.5).
But although this characteristic is quite eloquent, it is still not enough to understand how dangerous a cataclysm is.

After all, it happens that a weaker, but longer-lasting earthquake causes much more damage than a strong one. That’s why there is also an intensity scale. It evaluates the impact of vibrations on the earth's surface, as well as their consequences.

To assess this destructive phenomenon, various scales are used, but, as a rule, they are all 12-point. The most popular magnitude scale is Richter scale. If you compare it with the intensity scale, you can roughly imagine what consequences earthquakes of varying strengths lead to:

1-2 points - noted only on devices, although particularly sensitive people may feel slight tremors.
3-4 points - felt by almost everyone as light tremors, especially noticeable inside buildings (by slight rattling of objects and shaking).
5-6 points - quite strong fluctuations occur, during which cracks may appear in old houses, plaster may crumble, objects may fall from shelves, etc.
7-8 points - very strong fluctuations are observed, leading to the destruction of houses and the appearance of cracks in the ground.
9-10 points - a devastating earthquake, leading to the destruction of buildings, landslides and collapses, huge cracks in the earth's surface, etc.
Phenomena of such strength are observed about 10 times a year.
11-12 points - a catastrophic earthquake, the destructive consequences of which are difficult to predict. They usually happen once a year.

Consequences of earthquakes

Strong earthquakes can destroy buildings and various structures. As a result of such destruction, many people die.

And if the source is in the sea, then a tsunami hits the coast (a huge wave capable of sweeping away everything in its path). An earthquake is one of the most dangerous phenomena on our planet. And if you consider that they are almost impossible to predict, like many other phenomena... This becomes a real problem.

Earthquakes. Why do earthquakes happen?

Earthquake statistics

As we already know, earthquakes with a magnitude of 7-12 are considered dangerous. They are the ones that can lead to destruction and changes in the planet’s topography. And although it is impossible to say exactly how many such phenomena occur annually, it is possible to calculate the approximate number of the most powerful of them.

Two centuries ago, for example, there were about 40 earthquakes per year with a magnitude of 7 or higher. Now their number has increased tenfold. 400 strong earthquakes per year have already become the norm for the Earth. The trend is impressive, isn't it? And what will happen next?

Earthquakes

Earthquakes are underground tremors accompanied by vibrations of the earth's surface.

Causes and types

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

Earthquakes are tectonic, volcanic and landslide.

Tectonic earthquakes arise due to sharp displacements of mountain plates or as a result of the displacement of an oceanic platform under the continent.

After all, the surface of the earth consists of continental and oceanic platforms, which, in turn, consist of separate blocks. When blocks are placed on top of each other, they can rise up and mountains are formed, or they can fall down and depressions are formed, or one of the plates will go under the other.

All these processes are accompanied by vibrations or shaking of the earth.

Volcanic earthquakes occur due to the fact that streams of hot lava and gases press from below onto the surface of the Earth and thus make you feel that the earth is disappearing from under your feet. Volcanic earthquakes are usually not very strong, but can last quite a long time, sometimes several weeks.

Often such earthquakes warn of an imminent volcanic eruption, which is even more dangerous than the earthquake itself.

Sometimes voids form underground, for example, under the influence of groundwater or underground rivers that erode the ground. In these places, the earth cannot withstand its own gravity and collapses, causing a slight shaking.

It is called landslide earthquake.

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

The most destructive and terrible are tectonic earthquakes. The place where plates collide or a powerful explosion occurs due to the release of energy accumulated in the earth is called earthquake source, or hypocenter.

When the explosion occurs, a shock wave with a speed of more than 5 km/s (depending on the power of the explosion) begins to spread in all directions, reaches the surface of the earth (this area on the surface is called the epicenter, and it is located directly above the hypocenter) and diverges to the sides along circles.

The epicenter is where the worst destruction occurs, and on the outskirts of the area affected by the earthquake, people may not even feel anything.

Strength of earthquakes

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

The strength of an earthquake on the surface of the earth is measured in points on a special 12-point scale.

Destruction after a strong earthquake

Point scale for measuring earthquake strength:

1 point - Not felt.
Marked only with special devices
2 point - Very weak, noted only by domestic animals and some people in the upper floors of buildings
3 points - Weak. Only felt inside some buildings, like the shock of driving a truck
4 points - Moderate. You can hear the creaking of floorboards and beams, the clinking of dishes, and the shaking of furniture.
Inside the building, the shaking is felt by most people
5 points - Quite strong. Tremors are felt in the rooms as if heavy objects were falling. Window glass breaks, chandeliers and furniture sway
6 point - Strong. Heavy furniture sways, dishes break, books fall from shelves, only very dilapidated houses are destroyed
7 point - Very strong.
Old houses are being destroyed. In strong buildings, cracks appear and plaster crumbles. The water in rivers and lakes becomes cloudy
8 points - Destructive. Trees sway violently and strong fences break. Many strong buildings are being destroyed. Cracks appear in the soil
9 points - Devastating. Strong buildings are destroyed.
Earthquakes

Significant cracks appear in the soil
10 points - Destructive. Even strong buildings and bridges are destroyed. Landslides and collapses, cracks and bends in the soil occur
11th point - Disaster. Almost all stone buildings, roads, dams, and bridges are destroyed. Cracks with shifts form on the surface of the earth
12th point - Severe catastrophe. All structures are destroyed, the entire area is devastated.
River courses are changing

Seismology

The seismograph pen draws a curved line in the form of sharp zigzags when tremors begin

Science studies earthquakes seismology. In different countries of the world, scientists conduct observations of the behavior of the earth's crust. They are helped in this by special instruments - seismographs.

They measure and automatically record the slightest tremors occurring anywhere in the world. When the earth's surface oscillates, the main part of the seismograph - the suspended load - due to inertia, begins to move relative to the base of the device, and the recorder records the seismic signal transmitted to the marker.

An important task of seismology is earthquake prediction.

Unfortunately, modern science cannot yet accurately predict them. Seismologists can more or less reliably determine the area and strength of an earthquake, but its onset is very difficult to predict.

Can an earthquake shake the Earth?

In mid-May 1960, one of the most significant and destructive earthquakes occurred in Chile - the Great Chilean Earthquake.

Despite the fact that the main vibrations of the earth occurred in the southwestern part of South America - the epicenter of the earthquake was located near the city of Valdivia - their “echoes” reached other territories of our planet: in particular, the Hawaiian Islands and Japan. The phenomenon in which an earthquake that occurs in one part of the earth causes other parts of the earth to pulsate and tremble, even those located thousands of kilometers from the epicenter, is called “swinging” or “vibration” of the earth.