Where was the earthquake? The most powerful earthquakes in the world

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

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

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

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

Tectonic

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

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

Volcanic

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

Landslide

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

Technogenic

In some cases, the causes and consequences of earthquakes are often 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 begins to destroy it. In addition, an increase in seismic activity has been noticed in oil and gas production areas, as well as in the area of mines and quarries.

Artificial

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

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

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

The tremors begin

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

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

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

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

Characteristic

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

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

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

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

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

What is magnitude

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

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

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

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

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

Intensity scale

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

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

According to the intensity scale, the first destruction can occur already with magnitude six shocks, when thin cracks appear in the plaster. An earthquake of magnitude 11 is considered catastrophic (the surface of the earth's crust becomes covered with cracks and buildings are destroyed). The strongest earthquakes, capable of significantly changing the appearance of the area, are estimated at twelve points.

What to do during earthquakes

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

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

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

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

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

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

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

Major earthquakes have occurred throughout human history, with the earliest recorded dating back almost 2,000 BC. But it is only in the last century that our technological capabilities have reached the point where the impact of these disasters can be fully measured. Our ability to study earthquakes has made it possible to avoid catastrophic casualties, such as in the case of a tsunami, when people have the opportunity to evacuate from a potential danger area. But unfortunately, the warning system does not always work. There are several examples of earthquakes where the greatest damage was caused by the subsequent tsunami, and not by the earthquake itself. People have improved building standards and improved early warning systems, but they have never been able to completely protect themselves from disasters. There are many in various ways estimate the strength of the earthquake. Some people base it on the Richter scale, others on the number of deaths and injuries, or even the monetary value of the damaged property. This list of the 12 strongest earthquakes combines all of these methods in one.

Lisbon earthquake

The Great Lisbon Earthquake struck the Portuguese capital on November 1, 1755, causing enormous destruction. They were made worse by the fact that it was All Saints' Day and thousands of people attended mass in the church. Churches, like most other buildings, could not withstand the elements and collapsed, killing people. Subsequently, a tsunami 6 meters high hit. An estimated 80,000 died due to fires caused by the destruction. Many famous writers and philosophers dealt with the Lisbon earthquake in their works. For example, Emmanuel Kant, who tried to find a scientific explanation for what happened.

California earthquake

A major earthquake struck California in April 1906. Etched into history as the San Francisco earthquake, it caused much more damage. wide area. Downtown San Francisco was destroyed by a huge fire that followed. Initial figures mentioned 700 to 800 dead, although researchers claim the actual death toll was more than 3,000. More than half of San Francisco's population lost their homes as 28,000 buildings were destroyed by the earthquake and fires.

Messina earthquake

One of Europe's largest earthquakes struck Sicily and southern Italy in the early hours of December 28th, 1908, killing an estimated 120,000 people. The main epicenter of the damage was Messina, which was virtually destroyed by the disaster. The magnitude 7.5 earthquake was accompanied by a tsunami that hit the coast. A recent study suggested that the size of the waves was so huge because of an underwater landslide. Much of the damage was due to the poor quality of buildings in Messina and other parts of Sicily.

Haiyuan earthquake

One of the deadliest earthquakes on the list occurred in December 1920, with its epicenter in Haiyuan Chingya. At least 230,000 people died. Measuring 7.8 on the Richter scale, the earthquake destroyed almost every home in the region, causing significant damage to major cities like Lanzhou, Taiyuan and Xi'an. Incredibly, waves from the earthquake were visible even off the coast of Norway. According to a recent study, Haiyuan was the strongest earthquake to hit China during the 20th century. Researchers have also questioned the official death toll, suggesting there may have been more than 270,000. This number represents 59 percent of the population in the Haiyuan area. The Haiyuan earthquake is considered one of the most destructive natural disasters in history.

Chilean earthquake

IN total 1,655 were killed and 3,000 were injured after a magnitude 9.5 earthquake struck Chile in 1960. Seismologists called it the strongest earthquake ever to occur. 2 million people were left homeless and economic losses amounted to $500 million. The force of the earthquake caused a tsunami, with casualties in places as far away as Japan, Hawaii and the Philippines. In some parts of Chile, waves have moved building ruins 3 kilometers inland. The massive Chilean earthquake of 1960 caused a giant rupture in the ground extending over 1,000 kilometers.

Earthquake in Alaska

On March 27th, 1964, a strong 9.2 earthquake struck the Prince William Sound region of Alaska. As the second most powerful earthquake on record, it caused a relatively low number of deaths (192 deaths). However, significant property damage occurred in Anchorage, and tremors were felt in all 47 US states. Due to significant improvements in research technology, the Alaska earthquake has provided scientists with valuable seismic data, allowing them to better understand the nature of such events.

Kobe earthquake

In 1995, Japan was hit by one of its most powerful earthquakes when a magnitude 7.2 shock struck the Kobe region in south-central Japan. Although it was not the worst ever seen, the devastating impact was felt by a significant portion of the population—an estimated 10 million people living in the densely populated area. A total of 5,000 were killed and 26,000 were injured. The US Geological Survey estimated damage at $200 billion, with infrastructure and buildings destroyed.

Sumatra and Andaman earthquake

The tsunami that struck across the Indian Ocean on December 26, 2004 killed at least 230,000 people. It was caused by a large undersea earthquake off the west coast of Sumatra, Indonesia. His strength was measured at 9.1 on the Richter scale. The previous earthquake in Sumatra occurred in 2002. It is believed to have been a seismic pre-shock, with several aftershocks occurring throughout 2005. The main reason The huge number of casualties was the lack of any early warning system in the Indian Ocean capable of detecting an approaching Tsunami. A giant wave reached the shores of some countries, where tens of thousands of people died, for at least several hours.

Kashmir earthquake

Jointly administered by Pakistan and India, Kashmir was hit by a magnitude 7.6 earthquake in October 2005, killing at least 80,000 people and leaving 4 million homeless. Rescue efforts were hampered by conflicts between the two countries fighting over the territory. The situation was aggravated by the rapid onset of winter and the destruction of many roads in the region. Eyewitnesses spoke of entire areas of cities literally sliding off cliffs due to the destructive elements.

Disaster in Haiti

Port-au-Prince was hit by an earthquake on January 12, 2010, leaving half the capital's population without their homes. The death toll is still disputed and ranges from 160,000 to 230,000. A recent report highlighted that as of the fifth anniversary of the disaster, 80,000 people continue to live on the streets. The impact of the earthquake has created severe poverty in Haiti, which is the poorest country in the Western Hemisphere. Many buildings in the capital were not built in accordance with seismic requirements, and the people of the completely destroyed country had no means of subsistence other than the international aid provided.

Tohoku earthquake in Japan

The worst nuclear disaster since Chernobyl was caused by a magnitude 9 earthquake off the east coast of Japan on March 11, 2011. Scientists estimate that during the 6-minute earthquake of colossal force, 108 kilometers of the seabed rose to a height of 6 to 8 meters. This caused a large tsunami that damaged the coast of Japan's northern islands. The Fukushima nuclear power plant was badly damaged and efforts to salvage the situation are still ongoing. The official death toll is 15,889 dead, although 2,500 people are still missing. Many areas have become uninhabitable due to nuclear radiation.

Christchurch

The worst natural disaster in New Zealand's history claimed 185 lives on February 22, 2011, when Christchurch was hit by a powerful 6.3 magnitude earthquake. More than half of the deaths were caused by the collapse of the CTV building, which was built in violation of seismic codes. Thousands of other houses were also destroyed, including the city's cathedral. The government declared a state of emergency in the country so that rescue efforts could proceed as quickly as possible. More than 2,000 people were injured, and reconstruction costs exceeded $40 billion. But in December 2013, the Canterbury Chamber of Commerce said that three years after the tragedy, only 10 per cent of the city had been rebuilt.

It seems that natural disasters happen once every hundred years, and our vacation in one or another exotic country lasts only a few days. According to scientists, one or two earthquakes occur on the planet every minute.

Frequency of earthquakes of different magnitudes in the world per year

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

Earthquake intensity scale

Scale	Force	Description
	Not felt	Not felt.
	Very weak tremors	It is felt only by very sensitive people.
		It can only be felt inside some buildings.
	Intensive	It is felt by the slight vibration of objects.
	Quite strong	Sensible to sensitive people on the street.
		It is felt by everyone on the street.
	Very strong	Cracks may appear in the walls of stone houses.
	Destructive	Monuments are moved from their places, houses are severely damaged.
	Devastating	Severe damage or destruction of houses.
	Destructive	Cracks in the ground can be up to a meter wide.
	Catastrophe	Cracks in the ground can reach more than a meter. Houses are almost completely destroyed.
	Major disaster	Numerous cracks in the ground, collapses, landslides. The appearance of waterfalls, deviation of river flows. Not a single structure can withstand.

Mexico City, Mexico

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

The most destructive earthquakes were in 1985, when 7.5 people died. In 2012, the epicenter of the earthquake was in the southeastern part of Mexico, but vibrations were well felt in Mexico City and Guatemala, about 200 houses were destroyed.

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

Concepcion, Chile

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

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

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

Ambato, Ecuador

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

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

IN Lately Ecuador's seismic activity continues: 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 both cases there were no casualties .

Los Angeles, USA

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

History remembers the powerful earthquake of 1906, which claimed one and a half thousand lives. In 2014, sunny Los Angeles twice experienced tremors (magnitudes 6.9 and 5.1), which affected the city with minor destruction of houses and severe headaches for residents.

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

Tokyo, Japan

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

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

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

Repeatedly throughout its history, Tokyo disappeared from the face of the earth and was rebuilt again. The Great Kanto Earthquake of 1923 left the city in ruins, and twenty years later, after being rebuilt, it was destroyed by massive bombing by American air forces.

Wellington, New Zealand

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

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

In 2014, Wellington residents felt tremors from an earthquake 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 transparent sea water. On average, more than thirty-five earthquakes with a magnitude of 5-5.9 and one with a magnitude of 6-7.9 occur here per year.

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

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

Sumatra Island, Indonesia

Indonesia is rightfully considered the most seismically active region in the world. Particularly dangerous for last years The island of Sumatra managed to become the westernmost in the archipelago. It is located at the site of a powerful tectonic fault, the so-called “Pacific Ring of Fire.”

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

Medan is the largest city on the island and the third most populous in the country. As a result of two strong earthquakes in 2013, more than three hundred local residents were seriously injured and about four thousand houses were damaged.

Tehran, Iran

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

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

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

Chengdu, China

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

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

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

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

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. Seismic waves propagate from the source of the earthquake in all directions, gradually attenuating as they move away ( this process 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 was noted that tectonic activity is increasing in areas of construction of large reservoirs, mining natural gas and oil, the construction of large cities from imported materials and the production 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 depending largely 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.

When they occur 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 instruments - seismographs.

The place where the earthquake is most powerful is called the epicenter.

It is this piece of land that is considered the most dangerous for the existence of all living things.

Studying earthquakes

A detailed study of the nature of earthquakes makes it possible to prevent many of them and make the life of the population living in dangerous places more peaceful.

To determine the power and measure the strength of an earthquake, two basic concepts are used:

— magnitude;
— intensity;

The magnitude of an earthquake is a measure that measures the energy released during release from the source in the form of seismic waves.

The magnitude scale allows you to accurately determine the origins of vibrations.

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

Features and signs of earthquakes

Regardless of what causes an earthquake and in what area it is localized, its duration will be approximately the same.

One push lasts on average 20-30 seconds. But history has recorded cases when a single shock without repetitions could last up to three minutes.

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

Other signs of an imminent earthquake include:

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

How to behave during earthquakes?

How to behave during an earthquake to save your life?

- Maintain 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.

Probability of earthquakes occurring in the area Russian Federation 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 part of the mantle and are transmitted over long distances in the form of vibrations. The intensity of earthquakes is assessed in seismic scores; for the energy classification of earthquakes, magnitude is used (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 most widely used 12-point scale in the world, MSK-64 (Medvedev-Sponheuer-Karnik), dating back to the Mercali-Cancani scale (1902), is used in countries Latin America the 10-point Rossi-Forel scale (1883) was adopted, in Japan - a 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 may become 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 strength, small depth of the source and lack of vegetation, 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 have been 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, which most often devastate 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 losses during earthquakes are usually associated with high density population, 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 people 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 doorway or under a strong slab or board (table) capable of supporting the weight of a collapsing load.

Forecast and zoning of earthquakes

The task 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 generated 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 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 purpose, 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.

Score seven (very strong) - difficult to stand, walls cracking brick houses, flights of stairs and building ceilings fall, landslides and cracks appear on roads, and 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 that 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 on 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 earth. 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 most 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 when 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 point - 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 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.

One of the terrible and unpredictable natural phenomena occurring on planet Earth is an earthquake. The destructive power of this earthly catastrophe can reach colossal sizes 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 generated in large quantities 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 on houses, land 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 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, mining various types fossils, during the destruction of mountains and plains by man.

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

Large 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 appeared 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 natural processes such 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 enough a large number of places where earthquakes occur periodically. The main seismically active points here are mountainous areas such as Kamchatka, Eastern Siberia, the Caucasus, and Altai. Also, quite often, similar catastrophes of quite 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 a rough 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.

In the event that there is 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 and collect everything Required documents and things, turn off the water, lights and gas and close the doors. After which you need to leave as soon as possible locality and head to more safe 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.