The seismic belts of the Earth are the lines along which the boundaries between the lithospheric plates pass. If the plates move towards each other, then mountains are formed at the joints (such areas are also called mountain building zones). If the lithospheric plates diverge, then faults appear in these places. Naturally, such processes as the convergence-divergence of lithospheric plates do not remain without consequences - about 95% of all earthquakes and volcanic eruptions occur in these areas. That is why they are called seismic (from the Greek seismos - to shake).

It is customary to distinguish two main seismic belts: the latitudinal Mediterranean-Trans-Asian and the Pacific meridional perpendicular to it. The vast majority of all earthquakes occur in these two areas. If you look at the seismic hazard map, it becomes clearly visible that the zones highlighted in red and burgundy are located exactly in the location of these two belts. They stretch for thousands of kilometers, bending around the globe, on land and under water.

Almost 80% of all earthquakes and volcanic eruptions occur in the Pacific seismic belt, otherwise called the Pacific Ring of Fire. This seismic zone really, as if in a ring, encloses almost the entire Pacific Ocean. There are two branches of this belt - Eastern and Western.

The eastern branch starts from the shores of Kamchatka and goes along the Aleutian Islands, passes through the entire western coast of the Americas and ends in the South Antilles loop. In this area, most of the powerful earthquakes occur in the California Peninsula, which is due to the architecture of cities such as Los Angeles and San Francisco - it is dominated by houses one or two stories high with rare multi-storey buildings, mainly in the central parts of cities.

The western branch of the Pacific Ring of Fire stretches from Kamchatka through the Kuril Islands, Japan and the Philippines, covers Indonesia and, bending around Australia, through New Zealand reaches Antarctica itself. The area is home to many powerful underwater earthquakes, often leading to catastrophic tsunamis. Island states such as Japan, Indonesia, Sri Lanka, etc., are most affected by earthquakes and tsunamis in this region.

The Mediterranean-Trans-Asian Belt, as its name suggests, stretches across the entire Mediterranean Sea, including the South European, North African and Middle Eastern regions. Further, it stretches across almost all of Asia, along the ranges of the Caucasus and Iran to the Himalayas, to Myanmar and Thailand, where, according to some scientists, it connects with the seismic Pacific zone.

According to seismologists, this belt accounts for about 15% of world earthquakes, while the most active zones of the Mediterranean-Trans-Asian belt are considered to be the Romanian Carpathians, Iran and the east of Pakistan.

Minor seismic belts

There are also secondary zones of seismic activity. They are considered minor because they account for only 5% of all earthquakes on our planet. The seismic belt of the Atlantic Ocean begins off the coast of Greenland, stretches along the entire Atlantic and ends near the islands of Tristan da Cunha. There are no strong earthquakes here, and due to the remoteness of this zone from the continents, tremors in this belt do not bring destruction.

The western part of the Indian Ocean is also characterized by its own seismic zone, and although it is quite large in length (it reaches its southern end to Antarctica itself), earthquakes are not too strong here, and their centers are located shallow underground. There is also a seismic zone in the Arctic, but due to the almost complete desertion of these places, as well as due to the low power of tremors, earthquakes in this region do not have a particular impact on people's lives.

The most powerful earthquakes of the 20-21 centuries

Since the Pacific Ring of Fire accounts for up to 80% of all earthquakes, the most powerful and destructive cataclysms occurred in this region. First of all, it is worth mentioning Japan, which has repeatedly become a victim of the strongest earthquakes. The most destructive, though not the strongest in terms of the magnitude of its vibrations, was the earthquake of 1923, which is called the Great Kanto Earthquake. According to various estimates, 174 thousand people died during and from the consequences of this disaster, another 545 thousand were never found, the total number of victims is estimated at 4 million. The strongest Japanese earthquake (with a magnitude of 9.0 to 9.1) was the famous disaster of 2011, when a powerful tsunami caused by tremors off the coast of Japan caused destruction in coastal cities, and a fire at a petrochemical complex in Sendai and an accident on The Fokushima-1 nuclear power plant caused enormous damage to both the economy of the country itself and the ecology of the whole world.

The strongest of all documented earthquakes, the Great Chilean earthquake with a magnitude of up to 9.5 is considered, which occurred in 1960 (if you look on the map, it becomes clear that it also happened in the Pacific seismic belt). The disaster that claimed the largest number of lives in the 21st century is the 2004 Indian Ocean earthquake, when the powerful tsunami that followed it claimed the lives of nearly 300,000 people from nearly 20 countries. On the map, the earthquake zone refers to the western tip of the Pacific Rim.

Many large and destructive earthquakes also occurred in the Mediterranean-Trans-Asian seismic belt. One of these is the 1976 earthquake in Tangshan, when only according to the official data of the PRC, 242 419 people died, but according to some sources the number of victims exceeds 655 thousand, which makes this earthquake one of the deadliest in the history of mankind.

The seismic belts of the Earth are the zones where the lithospheric plates that make up our planet are in contact. The main characteristic of such areas is increased mobility, which can be expressed in frequent earthquakes, as well as in the presence of active volcanoes, which from time to time tend to erupt. Typically, these areas of the earth stretch for thousands of miles in length. Throughout this distance, a large fault in the earth's crust can be traced. If such a ridge is at the bottom of the ocean, it looks like a mid-ocean trench.

Modern names of the seismic belts of the Earth

According to generally accepted geographical theory, there are now two largest seismic belts on the planet. These include one latitudinal, that is, located along the equator, and the second - meridian, respectively, perpendicular to the previous one. The first is called the Mediterranean-Trans-Asian and it originates in the Persian Gulf, and the extreme point reaches the middle of the Atlantic Ocean. The second is called the Pacific meridional, and it passes in full accordance with its name. It is in these areas that the greatest seismic activity is observed. Mountain formations, as well as permanent volcanoes, have their place here. If these seismic belts of the Earth are viewed on a world map, it becomes clear that most of the eruptions occur precisely in the underwater part of our planet.

The largest ridge in the world

It is important to know that 80 percent of all earthquakes and volcanic eruptions occur in the Pacific Ridge. Most of it is located under salty waters, but it also affects some parts of the land. For example, in the Hawaiian Islands, precisely because of the fracture of the earth's rock, earthquakes constantly occur, which often lead to a large number of human victims. Further, this giant ridge includes the smaller seismic belts of the Earth. So, it includes Kamchatka, the Aleutian Islands. It affects the western coast of the entire American continent and ends as far as the South Antilles Loop. That is why all residential regions that are located along this line are constantly experiencing more or less strong earthquakes. Among the most popular giant cities in this volatile area is Los Angeles.

Seismic belts of the earth. The names of the less common ones

Now let us consider the zones of the so-called secondary earthquakes, or secondary seismicity. All of them are quite densely located within our planet, but in some places the echoes are not heard at all, while in other regions the tremors reach almost maximum. But it is worth noting that this situation is inherent only in those lands that are under the waters of the World Ocean. Secondary seismic belts of the Earth are concentrated in the waters of the Atlantic, in the Pacific Ocean basin, as well as in the Arctic and in some areas of the Indian Ocean. It is interesting that strong tremors, as a rule, fall precisely on the eastern part of all earth's waters, that is, "Earth breathes" in the Philippines region, gradually descending lower to Antarctica. To some extent, the foci of these strikes extend to the waters of the Pacific Ocean, but in the Atlantic it is almost always calm.

A more detailed consideration of this issue

As mentioned above, the seismic belts of the Earth are formed precisely at the junctions of the largest lithospheric plates. The largest of these is the meridian Pacific Ridge, along the entire length of which there are a huge number of mountain elevations. As a rule, the focus of shocks that causes shocks in this natural zone is subcrustal, so they spread over very long distances. The most seismically active branch of the meridian ridge is its northern part. Extremely high impacts are observed here, which often reach the California coast. It is for this reason that the number of skyscrapers that are being built in this area is always minimized. Please note that cities such as San Francisco, Los Angeles, in general, are one-story. High-rise buildings were erected only in the city center. Heading lower, to the south, the seismicity of this branch decreases. On the west coast of South America the tremors are no longer as strong as in the North, but subcrustal foci are still noted there.

Many branches of one large ridge

The names of the Earth's seismic belts, which are offshoots of the main meridian Pacific Ridge, are directly related to their geographic location. One of the branches is Eastern. It originates off the coast of Kamchatka, runs along the Aleutian Islands, then goes around the entire American continent and ends in the Falkland Islands. This zone is not catastrophically seismic, and the shocks that form within it are small. It is only worth noting that in the equator region an offshoot goes from it to the East. The Caribbean Sea and all the island states that are located here are already in the Antilles seismic loop. In this region, many earthquakes were previously observed, which brought many disasters, but today the Earth has "calmed down", and the tremors that are heard and felt in all resorts of the Caribbean do not pose any danger to life.

A little geographic paradox

If we consider the seismic belts of the Earth on the map, then it turns out that the eastern branch of the Pacific Ridge runs along the westernmost land coast of our planet, that is, along America. The western branch of the same seismic belt begins at the Kuril Islands, passes through Japan, and then divides into two others. It is strange that the names of these seismic zones were chosen exactly the opposite. By the way, the two branches into which this strip is divided also have the names "Western" and Eastern ", but this time their geographic affiliation coincides with the generally accepted rules. The eastern one goes through New Guinea to New Zealand. Quite strong tremors can be traced in this area, often of a destructive nature. The eastern branch covers the shores of the Philippine Islands, the southern islands of Thailand, as well as Burma, and finally connects with the Mediterranean-Trans-Asian belt.

An overview of the "parallel" seismic ridge

Now we will consider the lithospheric region, which is located closer to our region. As you already understood, the name of the seismic belts of our planet depends on their location, and in this case, the Mediterranean-Trans-Asian ridge is a confirmation of this. Within its length are the Alps, Carpathians, Apennines and islands located in the Mediterranean Sea. The greatest seismic activity occurs in the Romanian node, where strong shocks are often observed. Moving to the East, this belt captures the lands of Baluchistan, Iran and ends in Burma. However, the total percentage of seismic activity that falls on this area is only 15. Therefore, this region is quite safe and calm.

In my opinion, one of the most destructive natural phenomena is earthquake... It’s even scary to imagine all the horror and catastrophic consequences of this element. Giant waves caused by earthquakes are no less destructive - tsunami... Not so long ago I saw the movie "The Impossible". It very clearly shows the destructive power of these huge waves. The film made a strong impression on me. Fortunately, I live in the center of the European part of Russia, where such a phenomenon is simply impossible. I sincerely sympathize with people living in the vicinity of seismic belts.

Dangerous areas of the world where they are located

As I said, earthquakes are not possible in all parts of the planet. They occur mainly in seismically active places characterized by high mobility. These sites are located at the junctions of lithospheric plates, the movements in which lead to such a terrible phenomenon.

The earth is encircled, as it were, by three main seismically active regions. These areas are seismic belts.

Exists three main belts:

• Ring of Fire, or as it is also called by its location, - Pacific... It is characterized not only by earthquakes, but also by tsunamis and numerous volcanic eruptions.
• The second belt stretched from the Eurasian Alps to the Asian Himalayas.
• The third goes through the whole Atlantic Ocean.

Dangerous regions of Russia

But not the entire territory of Russia is seismically calm. Therefore, not all Russians are as lucky as I am. If you look at the seismic map of Russia, it is easy to see that the most dangerous areas are located in the south and east of the country.

In our country, serious tremors occur in the mountainous folding regions of the Caucasus, Altai, Siberia, as well as on Sakhalin Island, the Komandorskie and Kuril Islands.

One of the most powerful earthquakes in Russia happened just on Sakhalin Island in the village of Neftegorsk. It took the lives of most of the population of the village and completely destroyed it. After that, it was decided to resettle the survivors in other regions, and not to restore this village.

The seismic belts of the Earth are called the contact zones of the lithospheric plates that make up our planet. A key characteristic of these border zones is increased mobility and, as a consequence, high volcanic activity. 95% of all earthquakes occurring on the planet occur in seismic belts. Actually, these are zones of manifestation of the activity of the earth's crust, expressed in volcanic processes, earthquakes and mountain building.

The length of the belts is enormous: they encircle the globe for thousands of kilometers, run over land and along the ocean floor. Today, in geographical science, it is customary to distinguish two seismic belts: the Mediterranean-Trans-Asian - latitudinal belt, stretching along the equator - and the Pacific - meridional, running perpendicular to the latitudinal.

Mediterranean-Trans-Asian seismic belt

The belt passes through the Mediterranean Sea and the adjacent southern European mountain ranges, as well as the mountains of North Africa and Asia Minor. Further, it stretches along the ridges of the Caucasus and Iran, through Central Asia, the Hindu Kush to Kuen Lun and the Himalayas.

The most seismically active zones of the Mediterranean-Trans-Asian belt are the zone of the Romanian Carpathians, Iran and Baluchistan. From Baluchistan, the seismic activity zone stretches to Burma. Quite strong blows often occur in the Hindu Kush.

The zones of underwater activity of the belt are located in the Atlantic and Indian Oceans, and also partially in the Arctic. The seismic zone of the Atlantic runs through the Greenland Sea and Spain along the Mid-Atlantic Ridge. The zone of activity of the Indian Ocean through the Arabian Peninsula goes along the bottom to the south and southwest towards Antarctica.

Pacific seismic belt

More than 80% of all earthquakes on Earth occur in the Pacific belt. It passes along the mountain ranges encircling the Pacific Ocean, along the bottom of the ocean itself, as well as along the islands of its western part and Indonesia.

The eastern part of the belt is huge and stretches from Kamchatka through the Aleutian Islands and the western coastal zones of both Americas to the South Antilles loop. The northern part of the belt has the greatest seismic activity, which is felt in the California link, as well as in the region of Central and South America. The western part of Kamchatka and the Kuriles stretches towards Japan and beyond.

The eastern branch of the belt is full of winding and sharp turns. It originates on the island of Guam, passes to the western part of New Guinea and turns sharply east to the Tonga archipelago, from which it takes a sharp turn to the south. What shakes the southern zone of seismic activity of the Pacific belt, at the current time, it has not been sufficiently studied.

Seismic waves

Seismic waves are energy streams that spread across the earth's surface from the epicenter of an earthquake or artificial explosion. The main types of waves are voluminous and superficial... Body waves are the most powerful - they move in the bowels of the earth, while surface waves only travel along the surface.

Body waves:

• P waves (compression or primary waves) - the fastest, can move in different media (solid, liquid, gaseous), act in a similar way to a sound wave - post-bathing movements that capture rock particles;
• S waves (shear waves, shearing, side or secondary) - move slower than type P, cannot pass in a liquid medium.

Surface waves:

• Rayleigh waves - move along the surface of the earth in the same way as waves on water; has great destructive power. The vibrations felt during earthquakes and explosions are caused by this particular type of wave.
• Love waves - their movement is similar to the movement of a snake, pushing the breed to the sides, are considered the most destructive.

It has long been known that earthquakes are unevenly distributed over the earth's surface. They concentrate in seismic belts stretching for thousands of kilometers. Some belts, such as the belt along the Alps and the Himalayas, were known for a long time, others were identified later using seismographs installed in a single network throughout the Earth. It turned out that seismic belts of the earth strictly coincide with both world systems of relief: rifts and troughs. Outside of these systems, earthquakes rarely occur, but inside they happen constantly.

We still know little about the conditions existing in the sources of earthquakes, but there is no doubt that they arise as a result of the deformation of the lithosphere, when under the influence of stresses applied to it, the ultimate strength is surpassed and the lithosphere splits, catastrophically releasing a huge amount of energy, all these processes began to take place still before the appearance. Seismic belts mark the zones of the lithosphere split.... They break the outer solid shell of the Earth into large blocks, or, as they came to be called, plates.

With a seismicity map in front of him, any inquisitive person, even not at all experienced in plate tectonics, will not find it difficult to draw the boundaries of the lithospheric plates. To do this, it is enough to follow along the seismic belts. Thirteen main lithospheric plates can be distinguished: Eurasian, North American, South American, African, Philippine, Pacific, Coconut, Nazca and others. Their size can be thousands of kilometers. The composition of the plates includes both continents and ocean basins soldered to them up to the middle ridges. And only in a few cases (for example, in the Andes) the plate boundary coincides with the continent - ocean division (). The division of the lithosphere into plates bounded by seismic belts was one of the main facts in the theory of plate tectonics.

Earthquakes and seismic belts reflect interaction of lithospheric plates with each other... If earthquakes occur, this means that there is a split and deformation of the lithosphere; if there are no earthquakes, then, consequently, there are no deformations in the solid shell.

Tectonic activity on Earth is concentrated mainly along plate boundaries and manifests itself due to their interaction. How the plates move relative to each other also determines what kind of magmatism appears along their boundaries. That is, it can be assumed that the plate boundaries should also control the distribution of ore minerals, genetically related to igneous rocks.