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Causes of tsunamis

The distribution of tsunamis is usually associated with areas of strong earthquakes. It is subject to a clear geographical pattern, determined by the connection of seismic areas with areas of recent and modern mountain building processes.

It is known that most earthquakes are confined to those zones of the Earth within which the formation of mountain systems continues, especially young ones dating back to the modern geological era. The purest earthquakes occur in areas close to large mountain systems and depressions of seas and oceans.

In Fig. Figure 1 shows a diagram of folded mountain systems and areas of concentration of earthquake epicenters. This diagram clearly identifies two zones of the globe that are most prone to earthquakes. One of them occupies a latitudinal position and includes the Apennines, Alps, Carpathians, Caucasus, Kopet-Dag, Tien Shan, Pamir and Himalayas. Within this zone, a tsunami is observed on the coasts of the Mediterranean, Adriatic, Aegean, Black and Caspian seas and the northern part of the Indian Ocean. The other zone is located in the meridional direction and runs along the shores of the Pacific Ocean. The latter is, as it were, bordered by underwater mountain ranges, the peaks of which rise in the form of islands (Aleutian, Kuril, Japanese islands and others). Tsunami waves are generated here as a result of gaps between rising mountain ranges and deep-sea trenches that fall parallel to the ridges, separating island chains from the sedentary area of ​​the Pacific Ocean floor.

The direct cause of the occurrence of tsunami waves is most often changes in the topography of the ocean floor that occur during earthquakes, leading to the formation of large faults, sinkholes, etc.

The scale of such changes can be judged from the following example. During an earthquake in the Adriatic Sea off the coast of Greece on October 26, 1873, ruptures were noted in the telegraph cable laid at the bottom of the sea at a depth of four hundred meters. After the earthquake, one of the ends of the broken cable was discovered at a depth of more than 600 m. Consequently, the earthquake caused a sharp subsidence of a section of the seabed to a depth of about 200 m. A few years later, as a result of another earthquake, the cable laid on a flat bottom again broke, and its ends found themselves at a depth that differed from the previous one by several hundred meters. Finally, another year after the new tremors, the sea depth at the rupture site increased by 400 m.

Even greater disturbances of the bottom topography occur during earthquakes in the Pacific Ocean. Thus, during an underwater earthquake in Sagami Bay (Japan), about 22.5 cubic meters were displaced when a section of the ocean floor suddenly rose. km of water, which hit the shore in the form of tsunami waves.

In Fig. Figure 2a shows the mechanism of tsunami generation as a result of an earthquake. At the moment of a sharp subsidence of a section of the ocean floor and the appearance of a depression on the seabed, the pod rushes to the center, overflows the depression and forms a huge bulge on the surface. When a section of the ocean floor rises sharply, significant masses of water are revealed. At the same time, tsunami waves arise on the surface of the ocean, quickly spreading in all directions. They usually form a series of 3–9 waves, the distance between the crests of which is 100–300 km, and the height when the waves approach the shore reaches 30 m or more.

Another reason that causes a tsunami is the eruption of volcanoes that rise above the sea surface in the form of islands or located on the ocean floor (Fig. 2b). The most striking example in this regard is the formation of a tsunami during the eruption of the Krakatoa volcano in the Sunda Strait in August 1883. The eruption was accompanied by the release of volcanic ash to a height of 30 km. The menacing voice of the volcano was heard simultaneously in Australia and on the nearest islands of Southeast Asia. On August 27 at 10 o'clock in the morning, a gigantic explosion destroyed the volcanic island. At this moment, tsunami waves arose, spreading across all oceans and devastating many islands of the Malay Archipelago. In the narrowest part of the Sunda Strait, the wave height reached 30–35 m. In some places, the waters penetrated deep into Indonesia and caused terrible destruction. Four villages were destroyed on Sebezi Island. The cities of Angers, Merak and Bentham were destroyed, forests and railways were washed away, and fishing boats were abandoned on land several kilometers from the ocean shore. The shores of Sumatra and Java became unrecognizable - everything was covered with mud, ash, corpses of people and animals. This disaster brought the death of 36,000 inhabitants of the archipelago. Tsunami waves spread throughout the Indian Ocean from the coast of India in the north to the Cape of Good Hope in the south. IN Atlantic Ocean they reached the Isthmus of Panama, and in the Pacific Ocean - Alaska and San Francisco.

Cases of tsunamis during volcanic eruptions are also known in Japan. So, on September 23 and 24, 1952, there was a strong eruption of an underwater volcano on the Meijin Reef, several hundred kilometers from Tokyo. The resulting waves reached Hotidze Island, northeast of the volcano. During this disaster, the Japanese hydrographic vessel Kaiyo-Maru-5, from which observations were carried out, perished.

The third reason for a tsunami is the fall of huge rock fragments into the sea, caused by the destruction of rocks by groundwater. The height of such waves depends on the mass of material that has fallen into the sea and the height of its fall. So, in 1930, on the island of Madeira, a block fell from a height of 200 m, which caused the appearance of a single wave 15 m high.

Tsunami off the coast of South America

The Pacific coast within Peru and Chile is subject to frequent earthquakes. Changes occurring in the bottom topography of the coastal part of the Pacific Ocean lead to the formation of large tsunamis. Greatest height(27 m) tsunami waves reached the Callao area during the Lima earthquake in 1746.

If usually the decrease in sea level that precedes the onset of tsunami waves on the coast lasts from 5 to 35 minutes, then during the earthquake in Pisco (Peru) the receding sea waters returned only after three hours, and in Santa even after a day.

Often the onset and retreat of tsunami waves occur here several times in a row. Thus, in Iquique (Peru) on May 9, 1877, the first wave hit the coast half an hour after the main shock of the earthquake, and then within four hours the waves arrived five more times. During this earthquake, the epicenter of which was located 90 km from the Peruvian coast, tsunami waves reached the coasts of New Zealand and Japan.

On August 13, 1868, on the coast of Peru in Arica, 20 minutes after the earthquake began, a wave several meters high surged, but soon receded. With an interval of a quarter of an hour, it was followed by several more waves, smaller in size. After 12.5 hours, the first wave reached the Hawaiian Islands, and 19 hours later - the coast of New Zealand, where 25,000 people became victims. Average speed tsunami waves between Arica and Valdivia at a depth of 2200 m were 145 m/sec, between Arica and Hawaii at a depth of 5200 m – 170-220 m/sec, and between Arica and the Chatham Islands at a depth of 2700 m – 160 m/sec.

Huge waves, reaching tens of meters in height and crashing with terrible force on the coast, are called tsunami. This name comes from a Japanese phrase. It is denoted by two hieroglyphs and means in translation: “a large wave flooding the bay.” In reality, the wave is not just big, it is gigantic. Its height can reach 30-40 meters, and it can cover land for many kilometers. At the same time, the elements sweep away everything in its path. People and animals are dying, houses are being destroyed, utility networks are damaged and destroyed, and the fertile layer of soil is being washed away.

Human casualties can reach tens of thousands of people, since such disasters know no pity, while material losses are incalculable. But no less terrible is the grief of those who lost relatives and friends in this terrible natural disaster. The consequences of the tsunami are so terrible that they make the entire planet tremble, and the next disaster is included in the historical chronicle of the world's greatest tragedies.

Causes of tsunamis

There are several reasons for the occurrence of huge waves. The most basic one, which causes up to 85% percent of all tsunamis - underwater earthquakes, during which sharp fluctuations of the seabed occur. The enormous energy released during this process is transferred to the water column. Oceanic masses begin to be disturbed and scatter in waves from the epicenter of the earthquake.

Behavior of rogue waves

In the vast expanses of the sea, such waves are almost invisible. They have a flat shape, with a height not exceeding one meter and a length reaching hundreds of kilometers. The energy in such a wave is concentrated over a huge area, and even a fragile boat will not feel all the strength and power that will pass under it.

These fluctuations aquatic environment spread from enormous speed. It can be 500, 700, or even 1000 km/h - it all depends on the thickness of the sea water. As you approach the shore, the depth drops, and the speed decreases accordingly and the wavelength shortens. Its height begins to grow rapidly. It turns into a huge water shaft, which with a roar falls on the coastal zone. These thousands and thousands of tons of raging elements sweep away everything in their path.

Tsunami off the coast

Having done its terrible deed and spent all its energy, the ocean crawls away from the land exhausted, becomes quiet, accumulates strength - this can last 20, 40, or 60 minutes. But now the coastal water begins to slowly recede from the shore, exposing an uneven muddy bottom. The surrounding tormented world freezes anxiously in anticipation of something terrible and bad. Silence thickens, the air is filled with anxiety, turning into horror.

In the sea distance, a second, even larger wave of water begins to grow. It widens before our eyes, covers the horizon, breaking the silence with a terrible roar, collapses onto the earth's surface, finishing the terrible work begun by the first wave. Deadly energy destroys everything that still survives, kills everything that is still alive. Having had plenty of fun with their impunity and permissiveness, the elements leave, but the end of this horror is still far away.

An hour or so passes, and the long-suffering earth takes upon itself a third terrible blow. The nightmare can last five or six hours. Only after this time, having fully satisfied its basest instincts, does the ocean calm down. Having spent all the negativity, the marine environment before our eyes turns into a quiet, gentle, gentle and obedient blue expanse of water. Only the mutilated land reminds of the horror experienced, on which uprooted trees are scattered in disarray, the remains of houses are scattered, roads and flowering gardens are destroyed.

After the tsunami

Tsunami in the Pacific Ocean

This is the picture of this terrible natural phenomenon that appeared when the World Ocean arose. In general, a terrible cataclysm occurs in different coastal zones 6-7 times a century. But these are large tsunamis. Small ones are ten times more common. The waters of the Pacific Ocean gravitate most towards terrible killer waves, since the bottom of this huge body of water is cut by numerous gutters and faults, like deep wounds.

It is in these places that different tectonic plates come into contact. Geological processes occur here continuously, and hence increased seismic activity. The western peripheral zone of the Pacific Ocean poses a great danger. The untrustworthy Kuril-Kamchatka Trench and the Japanese Trench are located here. To the north is the Aleutian Trench, the behavior of which also leaves much to be desired.

In the east of the Great Ocean, the Peru-Chile Trench sets the tone, simply terrorizing the waters of South America. In the southern part of a huge reservoir, north of New Zealand, the Kermadec Trench stretches straight, like an arrow, bursting with seismically active processes. Well, on the eastern shores North America, exactly along cloudy California, there are as many as five faults stretching. This far from optimistic picture is completed by the Central American Trench, which can be considered native to Mexico, Guatemala and El Salvador.

The earth's crust in places of faults and trenches is constantly shaking, so earthquakes are frequent guests in these areas. But not every one of them is capable of generating a tsunami. To move huge masses of water, titanic energy is needed. This can only be provided by very strong ups and downs of the seabed. On the 12-point Richter scale, this is a magnitude of 7 or higher. It can only be higher than 9 points; there are no large magnitudes on Earth, so tremors of such strength are quite rare.

Otherwise, huge rogue waves would roil the coastal zone as often as changes in wind direction or seasonal temperature fluctuations. True, small tsunamis often appear off various coasts. But their energy reserve is so insignificant that they cannot cause serious harm even if they want to. They really have the power to ruin their nerves, to upset someone because of the loss of a fishing boat or boat, but such situations, as a rule, arise due to the absent-mindedness or inattention of the people themselves.

Tsunami in Japan

The height of terrible waves largely depends on the contours and topography of the coastline. The wave advances with a wide front and in those places where there is a steep coast or a bay cutting deep into the land, the roaring wave reaches its maximum height. If you are in a closed bay, then you may not even realize that just a few kilometers from this place everything is collapsing and dying.

Landslides and underwater eruptions

Another reason for the occurrence of rogue waves is a geological process such as landslides. In terrestrial conditions, it is common for a large mass of rock to slide down the side of a valley or river bank. Such a movement can last decades, or it can begin unexpectedly, proceed rapidly and end in a short time. Piles of earth slide into a valley or river, causing some damage to the environment.

Similar processes occur on the seabed, since there are no fewer mountains and hills here than on land. Sedimentary rocks accumulate on the slopes of underwater mountain ranges. Over time, their mass becomes critical, and they collapse down, creating vibrations in the surrounding aquatic environment. If there is enough energy, a tsunami will arise, which in magnitude may be in no way inferior to a similar wave formed by an earthquake.

Due to landslides, such waves appear on the sea surface much less frequently. Of the total number of tsunamis, this is only 7%. Even less common (5%) Tsunamis are caused by underwater volcanic eruptions. A huge amount of energy is also released here, which can disturb the thickness of ocean waters. In these cases, the wave can be even more powerful than during earthquakes, since additional energy is absorbed upon contact with magma.

These are, perhaps, all the main reasons that generate terrible waves and tremble huge masses of people who, by the will of fate, are forced to live in coastal areas. As for the confrontation with this element, the picture is very pessimistic. The determining factor here is timely notification of the population about an impending disaster. Forewarned is forearmed. This famous saying is universal; guided by it, many, many lives can be saved.

Ships washed ashore by tsunami

Preventive measures

Nowadays it is known that rogue waves are always a consequence of an earthquake. To detect powerful underwater tremors in time means to predict with a sufficient degree of probability the appearance of huge waves off the coast. True, notification of areas populated by people should be instantaneous. After all, a disturbance in the water environment spreads at tremendous speed and within half an hour can move hundreds of kilometers away from the epicenter of the earthquake.

Considering the causes of the tsunami, many states great attention pay attention to the creation of seismic stations in those places where active geological processes are taking place. The International Service for Warning the Population of an Impending Disaster has been established. Its centers are located on the island of Oahu in the suburbs of Honolulu and on six other islands of the Hawaiian archipelago. Employees are on duty here around the clock, processing information coming from dozens of seismic stations scattered across the Pacific Ocean.

If a tsunami is suspected, large areas are immediately notified, and plans to mobilize the population from dangerous zones come into force. Fortunately, in most of these cases, huge waves do not occur. Taking into account the peculiarities of the human psyche, the medal also has a reverse side. Frequent unfounded alarms lead to people gradually becoming discouraged and starting to ignore messages about danger. The element is very insidious and is just waiting for a person to relax and lose caution.

How to behave during a disaster

In any case, no matter how frequent the reports of an impending disaster are, it is better not to look at careless people, but to rely only on your common sense and sense of self-preservation. The first sign of tragedy is the disappearance of water near the shore. The ocean is slowly creeping away from the coastal zone, preparing to deliver a powerful blow. If this happens, there is no doubt that the rogue wave is already close. After this, there is nothing to think about and hope for chance. Delay is like death.

You need to immediately take your children, documents, money and leave or go as far from the coast as possible. Moving inland along the river bed is strictly prohibited - you must stay as far away from it as possible. The best option is to climb to a distant hill. This will be the safest place in the coastal zone. The most optimal thing is to move away from the coastline several kilometers: even very high waves are unlikely to reach a mark of five or more thousand meters from the ocean boundary.

But ships or yachts, peacefully dozing in the roadstead, when a tsunami approaches, have only one option - they need to immediately weigh anchor and go into the open ocean. As paradoxical as it may sound, they must rush at full speed towards the terrible wave. In the open sea, it is almost invisible, and only gains power, strength and height near the shore.

All of the above are not empty words, but quite real. guide to action. Tsunami is a terrible force. Only those who don’t put their lives on the line can underestimate it. Numerous historical facts serve as clear confirmation of this.

Historical background

Terrible waves have crashed onto the earth's surface in all centuries, but the first detailed description, with an attempt to scientifically substantiate this catastrophe, was given by the great Spanish historian and geographer, member of the Jesuit Order, José de Acosta (1539-1600). Just before leaving for Spain in 1586, fate provided him with the opportunity to observe a rogue wave in Peru. It was a terrible sight when, after a strong earthquake, a 25-meter-high water shaft fell on the capital of Lima. He broke through 10 km inland, causing trouble hundreds of times more than the most brutal invaders would have done.

Eruption of Krakatoa volcano

Volcano Krakatoa

The consequences caused by the tsunami resulting from the eruption were truly monstrous Krakatoa volcano in 1883. At that time, this name was not given to an active volcano on the island of Rakita, but to a quite decent-sized island located in the Sunda Strait, between the islands of Sumatra and Java.

The volcanic eruption on this island began in May 1883. It lasted until the end of August and consisted of strong emissions of magma and gas from the bowels of the earth, one after another. Logically, over time, the intensity and strength of emissions should have weakened. But in this case, events began to develop according to a different scenario.

The volcano became more and more inflamed, gradually falling into uncontrollable ecstasy. Finally, on a cloudy and gloomy morning on August 27, a terrible explosion occurred. A huge column of ash soared into the air to a crazy height of 30 km. After this, apparently having exhausted all its magmatic energy, the volcano calmed down exhaustedly. One could breathe easy, but it was the calm before the storm.

The fact is that a void of enormous volume and area formed under the volcano, since all the rock that lay there was thrown into the atmosphere. Everything would have been fine, but this empty space was located significantly below the level of the world's oceans. Countless tons of water began to press on the thin walls that were left without support. The problem was also aggravated by the island's solid surface, which was now simply hanging in the air.

The climax came the next day in August. The walls of the empty underground chamber of the volcano could not withstand the terrible loads. Cracks ran across the surface of the island: rocky rocks fell down. Sea water rushed into the openings, widening its passage, with a roar.

In essence, it turned out to be an open wound in the earth's crust. The hot magma located deep below interacted with the cold liquid medium. The result of this was a terrible explosion, the shock wave from which spread over 300 km, breaking trees on the islands, demolishing the roofs of houses, maiming animals and people. The roar of the explosion was heard at a distance of 4 thousand km.

Location of Krakatoa volcano on the map

Even worse than the shock wave was a huge tsunami, the height of which reached 30 meters. It hit the shores of Indonesia with furious fury, and the coastline of Southeast Asia experienced its force. The rogue wave reached the western coast of Australia and, with a roar, hit the shores of the island of Ceylon and the eastern coast of the Hindustan Peninsula. The island of Madagascar and the entire eastern coast of Africa recognized its echoes.

The rogue wave killed 48 thousand people. Vast coastal areas were disfigured beyond recognition. Tens of thousands of people were left homeless. The tragedy of the island of Krakatoa has written another bloody page in the history of world catastrophes.

Rogue waves in the 20th century

The twentieth century tried to keep up with previous centuries in terms of the number of tsunamis. In November 1952, 150 km. An earthquake measuring 8.5 on the Richter scale occurred off the coast of Kamchatka. As a result, a disturbance of the aquatic environment arose. Giant waves, the height of which reached 20 meters, swept away the city of Severo-Kurilsk from the face of the earth. Nearby settlements were also destroyed. According to the most conservative estimates, 3,000 people died.

Throughout the second half of the 20th century, Alaska fought off terrible waves. In total there were about ten tsunamis, but there were three large ones that resulted in human casualties and destruction. New Guinea also became a victim of evil fate. In 1998, a huge wave caused the death of one and a half thousand people.

Rogue waves in the 21st century

The beginning of the 21st century was marked by rogue waves along with all of humanity. True, they were exactly 4 years late, but they compensated for this with human sacrifices. This tragedy occurred at the end of December 2004. As a result of a powerful earthquake (8.5 on the Richter scale), a giant wave arose that hit the shores of Thailand, Sri Lanka and Myanmar. The number of victims exceeded 200 thousand people.

In 2007, in the Solomon Islands, located east of New Guinea, a huge wave, the height of which reached 12 meters, destroyed many residential buildings, causing enormous damage to people. 48 people died in this wave.

The terrible tragedies associated with the tsunami will apparently continue until scientific and technological progress, which is rapidly striding forward, comes up with effective ways fight them. It is clear that this is a matter of the distant future; in our time, only those who live in the depths of the continents can sleep peacefully, and do not appear on the coasts of the oceans at all or go there no more than once a year.

Taking into account the fact that 85% of the entire population of the planet has chosen the coastal zones of the oceans and seas, this problem is very acute for all humanity. In this situation, one can only hope for the composure, attentiveness and mobility of people, as well as the clear and well-functioning operation of warning services.

By the way, when a powerful earthquake occurred in January 2005 dangerously close to the Izu Islands (Japan), the notified population managed to evacuate in time, and not a single person was injured. Well, what can we say - the Japanese are again ahead of the rest.

The article was written by ridar-shakin

Based on materials from foreign and Russian publications

For last decade The number of natural disasters around the globe has more than doubled. The most dangerous natural phenomena include tsunamis - huge killer waves.

Do you think you know enough about this? Then try answering these simple questions:

• list the signs by which one can determine its approach;
• tell us what needs to be done to avoid being harmed by the rogue wave.

Didn't work out? Then read this article carefully, perhaps this information will one day help save your life.

What is a tsunami?

We will talk about a tsunami - you should know the causes and consequences of this phenomenon modern society. The well-known term came to us from Japan and it is not surprising because it is this country that most often suffers from rogue waves. denoted by two hieroglyphs: 津 - “bay, port, bay” and 波 - “wave”. Therefore, in direct translation, this word means “wave in the bay.” These are huge waves that originate in the depths of the ocean and crash onto the shore with enormous destructive force.

The damaging factors of a tsunami can be defined as primary and secondary. The primary ones include:

• wave blow;
• air wave preceding flooding;
• hydrodynamic pressure;
• secondary ones are:
• complete flooding of the area;
• beaching of ships;
• destruction of buildings, roads, bridges, power lines and other objects in the path of the wave;
• the death of all living things;
• soil erosion, destruction of agricultural plantings;
• fires.

Where does this phenomenon most often occur?

The causes of tsunamis are most often associated with geological activity. Most likely, a similar phenomenon can be found on the Pacific coast. This is primarily due to the high geoactivity of this basin. Over the past millennium, these areas have been hit by rogue waves more than 1,000 times. At the same time, in the Indian and Atlantic Oceans, this phenomenon was observed several times less frequently.

On the territory of Russia, the most dangerous, from the point of view of tsunami occurrence, are the coasts of the Kuril Islands and Kamchatka, as well as the island of Sakhalin.

Rogue Wave Parameters

When considering the causes of a tsunami, it is worth first of all to talk about what parameters characterize such waves and how they can be measured. Like any other wave, a tsunami has a length, height and speed of travel.

1. The wavelength is the horizontal distance between two peaks (crests) of adjacent waves. The average length of a rogue wave can range from 150 to 300 km.
2. The height is the distance between the crest and the bottom of one wave. Above the center of the tsunami, this figure can be quite small - from 1 to 5 meters.
3. Speed ​​is the linear speed of movement of a specific element, for example, a comb. Most often this figure ranges from 500 to 1000 km/h, which, you see, is a lot.

All indicators of a tsunami wave depend on the depth of the origin. The deeper the wave originates, the greater its length and the higher the speed of propagation, but the height will be just small. For example, the speed of tsunami propagation in the Pacific Ocean, whose average depth is about 4 km, is approximately 700-800 km/h. When approaching the coastline, the speed of wave propagation sharply decreases to 80-100 km/h. Thus, the shallower the depth, the shorter the waves, but the height increases sharply when approaching the shore. In some cases it can reach 45-50 meters.

Intensity

Before we talk about what causes a tsunami, let's consider the intensity parameters of this phenomenon. Yes, yes, a tsunami, like an earthquake, has a division expressed in points. There are six levels in total and they mean the following:

• 1 point - the phenomenon is very weakly expressed, such a tsunami can only be recorded by special instruments - seaographers;
• 2 points - a rather weak wave that can only flood a flat coast; it can also be noticed mainly by specialists;
• 3 points - a tsunami of medium power, anyone can notice it; it is characterized by flooding of the flat coast, slight destruction of coastal buildings; light craft may also be thrown ashore;
• 4 points - a fairly severe natural disaster; the coast is completely flooded, and all coastal buildings are significantly damaged; light motor vessels and fairly large sailboats were washed ashore and then washed back; the coastline is littered with sand, silt and tree debris; human casualties are also likely;
• 5 points - a very strong phenomenon, accompanied by numerous casualties; the coastline has been severely destroyed for many hundreds of meters, large ships have been thrown ashore; nearby rivers overflow their banks from a strong storm surge;
• 6 points - catastrophic consequences; the land is completely flooded many kilometers deep, there are massive casualties, and complete devastation of the surrounding areas is observed.

What causes killer waves?

So we come to the question of why these terrible waves arise. To begin with, let us briefly list the causes of a tsunami:

• landslides;
• earthquakes;
• volcanic eruptions;
• meteorite falls;
• human activity.

The main cause of a rogue wave is an underwater earthquake with a sharp rise or fall in the level of the seabed. About 85% of all tsunamis occur for this reason. But not every underwater earthquake is accompanied by the appearance of a huge wave. Most often this happens when the lesion is not too deep.

Another reason is landslides. They account for about 7-8% of the elements. This reason for the occurrence of storm waves and tsunamis is, as it were, secondary, since landslides most often occur as a result of earthquakes.

The third reason is underwater volcanic eruptions. Large underwater eruptions have much the same effect as earthquakes. The largest and most famous eruption occurred in 1883. caused a huge tsunami that destroyed more than 5,000 ships, killing about 36,000 people worldwide.

The rapidly developing nuclear energy industry has created the preconditions for the emergence of another reason for the appearance of giant waves - human activity. Various deep-sea tests, for example, atomic explosions, can also cause a phenomenon such as a tsunami.

A very small, but still percentage, is given to cosmic phenomena, for example, the fall of meteorites.

It is worth noting that giant waves are most often the result of not one, but a number of factors. And in this case they are especially destructive. These may be the main causes of a tsunami.

Consequences

One of the most terrible consequences of a tsunami, of course, is human casualties. Even one life of a person buried by a wave is already a huge grief. What can we say about the hundreds and thousands of dead.

In addition, tsunamis cause salinization and erosion of large areas of the coast, as well as complete flooding of coastal areas. All ships moored near the shore are destroyed, and nearby buildings and structures can be destroyed to the ground.

How to recognize an approaching tsunami?

The causes of a tsunami are more or less clear, but how to recognize the signs that portend trouble?

Birds and animals are usually the first to sense the approach and begin to leave their homes. A massive “relocation” of animals can begin either a few hours or a few days before the disaster. Probably, birds and animals feel certain energy waves sent by Mother Earth. In fact, animals are affected by an electromagnetic field: a whole stream of charged ions rises from the surface of the earth into the atmosphere, charging the air to the limit with electricity. By the way, not only animals feel this phenomenon - many so-called weather-dependent people begin to have unbearable headaches.

If you live on the coast, get yourself an aquarium and carefully observe its inhabitants. This is exactly what the Japanese do, who for many decades have been determining the approach of seismic activity by the behavior of aquarium catfish. In anticipation of shocks, these fish behave very restlessly, literally trying to jump out of the aquarium.

Clear signs of an approaching tsunami may look like this:

• the water quickly and suddenly moves away from the shore, leaving a wide strip of sand;
• there are signs of a small (or strong) earthquake, although this point is not at all necessary, since the epicenter of the earthquake may be located far in the ocean and not be felt at all on the shore;
• the movement of the waves is accompanied by sounds similar to thunder;
• changes in the behavior of animals, birds and fish (they can wash ashore).

What should you do if you notice a wave approaching?

If you notice the causes of a tsunami, such as an earthquake or a meteorite, or see clear signs of its approach, you should not hesitate for a second. Take your most valuable things and documents with you, take your children and elderly relatives and leave the coast inland as quickly as possible. Agree on a meeting place with your family in advance in case you lose each other.

If it is not possible to quickly leave a dangerous place, look for other ways to escape. It could be some kind of natural elevation - a mountain or a hillock. Tall permanent buildings made of stone or concrete are also suitable. It is best if they are located at least a little further from the shore.

You need to move along the shortest route, avoiding river banks and various water bodies - bridges, dams, reservoirs. A distance of at least 3-5 km from the coastline can be considered safe.

Try to remain calm - panic only gets in the way. The occurrence of a tsunami is usually detected by instruments and turned on. Never ignore these sounds, even if it turns out several times that the alarm is false.

Never stay to watch a tsunami or go close to the shore for 3-4 hours after the first wave arrives. The fact is that there is rarely only one wave - the second, or even the third can come in 30 minutes or even in 3 hours. Make sure it's all over before you return.

Knowing these simple rules can truly save your life. Follow them whenever you notice the first signs of a rogue wave approaching. Do not ignore the sounds of the siren even if everyone around you assures you that it is a false alarm.

Conclusion

Now you know exactly the causes of tsunamis and their possible consequences. I would like this knowledge to really help in a difficult situation. Remember, a tsunami is a very fast and extremely dangerous natural disaster. Knowing the causes of this phenomenon and basic rules of behavior can really save your life.

The distribution of tsunamis is usually associated with areas of strong earthquakes. It is subject to a clear geographical pattern, determined by the connection of seismic areas with areas of recent and modern mountain building processes.

It is known that most earthquakes are confined to those zones of the Earth within which the formation of mountain systems continues, especially young ones dating back to the modern geological era. The purest earthquakes occur in areas close to large mountain systems and depressions of seas and oceans.

In Fig. Figure 1 shows a diagram of folded mountain systems and areas of concentration of earthquake epicenters. This diagram clearly identifies two zones of the globe that are most prone to earthquakes. One of them occupies a latitudinal position and includes the Apennines, Alps, Carpathians, Caucasus, Kopet-Dag, Tien Shan, Pamir and Himalayas. Within this zone, a tsunami is observed on the coasts of the Mediterranean, Adriatic, Aegean, Black and Caspian seas and the northern part of the Indian Ocean. The other zone is located in the meridional direction and runs along the shores of the Pacific Ocean. The latter is, as it were, bordered by underwater mountain ranges, the peaks of which rise in the form of islands (Aleutian, Kuril, Japanese islands and others). Tsunami waves are generated here as a result of gaps between rising mountain ranges and deep-sea trenches that fall parallel to the ridges, separating island chains from the sedentary area of ​​the Pacific Ocean floor.

The direct cause of the occurrence of tsunami waves is most often changes in the topography of the ocean floor that occur during earthquakes, leading to the formation of large faults, sinkholes, etc.

The scale of such changes can be judged from the following example. During an earthquake in the Adriatic Sea off the coast of Greece on October 26, 1873, ruptures were noted in the telegraph cable laid at the bottom of the sea at a depth of four hundred meters. After the earthquake, one of the ends of the broken cable was discovered at a depth of more than 600 m. Consequently, the earthquake caused a sharp subsidence of a section of the seabed to a depth of about 200 m. A few years later, as a result of another earthquake, the cable laid on a flat bottom again broke, and its ends found themselves at a depth that differed from the previous one by several hundred meters. Finally, another year after the new tremors, the sea depth at the rupture site increased by 400 m.

Even greater disturbances of the bottom topography occur during earthquakes in the Pacific Ocean. Thus, during an underwater earthquake in Sagami Bay (Japan), about 22.5 cubic meters were displaced when a section of the ocean floor suddenly rose. km of water, which hit the shore in the form of tsunami waves.

In Fig. Figure 2a shows the mechanism of tsunami generation as a result of an earthquake. At the moment of a sharp subsidence of a section of the ocean floor and the appearance of a depression on the seabed, the pod rushes to the center, overflows the depression and forms a huge bulge on the surface. When a section of the ocean floor rises sharply, significant masses of water are revealed. At the same time, tsunami waves arise on the surface of the ocean, quickly spreading in all directions. Usually they form a series of 3-9 waves, the distance between the crests of which is 100-300 km, and the height when the waves approach the shore reaches 30 m or more.

Another reason that causes a tsunami is the eruption of volcanoes that rise above the sea surface in the form of islands or located on the ocean floor (Fig. 2b). The most striking example in this regard is the formation of a tsunami during the eruption of the Krakatoa volcano in the Sunda Strait in August 1883. The eruption was accompanied by the release of volcanic ash to a height of 30 km. The menacing voice of the volcano was heard simultaneously in Australia and on the nearest islands of Southeast Asia. On August 27 at 10 o'clock in the morning, a gigantic explosion destroyed the volcanic island. At this moment, tsunami waves arose, spreading across all oceans and devastating many islands of the Malay Archipelago. In the narrowest part of the Sunda Strait, the wave height reached 30-35 m. In some places, the water penetrated deep into Indonesia and caused terrible destruction. Four villages were destroyed on Sebezi Island. The cities of Angers, Merak and Bentham were destroyed, forests and railways were washed away, and fishing boats were abandoned on land several kilometers from the ocean shore. The shores of Sumatra and Java became unrecognizable - everything was covered with mud, ash, corpses of people and animals. This disaster brought the death of 36,000 inhabitants of the archipelago. Tsunami waves spread throughout the Indian Ocean from the coast of India in the north to the Cape of Good Hope in the south. In the Atlantic Ocean they reached the Isthmus of Panama, and in the Pacific Ocean they reached Alaska and San Francisco.

Cases of tsunamis during volcanic eruptions are also known in Japan. So, on September 23 and 24, 1952, there was a strong eruption of an underwater volcano on the Meijin Reef, several hundred kilometers from Tokyo. The resulting waves reached Hotidze Island, northeast of the volcano. During this disaster, the Japanese hydrographic vessel Kaiyo-Maru-5, from which observations were carried out, perished.

The third reason for a tsunami is the fall of huge rock fragments into the sea, caused by the destruction of rocks by groundwater. The height of such waves depends on the mass of material that has fallen into the sea and the height of its fall. So, in 1930, on the island of Madeira, a block fell from a height of 200 m, which caused the appearance of a single wave 15 m high.

Causes of tsunamis

The distribution of tsunamis is usually associated with areas of strong earthquakes. It is subject to a clear geographical pattern, determined by the connection of seismic areas with areas of recent and modern mountain building processes.

It is known that most earthquakes are confined to those zones of the Earth within which the formation of mountain systems continues, especially young ones dating back to the modern geological era. The purest earthquakes occur in areas close to large mountain systems and depressions of seas and oceans.

In Fig. Figure 1 shows a diagram of folded mountain systems and areas of concentration of earthquake epicenters. This diagram clearly identifies two zones of the globe that are most prone to earthquakes. One of them occupies a latitudinal position and includes the Apennines, Alps, Carpathians, Caucasus, Kopet-Dag, Tien Shan, Pamir and Himalayas. Within this zone, a tsunami is observed on the coasts of the Mediterranean, Adriatic, Aegean, Black and Caspian seas and the northern part of the Indian Ocean. The other zone is located in the meridional direction and runs along the shores of the Pacific Ocean. The latter is, as it were, bordered by underwater mountain ranges, the peaks of which rise in the form of islands (Aleutian, Kuril, Japanese islands and others). Tsunami waves are generated here as a result of gaps between rising mountain ranges and deep-sea trenches that fall parallel to the ridges, separating island chains from the sedentary area of ​​the Pacific Ocean floor.

The direct cause of the occurrence of tsunami waves is most often changes in the topography of the ocean floor that occur during earthquakes, leading to the formation of large faults, failures, etc.

The scale of such changes can be judged from the following example. During an earthquake in the Adriatic Sea off the coast of Greece on October 26, 1873, ruptures were noted in the telegraph cable laid at the bottom of the sea at a depth of four hundred meters. After the earthquake, one of the ends of the broken cable was discovered at a depth of more than 600 m. Consequently, the earthquake caused a sharp subsidence of a section of the seabed to a depth of about 200 m. A few years later, as a result of another earthquake, the cable laid on a flat bottom again broke, and its ends found themselves at a depth that differed from the previous one by several hundred meters. Finally, another year after the new tremors, the sea depth at the rupture site increased by 400 m.

Even greater disturbances of the bottom topography occur during earthquakes in the Pacific Ocean. Thus, during an underwater earthquake in Sagami Bay (Japan), about 22.5 cubic meters were displaced when a section of the ocean floor suddenly rose. km of water, which hit the shore in the form of tsunami waves.

In Fig. Figure 2a shows the mechanism of tsunami generation as a result of an earthquake. At the moment of a sharp subsidence of a section of the ocean floor and the appearance of a depression on the seabed, the pod rushes to the center, overflows the depression and forms a huge bulge on the surface. When a section of the ocean floor rises sharply, significant masses of water are revealed. At the same time, tsunami waves arise on the surface of the ocean, quickly spreading in all directions. They usually form a series of 3–9 waves, the distance between the crests of which is 100–300 km, and the height when the waves approach the shore reaches 30 m or more.

Another reason that causes a tsunami is the eruption of volcanoes that rise above the sea surface in the form of islands or located on the ocean floor (Fig. 2b). The most striking example in this regard is the formation of a tsunami during the eruption of the Krakatoa volcano in the Sunda Strait in August 1883. The eruption was accompanied by the release of volcanic ash to a height of 30 km. The menacing voice of the volcano was heard simultaneously in Australia and on the nearest islands of Southeast Asia. On August 27 at 10 o'clock in the morning, a gigantic explosion destroyed the volcanic island. At this moment, tsunami waves arose, spreading across all oceans and devastating many islands of the Malay Archipelago. In the narrowest part of the Sunda Strait, the wave height reached 30–35 m. In some places, the waters penetrated deep into Indonesia and caused terrible destruction. Four villages were destroyed on Sebezi Island. The cities of Angers, Merak and Bentham were destroyed, forests and railways were washed away, and fishing boats were abandoned on land several kilometers from the ocean shore. The shores of Sumatra and Java became unrecognizable - everything was covered with mud, ash, corpses of people and animals. This disaster brought the death of 36,000 inhabitants of the archipelago. Tsunami waves spread throughout the Indian Ocean from the coast of India in the north to the Cape of Good Hope in the south. In the Atlantic Ocean they reached the Isthmus of Panama, and in the Pacific Ocean they reached Alaska and San Francisco.

Cases of tsunamis during volcanic eruptions are also known in Japan. So, on September 23 and 24, 1952, there was a strong eruption of an underwater volcano on the Meijin Reef, several hundred kilometers from Tokyo. The resulting waves reached Hotidze Island, northeast of the volcano. During this disaster, the Japanese hydrographic vessel Kaiyo-Maru-5, from which observations were carried out, perished.

The third reason for a tsunami is the fall of huge rock fragments into the sea, caused by the destruction of rocks by groundwater. The height of such waves depends on the mass of material that has fallen into the sea and the height of its fall. So, in 1930, on the island of Madeira, a block fell from a height of 200 m, which caused the appearance of a single wave 15 m high.

Tsunami off the coast of South America

The Pacific coast within Peru and Chile is subject to frequent earthquakes. Changes occurring in the bottom topography of the coastal part of the Pacific Ocean lead to the formation of large tsunamis. The tsunami waves reached their highest height (27 m) in the Callao area during the Lima earthquake in 1746.

If usually the decrease in sea level that precedes the onset of tsunami waves on the coast lasts from 5 to 35 minutes, then during the earthquake in Pisco (Peru) the receding sea waters returned only after three hours, and in Santa even after a day.

Often the onset and retreat of tsunami waves occur here several times in a row. Thus, in Iquique (Peru) on May 9, 1877, the first wave hit the coast half an hour after the main shock of the earthquake, and then within four hours the waves arrived five more times. During this earthquake, the epicenter of which was located 90 km from the Peruvian coast, tsunami waves reached the coasts of New Zealand and Japan.

On August 13, 1868, on the coast of Peru in Arica, 20 minutes after the earthquake began, a wave several meters high surged, but soon receded. With an interval of a quarter of an hour, it was followed by several more waves, smaller in size. After 12.5 hours, the first wave reached the Hawaiian Islands, and 19 hours later - the coast of New Zealand, where 25,000 people became victims. The average speed of tsunami waves between Arica and Valdivia at a depth of 2200 m was 145 m/sec, between Arica and Hawaii at a depth of 5200 m – 170-220 m/sec, and between Arica and the Chatham Islands at a depth of 2700 m – 160 m/sec.

The most frequent and powerful earthquakes are observed in the area of ​​the Chilean coast from Cape Concepcion to the island of Chiloe. It is known that since the disaster of 1562, the city of Concepción suffered 12 strong earthquakes, and the city of Valdivia suffered 7 earthquakes from 1575 to 1907. The January 24, 1939 earthquake killed 1,000 people and left 70,000 homeless in and around Concepcion.

Destruction caused by the 1960 tsunami waves in the city of Puerto Monte

On May 21, 1960, a new earthquake shook the Chilean coast near Cape Concepcion, and then within 10 days shook the entire southern part of the country over a distance of 1,500 km. During this time, about a thousand people died and about 350,000 people were left homeless. In the cities of Concepción, Puerto Monte, Temuco and the island of Chiloe, 65,000 buildings were completely destroyed and 80,000 were seriously damaged. The strongest shock was on May 22, when the maximum amplitude of soil vibrations in Moscow was 1500 microns. This is three times the amplitude of the vibrations caused by the 1948 Ashgabat earthquake, the epicenter of which was located six times closer to Moscow.

The catastrophic shaking on May 22 generated tsunami waves that spread across the Pacific Ocean and beyond at a speed of 650-700 km/h. On the Chilean coast, fishing villages and port facilities were destroyed; hundreds of people were carried away by the waves. On the island of Chiloe, waves destroyed four-fifths of all buildings.

Consequences of the 1960 tsunami in the Hawaiian Islands

The giant wave not only devastated the Pacific coast all the way to California, but also crossed the Pacific Ocean, hitting Hawaii and the Philippines, the coasts of Australia and New Zealand, the Kuril Islands and Kamchatka. In Hawaii, in the city of Hilo, dozens of people died during the tsunami, many residents went missing and were injured.

Consequences of the 1960 tsunami off the coast of Japan

On the Japanese islands, 36,000 houses were flooded, 900 ships and fishing boats were capsized. On the island of Okinawa, 180 people died or went missing, and in the village of Momoishi, 150 residents died. Never before has it been observed that tsunami waves, having traveled such a huge distance, retained their destructive power.

At about 6 a.m. on May 24, tsunami waves, having traveled 16,000 km, reached the Kuril Islands and the shores of Kamchatka. A five-meter-high wave rushed onto the shore. However, measures to evacuate the population were taken in a timely manner and there were no casualties. On the island of Paramushir, where the ramparts were the highest, the berths of the local fishing collective farm were slightly damaged.

Tsunami off the coast of Japan

Tsunamis are usually accompanied by the most powerful, catastrophic earthquakes that occur on the Japanese Islands on average every seven years. Another reason that causes the formation of a tsunami off the coast of Japan is volcanic eruptions. It is known, for example, that as a result of a volcanic explosion on one of the Japanese islands in 1792, rocks with a volume of about 1 cubic meter were thrown into the sea. km. A sea wave about 9 m high, formed as a result of the fall of eruption products into the sea, demolished several coastal villages and brought the death of more than 15,000 residents.

The tsunami was especially powerful during the earthquake of 1854, which destroyed the country's largest cities - Tokyo and Kyoto. First, a nine-meter-high wave came ashore. However, it soon flowed away, drying up the coastal area at a great distance. Over the next 4-5 hours, five or six more large waves hit the shore. And after 12.5 hours, tsunami waves, moving at a speed of more than 600 km/h, reached the coast of North America in the San Francisco area.

After this terrible disaster, stone walls were erected on some parts of the coast of the island of Honshu to protect the coast from destructive waves. However, despite the precautions taken, during the earthquake of June 15, 1896, the island of Honshu was again severely damaged by devastating waves. An hour after the earthquake began, six or seven large waves hit the shore at intervals of 7 to 34 minutes, the maximum height of one of which was 30 m. The waves completely washed away the city of Minco, destroyed 10,000 buildings and killed 27,000 people. And 10 years later, during the earthquake of 1906, about 30,000 people again died on the east coast of the country during the onset of a tsunami.

During the famous catastrophic earthquake of 1923, which completely destroyed the Japanese capital, tsunami waves caused devastation on the coast, although they did not reach particularly large sizes, at least in Tokyo Bay. In the southern regions of the country, the consequences of the tsunami were even more significant: several villages in this part of the coast were completely washed away, and the Yokosuka Japanese naval base, located 12 km south of Yokohama, was destroyed. The city of Kamakura, located on the shores of Sagami Bay, was also severely damaged by sea waves.

On March 3, 1933, 10 years after the 1923 earthquake, a new strong earthquake occurred in Japan, not much inferior to the previous one. Tremors affected the entire eastern part of the island of Honshu. The greatest disasters for the population during this earthquake were associated with the onset of tsunami waves, which engulfed the entire northeastern coast of Honshu 40 minutes after the earthquake began. The wave destroyed the port city of Komaishi, where 1,200 houses were destroyed. A large number of villages on the coast were demolished. According to newspaper reports, about 3,000 people were killed or missing during this disaster. In total, more than 4,500 houses were destroyed by the earthquake and washed away by the waves, and more than 6,600 houses were partially damaged. More than 50,000 people were left homeless.

Destruction in the city of Komami after the tsunami in March 1933

Tsunami off the Pacific coast of Russia

The shores of Kamchatka and the Kuril Islands are also susceptible to tsunamis. Initial information about catastrophic waves in these places dates back to 1737. A well-known domestic traveler and geographer wrote: “... the shaking began and continued in waves for about a quarter of an hour, so strong that many Kamchadal yurts collapsed and the booths fell. Meanwhile, a terrible noise and excitement arose on the sea, and suddenly water rushed onto the shore to a height of three fathoms, which, without standing still, ran into the sea and moved away from the shores at a considerable distance. Then the earth shook a second time, the water came in opposite to the previous one, but at low tide it ran so far that it was impossible to see the sea. At the same time, rocky mountains appeared on the bottom of the sea in the strait between the first and second Kuril Islands, which had never been visible before, although earthquakes and floods had occurred before.

A quarter of an hour after all this, the shocks of a terrible earthquake, incomparable in its strength, followed, and then a wave thirty fathoms high rushed onto the shore, which still quickly ran back. Soon the water entered its banks, fluctuating at long intervals, sometimes covering the shores, sometimes escaping into the sea.”

During this earthquake, massive rocks collapsed, and the incoming wave threw blocks of stone weighing several pounds onto the shore. The earthquake was accompanied by various optical phenomena in the atmosphere. In particular, Abbot Prevost, another traveler who observed this earthquake, wrote that fiery “meteors” could be seen on the sea, scattered over a wide area.

noticed all the most important features of a tsunami: an earthquake, a drop in sea level preceding the flood, and, finally, the onset of huge destructive waves.

Enormous tsunamis on the coasts of Kamchatka and the Kuril Islands took place in 1792, 1841, 1843, 1918. A series of earthquakes during the winter of 1923 caused repeated onsets of catastrophic waves. There is a well-known description of the tsunami on February 4, 1923, when “three waves rushed onto the land of the eastern coast of Kamchatka, one after another, tore off the coastal ice (fast ice a fathom thick), rushed along with it over the coastal spit, and flooded low places. The ice in a low place near Semyachik was thrown out almost 1 verst 400 fathoms from the shore; at higher elevations the ice remained at a height of three fathoms above sea level. In the sparsely populated areas of the east coast, this unprecedented phenomenon caused some damage and destruction.” The natural disaster affected a vast coastal zone with a length of 450 km.

On April 13, 1923, renewed tremors caused tsunami waves up to 11 m high, which completely destroyed the coastal buildings of fish canning factories, some of which were cut off by hummocky ice.

Strong tsunamis were reported on the coast of Kamchatka and the Kuril Islands in 1927, 1939 and 1940.

On November 5, 1952, an earthquake occurred on the eastern coast of Kamchatka and the Kuril Islands, reaching 10 points and accompanied by a tsunami of exceptional consequences, which caused severe destruction in Severo-Kurilsk. It began at 3:57 a.m. local time. At 4 hours 24 minutes, i.e. 26 minutes after the start of the earthquake, the sea level quickly dropped and in some places the water retreated from the shore by 500 m. Then strong tsunami waves hit the section of the Kamchatka coast from Sarychev Island to the Kronotsky Peninsula. Later they reached the Kuril Islands, capturing a strip of coast about 800 km long. The first wave was followed by a second, even stronger one. After her arrival on the island of Paramushir, all buildings located no higher than 10 m above sea level were destroyed.

One of the houses in the city of Severo-Kurilsk, carried by a wave to the port part of the city during the tsunami in November 1952

Tsunami in Hawaii

The coasts of the Hawaiian Islands are often subject to tsunamis. Over the past half century alone, destructive waves have struck the archipelago 17 times. The tsunami in Hawaii in April 1946 was very powerful.

From the area of ​​the earthquake's epicenter near Unimak Island (Aleutian Islands), the waves moved at a speed of 749 km/h. The distance between the crests of the waves reached approximately 150 km. The famous American oceanologist, who witnessed this natural disaster, F. Shepard, noted a gradual increase in the height of the waves that hit the shore at intervals of 20 minutes. The tide gauge readings were successively 4, 5, 2 and 6.8 m above the tide level.

The damage caused by the sudden onset of the waves was very great. Much of the city of Hilo on the island of Hawaii was destroyed. Some houses collapsed, others were carried by water over a distance of more than 30 m. The streets and embankments were cluttered with debris and blocked by barricades of mangled cars; Here and there the ugly hulks of small ships stood abandoned by the waves. Bridges and railways were destroyed. On the coastal plain, among the crushed, uprooted vegetation, numerous blocks of coral were scattered, and the corpses of people and animals could be seen. The disaster claimed 150 lives and caused a loss of $25 million. This time, waves of prices reached the shores of North and South America, and the largest wave was noted near the epicenter - in the western part of the Aleutian Islands. The Scotu Cap lighthouse, which stood at an altitude of 13.7 m above sea level, was destroyed, and the radio mast was also demolished.

A boat washed ashore during the 1946 tsunami in Hawaii

Application

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Rice. Fig. 2. Scheme of the occurrence of tsunami waves during a displacement of a section of the seabed (a) and during an underwater eruption (b)

Literature:

1. Tsunami. – Leningrad: 1964

2. Seismic sea ​​waves prices. – Leningrad: 1981

3. Poniavin prices. – Leningrad: 1965

4. The tsunami problem. Collection of articles. – M.: 1968

5. , Go tsunami on the east coast of the Pacific Ocean. – M.: 1975

6. , Go tsunami on the west coast of the Pacific Ocean. – M.: 1974

A tide gauge is a device that records sea level fluctuations.