The largest tsunami in the world and its height. The biggest tsunami in the world

Tsunamis are the largest and most powerful ocean waves that sweep away everything in their path with terrifying force. A feature of such a dangerous natural disaster is the size of the moving wave, its enormous speed, the gigantic distance between the crests, which reaches tens of kilometers. The tsunami poses an extreme danger to the coastal zone. Approaching the shore, the wave picks up tremendous speed, shrinks in front of an obstacle, grows significantly in size and inflicts a crushing and irreparable blow to the land zone.

What caused this huge surge of water, which leaves no chance for the existence of even the highest and fortified structures? What natural forces can create a water tornado and deprive cities and regions of the right to survive? The movement of tectonic plates and splits in the earth's crust are the worst harbingers of the collapse of a giant stream.

The largest tsunami in the world in the history of mankind

What is the largest wave in the world? Flipping through the pages of history. The date of July 9, 1958 is well remembered by the people of Alaska. It was this day that became fatal for the Lituya Fjord, which is located in the northeastern part of the Gulf of Alaska. The harbinger of the historical event was an earthquake, the magnitude of which, according to measurements, is 9.1 points. This is what caused the terrifying rockfall, which caused the collapse of rocks and a wave of unprecedented magnitude.

The whole day of July 9 was clear and sunny weather. The water level dropped by 1.5 meters, fishermen were fishing on ships (Lituya Bay has always been a favorite place for avid fishermen). Toward evening, around 22:00 local time, a landslide that rolled into the water from a height of 910 meters pulled huge stones and blocks of ice after it. The total weight of the mass was approximately 300 million cubic meters. The northern part of the bay of Lituya Bay was completely flooded with water. At the same time, a giant pile of stones was thrown to the opposite side, as a result of which the entire green massif of the Fairweather coast was destroyed.

A landslide of this magnitude provoked the appearance of a huge wave, the height of which was 524 meters! This is approximately a house of 200 floors! It was the largest and highest wave in the world. The gigantic force of the flow of ocean water literally washed away Lituya Bay. The tidal wave picked up speed (by this time it had already accelerated to 160 km / h) and rushed towards the island of Cenotaphia. Terrible landslides simultaneously descended from the mountains to the water, carrying a column of dust and stones. The wave was so large that the foot of the mountain was hidden under it.

Trees and green spaces that covered the slopes of the mountains were uprooted and sucked into the water column. The tsunami now and then rushed from side to side inside the bay, covering the points of the shallows and sweeping away the forest covers of the high northern mountains in its path. From the spit of La Gaussy, which separated the waters of the bay and Gilbert's Bay, there was not a trace left. After everything calmed down, on the shore one could see catastrophic cracks in the ground, severe destruction and blockages. The buildings erected by the fishermen were completely destroyed. The scale of the disaster could not be estimated.

This wave claimed the lives of about three hundred thousand people. Only the longboat managed to escape, which, by some incredible miracle, was thrown out of the bay and thrown across the shallows. Once on the other side of the mountain, the fishermen were left without a boat, but were rescued two hours later. The bodies of the fishermen of another longboat were carried away into the abyss of water. They were never found.

Another terrible tragedy

Terrible destruction remained after the invasion of the tsunami on December 26, 2004 for the inhabitants of the coast of the Indian Ocean. A powerful jolt in the ocean caused a disastrous wave. In the depths of the Pacific Ocean, near the island of Sumatra, a fracture of the earth's crust occurred, which provoked a displacement of the bottom over a distance of more than 1000 kilometers. The largest wave ever to hit the coast came from this fault. At first, its height was no more than 60 centimeters. But it accelerated, and now a 20-meter shaft was rushing at an insane, unprecedented speed of 800 kilometers per hour towards the islands of Sumatra and Thailand to the east of India and Sri Lanka to the west! In eight hours, the terrible power of a tsunami, unprecedented in history until now, circled the entire coast of the Indian Ocean, and in 24 hours the entire World Ocean!

The biggest destruction happened on the coast of Indonesia. The tidal wave buried cities and districts tens of kilometers inland. The islands of Thailand have become a mass grave for tens of thousands of people. The inhabitants of the coastal areas had no chance of salvation, since the water blanket held the cities under it for more than 15 minutes. Huge human casualties were the result of a natural disaster. The economic losses were also impossible to count. More than 5 million people were forced to leave their homes, more than one million needed help, two million people needed new housing. International organizations responded and helped the victims in every possible way.

Disaster in Prince William Bay

Strong, irreplaceable losses were caused by an earthquake on March 27, 1964 in the Prince William Sound (Alaska) of 9.2 on the Richter scale. They covered a huge area of ​​800,000 square kilometers. Such a powerful push from a depth of more than 20 kilometers can be compared with the simultaneous explosion of 12,000 atomic bombs! The western coast of the United States of America was significantly affected, which literally covered a huge tsunami. The wave reached the Antarctic and Japan. Villages and settlements, enterprises, the city of Valdez were wiped off the face of the earth.

The wave swept away everything that came in its way: dams, concrete blocks, houses, buildings, ships in the port. The wave height reached 67 meters! This, of course, is not the biggest wave in the world, but it brought a lot of destruction. Fortunately, a deadly stream claimed the lives of about 150 people. The number of victims could be much higher, but due to the sparsely populated areas of these places, only 150 local residents died. Given the area and the gigantic power of the stream, they had no chance of surviving.

Great East Japan Earthquake

What force of nature destroyed the coast of Japan and brought irreparable losses to its inhabitants, one can only imagine. After this catastrophe, the consequences will be felt for many years to come. At the junction of the world's two largest lithospheric plates, an earthquake with a power of 9.0 on the Richter scale, and approximately twice the force of the tremors caused by the earthquake in the Indian Ocean in 2004, occurred. The tragic event of a huge scale is also called the "Great East Japan Earthquake". Literally in 20 minutes, a terrifying wave, the height of which exceeded 40 meters, reached the shores of Japan, where there were a large number of people.

About 25 thousand people became victims of the tsunami. It was the biggest wave in the history of the inhabitants of the East. But that was only the beginning of the disaster. The scale of the tragedy grew with every hour after the attack by the most powerful stream of the Fokushima-1 nuclear power plant. The system of the power plant went out of operation due to tremors and shock waves. The failure was followed by the meltdown of the reactors at the power units. Today, a zone within a radius of tens of kilometers is a zone of exclusion and disaster. About 400 thousand buildings and structures were destroyed, bridges, railways, roads, airports, ports and shipping stations were destroyed. It will take years to rebuild the country after the terrible catastrophe brought by the highest wave.

Disaster on the coast of Papua New Guinea

Another disaster struck the coast of Papua New Guinea in July 1998. An earthquake with a magnitude of 7.1 on the measurement scale, initiated by a powerful landslide, caused a wave of more than 15 meters in height, which took the lives of more than 200 thousand people, leaving thousands more homeless on the island. Before the invasion of ocean water, there was a small bay called Varupu, the waters of which washed two islands, where the people of Varupu peacefully lived, worked and traded. Two powerful and unexpected impulses from underground happened with an interval of 30 minutes.

They set in motion a huge shaft, which caused strong waves that demolished several villages from the face of New Guinea for a length of 30 kilometers. Residents of seven other settlements needed medical assistance and were hospitalized. The sea level in the capital of New Guinea, Rabaul, has risen by 6 centimeters. A tidal wave of this magnitude has not been observed before, although in this region local residents often suffer from disasters such as tsunamis and earthquakes. A giant wave destroyed and swept under water an area of ​​more than 100 square kilometers to a depth of 4 meters.

Tsunami in the Philippines

Exactly until August 16, 1976, there was a small island of Mindanao in the oceanic depression of Cotabato. It was the most southern, picturesque and exotic place among all the islands of the Philippines. Local residents could not at all predict that a terrible earthquake with a power of 8 points on the Richter scale would destroy this amazing place, washed by the seas from all sides. A huge force formed a tsunami as a result of an earthquake.

The wave seemed to cut off the entire coastline of Mindanao. 5 thousand people who did not have time to escape died under the shelter of sea water. Approximately 2.5 thousand inhabitants of the island were not found, 9.5 thousand received various degrees of injury, more than 90 thousand lost their homes and remained on the street. It was the strongest activity in the history of the Philippine Islands. Scientists who studied the details of the disaster found that the power of such a natural phenomenon caused the movement of the water mass, which provoked a shift in the islands of Sulawesi and Borneo. It was the worst and most devastating event in the history of the island of Mindanao.

A tsunami is a huge wave that moves the entire water column. The causes of this phenomenon may be the impact of celestial bodies that have fallen into the ocean waters, landslides, human actions (for example, nuclear tests) and earthquakes. It was precisely earthquakes that became powerful impulses for the appearance of waves of destructive action, which represented the largest tsunami in the world. Where were such phenomena recorded, and what consequences were they characterized by?

Lituya Bay: the highest wave in history (1958)

The highest wave ever observed was in 1958 in Alaska. Its occurrence was associated with an earthquake, followed by a further landslide. Stone and ice masses fell from rocky cliffs into the water, which caused a huge wave of 524 meters. The tsunami completely washed away the La Gaussy spit, which served as a separator between the main water area of ​​the bay and Gilbert Bay.

Tsunami: Indian Ocean (2004)

This is the largest tsunami in the world, known for having a history of devastating waves that destroy many settlements and cause the death of many people. It swept through fourteen countries located near the Indian Ocean, became the most deadly and destructive in its strength, since it caused the death of over 230,000 people. Most of the victims of the huge waves were in India, Thailand, Indonesia and Sri Lanka.

It all started with an underwater earthquake, which was equal to 9.3 points. It provoked the emergence of incredibly high waves (their height was 30 meters), which bring destruction and death. Fifteen minutes after the tremors, coastal zones were flooded with large waves. But thanks to the accumulated knowledge about the tsunami, some people living here managed to save their lives, although most of the settlements located on the coasts were taken by surprise, which led to mass casualties of the elements.

Tohuku (2011)

The 40-meter tsunami waves that hit Japan and are the consequences of an earthquake of 9 points led to very sad results - the number of dead and missing people was approximately 25,000 people, about 125,000 buildings were destroyed. And the worst thing was that the nuclear power plant was damaged, which became a real disaster on an international scale. And today, the consequences of what happened have not yet been fully studied, but then increased radioactive radiation was detected even at a distance of 200 miles from the power plant.

Tsunami of Valdivia (Chile, 1960)

The strongest tremors (9.5 points) off the southern Chilean coast led to the awakening of the hibernation of the volcano and the emergence of huge waves of destructive force. They were 25 meters high. The impact of the tsunami was experienced not only by different regions of Valdivia, but also by Hawaii and Japan. This large tsunami swept across the Pacific Ocean, then claimed the lives of 60 people living in Hawaii. After the devastating impact on Hawaii, huge waves appeared in Japan, claiming an additional 140 lives. In total, 6,000 deaths were counted in this natural disaster.

Tsunami: Moro Bay (1976)

This tsunami was no less devastating and caused the death of 5,000 people, and approximately 2,200 more are considered missing without a trace. 90,000 people living on the island of Mindanao (Philippines) were deprived of their homes. The height of the waves of this tsunami, which was the result of shocks of 7.9 points, was approximately 4.5 meters. Over the entire existence of the Philippines, the impact of these waves has become a huge disaster in its consequences, because many settlements simply disappeared.

Tsunami: Papua New Guinea (1998)

First, there was a 7-magnitude earthquake. No one could have imagined that it could lead to a tsunami. But after powerful tremors, a landslide appeared, and as a result, waves appeared, reaching a height of 15 meters. Huge waves, rushing to the coast, caused the death of more than 2,000 local residents, 10,000 people were deprived of their homes. Many settlements were badly destroyed by huge waves, and some were simply destroyed. However, after this tsunami, scientists obtained important information regarding the nature of the occurrence of destructive waves, which then could help prevent the death of many people in such natural disasters.

Natural disasters occur on our planet quite often: fires, hurricane winds, abnormal rains, but when they talk about the occurrence of a tsunami, this danger is perceived as an apocalypse. And all because in the history of mankind there have already been tsunamis with colossal destruction and loss of life.

Before moving on to an overview of the most destructive tsunamis in the history of mankind, we will briefly talk about: why tsunamis occur, what are the signs and the rules of conduct during this natural disaster.

So, tsunamis are huge in height and wavelength, which are formed as a result of impact on the bottom of the ocean or sea. The largest and most destructive tsunamis are formed when there is a strong impact on the bottom, for example, during an earthquake whose epicenter is close enough to the coast with a magnitude on the Richter scale of 6.5 points.

How to recognize the appearance of a tsunami?

• - an earthquake with a magnitude of more than 6.5 in the waters of the sea or ocean. On land, tremors can be felt weakly. The stronger the shocks are felt, the closer the epicenter and the greater the likelihood of a tsunami. Indeed, in 80% of cases, a tsunami is formed due to underwater earthquakes;
• - an unexpected tide. When, for no apparent reason, the coastline goes far into the sea and the coastal bottom is exposed. The farther the water has moved from the shore, the stronger the wave will be;
• - The unusual behavior of animals. For example, they begin to hide in dwellings, worry, whine, gather in groups, which was not typical for them before.

How to survive during a tsunami?

Rules of conduct during a tsunami.

If you are in a seismically dangerous region and on the coast of the Pacific or Indian Ocean, then at the first tremors and the departure of water from the coastline, you must immediately go as far as possible inland, at least 3-4 km from the coastline. It is advisable to climb some hill with a height of more than 30 meters: a hill or some large and strong concrete structure, for example, a 9-storey building.

Since 2004, several countries have developed a tsunami warning system. As soon as an earthquake occurs near the coast, special services, based on the strength of the earthquake and the distance from the coast, calculate how strong and destructive the tsunami has. Immediately, a decision is made to evacuate the population from dangerous areas.

When receiving a message about an impending tsunami, you should take documents, drinking water, money with you and go to a safe area. You should not take extra things, as they can fetter or cause inconvenience.

It is important to know that tsunamis are most often not one wave, but a series of waves. Therefore, after the first or second wave collapses, in no case should you leave the flooded area. After all, the most destructive may not be the first and second wave. According to statistics, people quite often die or go missing when they try to leave the flooded area, and suddenly the water begins to rapidly decrease back into the ocean, taking cars, people, trees with it. It is important to remember that the period between tsunami waves can range from 2 minutes to several hours.

If you suddenly realize that water is and is and you cannot hide on your hill, then you should find a suitable object in the water that could serve as a means of navigation. You also need to figure out where you will swim before jumping into the water. You should also get rid of shoes and wet clothes so that nothing interferes and does not hinder movement.

Saving another person is worth it when you are sure that you can handle it. A drowning person should be prompted if you see an object nearby that can serve as a swimming aid, if you decide to help yourself, then you should swim up behind and grab your hair and pull your head above the water so that the drowning person can breathe and the panic goes away. If you see a person who is carried away by a stream of water, then you should first throw a rope, a stick, any other object with which you can catch and pull the person out of the stream. There is no point in throwing yourself over the course, since most likely you will also be carried away into the ocean.

You should leave your shelter only when the local authorities somehow notify about it, for example, a helicopter will fly with a horn or by radio. Or when you see the rescuers, ask them if there will be more waves and only after that you should leave your shelter.

The world's largest tsunami and its consequences

Now let's give a few statistics, which tsunamis were the strongest in the history of mankind.

In Chile in 1960 there was a strong earthquake with a magnitude of 9.5 points, the wave height reached 25 meters, 1263 people died. This natural disaster entered the history of catastrophes as the "Great Chilean Earthquake".

In December 2004, one of the strongest earthquakes with a magnitude of 9 points occurred in the Indian Ocean. This powerful earthquake caused waves of monstrous force. The wave height reached almost 51 meters off the island of Sumatra in Indonesia.

In terms of the number of victims, this was the largest and most destructive tsunami. As a result of this natural disaster, mainly Asian countries were affected: Indonesia, especially the island of Sumatra, Sri Lanka, the coast of Thailand, southern India, the island of Somalia and other countries. The total death toll is enormous - 227,898 people. This is only official data, some scientists believe that there were more than 300,000 victims, since a large number of people were missing, they could have been carried into the ocean. The main reason for such a large number of victims was that people in these countries were not warned about the threat. In the same way, people died due to the fact that after the first wave they returned to their homes, believing that everything was behind them. However, soon the next wave arrived from the ocean and covered the coast.

In Japan in 2014, the "Great East Japan Earthquake" occurred, with a magnitude of 9 points, the wave height reached 40.5 meters. It was the largest tsunami in terms of destruction, as 62 cities and villages were affected. The height and strength of the destruction of these waves surpassed all scientific calculations of scientists.

The next tsunami, which occurred in the Philippines, also claimed a large number of lives - 4,456 people died, the magnitude of the earthquake was 8.1, and the wave height was 8.5 meters.

Then comes the 1998 tsunami in Papua New Guinea, killing 2,183 people. The earthquake was 7 points, and the waves reached 15 meters.

The tsunami with the largest waves occurred in Alaska in 1958 during a landslide. A huge amount of terrestrial rocks and ice fell into the waters of Lutuya Bay from a height of more than 1000 meters, this caused a tsunami, the height of which near the coast reached more than 500 meters! It is the Alaskan wave that is called the world's largest tsunami.

Watch a movie about the ten most destructive tsunamis in human history below.

Inscription (in hieroglyphs) carved in stone

December 26, 2004 in the Indian Ocean near about. Sumatra was hit by a strong earthquake and the subsequent tsunami, which led to unprecedented casualties and destruction in history (more than 260 thousand victims). The catastrophe was global in nature: not only areas in the immediate vicinity of the epicenter were affected, but also sections of the coast thousands of kilometers away from it. Waves were recorded everywhere - in the Atlantic, the Pacific Ocean, on the coast of Antarctica, etc. In fact, we were witnesses of a catastrophe on a planetary scale, standing on a par with the fall of the Tunguska meteorite, the explosion of the Krakatoa volcano, etc. Search teams discovered coastal areas in the south of Sumatra, where the height of the flood reached 35 m! It's taller than a 12-story building.

What is a tsunami? The word is of Japanese origin and means big wave. Japan is the country most frequently attacked by these monstrous waves. There, on the shore, you can find ancient stone pillars with inscriptions warning of the danger of a tsunami.

Given the specific nature of the damaging factors of a tsunami, this natural disaster can be attributed to one of the most inevitable natural phenomena. The monstrous volumes of sea water rolling onto the coast, in most cases, cannot be stopped by artificial protective structures. The height of the flood sometimes exceeds 10 m, and in some areas of the coast (in the area of ​​the shallow shelf, in the mouths of rivers, etc.), the wave takes the form of a boron (a seething water shaft, a water wall). Moving at great speed deep into the coast, this wave of water accumulates colossal dynamic energy, destroying ships and buildings on its way (Fig. 1).

Rice. 1. Wave in the form of a bore

Such waves arise in most cases as a result of a strong underwater earthquake. However, cases are known when a tsunami occurred in the case of explosions of underwater volcanoes, rocks falling into the water, underwater landslides, etc. In fig. Figure 2 shows various mechanisms of tsunami wave excitation: seismic, volcanic, landslide, meteorological. What unites all these mechanisms? The general effect is the rapid displacement of significant volumes of water: as a result of a seismo-tectonic fault of the bottom, a volcanic explosion on the ocean floor, the introduction of huge masses of a landslide moving along a sloping bottom into the water, or a sharp change in atmospheric pressure (the water surface experiences a sudden effect of the atmosphere, for example, during a thunderstorm).

Rice. 2. Various mechanisms of excitation of tsunami waves

Tsunami waves are so-called long waves - the distance from crest to crest (wavelength) is much greater than the depth of the ocean. From the point of view of hydrodynamics, tsunami waves are similar in nature to tides. Tsunamis and tides are different from ordinary wind (storm) waves and sea swell. Wind waves affect only the upper layer of the ocean; at a depth of 50 m, waves are no longer felt. And the tides and currents caused by the tsunami wave involve the movement of the entire water mass - from the bottom to the surface (Fig. 3).

Rice. 3. Trajectories of water particles of wind waves and tsunami waves

The speed of tsunami wave propagation is determined by the depth of the ocean H and free fall acceleration g: . (Unfortunately, the derivation of the formula for the speed of long gravitational surface waves is difficult for the school. However, using dimensional analysis, it can be derived up to a constant. If the liquid is infinitely deep, the only quantity that has a linear size is the wavelength. Another physical parameter is gravitational constant g, which provides the restoring force during vibrations of water particles. There are no other physical parameters that affect the speed. Then the velocity dimension can only be formed from the combination . Accordingly, or, in the simple case, (when . For shallow liquid ~ H and the formula is more complicated, dimensional analysis is indispensable. It is worth noting that the velocity of long waves is written almost in the same way as the velocity of liquid outflow from a vessel with a hole in the bottom, the filling height of which is equal to H: .)

When approaching the coast, the depth of the ocean decreases, and the wave slows down. The kinetic energy of liquid particles, distributed vertically, is concentrated in an ever smaller column of liquid. That is why the height of the wave increases as it approaches the shore. The height of a tsunami wave in the open ocean is usually small, no more than 1 m (Fig. 4). However, approaching the shore, the crest of the wave becomes higher and steeper, and finally, in shallow water, it collapses and a forest is formed.

Rice. 4. Scheme of the formation and propagation of a tsunami wave

In the deep ocean H\u003d 4000 m) the wave propagation speed is huge: (720 km / h). That's roughly the speed of a jet plane! When the wave breaks into shallow water H= 10 m), the speed is reduced to "automobile", (36 km/h), but the height of the crest can reach 10 meters or more!

Specialists of the tsunami warning service, having received information about a strong underwater earthquake (the position of the epicenter), calculate the time for the wave to approach the shore using the formula , where x and y are the coordinates of the point on the depth map. On fig. Figure 5 shows such a map of the Pacific Ocean, on which the isolines of the travel times of the Shikotan tsunami wave on October 4, 1994 are plotted. It can be seen that the wave reached the coast of the southernmost part of South America in about a day. Based on such calculations, a decision is made: whether it is necessary to evacuate the population immediately or whether there is time to prepare for it.

Like all types of waves (sound, light, radio waves), tsunamis experience attenuation, reflection, refraction and scattering.

Rice. Fig. 5. Calculation of travel times for the Shikotan tsunami on October 4, 1994. Isolines are plotted in hours. The epicenter is marked with a black circle.

Wave damping. In an open ocean with a flat bottom, the wave energy decays as 1/ r, where r is the distance from the source. Accordingly, the amplitude (height) of the wave decreases as . This attenuation is sometimes referred to as geometric divergence. In addition to the effect of geometric divergence, the wave is attenuated due to scattering by inhomogeneities in the bottom topography.

Reflection. The reflection of a wave from a steep bank leads to a doubling of its amplitude on the bank. If the amplitude of the incoming wave is 5 m, then the height will be 10 m when reflected on the coast line. The reflection coefficient from the coast-wall is close to 1. However, if the coast is sloping, when the wave enters shallow water, the crest collapses. It turns out that when the wave height a is comparable to the water depth H, the difference between the velocities of the “bottom” of the wave and its crest becomes significant. The top of the wave, the speed of which is equal to , catches up with the bottom, moving at a speed , which causes the collapse (Fig. 6). Naturally, after this the reflection coefficient becomes substantially less than unity. Wave energy in this case is spent on friction in the turbulent flow.

Rice. 6. Collapse of a tsunami wave when entering shallow water

Refraction. The refractive index for tsunami waves is the speed . The shallower the water depth, the slower the spread. Accordingly, the "beam" of a tsunami always bends towards shallow water. Features of the bottom topography can create additional effects. On the shelf, the average depth of which is 200 m, so-called "captured" waves can form. If the tsunami source is located within the extended shelf, part of the tsunami rays cannot leave the shallow part and go into the deep ocean due to the effect of total internal reflection (Fig. 7).

Rice. 7. Scheme of the formation of trapped and emitted waves

The waves captured by the shelf, propagating along the coast, practically do not attenuate. This feature of the wave field is called a waveguide. The waveguide phenomenon can occur not only near the coast. Academician M.M. Lavrentiev showed that tsunami-waveguides can also form above underwater ridges. In this case, the effect of total internal reflection appears to the right and left of the ridge axis.

Tsunami hazardous areas. Most often, tsunamis occur in areas of high seismicity. These primarily include the so-called subduction zones or, in other words, the junction zones of the oceanic and continental tectonic plates. The map of the Pacific Ocean (Fig. 8) clearly shows that the strongest earthquakes and tsunamis occurred in the 20th century. along the perimeter of the ocean in the vicinity of the continental slope in the ocean. According to the theory of plate tectonics, oceanic plates are constantly “moving apart” in both directions from the mid-ocean ridge towards the mainland (Fig. 9) at a rate of several centimeters per year. The source of such plate movement is the constant outflow of magma from the depths of the Earth in the area of ​​mid-ocean ridges. Colliding with the continental plate, the relatively thin oceanic plate plunges deep into the Earth. The constant "pressure" of the oceanic plate gradually leads to the accumulation of elastic compression energy in the earth's crust, which is eventually released in the form of a powerful earthquake - a tectonic fault appears. Part of the bottom goes up and part goes down. This displacement can reach several meters or more, while the horizontal dimensions of the source sometimes exceed 1000 km. It is this sudden displacement of the bottom, formed when a tectonic fault occurs in the earth's crust, that forms giant tsunami waves in the ocean.

Rice. 8. Map of the Pacific Ocean. The tsunami sources in the 20th century are shown.

Rice. 9. Tectonic scheme of earthquake occurrence in the subduction zone

The main subduction zones are located along the perimeter of the Pacific and Atlantic oceans. The most tectonically active areas are adjacent to the coasts of Japan, Chile, the Kuril Islands, Kamchatka, the Aleutian Islands, Alaska and Indonesia. Here, the rate of movement of the oceanic plate reaches 6–8 cm/year. As a result, powerful underwater earthquakes and tsunamis occur here from time to time. The most terrible tsunami in our country hit the coast of the Kuril Islands and Kamchatka on November 4, 1952 as a result of an underwater earthquake. Then the village of Severokurilsk was completely washed away and about 3,000 people died. The last tsunami occurred off the coast of about. Shikotan October 2, 1994 No one died, but on about. Kunashir were flooded and washed away houses in the lowlands, several fishing boats washed ashore.

Estimation of tsunami energy. Let's try to estimate the energy carried by tsunami waves. During an earthquake, an initial displacement of the ocean surface is formed above the source. We can assume that the entire tsunami energy at this moment is represented as the potential energy of the rise of the liquid column above the source. Let us denote the average height of the displacement of the ocean surface as a. Then the potential energy is expressed by the formula , where is the density of water, and S is the area of ​​the hearth. Let's take the size of the source 100 . 1000 km . km - this is typical for powerful earthquakes. For a source with an average surface displacement height a = 0.5 m, approximately 10 21 erg (10 14 J) is obtained, which is equal to the energy of the bomb detonated in Hiroshima. However, according to the calculations of the Canadian scientist T. Murthy, the energy of the tsunami on December 26, 2004 turned out to be 390 times greater! This means that the average height of the initial level disturbance was about 10 m.

As can be seen from fig. 8, in the twentieth century. in the area south of Sumatra, not a single powerful earthquake capable of causing a tsunami was observed. Scientists suggest that such a long "silence" of the subduction zone led to the accumulation of huge compression energy, which was released on December 26, 2004.

On fig. 10 shows a map of the Indian Ocean, where the epicenter of the main seismic shock and subsequent aftershocks (earthquakes of lesser power) are plotted. The length of the fault zone exceeded 1000 km. The presumed source of the tsunami is marked in gray. The map shows the isolines of the tsunami travel times. It is clearly seen that for most of the affected coasts, the "time margin" was sufficient to organize the evacuation of the population from the coastal zone. However, there was no tsunami warning service in the area. People didn't know what a tsunami was. Moreover, when the water began to recede, many on the shore went deeper into the low tide zone to collect shells and corals. A few minutes later the wave came. In some areas about. Sumatra shaft swept into the depths of 10 km! The consequences were terrible. In the coastal zone and on small islands, entire villages were washed away. People, falling into a raging stream, died from a collision with floating objects. This stream was a "porridge" of the wreckage of houses and trees, parts of cars and people. There was little chance of survival in it.

Rice. 10. Map of the Indian Ocean. The epicenter of the main earthquake and subsequent aftershocks is plotted. The region of the supposed source of the tsunami is circled in black. The isolines of the tsunami wave are plotted

On fig. 11 shows how high the vegetation was washed away on a small island. The next two photographs (Fig. 12) are space images of the Andaman Islands before and after the tsunami. It is clearly seen that as a result of the earthquake, part of the land sank into the sea.

Rice. 11. The result of the impact of the tsunami wave on December 26, 2004 on the island. Sumatra. You can clearly see how high the level of the ocean has risen.

Rice. 12. Consequences of the December 26, 2004 earthquake and tsunami in the Indian Ocean (space images before and after the tsunami)

How to escape from a tsunami? The tsunami has the maximum amplitude directly near the seismic source. Therefore, here the first sign of a tsunami is the earthquake itself. Residents of the Kuril Islands and Kamchatka are well aware that after tremors it is necessary to quickly leave the coastal zone. Sometimes, before the arrival of a wave, the sea quickly recedes from the coast, exposing the bottom for hundreds of meters. Many witnesses note the onset of "silence" before the arrival of the main wave. This unusual ebb is a sign of an approaching tsunami wave. And the onset of “silence” is due to the fact that a fast ebb current “carries away” wind waves from the shore - the noise of the surf subsides. The appearance of a foaming shaft on the horizon means the approach of a tsunami. You need to get upstairs immediately! Many people escaped by climbing strong trees, hiding on the roof of a strong building. It is known that many animals and people from nomadic tribes somehow felt the catastrophe and went to the mountains.

Evgeniy Aleksandrovich Kulikov graduated from Moscow Institute of Physics and Technology in 1973. In 1973–1986. worked at the Institute of Marine Geology and Geophysics, Far Eastern Branch of the Russian Academy of Sciences, in 1979 he defended his dissertation for the title of Candidate of Physical and Mathematical Sciences. Now he is the head of the tsunami laboratory at the Institute of Oceanology. P.P. Shirshov of the Russian Academy of Sciences, author of about a hundred scientific publications on tsunamis, wave processes in the marginal regions of the ocean, etc., including two monographs, one of the largest amateur experts on the ideas of Juche (the teachings of Kim Il Sung), for which was awarded a badge with the image of the Great Leader, an adherent of theoretical cooking (see the site http://www.proza.ru/author.html?kulikove) and the founder of a new sport of banana throwing (http://kulikov.korolev.net.ru). She has three now grown children.

Monster waves, white waves, killer waves, rogue waves - all this is the name of one terrible phenomenon that can take a ship by surprise. TravelAsk will talk about the biggest waves in the world.

What is the peculiarity of giant waves

Killer waves are fundamentally different from tsunamis (and we will also tell you about the biggest tsunamis). The latter come into action as a result of natural geographical disasters: earthquakes or landslides. A giant wave appears suddenly, and nothing portends it.

And what's more, they long time were considered fiction. Mathematicians even tried to calculate their height and peculiarity of dynamics. However, the cause of the giant waves has not been established.

First recorded giant wave

Such an anomaly was first recorded on January 1, 1995 on the Dropner oil platform in the North Sea off the coast of Norway. The height of the wave reached 25.6 meters, and they called it the Dropner wave. In the future, space satellites were used to conduct research. And within three weeks, another 25 giant waves were recorded. In theory, such waves can reach 60 meters.

The highest killer waves in history

The most gigantic wave in history was noted on the territory of the Agulhas Current (South Africa) in 1933 by sailors from the American ship Ramapo. Its height was 34 meters.

In the mid-Atlantic, the Italian transatlantic liner Michelangelo was hit by a killer wave in April 1966. As a result, two people were washed out to sea, and 50 were injured. The ship itself was also damaged.

In September 1995, the Queen Elizabeth 2 liner recorded a 29-meter rogue wave in the North Atlantic. However, the British transatlantic ship turned out to be not one of the timid: the ship tried to "saddle" the giant, which appeared right on the course.

In 1980, a meeting with a white wave ended in tragedy for the English cargo ship Derbyshire. The wave broke through the main cargo hatch and flooded the hold. 44 people died. It happened off the coast of Japan, the ship sank.

On February 15, 1982, in the North Atlantic, a huge wave covered a drilling platform owned by Mobil Oil. She broke the windows and flooded the control room. As a result, the platform capsized, killing 84 crew members. This is a sad record for today in the number of deaths from a killer wave.

In 2000, the British cruise ship Oriana was hit by a 21-meter wave in the North Atlantic. Before that, a distress signal was received on the liner from a yacht that was damaged due to the same wave.

In 2001, all in the same North Atlantic, a giant wave hit the luxury tourist liner Bremen. As a result, a window on the bridge was broken, because of this, the ship was drifting for two hours.

Dangers on the lakes

Rogue waves can also appear on lakes. So, on one of the Great Lakes, the Upper, the Three Sisters meet - these are three giant waves that follow each other. The ancient Indian tribes who lived in this territory also knew about them. True, according to legend, the waves appeared due to the movement of a giant sturgeon that lived at the bottom. The sturgeon has never been discovered, but the Three Sisters appear here and now. In 1975, the Edmund Fitzgerald cargo ship, which was 222 meters long, sank precisely because of a collision with these waves.