Tsunamis have been a nightmare for island residents throughout the centuries. These multi-meter waves with enormous destructive force swept away everything in their path, leaving behind only bare earth and debris. Scientists have been keeping statistics on monstrous waves since the nineteenth century; during this period, more than a hundred tsunamis of varying power were recorded. Do you know what the biggest tsunami in the world was?
Tsunami: what is it?
It is not surprising that the term “tsunami” was first introduced by the Japanese. They suffered from giant waves more often than anyone, because the Pacific Ocean generates the largest number of destructive waves than all other seas and oceans combined. This is due to the topography of the ocean floor and the high seismicity of the region. IN Japanese The word "tsunami" consists of two hieroglyphs meaning flood and wave. Thus, the very meaning of the phenomenon is revealed - a wave in the bay, sweeping away all life on the coast.
When was the first tsunami recorded?
Of course, people have always suffered from tsunamis. Ordinary island residents came up with their own names for rogue waves and believed that the gods of the seas were punishing people by sending destructive waves at them.
The first tsunami was officially recorded and explained at the end of the sixteenth century. This was done by the monk of the Jesuit church, Jose de Acosta, he was in Peru when a wave about twenty-five meters high hit the shore. It swept away all the settlements around in a few seconds and moved ten kilometers deep into the continent.
Tsunami: causes and consequences
Tsunamis are most often caused by earthquakes and underwater volcanic eruptions. The closer the earthquake epicenter is to the coast, the stronger the rogue wave will be. The largest tsunamis in the world that have been recorded by mankind could reach speeds of up to one hundred and sixty kilometers per hour and exceed three hundred meters in height. Such waves leave no chance of survival for any living creature caught in their path.
If we consider the nature of this phenomenon, then it can be briefly explained as the simultaneous repression large quantity water masses Eruptions or earthquakes raise the ocean floor sometimes by several meters, which causes water vibrations and forms several waves diverging from the epicenter in different directions. Initially, they do not represent something terrible and deadly, but as they approach the shore, the speed and height of the wave increases, and it turns into a tsunami.
In some cases, tsunamis are formed as a result of giant landslides. During the twentieth century, about seven percent of all gigantic waves arose for this reason.
The consequences of the destruction left behind by the world's largest tsunami are terrible: thousands of casualties and hundreds of kilometers of land filled with debris and mud. In addition, there is a high probability of the spread of infectious diseases in the disaster area due to the lack of drinking water and rotting bodies of the dead, the search for which is not always possible to organize in the shortest possible time.
Tsunami: is it possible to escape?
Unfortunately, the global warning system for a possible approaching tsunami is still imperfect. IN best case scenario people learn about danger a few minutes before the wave hits, so it is necessary to know the signs of impending disaster and the rules of survival during a cataclysm.
If you are on the sea or ocean coast, then carefully monitor earthquake reports. A shaking of the earth's crust with a magnitude of about seven on the Richter scale that occurred somewhere nearby can serve as a warning of a possible tsunami strike. The approach of a rogue wave is signaled by a sudden low tide - the ocean floor is quickly exposed for several kilometers. This is a clear sign of a tsunami. Moreover, the further the water goes, the stronger and more destructive the arriving wave will be. Often like this natural disasters Animals have a presentiment: a few hours before the cataclysm, they whine, hide, and try to go deeper into the island or mainland.
To survive a tsunami, you need to leave the dangerous area as soon as possible. Do not take a lot of things with you; drinking water, food and documents will be enough. Try to get as far away from the coast as possible or go up to the roof multi-storey building. All floors after the ninth are considered safe.
If the wave does overtake you, then find an object that you can hold on to. According to statistics, most people die when the wave begins to return back to the ocean and carries away all the objects it comes across. Keep in mind that a tsunami almost never ends in one wave. Most often, the first one will be followed by a series of two or even three new ones.
So, when were the biggest tsunamis in the world? And how much destruction did they cause?
This disaster does not fit any of the previously described incidents on the sea coast. To date, the megatsunami in Lituya Bay has become the largest and most destructive in the world. Until now, eminent luminaries in the field of oceanology and seismology are arguing about the possibility of repeating such a nightmare.
Lituya Bay is located in Alaska and extends eleven kilometers inland, its maximum width does not exceed three kilometers. Two glaciers descend into the bay, which became the unwitting creators of a huge wave. The 1958 tsunami in Alaska was caused by an earthquake that occurred on July 9th. The power of the shocks exceeded eight points, which caused a huge landslide into the waters of the bay. Scientists have calculated that thirty million fell into the water in a few seconds. cubic meters ice and stones. Parallel to the landslide, the subglacial lake sank thirty meters, from which released water masses rushed into the bay.
A huge wave rushed onto the coast and circled the bay several times. The height of the tsunami wave reached five hundred meters, the raging elements completely demolished the trees on the rocks along with the soil. This wave is currently the highest in human history. An amazing fact is that only five people died as a result of the powerful tsunami. The fact is that there are no residential settlements in the bay; at the time the wave arrived in Lituya there were only three fishing boats. One of them, along with the crew, immediately sank, and the other was lifted by a wave to its maximum height and carried out into the ocean.
Indian Ocean avalanche 2004
The 2004 Thailand tsunami shocked everyone on the planet. As a result of the destructive wave, more than two hundred thousand people died. The cause of the disaster was an earthquake in the Sumatra region on December 26, 2004. The tremors lasted no more than ten minutes and exceeded nine points on the Richter scale.
A thirty-meter wave swept with great speed throughout the Indian Ocean and went around it, stopping near Peru. Almost all island countries were affected by the tsunami, including India, Indonesia, Sri Lanka and Somalia.
Having killed several hundred thousand people, the 2004 tsunami in Thailand left behind destroyed homes, hotels and several thousand local residents who died as a result of infections and poor-quality drinking water. At the moment, this tsunami is considered the largest in the twenty-first century.
Severo-Kurilsk: tsunami in the USSR
The list of “The largest tsunamis in the world” must include the wave that hit the Kuril Islands in the middle of the last century. An earthquake in the Pacific Ocean caused a twenty-meter wave. The epicenter of the earthquake with a magnitude of seven was located one hundred and thirty kilometers from the coast.
The first wave arrived in the city about an hour later, but most local residents were in shelter on higher ground away from the city. No one warned them that a tsunami was a series of waves, so all the townspeople returned to their homes after the first one. A few hours later, the second and third waves hit Severo-Kurilsk. Their height reached eighteen meters, they almost completely destroyed the city. More than two thousand people died as a result of the cataclysm.
Rogue wave in Chile
In the second half of the last century, Chileans faced a terrifying tsunami that killed more than three thousand people. The cause of the giant waves was the most powerful earthquake in the history of mankind, its magnitude exceeded nine and a half points.
A wave twenty-five meters high covered Chile fifteen minutes after the first shocks. In one day, it covered several thousand kilometers, destroying the coasts of Hawaii and Japan.
Despite the fact that humanity has been “familiar” with tsunamis for quite some time, this natural phenomenon is still one of the little studied. Scientists have not learned to predict the appearance of rogue waves, so, most likely, in the future the list of their victims will be replenished with new deaths.
Why do Nazaré have the biggest waves in the world? July 15th, 2017
There is a place in the world from which photo and video reports of giant waves are often taken. For the last few years, records in Big Wave surfing for the largest wave taken (both by hand and with the help of a jet) have been set on the same wave, Nazaré. The first such record was set by Hawaiian surfer Garrett McNamara in 2011 - the wave height was 24 meters. Then, in 2013, he broke his record by riding a wave 30 meters high.
Why is this place the biggest waves in the world?
Let's first remember the mechanism of wave formation:
So, it all starts far, far away in the ocean, where strong winds blow and storms rage. As we know from the school geography course, the wind blows from the area with high blood pressure to the area of decline. In the ocean, these areas are separated by many kilometers, so the wind blows over very large area ocean, transferring part of its energy to water due to the force of friction. Where this happens, the ocean is more like a bubbling soup - have you ever seen a storm at sea? It's about the same there, only on a larger scale. There are small and large waves, all mixed up, superimposed on each other. However, the energy of water also does not stand still, but moves in a certain direction.
Due to the fact that the ocean is very, very large, and the waves different sizes moving at different speeds, during the time until all this seething mess reaches the shore, it is “sifted”, some small waves add up to others into large ones, others, on the contrary, are mutually destroyed. As a result, what is called Groung Swell comes to the shore - smooth ridges of waves, divided into sets of three to nine with large intervals of calm between them.
However, not every swell is destined to become a surfable wave. Although, it would be more correct to say - not everywhere. In order for a wave to be caught, it must crash in a certain way. The formation of a wave for surfing depends on the structure of the bottom in coastal zone. The ocean is very deep, so the mass of water moves evenly, but as it approaches the shore, the depth begins to decrease, and the water, which moves closer to the bottom, for lack of any other way out, begins to rise to the surface, thereby raising waves. In the place where the depth, or rather shallowness, reaches a critical value, the rising wave can no longer become larger and collapses. The place where this happens is called the lineup, and that’s where the surfers sit, waiting for the right wave.
The shape of the wave directly depends on the shape of the bottom: the sharper the shallows become, the sharper the wave. Typically, the sharpest and even trumpeting waves are born where the height difference is almost instantaneous, for example, at the bottom of a huge rock or the beginning of a reef plateau.
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Where the drop is gradual and the bottom is sandy, the waves are flatter and slower. These are the waves that are best suited for learning to surf, which is why all surf schools conduct their first lessons for beginners on sandy beaches.
Photo 3. 
Of course, there are also other factors that affect the waves, for example, the same wind: it can improve or worsen the quality of waves depending on the direction. In addition, there are so-called wind swells, these are waves that do not have time to be “sifted” by distance, since the storm is raging not so far from the coast.
So, now about the highest waves. Thanks to the winds, enormous energy is accumulated, which then moves towards the coast. As it approaches the shore, the oceanic swell transforms into waves, but unlike other places on our planet, a surprise awaits it off the coast of Portugal.
Photo 4. 
The thing is that it is in the area of the city of Nazaré that the seabed is a huge canyon 5000 meters deep and 230 kilometers long. This means that the oceanic swell does not undergo changes, but reaches, as it is, all the way to the continent, falling on the coastal rocks with all its might. The height of a wave is usually measured as the distance from the crest to the base (where, incidentally, something like a trough is often sucked in, which increases the height compared to what it would be if measured by mean sea level at a given tide height).
Photo 5. 
However, unlike waves such as Mavericks or Teahupoo, on Nazar the crest, even if it collapses, never hangs over the base; moreover, it is separated from the bottom point by about 40 meters along the horizontal axis. Due to spatial distortion of perspective, when looking from the front we see a body of water 30 meters high, technically it is even larger, but this is not the height of the wave. That is, strictly speaking, Nazaré is not a wave, but a water mountain, a pure oceanic swell, powerful and unpredictable.
Photo 6. 
However, the fact that Nazaré is not exactly a wave does not make this spot any less scary or dangerous. Garrett McNamara says Nazaré is incredibly difficult to navigate. Usually three people help him in the water: one pulls him out on a jet to the line-up, accelerates him into the wave and does not swim far to make sure that everything is okay with the surfer. He is supported by a second jet, as well as a third one a little further away, whose driver is watching all three. Also, Garrett’s wife stands on the rock near the lighthouse and tells him on the radio what waves are coming and which ones can be taken. On the day he set his second record, not everything went smoothly. The first driver was knocked off the jet by a wave, so the second had to pull Garrett out of the foam, and the third hurried to help the first. Everything was done clearly and quickly, so no one was hurt.
Photo 7. 
Garrett himself says the following: “of course, all these safety nets and technical devices in big wave surfing are a kind of cheating. And in principle, you can do without them, but in this case the chances of dying are much higher. As for me personally, since I had a wife and children, I feel more responsibility for them and fear for my life, so I go to all technical lengths to make it as likely as possible to return home alive.”
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sources
: “When I read about the wave height caused by the tsunami in 1958, I couldn’t believe my eyes. I checked it once, twice. It's the same everywhere. No, they probably made a mistake with the comma, and everyone is copying each other. Or maybe in units of measurement?
Well, how else, what do you think, could there be a wave from a tsunami 524 meters high? HALF A KILOMETER!
Now we will find out what really happened there.”
Here's what an eyewitness writes:
“After the first shock, I fell out of bed and looked towards the beginning of the bay, where the noise was coming from. The mountains trembled terribly, stones and avalanches rushed down. And the glacier in the north was especially striking; it is called the Lituya glacier. It is usually not visible from where I was anchored. People shake their heads when I tell them that I saw him that night. I can't help it if they don't believe me. I know that the glacier is not visible from where I was anchored in Anchorage Bay, but I also know that I saw it that night. The glacier rose into the air and moved forward until it became visible.
He must have risen several hundred feet. I'm not saying it was just hanging in the air. But he was shaking and jumping like crazy. Large pieces of ice fell from its surface into the water. The glacier was six miles away, and I saw large chunks falling off it like a huge dump truck. This continued for some time - it is difficult to say how long - and then suddenly the glacier disappeared from view and a large wall of water rose above this place. The wave went in our direction, after which I was too busy to say what else was happening there.”
On July 9, 1958, an unusually severe disaster occurred in Lituya Bay in southeastern Alaska. In this bay, which extends more than 11 km into the land, geologist D. Miller discovered a difference in the age of trees on the hillside surrounding the bay. From tree rings, he estimated that the bay had experienced waves with maximum heights of several hundred meters at least four times in the last 100 years. Miller's conclusions were viewed with great distrust. And then on July 9, 1958, a strong earthquake occurred on the Fairweather fault north of the bay, causing the destruction of buildings, the collapse of the coast, and the formation of numerous cracks. And a huge landslide on the mountainside above the bay caused a wave of record height (524 m), which swept through the narrow, fjord-like bay at a speed of 160 km/h.
Lituya is a fjord located on the Fairweather fault in the northeastern part of the Gulf of Alaska. It is a T-shaped bay 14 kilometers long and up to three kilometers wide. The maximum depth is 220 m. The narrow entrance to the bay is only 10 m deep. Two glaciers descend into Lituya Bay, each of which is about 19 km long and up to 1.6 km wide. During the century preceding the events described, waves over 50 meters high had already been observed in Lituya several times: in 1854, 1899 and 1936.
The 1958 earthquake caused a subaerial rockfall at the mouth of the Gilbert Glacier in Lituya Bay. This landslide caused more than 30 million cubic meters of rock to fall into the bay and create a megatsunami. This disaster killed 5 people: three on Hantaak Island and two more were washed away by a wave in the bay. In Yakutat, the only permanent locality near the epicenter, infrastructure facilities were damaged: bridges, docks and oil pipelines.
After the earthquake, a study was carried out of a subglacial lake located northwest of the bend of the Lituya Glacier at the very beginning of the bay. It turned out that the lake dropped by 30 meters. This fact served as the basis for another hypothesis of the formation of a giant wave more than 500 meters high. Probably, during the glacier's descent, a large volume of water entered the bay through an ice tunnel under the glacier. However, the runoff of water from the lake could not be the main cause of the megatsunami.
A huge mass of ice, stones and earth (volume of about 300 million cubic meters) rushed down from the glacier, exposing the mountain slopes. The earthquake destroyed numerous buildings, cracks appeared in the ground, and the coastline slid. The moving mass fell on the northern part of the bay, filled it up, and then crawled onto the opposite slope of the mountain, tearing off the forest cover from it to a height of more than three hundred meters. The landslide generated a giant wave that literally swept Lituya Bay towards the ocean. The wave was so great that it swept entirely over the entire sandbank at the mouth of the bay.
Eyewitnesses to the disaster were people on board the ships that dropped anchor in the bay. The terrible shock threw them all out of their beds. Jumping to their feet, they could not believe their eyes: the sea rose. “Giant landslides, raising clouds of dust and snow in their path, began to run along the slopes of the mountains. Soon their attention was drawn completely fantastic spectacle: The mass of ice of the Lituya Glacier, located far to the north and usually hidden from view by the peak that rises at the entrance to the bay, seemed to rise above the mountains and then collapse majestically into the waters of the inner bay.
It all seemed like some kind of nightmare. Before the eyes of the shocked people, a huge wave rose up and swallowed the foot of the northern mountain. After that, she swept across the bay, tearing trees off the mountain slopes; falling like a water mountain onto the island of Cenotaph... rolled over the highest point of the island, rising 50 m above sea level. This entire mass suddenly plunged into the waters of the narrow bay, causing a huge wave, the height of which apparently reached 17-35 m. Its energy was so great that the wave rushed furiously across the bay, sweeping the slopes of the mountains. In the inner basin, the impact of the waves on the shore was probably very strong. The slopes of the northern mountains facing the bay are exposed: where used to grow up dense forest, now there were bare rocks; This pattern was observed at altitudes of up to 600 meters.
One longboat was lifted high, easily carried across the sandbar and dropped into the ocean. At that moment, when the longboat was carried over the sandbank, the fishermen on it saw below them standing trees. The wave literally threw people across the island into the open sea. During a nightmare ride on a giant wave, the boat pounded against trees and debris. The longboat sank, but the fishermen miraculously survived and were rescued two hours later. Of the other two longboats, one safely withstood the wave, but the other sank, and the people on it went missing.
Miller found that the trees growing at the upper edge of the exposed area, just below 600 m above the bay, were bent and broken, their fallen trunks pointing towards the top of the mountain, but the roots were not torn from the soil. Something pushed these trees up. The enormous force that accomplished this could not have been anything other than the top of a gigantic wave that swept over the mountain on that July evening in 1958.”
Mr. Howard J. Ulrich, in his yacht, which is called "Edri", entered the waters of Lituya Bay about eight in the evening and anchored in nine meters of water in a small cove on the southern shore. Howard says that suddenly the yacht began to rock violently. He ran out onto the deck and saw how in the northeastern part of the bay the rocks began to move due to the earthquake and a huge block of rock began to fall into the water. About two and a half minutes after the earthquake, he heard a deafening sound from the destruction of rock.
“We definitely saw that the wave came from Gilbert Bay, just before the earthquake ended. But at first it was not a wave. At first it was more like an explosion, as if the glacier was splitting into pieces. The wave grew from the surface of the water, at first it was almost invisible, who would have thought that then the water would rise to a height of half a kilometer.”
Ulrich said that he observed the entire process of development of the wave, which reached their yacht in a very a short time- something like two and a half or three minutes since she was first noticed. “Since we didn’t want to lose the anchor, we pulled out the entire anchor chain (about 72 meters) and started the engine. Halfway between the northeastern edge of Lituya Bay and Cenotaf Island, a thirty-meter-high wall of water could be seen that stretched from one shore to the other. When the wave approached the northern part of the island, it split into two parts, but after passing the southern part of the island, the wave became one again. It was smooth, only there was a small ridge on top. When this mountain of water approached our yacht, its front was quite steep and its height was from 15 to 20 meters.
Before the wave arrived at the place where our yacht was located, we did not feel any drop in the water or other changes, with the exception of a slight vibration that was transmitted through the water from the tectonic processes that began to operate during the earthquake. As soon as the wave approached us and began to lift our yacht, the anchor chain crackled violently. The yacht was carried towards the southern shore and then, on the reverse course of the wave, towards the center of the bay. The top of the wave was not very wide, from 7 to 15 meters, and the trailing front was less steep than the leading one.
As the giant wave swept past us, the surface of the water returned to its normal level, however, we could observe a lot of turbulent eddies around the yacht, as well as chaotic waves six meters high that moved from one side of the bay to the other. These waves did not create any noticeable movement of water from the mouth of the bay to its northeastern part and back.”
After 25-30 minutes the surface of the bay calmed down. Near the banks one could see many logs, branches and uprooted trees. All this rubbish slowly drifted towards the center of Lituya Bay and towards its mouth. In fact, during the entire incident, Ulrich did not lose control of the yacht. When the Edri approached the entrance to the bay at 11 pm, a normal current could be observed there, which is usually caused by the daily ebb of ocean water.
Other eyewitnesses to the disaster, the Swenson couple on a yacht called the Badger, entered Lituya Bay around nine in the evening. First, their ship approached Cenotaf Island, and then returned to Anchorage Bay on the northern shore of the bay, not far from its mouth (see map). The Svensons anchored at a depth of about seven meters and went to bed. William Swenson's sleep was interrupted by strong vibrations from the yacht's hull. He ran to the control room and began to time what was happening.
A little over a minute after William first felt the vibration, and probably just before the end of the earthquake, he looked towards the northeastern part of the bay, which was visible against the backdrop of Cenotaph Island. The traveler saw something that he initially mistook for the Lituya glacier, which rose into the air and began to move towards the observer. “It seemed like this mass was solid, but it jumped and swayed. Large pieces of ice were constantly falling into the water in front of this block.” After a short time, “the glacier disappeared from sight, and instead of it, a a big wave and went in the direction of the La Gaussy spit, just where our yacht was anchored.” In addition, Svenson noticed that the wave flooded the shore at a very noticeable height.
When the wave passed Cenotaf Island, its height was about 15 meters in the center of the bay and gradually decreased near the shores. She passed the island approximately two and a half minutes after she was first seen, and reached the yacht Badger another eleven and a half minutes (approximately). Before the wave arrived, William, like Howard Ulrich, did not notice any drop in water level or any turbulent phenomena.
The yacht "Badger", which was still at anchor, was lifted by a wave and carried towards the La Gaussie spit. The stern of the yacht was below the crest of the wave, so that the position of the vessel resembled a surfboard. Svenson looked at that moment at the place where the trees growing on the La Gaussy spit should have been visible. At that moment they were hidden by water. William noted that above the tops of the trees there was a layer of water equal to approximately two times the length of his yacht, about 25 meters.
Having passed the La Gaussi spit, the wave subsided very quickly. In the place where Swenson's yacht was moored, the water level began to drop, and the ship hit the bottom of the bay, remaining afloat not far from the shore. 3-4 minutes after the impact, Swenson saw that water continued to flow over the La Gaussie Spit, carrying logs and other debris from forest vegetation. He wasn't sure it wasn't a second wave that could have carried the yacht across the spit into the Gulf of Alaska. Therefore, the Svenson couple left their yacht, moving onto a small boat, from which they were picked up by a fishing boat a couple of hours later.
There was a third vessel in Lituya Bay at the time of the incident. It was anchored at the entrance to the bay and was sunk huge wave. None of the people on board survived; two were believed to have died.
What happened on July 9, 1958? That evening, a huge rock fell into the water from a steep cliff overlooking the northeastern shore of Gilbert Bay. The collapse area is marked in red on the map. The impact of an incredible mass of stones with very high altitude caused an unprecedented tsunami, which wiped out from the face of the earth all life that was located along the entire coast of Lituya Bay right up to the La Gaussi spit.
After the wave passed along both shores of the bay, there was not only no vegetation left, but even no soil; there was bare rock on the surface of the shore. The damage area is shown on the map yellow. The numbers along the shore of the bay indicate the height above sea level of the edge of the damaged land area and approximately correspond to the height of the wave that passed here.
What causes the appearance of most waves in the oceans and seas, about the destructive energy of waves and about the most gigantic waves and the largest tsunamis that man has ever seen.
The highest wave
Most often, waves are generated by the wind: air moves the surface layers of the water column at a certain speed. Some waves can accelerate up to 95 km/h, and the wave can be up to 300 meters long; such waves travel huge distances across the ocean, but most often they kinetic energy extinguished, consumed even before they reach land. If the wind subsides, then the waves become smaller and smoother.The formation of waves in the ocean follows certain patterns.
The height and length of the wave depend on the wind speed, the duration of its influence, and the area covered by the wind. There is a correspondence: the greatest height of a wave is one-seventh of its length. For example, a strong breeze generates waves up to 3 meters high, an extensive hurricane - on average up to 20 meters. And these are truly monstrous waves, with roaring foam caps and other special effects.
The highest normal wave of 34 meters was recorded in the Agulhas Current (South Africa) in 1933 by sailors on board the American ship Ramapo. Waves of this height are called “rogue waves”: even a large ship can easily get lost in the gaps between them and die.
In theory, the height of normal waves can reach 60 meters, but such waves have not yet been recorded in practice.
In addition to the usual wind origin, there are other mechanisms of wave formation. The cause and epicenter of the birth of a wave can be an earthquake, a volcanic eruption, a sharp change in the coastline (landslides), human activity (for example, nuclear weapons testing) and even the fall of large celestial bodies - meteorites - into the ocean.
The biggest wave
This is a tsunami - a serial wave that is caused by some powerful impulse. The peculiarity of tsunami waves is that they are quite long; the distance between the crests can reach tens of kilometers. Therefore, in the open ocean, a tsunami does not pose a particular danger, since the height of the waves is on average no more than a few centimeters, in record cases - a meter and a half, but the speed of their propagation is simply unimaginable, up to 800 km / hour. From a ship on the open sea they are not noticeable at all. A tsunami acquires destructive power as it approaches the coast: reflection from the coast leads to a compression of the wavelength, but the energy does not disappear anywhere. Accordingly, its (wave) amplitude, that is, height, increases. It is easy to conclude that such waves can reach much higher heights than wind waves. 
The worst tsunamis are caused by significant disturbances in the topography of the seabed, such as tectonic faults or shifts, due to which billions of tons of water begin to abruptly move tens of thousands of kilometers at the speed of a jet aircraft. Disasters occur when this entire mass slows down on the shore, and its colossal energy first goes to increase in height, and ultimately collapses onto the land with all its power, a wall of water.
The most tsunami-hazardous places are bays with high banks. These are real tsunami traps. And the worst thing is that a tsunami almost always comes suddenly: in appearance, the situation at sea can be indistinguishable from low tide or high tide, an ordinary storm, people do not have time or do not even think about evacuating, and suddenly they are overtaken by a giant wave. Not many places have developed a warning system.
Territories with increased seismic activity are areas of particular risk in our time. No wonder the name of this natural phenomenon is of Japanese origin.
The worst tsunami in Japan
The islands are regularly attacked by waves of different calibers, and among them there are truly gigantic ones that entail human casualties. An earthquake off the east coast of Honshu in 2011 caused a tsunami with wave heights of up to 40 meters. The earthquake is estimated to be the strongest in the recorded history of Japan. The waves struck along the entire coast, together with the earthquake they claimed the lives of more than 15 thousand people, many thousands were missing. 
Another of the highest waves in Japanese history hit the western island of Hokkaido in 1741 as a result of a volcanic eruption; its height is approximately 90 meters.
The biggest tsunami in the world
In 2004, on the islands of Sumatra and Java, a tsunami caused strong earthquake in the Indian Ocean, turned into a major disaster. According to various sources, from 200 to 300 thousand people died - a third of a million victims! To date, this particular tsunami is considered the most destructive in history. 
And the record holder for wave height is named “Lituya”. This tsunami, which swept through Lituya Bay in Alaska at a speed of 160 km/h in 1958, was triggered by a giant landslide. The wave height was estimated at 524 meters.
Meanwhile, the sea is not always dangerous. There are “friendly” seas. For example, not a single river flows into the Red Sea, but it is the cleanest in the world. .
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