Describe this phenomenon as a tsunami. How a tsunami is formed. Tsunami caused by volcanoes

A tsunami is one of the most dangerous disasters that can occur on our planet. Only earthquakes and eruptions of underground magma can compare with them in their consequences.

It is quite natural that, like most other terrible events, a tsunami arouses considerable interest among humanity. Some are looking for information about what destruction giant waves have caused throughout the history of mankind or, others are interested in how a tsunami occurs, and still others want to know what parameters it is characterized by. And they do it right - forewarned is forearmed.

The process of tsunami formation

An earthquake occurring underwater or near the coast (less commonly, an earthquake) leads to vibrations of the ocean surface. Masses of water moving vertically cause the appearance of not too high, but rather long waves that can travel several thousand kilometers at a speed of up to 1000 km/h and reach the shore. Approaching the coastal zone, it slows down and decreases in length, while simultaneously increasing in height. The narrower the bay or bay that the waves reach, the higher they will be - sometimes their size exceeds 50 m. However, even a ten-meter tsunami is already enough to create significant destruction.

Main signs of a tsunami

You can find out about the occurrence of a tsunami thanks to warning systems, which are certainly available in tsunami-prone areas. Although there are signs of a tsunami, visible even to the naked eye to ordinary people who find themselves in the coastal zone shortly before the occurrence of this natural phenomenon. Among them are:

– rapid retreat of the sea from the coast;

– tremors indicating an earthquake occurring nearby, which, as is known, can lead to a tsunami;

– numerous debris of various origins floating on the surface of the water, and sharp surges of water at the edge of the ice or reefs.

Factors accompanying a tsunami

As a rule, the occurrence of a tsunami is accompanied by destructive consequences that are caused by factors such as the action of first a sea wave and then an air wave, as well as hydrodynamic pressure.

Secondary factors in the occurrence of the phenomenon are:

– flooded area;

– destroyed buildings;

– dead people and animals;

– contaminated water and soil (which can, in turn, lead to the emergence and spread of infections);

– destroyed forests and agricultural lands.

Tsunamis and their characteristics

The main characteristics for this natural phenomenon are:

– the height of the tsunami wave, that is, the vertical distance from its crest to its base. When it occurs, this value is 0.5–5 m, but near the shore it can reach 70 m;

– wavelength equal to the distance between the crests of adjacent waves. Usually this value ranges from one to several tens (less often, up to two to three hundred) kilometers and depends on the depth of the ocean;

– the speed at which the tsunami moves. Typically between 50 and 100 km/h for the main part of the route, although 1,000 km/h can sometimes be reached near the epicenter.

Tsunami intensity scale

Based on their intensity, tsunamis are divided into 6 main types. This classification of tsunamis allows us to characterize the consequences of their action:

– 1 point means that the element was registered only by instruments. Most people are not even aware of such tsunamis;

– a tsunami with an intensity of 2 points can slightly flood the coast, but, again, only specialists can distinguish it from ordinary ocean waves;

– 3 points indicates that the tsunami has become noticeable. Small boats may become beached;

– 4 points. The destruction is quite serious, buildings are damaged, ships are washed ashore and even thrown onto it;

– a magnitude 5 tsunami destroys buildings and can lead to death;

– the element, the intensity of which reaches six points, devastates the coast almost completely.

Probably everyone knows what a tsunami is these days. But not everyone knows about the causes of tsunamis, how you can notice approaching waves in advance and, most importantly, how to escape from them.

It is not uncommon to hear in the news a report about a tsunami and its consequences and victims. In one year, on average, there are 5 tsunamis of varying strengths, fortunately, these are mostly waves of low strength and, accordingly, low height. Powerful tsunamis (wave heights above 20 meters) occur on average once every 10-20 years, of medium strength, with wave heights from 5 to 20 meters - once every 3-5 years.

The main difference between a tsunami and ordinary waves is not the height, as many believe. Waves driven by the wind can also reach considerable sizes; a tsunami is not just a wave, it is the movement of the entire thickness of water. This determines the ability of a tsunami to reach land and flood coastal areas.

Another important distinguishing feature of a tsunami is that it does not consist of one wave, their number can range from 2 to 25, depending on the duration and intensity of the underwater earthquake. The distance between ridges often exceeds several hundred kilometers, i.e. The time interval between tsunami waves can be 1 hour or even more. Therefore, after a tsunami, you should never go ashore without waiting 2-3 hours.

Causes of tsunami

Most tsunamis are caused by underwater earthquakes, but other factors can also cause destructive waves:

1. Per share underwater earthquakes accounts for 85% of cases. During tremors, vertical movement of the bottom occurs, i.e. separate plot earth's crust can fall or rise relative to its level. At this time, water will strive to fill the resulting void, which will cause oscillatory movement of water and, as a result, the formation of waves. For a tsunami to form, the earthquake source must be relatively close to the bottom, so not all underwater seismic activity poses a great threat.

2. About 7% of tsunamis are caused by large-scale landslides. To be fair, it should be noted that the cause of landslides themselves in most cases is earthquakes. Landslides are divided into underwater and terrestrial, but they have the same principle - a huge mass of mud, ice, rocks, sharply sinking to the bottom, generates the same oscillatory movements of water. Underwater landslides often occur in the Indonesian region because the ocean floor there is very unstable. The largest tsunami caused by a land-based landslide was recorded in 1958 off the coast of Alaska; a huge mass of ice, breaking away from a glacier, fell into the water from a height of more than a kilometer and generated a wave 520 meters high!

3. Eruptions underwater volcanoes also often generate large waves. “Volcanic” tsunamis are dangerous because the waves are formed not only from the explosion, but also from the filling of the caldera with water. In other words, such tsunamis are more dangerous and longer lasting.

4. A tsunami can also be caused by a large object falling into the water. cosmic body, for example, a meteorite or comet. This happens, of course, extremely rarely, but the force of such waves will be enough to wipe out literally everything from the face of the Earth.

5. It can also form waves up to 20 meters high, but it will not be quite a tsunami, since only the surface part of the water will move. Such waves can cause quite significant damage.

During a tsunami, waves travel in a circle from the epicenter. The speed of waves in the open ocean can reach almost 1000 km/h, and their height in deep water often does not reach even a meter. Destructive huge waves begin to form when the water overtakes shallow water, the speed of water movement is greatly reduced, but the power increases significantly.

The main danger of a tsunami is very fast movement. Even if the underwater earthquake was immediately detected by special sensors and the authorities immediately announced the evacuation of coastal areas, not all people will have time to leave the coast - everything happens very quickly.

Signs of an imminent tsunami.

The rapid and sudden retreat of water from the coastline indicates the imminent approach of a tsunami, and the further the water recedes, the higher the waves will be. Only in very rare cases can this sign be neglected.

To escape from a tsunami, you should move as far away from the coast as possible. If there is no more time, then you need to try to climb as high as possible, onto hills, mountains or any other heights.

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A giant wave never appears just like that, the main thing is to have an idea of the dangerous regions and take precautions.

Causes of tsunamis

Tsunamis are caused by earthquakes, but not every earthquake will necessarily cause a tsunami.
Experts associate the Great Lisbon earthquake of 1755, which killed more than 50 thousand people off the coast of Spain and Portugal, with the tidal effects of the Moon and Sun on the earth's crust.
The 1998 tsunami, which destroyed everything in its path in the Papua New Guinea region, was caused by a landslide, the collapse of which, in turn, was provoked by a moderately powerful earthquake ().
So-called “meteorological” tsunamis appear against the background of typhoons: after a sharp turn of the typhoon to the side, the resulting wave can continue to move independently (for example, the 2011 tsunami in the area of the English city of Plymouth was caused by a storm in the Bay of Biscay).
“Exclusive” tsunamis occur as a result of underwater volcanic eruptions (for example, the tsunami of 1883, formed after the eruption of the Krakatoa volcano), meteorite falls (a National Geographic channel documentary mentions traces of a tsunami that remained in the state of Texas after a meteorite fell 65 million years ago ) and man-made disasters.

Philippines, Malay Archipelago

The Philippine islands are located in a seismically active zone. And where there are earthquakes, there are tsunamis, and it is impossible to predict which of the seven thousand islands will be hit this year. In 2013, these were the islands of Samar and Leyte, where waves up to 5 meters high claimed the lives of 10 thousand people and left about half a million local residents homeless. And the worst tsunami in the history of the Philippines occurred in 1976, when, as a result of an earthquake in the Cotabato Trench, a wave hit the island of Mindanao, killing 8 thousand people.

Gizo, Solomon Islands

The Solomon Islands, tiny pieces of land scattered across the Pacific Ocean, are defenseless against the destructive power of a tsunami, which was confirmed in 2007, when the cities of Gizo and Noro completely disappeared under water.

Honshu, Japan

In 2012, a 7.9 magnitude earthquake occurred near Philippine city Guan, a tsunami a little more than half a meter high “rolled back” to Japan, covering the capital region and Fukushima Prefecture. There is no comparison with the truly horrific destruction of 2011, when a magnitude 9 earthquake, dubbed the Great East Japan Earthquake, was followed by a tsunami up to 40 meters high, flooding an area of 561 square kilometers.

The greatest impact occurred in Miyagi Prefecture (327 km 2), and the highest wave height (40.5 meters) was recorded in Iwate Prefecture. Considering that the word “tsunami” itself came to us from the Japanese language (literally translated as “big wave in the harbor”), the Japanese, who had been familiar with this natural phenomenon for centuries, were not prepared for a tragedy of such magnitude.

Maldives

Despite its seemingly vulnerable position, the Maldives archipelago experienced its only major tsunami in 2004. There is a threat, but coral reefs serve as a reliable natural defense system for the island from surprises from the ocean.

More dangerous than a wave

The mechanism of tsunami formation differs from the mechanism of formation of an ordinary wave, and this is where its danger lies.
In a strong wind, the height of an ordinary wave can significantly exceed the height of an average 5-meter tsunami and even reach 20 meters, but the length of such a wave is no more than a couple of hundred meters.
During underwater earthquakes, the entire thickness of water comes into motion, so the length of the tsunami wave is measured in thousands of kilometers, and the speed can reach 1000 km/h.
An ordinary wave is driven by the wind, but a tsunami carries a huge charge of energy, moving towards land with all its might.
While a storm wave in narrow spaces loses its pressure, the power of a tsunami, on the contrary, is concentrated there, and it destroys everything in its path.

Phuket, Thailand

An underground earthquake with tremors of 9.0 magnitude brought death and destruction to the Thai island of Phuket in 2004. Despite the fact that the epicenter of the earthquake was in the Indian Ocean near the island of Sumatra, the subsequent tsunami reached the shores of Indonesia, Thailand, Sri Lanka, India and even South Africa. Three waves hit each other in turn, leaving numerous buildings, local residents and tourists underwater.

Hilo, Hawaii

In the Hawaiian Islands, more precisely, in the city, the International Tsunami Warning Service is located. The location was not chosen by chance: Hawaii is regularly covered by waves about 2 meters high, with the main impact falling on the city of Hilo, which is located on the shore of the bay of the same name. Despite the small wave height, Hawaiian tsunamis are among the most dangerous, since if a person gets caught in a tsunami wave on one of the local sandy bays with a very short beach, he will simply be smashed against the rocks. But if you are careful, there is nothing to worry about: all such areas are marked with warning signs, and sirens are installed along the shores of the islands.

Alaska, USA

Alaska suffered two powerful tsunamis in a row: in 1957 and 1958, giant waves covered Andreanova Island and Lituya Bay, respectively. In 1958, the wave was so powerful that it actually destroyed an entire strip of land - the La Gaussy spit.

Kamchatka, Russia

Tsunami waves come to Kamchatka from an earthquake-prone zone, which is located in the Kuril-Kamchatka and Aleutian trenches. The three most powerful attacks of ocean waters occurred in the last century: in 1923, the wave height reached 30 meters, in 1952 - 15 meters, in 1960 - 7 meters.

Iquique, Chile

On May 22, 1960, a magnitude 9.5 earthquake occurred near the Chilean city of Valdivia, the strongest earthquake in modern history humanity. And of course, there was a tsunami: in addition to the damage caused directly to the Chilean coast by a 20-meter wave, it reached Alaska, the shores of the Kuril Islands, Japan and overwhelmed the Hawaiian city of Hilo, carrying about 6 thousand people into the ocean. In 2014, residents of the port town of Iquique were evacuated, where a two-meter tsunami wave arrived after an 8.2 magnitude earthquake.

Acapulco, Mexico

Despite the fact that the 7.2 magnitude earthquake that occurred in April 2014 did not cause a tsunami, the Mexican resorts of Acapulco and Zihuatanejo are under constant threat of the sudden arrival of a rogue wave. So if the ocean suddenly retreats from the shore, it’s time to run.

Tsunami statistics

What to do if “covered”

If you are in the coastal area and feel an earthquake, leave the shore within 15-20 minutes.
If you did not feel the earthquake, you can guess that a tsunami is approaching by the strong ebb of the tide.
While the tsunami is approaching, do not waste time under any circumstances: do not go down to look at the exposed seabed, do not film the wave. Immediately look for a hill at least 40 meters in height, preferably warning others about the danger, without causing panic.
If you are in a building (such as a hotel) and there is no time to find higher ground, go to the upper floors of the building and barricade the windows and doors. Borrow without dangerous place: There should be no potentially dangerous objects near you (such as cabinets that could fall or mirrors that could break).
If you are unable to find a hill, try to take cover behind any significant obstacle for the water (for example, a strong, tall tree or large stone) and cling to it so that you do not get carried away by the flow of water into the ocean.
If a tsunami finds you on the open sea (for example, you were on a ship and you were thrown into the water by a wave), do not panic, take a breath, group yourself and cover your head with your hands. Having surfaced, get rid of wet clothes as quickly as possible and find any object that you can cling to (in 2004 in Thailand, one of the survivors managed to swim out by clinging to the tail of a crocodile, and another to a python).
After the storm has passed, do not return to the sea for 2-3 hours: a tsunami is a series of waves.

Photo: thinkstockphotos.com, flickr.com

Over the past 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.

Did not 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 tsunamis - causes and consequences this phenomenon modern society should know. Famous 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 movement.

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.
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.
Speed is the linear speed of movement of a specific element, for example, a ridge. 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 and 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 several times it turns out 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 a tsunami and their possible consequences. I would like this knowledge to really help in 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.

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 characters 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 displacement of a large amount of 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, in the disaster area there is a high probability of the spread of infectious diseases due to a 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 the best case, people become aware of the danger a few minutes before the wave hits, so it is necessary to know the signs of impending trouble 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 move as far away from the coast as possible or climb onto the roof of a multi-story 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 estimate that thirty million cubic meters of ice and stones fell into the water in a few seconds. 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 enormous 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.