In the depths of the Earth's interior, certain processes are constantly taking place, and they equally affect both land areas and part of the crust under the bottom of the world's oceans.


Tectonic plates shift, layers collide, causing vibrations, and underground volcanoes erupt. Underwater earthquakes do not go unnoticed: these phenomena cause huge waves, often reaching the continents. These waves are called tsunami- translated from Japanese language term means "a giant wave that came into the harbor" .

The column of water that moves as a result of vibrations of the seabed is practically harmless far from land. But the closer to the shore the wave moves, the more power it gains, and the higher its crest becomes. The lower layers of water, passing along the bottom and encountering resistance, further increase the energy of the upper layers.

A tsunami can move at speeds of up to 800 kilometers per hour, and the wave height is often ten, twenty, or even thirty meters. This mass of water, falling onto the shore, destroys everything in its path, throwing debris many kilometers inland. The danger of a tsunami also lies in the fact that it is not a single wave: there can be up to a dozen waves in total, with the third and fourth being the most dangerous.

But a tsunami may not look like waves, but like a series of rapidly changing strong ebbs and flows, which carries no less danger.

Causes of tsunamis

Up to 7% of all tsunamis are caused by landslides, when huge blocks of earth rocks or ice falls into the water. In 1958, in Alaska, such a landslide led to the formation of a wave 524 meters high.


Underwater landslides in river deltas are also dangerous. Landslide tsunamis regularly occur in Indonesia and result in twenty-meter tsunamis. Another 5% of cases occur due to underwater volcanic eruptions. Human activity can also lead to a tsunami, for example, testing of deep weapons.

Up to 85% of all cases where tsunamis were recorded are associated with. At the same time, the ocean bottom shifts vertically, and the surface of the water begins to move, trying to return to its previous level. Tsunamis are mainly generated by earthquakes with sources located close to the surface.

During earthquakes, surface waves called local tsunamis emanate from the site of vertical shear. The height of such waves can reach thirty meters. At the same time, underwater waves diverge from the epicenter, passing through the entire thickness of the water, from the bottom to the surface, and moving at a speed of 600 to 800 kilometers per hour.

As the depth of the ocean decreases, the energy of such a wave is concentrated closer to the surface, resulting in such distant tsunamis hitting the shore. A remote tsunami can cross from end to end of the Pacific Ocean in a day, reaching from the coast of Chile to the islands of Japan.

Moreover, it is almost impossible to notice such a wave in the ocean - with a length of 200-300 kilometers, it has a height of up to a meter. This is the main insidiousness of the tsunami.

How to understand that a tsunami is approaching?

In any case, an earthquake can become a harbinger of a tsunami for coastal regions. Sometimes, before the arrival of a large wave off the coast, there is a sharp ebb of tide and exposure of a wide strip of the seabed, which can last from several minutes to half an hour.


Animals show increased anxiety before the arrival of a tsunami, trying to climb to elevated places.

What to do if you find yourself in a tsunami zone?

The most dangerous areas from this point of view are the coast, harbors, bays with a height of no more than 15-30 meters above sea level. If you are in such an area and expect that a tsunami will soon come ashore, keep documents, a minimum supply of food and things collected in case of emergency evacuation.

It’s worth looking at the hills in advance, high buildings, where one could climb to avoid danger. It is worth remembering that a distance of two to three kilometers from the shore can be considered relatively safe. Since it is impossible to predict either the number or frequency of waves, it is better not to approach the coast for two to three hours after the last wave arrived.

Knowing these simple rules could have saved many lives during the 2004 Southeast Asian tsunami. Then dozens of people wandered around the shallows after a sudden low tide, collecting shells and fish. Hundreds more returned to shore after the first wave of the tsunami to check if their homes were safe, unaware that the first wave would be followed by others.

The worst tsunamis of our century

In 2004, trouble came to Southeast Asia. At the end of December, an earthquake with a magnitude of more than 9 occurred in the Indian Ocean. The tsunami passed through Indonesia, Sri Lanka, Thailand and the coast of Africa. More than 235 thousand people died. The situation has been aggravated by the fact that at this time of year thousands of tourists come to Asian countries to meet New Year on the warm sea. The tsunami destroyed a lot of resort regions in several countries.


In March 2011, a powerful earthquake occurred in Japan, causing a forty-meter tsunami. The disaster brought the death of nearly 16 thousand people, and more than seven thousand are still considered missing. A tsunami and earthquake destroyed the Fukushima-1 nuclear power plant, and people are still eliminating the consequences of this accident.

Many people have heard the word “tsunami” more than once, but not everyone knows what it really is. From Japanese it is literally translated as “harbour” (“tsu”) and “wave” (“nami”).

This manifestation of nature makes us once again think about her majesty and freeze in front of her incommensurable power.

Tsunami danger

The danger posed by a tsunami has several factors. For starters, this is a remarkable force of destruction that moves with the water. Man, compared to this power, is just a small straw. Secondly, predicting the time of occurrence of a tsunami and its specific location is very difficult, almost impossible. Thirdly, it is impossible to see the thickness of the water moving towards the shore either from the air or from a ship. The fact is that the wave that brings a tsunami to the shore is visually no different from any other. Its peculiarity lies below, in the water itself. It takes with it not only the upper surface of the liquid, but “scoops” it up from the very bottom.

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After all, distances of several thousand kilometers can lie from the place of “birth” of a tsunami wave to its deadly arrival. That is, the wave travels this entire distance in the water column, and, as you know, under such circumstances it is not very loyal to all objects that get in its way. Due to the lack of resistance along the way, it retains and accumulates a colossal supply of energy, which then falls on land and people.

However, what creates these deadly waves? Some people are mistaken in claiming that tsunamis originate in seismically hazardous areas. This reason is far from the only one. For example, volcanic eruptions on the ocean floor and landslides (they can have starting points below sea level) also lead to the release of huge amounts of energy that must be released somewhere. First, the lower layers of water shift, causing very strong vibrations, which force the entire thickness of the water to move and move towards the shore, carrying colossal reserves of energy.

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Some people put tsunamis next to the phenomena of ebb and flow, but this is fundamentally wrong. It is known that ebb and flow occur due to the gravitational forces of the Earth and the Moon’s satellite, their interaction with the Sun - read more in our article: what causes ebbs and flows. As for the tsunami, the gravitational forces of celestial bodies do not affect it at all.

Interestingly, the speed of the wave in some cases reached a huge value of 950 kilometers per hour!

Calculating the speed of a specific water flow is quite simple. It is necessary to take the acceleration of gravity (about 9.8 m/s), multiply it by the depth from which the wave begins its path (in meters), and take the square root of this value.

As it approaches the shore, the tsunami begins to reduce its speed as its depth decreases. If previously the entire mass of water moved in its “native” aquatic environment, here it has to come into contact with the shore, which reduces the speed of the wave. When the depth is no longer sufficient to contain all the moving water, the wave begins to rise to the surface.(Japanese) - giant waves with destructive power. They are caused by underwater, or underwater landslides. These phenomena are usually accompanied by a strong underground shock transmitted by water to the surface, which can be unsafe for ships in the area. The subsequent waves caused by the impact are almost impossible to notice in the open ocean, since they are very flat here. But they spread at enormous speed (up to 1000 km/h). Approaching the shore, they become steeper and higher, acquiring terrible destructive power. As a result, gigantic water shafts with a height of 10 to 50 meters or more can collapse on the coast.

The largest tsunamis in the last 10 years have caused widespread human disaster, destruction and economic costs. . The more tragic of them wiped out residential areas. According to scientific data, a greater number of destructive waves occurring is due to tremors in the depths Pacific Ocean.

The article provides a list of the most global disasters of 2005-2015 (added to 2018) in chronological order.

1.

An earthquake with an amplitude of 6.8 on the islands of Izu and Miyake in 2005 caused a tsunami. The waves reached up to 5 meters in height and could have caused casualties, because the water moved at very high speed and had already rolled from one island to another in half an hour. Since the population was evacuated from dangerous points in a timely manner, the tragedy was avoided. No human casualties were recorded. This is one of the largest tsunamis to hit the Japanese islands in the last ten years.

2. Tsunami on the island of Java in 2006

The 10 largest disasters in several years include the tsunami that hit the island of Java in 2006. Deadly sea waves claimed the lives of more than 800 people. The height of the waves reached 7 meters and demolished most of the island's buildings. About 10 thousand people were injured. Thousands of people were left homeless. Foreign tourists were also among the dead. The cause of the disaster was a powerful earthquake in the depths of the Indian Ocean, which reached 7.7 on the Richter scale.

3.

An earthquake with an amplitude of 8 points struck the Solomon Islands and New Guinea in 2007. It caused a 10-meter tsunami wave that destroyed more than 10 villages. About 50 people died and thousands were left homeless. More than 30 thousand residents suffered damage. Many residents refused to return after the disaster, and for a long time stayed in camps that were built on top of the hills of the island. This is one of the largest tsunamis in history last years caused by an earthquake in the depths of the Pacific Ocean .

4.

Cyclone, called Nargis, hit Myanmar in 2008. The destructive force, which claimed the lives of 90 thousand residents of the state, is classified as a meteotsunami. More than a million people were injured and suffered damage due to the natural disaster. The meteotsunami turned out to be so destructive that it left no trace of some populated areas. The city of Yangon suffered the greatest damage. Due to the scale of the disaster that the cyclone caused, it is included in the top 10 largest natural disasters in recent times.

5.

The Samoan Islands fell victim to a tsunami in 2009 due to an earthquake in the Pacific Ocean exceeding 9 points. A fifteen-meter wave reached residential areas of Samoa, and within a radius of several kilometers destroyed all buildings. Several hundred people died. A powerful wave reached all the way to the Kuril Islands and was a quarter of a meter high. Global human losses were avoided thanks to the timely evacuation of the population. The impressive height of the waves and the powerful earthquake put the tsunami in the top 10 worst tsunamis in recent years.

6.

The coast of Chile was hit by a major earthquake in 2010, which caused a raging tsunami. The waves swept across 11 cities and reached five meters in height. The disaster estimates hundreds of deaths. Residents of Easter was evacuated in a timely manner. The earthquake itself, which caused the shaking of the Pacific waves, caused a greater number of casualties. As a result, the Chilean city of Concepcion shifted several meters from its previous position. The tsunami that hit the coast is considered one of the largest in ten years.

7.

The largest disaster that has befallen the earth in recent years occurred on the Japanese Islands in the city of Tohuku in 2011. The islands were hit by an earthquake with an amplitude of 9.1 points, which caused a global tsunami. Destructive waves reaching 40 meters covered the islands and spread over several kilometers in the area. More than 20 thousand people died in the natural disaster, and more than 5 thousand received various injuries. Many people are considered missing. Natural disasters caused an accident at a nuclear power plant, which led to an emergency situation in the country due to the resulting radiation. The waves reached the Kuril Islands and reached 2 meters in height. This is one of the strongest and most tragic tsunamis in the last 10 years in terms of its scale.

8.

A typhoon that hit the Philippine Islands in 2013 caused a raging tsunami. Sea waves reached a height of 6 meters near the coast. Evacuation has begun in dangerous areas. But the typhoon itself managed to claim the lives of more than 10 thousand people. The water made its way about 600 kilometers wide, sweeping away entire villages from the face of the island. The city of Tacloban ceased to exist. A timely evacuation of people in areas where a disaster was expected was carried out. Numerous losses associated with natural disasters, give the right to consider the tsunami in part of the Philippine archipelago one of the most global in ten years.

9.

The tsunami in the Chilean city of Iqueque, which occurred in 2014, was associated with a large earthquake measuring 8.2 on the Richter scale. Chile is located in an area with high seismic activity, so earthquakes and tsunamis are common events in this area. This time, a natural disaster led to the destruction of the city prison, as a result of which about 300 prisoners left its walls. Despite the fact that the waves reached 2 meters in height in some places, numerous losses were avoided. A timely evacuation of residents of the coasts of Chile and Peru was announced. Only a few people died. The tsunami is the most significant that occurred last year on the Chilean coast.

10.

In September 2015, an earthquake occurred in Chile, reaching 7 points. In this regard, Japan was hit by a tsunami, the waves of which exceeded 4 meters in height. The largest Chilean city, Coquimbo, was seriously damaged. About ten people died. The rest of the city's population was promptly evacuated. In some areas the wave height reached a meter and caused some destruction. The latest disaster in September completes the list of the 10 most global tsunamis of the last decade.

+ Tsunami in Indonesia near the island of Sulawesi in 2018

On September 28, 2018, in the Indonesian province of Central Sulawesi, near the island of the same name, a powerful earthquake with a magnitude of 7.4 occurred, which subsequently caused a tsunami. As a result of the disaster, more than 2,000 people died and about 90 thousand lost their homes.

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Tsunami (Japanese for “large harbor wave”) are marine gravity waves that result from the upward or downward displacement of extended sections of the seabed during underwater and coastal earthquakes. The propagation speed is from 50 to 1000 km/h. The height in the area of ​​occurrence is from 0.1 to 5 m, near the coast - from 10 to 50 m and higher.

Tsunamis cause devastating destruction on land. For many centuries, this unbridled natural phenomenon has kept people in fear, and therefore there are many misconceptions about these rogue waves.

A tsunami is a huge wave. Firstly, this is not one wave, but a whole series of waves coming ashore one after another. Their number ranges from 3 to 25.
Secondly, not every wave is a tsunami. Storm, ship and other waves are the movement of only the upper layer of water, while a tsunami is the movement of its entire thickness.

A tsunami is caused by an underwater earthquake. A seaquake causes a tsunami in most cases, but not always. Other causes may include typhoons, tropical cyclones, underwater landslides or volcanic eruptions. The largest waves are formed when a cosmic body - a comet or meteorite - enters the ocean. The consequences of such a catastrophe can only be imagined and are unlikely to be survived. At one time, even dinosaurs died from this.

Any sea earthquake threatens to cause a tsunami. For a tsunami to occur, the displacement of the bottom surface must be lightning fast and large enough to set the water column in motion. In addition, the source of the earthquake should not be too deep (up to 20 km). Therefore, not every change in the topography of the ocean floor generates a giant wave.

Tsunamis occur only in warm seas. This myth arose because most tsunamis occur in the Pacific Ocean, where seaquakes and underwater volcanic eruptions occur, and Japan and the Pacific Islands most often suffer from their effects. When it comes to landslide tsunamis caused by rock collapse on sea cliffs, they can happen anywhere! In 1964, due to an earthquake and subsequent ice collapse, a tsunami occurred in Alaska. It amazed with the height of its waves: 60 meters!

Before a tsunami begins, the water recedes from the shore. Canadian mathematician Walter Craig came to the conclusion that only half of the time the water actually moves away from the shore, foreshadowing a tsunami. This depends, first of all, on the wavelength, and not on the power of the tsunami, as previously thought.

A tsunami is always a tall wave! Revealing the secret of the occurrence of this natural phenomenon, it must be said that in fact the height of the tsunami depends on its energy. And the further from the epicenter, the higher the wave level. While in the open sea a tsunami does not exceed a meter, but moves at breakneck speed, in the shallows the wave slows down and gains height. By the way, there may be no wave at all, and the tsunami will pass through as a series of rapid ebbs and flows. So a tsunami is not just a wall of water hitting the shore, but the movement of the entire water layer, multiplying its destructive power when it meets land.

The tsunami comes unnoticed, which is why it is so difficult to escape from it. Indeed, the distinctive feature of a tsunami is its sudden appearance. But all the same, it makes itself felt, and if you are careful, you can notice the approaching disaster. If the cause of a giant wave is an earthquake, everyone on the shore feels the tremors, even if they are not strong. When water moves strongly, small particles glow marine organisms. If a tsunami occurs in cold seas, ice breaks and underwater currents arise. In addition, water can move away from the shore, drying up the bottom, or, conversely, slowly rise.

The first wave of a tsunami is always the largest. This is wrong. Since tsunami waves move one after another, and the distance between them can reach several tens or even hundreds of kilometers, they reach the coast after a certain time (from a couple of minutes to a whole hour). After the first wave, the shore becomes wet, thereby reducing resistance for subsequent waves. They are always more destructive.

Animals always sense the approach of a tsunami. Indeed, during the huge tsunami on the coast of Sri Lanka in 2004, not a single animal was found dead. Eyewitnesses claim that even fish tried to hide from the approaching elements by hiding in corals. But the truth is that not all animals are predictors of disaster. For some, the threat will become obvious, while others will not react to it. Therefore, it would be wrong to rely on the intuition of our smaller brothers in everything.

The only thing that can save you from a tsunami is a quick escape deep into the coast. Indeed, this is true, but it is important not only to run away from the coastline, but also to fulfill the simplest requirements: firstly, do not move along river beds, where a tsunami wave will quickly overtake you. Secondly, when going into the mountains, move up the slope, rising to a height of at least 30 meters from the coastline. Thirdly, if you are on a ship, boat or any other vessel, it is pointless to seek salvation on the shore, and it is better to go further out to sea. Finally, remember that the tsunami is coming back. Only after a certain time has passed can you return to shore.