In Japanese, the character "tsu" is a bay or bay, "nami" is a wave. Together, both hieroglyphs are translated as "a wave that floods the bay." The catastrophic consequences of two tsunamis that hit the shores of the Indian Ocean in 2004 and Japan in 2011 clearly demonstrated that reliable protection against this formidable natural phenomenon has not been found to this day ...

Tsunami - what is it?

Contrary to popular belief, a tsunami is not at all one gigantic wave that unexpectedly swoops ashore and sweeps away everything in its path. In fact, a tsunami is a series of marine gravitational waves of very large length, resulting from the shift of extended sections of the bottom during strong underwater earthquakes or, occasionally, for other reasons - as a result of volcanic eruptions, giant landslides, falling asteroids, underwater nuclear explosions.

How does a tsunami occur?

The most common cause of a tsunami is the vertical movement of the bottom during underwater earthquakes. When part of the bottom sinks and part rises, the mass of water comes into oscillatory motion. In this case, the surface of the water tends to return to its original level - the average level of the ocean - and thus generates a series of waves.

The speed of tsunami propagation at a sea depth of 4.5 km exceeds 800 km/h. But the wave height in the open sea is usually small - less than a meter, and the distance between the crests is several hundred kilometers, so it is not so easy to notice a tsunami from the deck of a ship or from an airplane. On the ocean expanses for any vessel, a meeting with a tsunami is not dangerous. But when the waves enter shallow water, their speed and length decrease, and the height increases sharply. Near the coast, the wave height often exceeds 10 m, and in exceptional cases it reaches 30-40 m. Then the impact of the elements inflicts colossal damage on coastal cities.

However, often huge destruction is caused by tsunami waves and relatively small heights. At first glance, this seems strange: why do the outwardly more formidable waves that arise during a storm not lead to similar casualties? The fact is that the kinetic energy of a tsunami is much higher than that of wind waves: in the first case, the entire water column moves, and in the second, only the surface layer. As a result, the pressure of water splashing onto land during a tsunami is many times higher than during a storm.

Another factor should not be discounted. During a storm, the excitement builds up gradually, and people usually have time to move to a safe distance before danger begins to threaten them. A tsunami always comes suddenly.

Today, about 1000 cases of tsunamis are known, of which more than a hundred had catastrophic consequences. Geographically, the periphery of the Pacific Ocean is considered the most dangerous region - approximately 80% of all tsunamis occur there.

It is impossible to completely protect the coast from a tsunami, although in some countries, especially in Japan, they tried to build breakwaters and breakwaters in order to weaken the force of the waves. However, there are cases when these structures played a negative role: tsunamis destroyed them, and pieces of concrete picked up by water flows only exacerbated the damage on the coast. The hopes for protection from the trees planted along the shore did not come true either. To extinguish the energy of the waves, you need too much forest plantation, and there is simply no such area in most coastal cities. Well, a narrow strip of trees along the embankment cannot provide any resistance to the tsunami.

One of the important measures to protect the population of dangerous regions from destructive waves was the international tsunami warning system created in the Pacific region. 25 states, including Russia, take part in its work. Scientists from different countries, based on a comprehensive analysis of the zones of strong earthquakes, are trying to determine whether they were the cause of the formation of a tsunami in the past, and what is the likelihood of a tsunami in the future. The main research center of the system, located in the Hawaiian Islands in Honolulu, continuously monitors the seismic situation and the level of the Pacific Ocean surface.

In our country, the Far East tsunami warning service consists of three regional services: Kamchatka, Sakhalin regions and Primorsky Krai. In the Kamchatka region, in particular, there is a tsunami station of the territorial administration for hydrometeorology and environmental monitoring and a seismic station of the Institute of Physics of the Earth of the Russian Academy of Sciences.

The most destructive tsunamis of the past

It is possible that the most catastrophic tsunami in the history of mankind occurred in ancient times, although it has come down to us in the form of myths and legends. Approximately in 1450 BC. from the giant wave that the Santorini volcano provoked, an entire civilization perished. 120 km from the volcano is Crete, which at that time was one of the most powerful powers in the Mediterranean. But the tsunami at one point inflicted colossal damage on the island of Crete, from which the previously prosperous state could not recover. It collapsed, and many of its cities were abandoned for two and a half thousand years.

Giant tsunami waves followed the devastating Lisbon earthquake on November 1, 1755. The source of the earthquake, obviously, was at the bottom of the ocean. The total number of victims from the waves and the earthquake is estimated at approximately 60,000 people.

In 1883, as a result of a series of eruptions of the Krakatau volcano in Indonesia, a powerful tsunami was formed, from which the islands of Java and Sumatra suffered the most. Waves up to 40 m high wiped out about 300 villages, more than 36 thousand people died. Near the city of Teluk Betung, a Dutch warship, the gunboat Berouw, was abandoned 3 km inland and ended up on a mountainside at a height of 9 m above sea level. Seismic waves passed two or three times around the Earth, and from the ash thrown into the atmosphere in Europe, unusual red dawns were observed for a long time.

The most destructive tsunami of the 20th century hit the coast of Chile on May 22, 1960. The tsunami and its parent earthquake, which measured 9.5 on the Richter scale, killed 2,000 people, injured 3,000, left 2 million homeless, and caused $550 million in damage. The same tsunami killed 61 people in Hawaii, 20 in the Philippines, 3 in Okinawa and more than 100 in Japan. The wave height on Pitcairn Island reached 13 m, in Hawaii - 12 m.

The most unusual tsunami

In 1958, a tsunami was formed in Lituya Bay in Alaska, caused by a giant landslide - about 81 million tons of ice and solid rock collapsed into the sea due to an earthquake. The waves reached an incredible height of 350-500 m - these are the largest waves of all recorded in history! The tsunami washed away all vegetation from the slopes of the mountains. Fortunately, the shores of the bay were uninhabited, and human casualties were minimal - only two fishermen died.

Tsunami in the Russian Far East

On April 4, 1923, a strong earthquake occurred in the Kamchatka Bay. After 15-20 minutes, a wave approached the top of the bay. On the coast, two fish factories were completely destroyed, the village of Ust-Kamchatsk was badly damaged. The ice on the Kamchatka River was broken for 7 km. At 50 km southwest of the village, the maximum height of water rise on the coast was observed - up to 30 m.

On the territory of Russia, the most catastrophic tsunami occurred on the night of November 4-5, 1952 on the Far Eastern island of Paramushir, where the city of Severo-Kurilsk is located. At about 4 am, the strongest tremors began. Half an hour later, the earthquake stopped, and the people who left their homes returned to their homes. Only a few remained outside and noticed the approaching wave. They managed to hide in the hills, but when they went down to inspect the destruction and look for relatives, a second, even more powerful water shaft, about 15 m high, collapsed on the city. did not notice, but early in the morning they were surprised at the large amount of garbage and various objects floating around. When the morning mist cleared, they saw that there was no city on the shore.

On the same day, the tsunami also reached the shores of Kamchatka and caused serious damage to a number of villages. In total, more than 2,000 people died, but in the USSR until the early 1990s, almost no one knew about the events of that tragic night.

The tsunami that occurred on May 23, 1960 off the coast of Chile reached the shores of the Kuriles and Kamchatka about a day later. The highest level of water rise was 6-7 m, and on the territory of the Khalaktyrsky beach near Petropavlovsk-Kamchatsky - 15 m. In the bays of Vilyuchinskaya and Russkaya, houses were destroyed and outbuildings were washed into the sea.

Tsunami propagation in the Pacific Ocean (the most destructive waves are black and red) after the 1960 earthquake. Map prepared by the US National Oceanic and Atmospheric Administration (NOAA)

Indian Ocean disaster (2004)

After an earthquake measuring about 9 on the Richter scale with an epicenter in the northern part of the island of Sumatra in Indonesia, which occurred on the night of December 26, 2004, a powerful tsunami covered the Indian Ocean. More than 1,000 kilometers of fault line, created by the movement of large layers of the earth's crust on the ocean floor, generated a huge release of energy. The waves hit Indonesia, Sri Lanka, India, Malaysia, Thailand, Bangladesh, Myanmar, the Maldives and Seychelles and reached Somalia, located at a distance of 5,000 km from the epicenter of the earthquake. More than 300 thousand people became victims of the tsunami, including foreign tourists from many countries who were vacationing in Indonesia and Thailand in those days. Most of the dead were in Indonesia (more than 180 thousand) and Sri Lanka (about 39 thousand).

Such numerous victims are largely due to the lack of elementary knowledge of the impending danger among the local population. So, when the sea receded from the shore, many locals and tourists remained on the shore - out of curiosity or out of a desire to collect the fish left in the puddles. In addition, after the first wave, many returned to their homes to assess the damage or try to find loved ones, not knowing that others would follow the first wave.

Tsunami in Japan (2011)

The cause of the tsunami was a strong earthquake with a magnitude of 9.0-9.1 points, which occurred on March 11, 2011 at 14:46 local time (8:46 Moscow time). The center of the earthquake was at a depth of 32 km, at a point with coordinates 38.322° N. 142.369° E east of the island of Honshu, 130 km east of the city of Sendai and 373 km northeast of Tokyo. In Japan, the tsunami caused widespread destruction along the east coast. The maximum wave height was observed in Miyagi Prefecture - 10 m. The tsunami flooded the Sendai airport, washed away one passenger train, and caused serious damage to the Fukushima I nuclear power plant. In Sendai alone, the tsunami caused the death of about 300 people. The total damage caused to the country's economy amounts to hundreds of billions of dollars.

According to official figures, the death toll from the earthquake and tsunami was 15,892 people, with another 2,576 people missing. 6152 people were seriously injured. According to unofficial data, the number of victims is much higher. According to media reports, 9,500 people are missing in the city of Minamisanriku alone.

Numerous photographic documents paint a truly apocalyptic picture of the destruction:

The tsunami was observed along the entire Pacific coast - from Alaska to Chile, but outside of Japan it looked much weaker. The tourist infrastructure of Hawaii suffered the most - in Honolulu alone, about 200 private yachts and boats were wrecked and sunk. On the island of Guam, waves tore off the moorings of two nuclear submarines of the US Navy. In the city of Crescent City in California, more than 30 boats and boats were damaged, one person died.

According to the Russian Emergencies Ministry, due to the threat of a tsunami in the Kuril Islands, 11,000 residents were evacuated from coastal areas. The highest wave height - about 3 m - was recorded near the village of Malokurilskoe.

Tsunami in cinema

In the popular genre of disaster films, tsunamis have attracted the attention of screenwriters and directors more than once. An example is the feature film "Tsunami" (South Korea, 2009), frames from which are given below.

What is a tsunami? How is this natural phenomenon formed? What are the reasons for these giant waves? By what signs can you determine that a tsunami is coming. Let's take a closer look at where they most often occur and give statistics on the most devastating natural disasters that have occurred due to tsunamis over the past 50-60 years.

What is a tsunami?

The definition of the word tsunami when translated from Japanese means "wave in the harbor." i.e. tsunamis are large and long waves that are formed due to the impact on the entire water column. This is the difference between a simple large storm wave and a tsunami, since in a large storm wave the impact occurs only on the surface, while in a tsunami the entire water column is affected. Of course, the larger the body of water, the larger and longer the tsunami. Tsunamis can only form in the seas and oceans. When a tsunami most often forms not one wave, but several, which are thrown onto land with a time interval between them from 2 minutes to 2 hours.

Causes of a tsunami

Scientists share several reasons for the occurrence of such a natural phenomenon as a tsunami. The tsunami mainly comes from the impact on the bottom of the sea or ocean, as a result of which a force is released, which forms the movement of the entire water column - that is, a tsunami.

These are such natural phenomena as:

• - underwater earthquakes;
• - landslides;
• - underwater volcanic eruptions;
• - the fall of a large celestial body into the ocean or sea (for example, the Tunguska meteorite);
• - military tests (for example, tests of nuclear weapons in the ocean or sea).

How does a tsunami occur due to earthquakes?

Large waves are formed due to the displacement of lithospheric plates, while the plates themselves begin to move as a result of underwater earthquakes. The mechanism of wave formation as a result of the displacement of lithospheric plates is as follows: one plate begins to crawl under another, as a result, a sufficiently large force is formed that lifts up the second lithospheric plate, this effect also sets the water column in motion.

Other Causes of a Tsunami

Landslides are another cause of such waves as tsunamis. For example, off the coast of Alaska, a large landslide occurred and a large amount of ice and earth rocks collapsed into the water from a great height, resulting in a large and long wave. Off the coast of Alaska, the wave reached a height of more than 500 meters.

Tsunamis as a result of the eruption of an underwater volcano are formed in much the same way as during an earthquake. Since as a result of a volcanic eruption, explosions occur, and when they have great power, they are also ways to cause large and long waves, i.e. tsunamis.

What are tsunamis?

Scientists divide different types of tsunamis depending on the strength and height of the waves, as well as on the catastrophic consequences that these waves cause. Waves from earthquakes can form both large ones from 10 meters in height, and very small ones - waves of 1-2 meters. The farther from the coast, the less destructive effect a tsunami has.

The most destructive tsunamis occur when the epicenter of an earthquake is close to the coast, with an earthquake magnitude of 6.5 on the Richter scale. And with a small earthquake somewhere in the center of the ocean, they can cause waves from 1 meter, which are not dangerous even for ships and liners that are nearby. This is because the tsunami gains its strength and power as it approaches the shore. That is why, being in seismically dangerous coastal zones, you need to know the main signs of a tsunami.

Signs of a tsunami:

• - earthquakes - the more intense the tremors, the stronger the wave will be;
• - a sharp ebb - the farther the sea and ocean coast goes inland, the higher and more powerful the wave will be.

What regions are seismically dangerous zones where a tsunami can form?

Most often, tsunamis form on the coasts of the Pacific Ocean, since more than 80% of the active volcanoes of our planet are located in its waters, and 80% of all earthquakes occur at the bottom of this ocean. Dangerous zones include the western coast of Japan, Sakhalin Island, the coast of Peru, India, Australia, Madagascar.

Tsunamis are among the most dangerous hydrological phenomena of natural origin. Tsunami is a type of sea waves. The word "tsunami" comes from Japanese and means "big wave".

Sea waves are oscillatory movements of the aquatic environment of the seas and oceans, caused by the force of the winds, tides, underwater earthquakes and volcanic eruptions.

Tsunamis are not associated with winds, storms and hurricanes. Tsunamis also occur in calm weather, because they originate at the bottom of the ocean (sea) as a result of geological changes in the lithosphere. The causes of tsunamis can be sharp shifts of the bottom during strong earthquakes, large underwater landslides and volcanic eruptions.

Tsunami- These are marine gravity waves of great length, resulting from the vertical shift of significant sections of the seabed.

In most cases, tsunamis are caused by underwater earthquakes occurring under the ocean floor or near its coast. Tsunamis can also be generated by eruptions of underwater volcanoes. However, tsunamis occur only after those earthquakes that are associated with the rapid formation of faults, collapses and landslides at the bottom of the ocean. The fault is a rapid displacement of blocks of bottom rocks of the earth's crust and gives an impetus that sets in motion huge masses of water. This displacement pushes the water and causes a tsunami to form.

Big wave - Tsunami. Japanese artist of the 19th century K. Hokusai.

A tsunami, like any sea wave, is characterized by the height, length and speed of the waveform.

The height of a sea wave is the vertical distance between the crest of a wave and its bottom. Wavelength is the horizontal distance between two peaks (crests) of adjacent waves. The speed of movement of a waveform is the linear speed of horizontal movement of some element of the wave, such as a crest.

The height of a tsunami wave above its source in the ocean is 1–5 m. The wavelength can be 150–300 km. Tsunami propagation speed ranges from 50 to 1000 km/h.

The wavelength of a tsunami, its height and propagation speed depend on the depth of the ocean. The greater the depth of the ocean, the greater the wavelength and the speed of its propagation, the lower the wave height. Thus, the speed of tsunami propagation when crossing the waters of the Pacific Ocean, where the average depth is about 4 km, is 650-800 km/h, and when propagating along deep-sea places in the ocean, it can reach 1000 km/h. When a tsunami approaches the coast, where the depth decreases to 100 m, the tsunami propagation speed drops to 100 km/h. With a decrease in depth, the wavelength decreases, but the height of a tsunami wave when it enters shallow water increases sharply and can reach from 10 to 50 m.

Thus, when approaching the shore and, especially, when entering narrowing bays, tsunamis slow down their speed, but their height increases sharply. As a result, giant water shafts 10-15 m high, and sometimes up to 30-50 m high, can collapse on the coast. The damage caused by a tsunami can many times exceed the consequences of the earthquakes that caused them.

Where do tsunamis most often occur on Earth?

Most often, tsunamis hit the shores of the Pacific Ocean (75%), which is associated with the high volcanic activity of this basin. Over the past millennium, the Pacific coast has been hit by tsunamis about 1000 times, while tsunamis have been observed on the coasts of the Atlantic and Indian Oceans only a few dozen times.

In Russia, the eastern coast of Kamchatka and the Kuril Islands, Sakhalin Island and the Pacific coast are most prone to tsunamis.

Having a high speed of movement and a huge mass (in 1 m 3 of water, 1 ton of mass), a tsunami has an enormous destructive power. Running into oncoming coastal obstacles, the wave brings down all its energy on them, rising above them as a huge water wall, crushes, destroys and destroys everything that comes in its way. The destructive power of a tsunami is directly proportional to the speed at which the wave comes ashore.

The intensity of a tsunami based on the results of impact on the coast is estimated on a conditional six-point scale.

• 1 point- the tsunami is very weak, the wave is recorded only by special instruments (seaographs).
• 2 points- weak tsunami, can flood the flat coast. It is noticed only by experts.
• 3 points- average tsunami, noted by everyone. The flat coast is flooded, light ships can be washed ashore, port facilities are subject to minor damage.
• 4 points- strong tsunami. The coast is flooded. Coastal buildings are damaged, have weak and strong damage. Large sailing and small motor boats are washed ashore and then washed back into the sea. The shores are littered with sand, silt, tree fragments, human casualties are possible.
• 5 points- a very strong tsunami. The coastal areas are flooded. Breakwaters and breakwaters are badly damaged. Large ships washed ashore. The damage is also great in the interior parts of the coast. Buildings and structures have strong, medium and weak destruction depending on the distance from the coast. There are high storm surges at river mouths. There are human casualties.
• 6 points- catastrophic tsunami. Complete devastation of the coast and coastal areas. The land is flooded for considerable distances inland.

Varieties of tsunami

The scale of the consequences of a tsunami depends on the destructive power of the wave, the nature and natural features of the shore and coast, the effectiveness and timeliness of the measures taken to reduce damage.

Tsunamis are especially dangerous for settlements, cities and structures located on low-lying shores of the ocean, as well as those located at the top of bays and bays that are wide open to the ocean, where tsunamis drive a large mass of water, flooding the mouths and valleys of rivers 2-3 km from the sea. Tsunamis can cause large areas to be flooded with seawater.

History knows many examples of catastrophic tsunamis.

In 1703, about 100 thousand people died as a result of a tsunami in Japan.

In October 1994, a 2-3 m high tsunami hit the southern islands of the Kuril chain and the Japanese island of Hokkaido, which led to great destruction and loss of life.

The most powerful earthquake and the tsunami that followed it with a force of 8.9 points were noted in December 2004 in Southeast Asia. The earthquake, which occurred northwest of the island of Sumatra, caused a powerful tsunami that, moving at a speed of 800 km/h, hit the coasts of nine countries. Over 200 thousand people died as a result of the natural cataclysm. The population of Sri Lanka, Thailand, and Indonesia was especially affected.

Test yourself

1. Describe the natural phenomenon of a tsunami.
2. What consequences of a tsunami pose a danger to human life?

After lessons

In the safety diary, give examples of tsunamis that occurred in the world at the beginning of the 21st century. Specify their consequences and actions for protection of the population. Examples can be collected using the Internet and the media.

Tsunami statistics demonstrate the destructive power of this natural phenomenon. Japan in 2016 was covered by a tsunami with a wave height of up to 1.5 m, which reached the Fukushima-1 nuclear power plant, which is in emergency condition.

This natural phenomenon is associated with the movement of the Earth's lithospheric plates. raises one plate above another. The condition for the formation of a wave is a significant movement along the vertical of this section of the seabed. The magnitude of the wave rise at the place of movement is related not only to the distance that the plate has risen, but also to the strength of the seismic shock.

According to the laws of physics, unevenly high columns of liquid along the edges of the fault are an unstable system. Therefore, the pillars are aligned due to the formation of a wave, “overflowing” from a high column to a low one. The atmosphere is also involved in restoring disturbed equilibrium. Directed winds (hurricanes) tend to move the volume of "raised" water in the direction of its "fall".

From the point of view of wave phenomena, the occurrence of a tsunami is associated with the formation of long waves with a high speed of movement. At the same time, the propagation of waves in the open sea contributes to their attenuation, but this does not happen in the case of a long tectonic fault. Conditions for the formation of a tsunami:

• the bottom section should move vertically to a considerable height;
• the tectonic fault should have a large extent (with a small source, the waves will die out before reaching the shore);
• the rate of rise of the ocean floor section must be high (otherwise the rise of the wave is gently compensated).

The occurrence of a tsunami as a result of an earthquake is a frequent variant of this phenomenon.

Where do waves of destructive force come from

Earthquakes are common causes of tsunamis. The tsunami does not depend on the strength of the earthquake, since the shifts are not always noticeable in the deep waters of the ocean. Other reasons (7%) and some (5%). In 1883, due to the volcano Krakatau, which exploded near the island of Java, tsunami waves killed 36,000 people.

The most dangerous earthquakes with seismic activity 12 points. But for 10 years, this has not been observed. In addition to natural tsunamis, huge waves can be caused by human activities, such as a nuclear explosion in the ocean or sea. The formation of waves can also be associated with the fall of a large meteorite. Recently, an opinion has arisen that an iceberg falling into the water can raise a wave comparable to a tsunami.

Phenomenon classification

Tsunami statistics classify their types differently, dividing them by intensity, wave height, origin and number of victims.

Unlike surface waves, which can be generated by strong winds or storms, ocean tsunamis form from the bottom to the top. A huge volume of water is displaced. The height of the wave is greater, the greater the depth of the ocean.

A tsunami in the ocean does not pose a serious danger, since most of the wave is underwater. As the shore approaches, the danger increases along with the magnitude of the wave. In shallow water, the back waves catch up with the front ones, and the superposition of one on top of the other causes an increase in height, in some cases up to 50 meters.

The dangerous factor is the speed of the tsunami. It averages 400-500 km per hour, and in the Pacific Ocean it can reach 800 km per hour.

Before the first powerful wave, a low tide may occur, misleading people resting off the coast. A rapidly approaching wave crashes down on the coast and rolls back. However, the maximum tsunami height does not fall on the first wave. After two or three hours, the next flow of water floods the seashore and penetrates several kilometers deep, demolishing buildings, people and animals. Sometimes a wave breaks on land for 10 km or more.

The most destructive waves in history

Catastrophes associated with the flooding of coastal zones, as tsunami statistics show, have occurred in the world more than once. The most destructive waves in the history of mankind are presented by year in the table:

Year	Place	Effects
365 CE e.	In the mediterranean	Demolished the city of Alexandria in Egypt, thousands of victims
1737	On Kamchatka	A wave 30 fathoms high (about 65 meters) flooded the banks, washed away houses,. It was the first tsunami in Russia
1775	Atlantic Ocean	Six-meter waves covered Portugal, Spain, Morocco
1883	In Indonesia	The coasts of Java and Sumatra are flooded
1896	Tsunami in the USA (California)	City of Santa Barbara flooded
1896	Tsunami in Japan	27122 victims
1906	Pacific Ocean	Destroyed residential areas in Colombia and the city of Rioverde in Ecuador, 1,500 victims
1946	USA	Tsunami in Alaska destroys lighthouse and reaches Hawaii, 159 victims
1958	USA (Alaska)	The wave reached a height of 524 m
1960	Tsunami in Chile	A wave of 11 meters reached the opposite shores of the ocean, flooded the Philippines and the island of Okinawa
1964	USA (Oregon, California)	Tsunami in America destroyed 3 villages, 122 people died
1976	Philippines	5,000 victims
1998	Papua New Guinea	2313 casualties, seven villages washed away
2004	In the Indian Ocean (Thailand, Sri Lanka, Maldives)	The largest tsunami in a 40-year interval, 225,000 victims. The earthquake caused a fault more than 100 km long.

The last tsunami in Thailand in 2004, which originated in South Asia, reached the coast of Africa and flooded the coastal zone of Somalia. Waves covered the western part of Thailand. The devastating tsunami in Phuket destroyed the entire infrastructure of the resort town.

The waves swept away Karon Beach and other world-famous holiday destinations (Patong, Kamala and Kata). The approaching wave in Phuket was not immediately visible, so especially many tourists died in the coastal zone. The number of victims in Thailand has reached 8.5 thousand people. Coastal areas in Sri Lanka were flooded for tens of kilometers. This tsunami in India and Indonesia flooded densely populated shores, destroying people and buildings.

There was much less destruction in the Maldives, scientists believe that the coral reefs surrounding the islands are a natural defense against high waves.

Characteristics of a tsunami

As tsunami statistics show, the danger of this phenomenon is largely related to the speed of events. There is a relationship between characteristics and consequences. The main characteristics of the tsunami:

• tsunami wave speed and height;
• wavelength (segment between two waves);
• wave period (time interval between the passage of two waves).

The degree of destruction and the number of victims depend on all these parameters.

Why are water shafts dangerous?

A rapidly advancing tsunami carries an air stream in front of it, comparable in strength to a blast wave. Possible consequences of a tsunami:

• powerful waves destroy everything in their path and flood the territory. The resulting flood from the tsunami contributes to the further destruction of buildings. pollute the soil and drinking water with foreign substances, contributing to the development of infectious diseases;
• destruction of buildings and communications;
• death of people and animals;
• the destruction of sea vessels standing near the shore;
• destruction of soil cover and .

Natural disaster protection

Tsunami statistics show that it is impossible to prevent. Only a few mitigation measures are available:

• the prediction of the onset of a wave is associated with the observation of seismic activity;
• constant monitoring of the movement of the shafts;
• informing the population by all available means;
• timely evacuation of people and animals;
• construction of hydraulic structures, in the risk zone of high waves.

Natural disasters bring losses to the state. And for people, the economy and nature, sometimes irreparable consequences. Thousands of tsunami victims over the past 10 years are a disappointing statistic.

Many people die because of ignorance and wrong actions. Evidence of this are the videos of eyewitnesses, of which not all of them survived the onset of the elements, busy shooting a bright phenomenon. Such a frivolous attitude to danger is distinguished by a belated sense of self-preservation.

How to escape from a tsunami? The emerging tsunami threat requires rapid mobilization. Collection of documents and personal belongings should be done as soon as possible. It is optimal to move inland to an elevation, at least 2–3 km from the coast.

The coastal zone receives the strongest blow from the elements. If you are on the beach, then you need to find shelter in a building on a hill, be sure to be strong. While indoors, you need to close all windows and doors and move to a high floor.

If the wave caught in the sea, you need to get together and cover your head with your hands, taking a deep breath, then emerge and throw off excess clothes. After waiting for the return wave, you need to find shelter and hide. As a protection against a tsunami on the shore, a powerful tree or a solid building can act, behind which you can hide.

When going on vacation to the countries neighboring the Pacific Ocean, it is useful to get information about the actions in case of a tsunami and the existing warning system. Usually people become victims of a tsunami, and curious tourists are caught off guard, collecting shells during low tide, preceding a powerful wave. The number of destructive waves over the past 10 years has increased worldwide.

In 2012, a film based on real events, The Impossible, was released, dedicated to the victims of the tsunami in Thailand. The consultants were eyewitnesses of the tsunami (a doctor from Spain, her husband and three sons).

The last tsunami in Cyprus occurred in 1908. Scientists believe that destructive waves form in the Mediterranean Sea once every 100 years. The same is true in Greece, Turkey and other countries washed by this sea. It is generally accepted that Australia is vulnerable to a tsunami from the east coast of the Pacific Ocean.

In 2016, there was a powerful earthquake in New Zealand, which caused a wave of 2.5 meters that hit the shores. An infrequent guest of the tsunami in the Dominican Republic. To understand in what years there were tsunamis in this country, let's turn to history:

• a powerful earthquake in 1751 caused the most tragic destruction, including from high water masses;
• 1842 waves reached 2 meters;
• 1946 the northern coast of the country was destroyed, five-meter waves flooded the coast, 1950 people died.

The latest tsunami statistics do not include this area among the most dangerous. Natural disasters in the Far East are a fairly common thing due to its location. Waves covered coastal areas in 1923, 1952 and 1960. Excavations by scientists found that 8,000 years ago, volcanic eruptions caused more than 50 megatsunamis in the region.