Causes of a tsunami.

In most cases (about 85%), tsunamis are caused by vertical displacements of the seabed during earthquakes. At the same time, the subduction (subduction) of one lithospheric plate under another causes a sudden uplift of the latter, and with it the uplift of huge masses of water.

Surface waves diverge from the place of uplift. They reach the nearest coasts and are called local tsunamis. These waves can reach a height of 30 meters and cause great destruction on the coast near the epicenter of the earthquake.

But the uplift of the sea floor generates a series of underwater waves similar in nature to sound or shock waves.

They spread in the water column from the surface to the bottom of the ocean at a speed of 600-800 km/h. When such waves approach distant shores, their energy is concentrated due to a decrease in depth. There are surface waves, which fall on the shore. These tsunamis are called remote.

Such waves are capable of crossing the Pacific Ocean from Chile to Japan at a speed of 200 m/s in 22-23 hours.

In the ocean, due to its length of 200-300 km and a height of only 0.5 meters, they are not noticeable from the surface of the water and from the air.

Another cause of tsunamis is landslides above or below the water level. Such waves occur in 7% of cases and are of local importance. But their height at the same time can reach more than 20 meters and cause corresponding destruction. And under certain conditions, such as, for example, during an earthquake in Alaska and a landslide in Lituya Bay in 1958, a wave that reached the opposite shore of the bay had a height of 524 meters.

Approximately 5% of tsunamis are caused by volcanic eruptions. A classic example is the explosion of the Krakatoa volcano near the island of Java in 1883. The resulting waves caused the death of 36,000 people, and their effect was felt in all the harbors of the world.

The consequences of the tsunami.

In addition to the death of people, tsunamis cause flooding of significant coastal areas and soil salinization, destruction of buildings and structures, soil erosion, damage to ships moored near the coast.

To reduce the damage from the consequences of the tsunami, construction should be carried out outside the zone of their impact. If this is not possible, build buildings so that they take blows with their short side, or place them on strong columns. In this case, the wave will pass freely under the building without damaging it.

If there is a threat of a tsunami, ships moored near the coast must be taken out to sea.

Tsunami harbingers.

Unfortunately, there are few of them. This is, first of all, an earthquake, even if it is weak. We cannot know where it happened, on land or under the seabed, how powerful it is, and whether it caused a tsunami. Therefore, being on the seashore, any earthquake should be considered a tsunami harbinger.

In some cases, before the arrival of the tsunami, atypical, untimely low tides are observed lasting from several minutes to half an hour.

The occurrence of such a low tide after an earthquake should alert. (a photo)

Eyewitnesses often note the atypical behavior of animals that show concern, try to leave the coastal strip and, allegedly, climb to elevated places.

The combination of all the listed tsunami harbingers should not be in doubt, and the only correct action in this situation is to take rescue measures.

What to do in the event of a tsunami.

Areas along the coast, sea bays, harbors, the height of which does not exceed 15 meters above sea level, are considered to be tsunami hazardous. And if local tsunamis are expected, then areas with a height of less than 30 meters.

Being in such areas, you should think over in advance the sequence of your actions in case of danger.

We must make sure that the documents, the minimum necessary things and products are always at hand.

Arrange with family members for a rendezvous point after a disaster, consider evacuation routes from a dangerous coastal area, or designate places to escape if evacuation is not possible. It can be local hills or high capital buildings. It is necessary to move to them by the shortest route, avoiding low places. A distance of 2-3 km is considered safe. from the shore.

Be aware that when observing tsunami warnings, tremors, or local tsunami warnings, the time to rescue can be measured in minutes.

The occurrence of distant tsunamis is recorded by warning systems and the forecast is reported on radio and television. Such messages are preceded by the sounds of sirens.

It is impossible to predict the number, height of waves, as well as the interval between them. Therefore, after each wave, it is dangerous to approach the shore for 2-3 hours. It is advisable to use the gap between the waves to find the safest place.

Any earthquake felt on the seashore should be considered a tsunami hazard.

You can not approach the coast to look at the tsunami. It is believed that if you see a wave and are in a low place, it is too late to save yourself.

Compliance with these simple rules of conduct, knowledge of tsunami precursors could reduce the number of victims of the tsunami in the Indian Ocean in 2004. Indeed, according to eyewitnesses (this can also be seen on the recorded videos), many people used such a tsunami harbinger as the ebb before the arrival of the waves to walk along the seabed and collect marine animals. (a photo)

With the right behavior, the number of people who survived could reach tens of thousands.

Knowing the causes of a tsunami, as well as ways to reduce the damage from the consequences of a tsunami, can one day help you save your life, the lives of your loved ones and property.

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, asteroid falls, 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 area of ​​forest plantations, 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 km of fault lines, 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 imminent 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. Only in Sendai, 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 Ministry of Emergency Situations, 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.

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. A 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 the lithospheric plates is as follows: one plate begins to crawl under the other, as a result, a sufficiently large force is formed that lifts the second lithospheric plate upwards, and this effect also sets the water column in motion.

Other Causes of a Tsunami

The next cause of such waves as tsunamis is landslides. For example, a large landslide occurred off the coast of Alaska 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 the occurrence of 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 go deeper, 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.

gender of nouns

6th grade

Verification work number 4.

Target:

1. Reveal the skills to determine the classifying feature of a noun - gender.
2. To check the skills of word analysis at the level of phonetic, morphemic, morphological.
3. Punctuation skills.

Dictation.

"Tsunami"

Tsunami is a Japanese word. These ominous waves, which are often preceded by a sudden ebb, claim more human lives than all other maritime disasters.

A grandiose spectacle - a real tsunami, a single wave, born of a large earthquake.

At first this wave is very high, then it moves away from the place of birth and quickly becomes lower and lower, and in the open ocean it can hardly be distinguished from other waves.

Ships, having met a tsunami, often do not notice anything, but its peaceful appearance is deceptive: the wave carries colossal force.

Having reached the coastal shallows, it suddenly grows to a dizzying height. The sea emerges from the shore and moves towards the land like a huge wall.

At the top of the blue-gray wall, white breakers boil.

Then the wall collapses, pouring millions of tons of salt water into piers, port facilities, and houses, and entire villages.

Assignments to the text.

1. Have you ever heard of a tsunami?

   What is a tsunami?

   Express your attitude to this phenomenon of nature. (3 p.)

2. Determine the gender of the indeclinable word "tsunami".

   How did you do this? (2 p.).

3. Give an example of an indeclinable word.

   What, in your opinion, is the reason for this phenomenon?

   Explain. (3 p.).

4. What do you know about common nouns?

   Give an example, explain the reason for this grammatical phenomenon. (3p.),

5. Which nouns do not have gender differences? (2 p.)
6. Find a sentence with a dash and explain its statement. (3 p.).
7. Underline the grammar in this sentence.

   How is it expressed? (2 p.).

8. Explain the spelling of the words:

Colossal, grows, millions, coastal, blue-gray, salty.

1. Take the words apart:

Preceded by, earthquake, removed, dizzying, harbor.(3 p.).

Grammar assignment scale.

24 – 22 p…………………………………………”10”

21 – 20 p…………………………………………”9”

19 - 18 p……………………………………… "8"

17 - 16 p………………………………………. "7"

15 - 13 p………………………………………. "6"

12 - 11 p……………………………………….. "5"

10 - 8 p…………………………………………. "4"

7 - 6 p……………………………………………. "3"

5 - 4 p……………………………………………. "2"

3 - 1 p……………………………………………. "1"

Tsunami word

The word tsunami in English letters (transliteration) - tsunami

The word tsunami consists of 6 letters: a and m n u ts

Meanings of the word tsunami.

What is a tsunami?

Tsunami (translated from Japanese means "high wave in the bay") - long waves generated by a powerful impact on the entire water column in the ocean or other body of water.

Encyclopedic Fund of Russia

Tsunamis, huge sea waves associated mainly with underwater earthquakes, but sometimes arising from volcanic eruptions on the ocean floor, which can cause the formation of several waves ...

Encyclopedia Around the World

Tsunami tsunamis are sea waves of very large length that occur during strong underwater and coastal earthquakes, as well as during volcanic eruptions or large rockfalls from a coastal cliff.

Geographic Encyclopedia

Tsunamis are giant waves generated by earthquakes, whose epicenter is under the ocean floor.

Near the coast, the height of a tsunami can reach 10–30 meters and move towards the coast at a tremendous speed.

Japan from A to Z. - 2009

"Tsunami 3D"

What is a tsunami

Bait is a thriller film directed by Kimble Randall. World premiere - September 6, 2012, premiere in Russia - September 27, 2012. The film takes place in a small town in Australia, located on the coast of the ocean.

en.wikipedia.org

TSUNAMI (TSUNAMI)

TSUNAMI (TSUNAMI) - huge, destructive wave forces that occur when a local change in the water level during underwater earthquakes.

Their propagation speed is 400-800 km/h. The height when approaching the coast reaches 15-30 m or more.

Geological dictionary. — 1978

Tsunami deposits

Tsunami deposits are accumulative deposits left on coasts after exposure to tsunami waves.

From the tsunami deposits, you can restore such wave parameters as height (runup) ...

en.wikipedia.org

Attention, tsunami!

"Attention, tsunami!" - Soviet adventure film of 1969. Seven sailors serve at a remote warning post located in the Pacific Ocean.

One day, a tsunami hits the island. A giant wave destroys the bunker.

en.wikipedia.org

ATTENTION, TSUNAMI!, USSR, Odessa Film Studio, 1969, b/w, 82 min. Heroic film story. Remote warning post in the Pacific Ocean. Seven sailors carry out their service, the peaceful course of which is interrupted by the tsunami that hit the island.

Film Encyclopedia. — 2010

Tsunami Strength Scale

The tsunami strength rating scale is a four-point scale for assessing the strength (intensity) of a tsunami by their impact on ground objects and by wave height (M).

Proposed by K. Iida and A. Imamura Moderate tsunami…

Dictionary of terms MChS. — 2010

Earthquake and Tsunami of Meiji Sanriku (1896)

The Meiji Sanriku earthquake and tsunami is one of the most devastating natural disasters in Japanese history. An earthquake of magnitude 7.2 on June 15, 1896 created a tsunami with a higher magnitude of 8.2…

en.wikipedia.org

Russian language

Tsunami station, -i.

Orthographic dictionary.

Tsunamis are very long sea waves that occur during strong underwater and coastal earthquakes, as well as during volcanic eruptions or large rockfalls from a coastal cliff.

Geographic Encyclopedia

Usage examples for tsunami

No tsunami warning was issued after the earthquake.

The declared threat of a tsunami on the sea coast of Sakhalin was subsequently removed.

developed a tsunami barrier system that automatically responds to wave impacts.

Information about the victims on the territory of the Russian Federation has not yet been received, as well as about the threat of a tsunami.

The first performances of the group took place in April 2011 in Japan, shocked by the earthquake and tsunami.

tsunami- an incredibly dangerous phenomenon of nature. Terrible consequences make you feel out of place. But as they say, you need to know your enemy personally, so learn more about this evil nature:

The most at risk from tsunamis are: California, Hawaii, Oregon and Washington. Hawaii is the highest risk and has about 1 tsunami per year and a dangerous tsunami every 7 years.

Alaska was hit by an extremely strong earthquake. This triggered a tsunami wave that was very destructive southeast of Alaska, Vancouver and Canada.

Waves ranged in size from 6 to 21 feet. The tsunami killed more than 120 people and caused more than $106 million in damage. It was the most expensive tsunami for the western United States and Canada.
Scientists have found that the impact of a moderately large asteroid (approximately 5-6 km in diameter) in the middle of the Atlantic Ocean will create a tsunami that will travel two-thirds of the United States. Coastal cities will destroy such a tsunami.
Nuclear explosions can create a tsunami, but so far no test results.

Tsunami is a catastrophic natural phenomenon

In addition, such tests are currently prohibited by international agreements.

What causes a tsunami?

An underwater earthquake or other severe disturbance that causes a sudden increase or decrease in the mass of water over the affected area.

This sudden flow of water creates a series of strong waves.
The most common causes of tsunamis are underwater earthquakes, which cause significant changes in the ocean floor and the movement of large amounts of water.
Tsunamis can also be triggered by other underwater events such as volcanic eruptions and landslides.
Tsunamis can also be associated with events above the ocean floor.

These events may include meteor impacts in the ocean, large landslides near coasts, materials from volcano eruptions, or the formation of landslides. The consequences of a tsunami caused by such factors are usually localized.
More than 75 percent of tsunamis are associated with underwater earthquakes.

Where do tsunamis occur??

Most tsunamis occur in the Indian and Pacific Oceans.

Areas of the Pacific Ocean are frequent earthquakes. This border is known as the "ring of fire". There are two main subduction zones in the Indian Ocean that can also create tsunamis.
Earthquakes in the subduction region are the most common source of destructive tsunamis. These earthquakes are formed when two tectonic plates meet, one under the other. The dip plate extends to the top plate, causing a bend.

The top plate returns to its original position, thereby moving the sea water.

In December 2004, an earthquake off the coast of Indonesia caused the sea surface, such as a tsunami, to move away from the epicenter 10 minutes after the event.

In this figure, the red arrows indicate the direction in which the top plate is deformed by pulling and lowering the bottom plate.

Tsunami can really move!

• In deep ocean waters, waves are created with long waves, but usually no more than one meter in height.

  Tunisian waves can be hundreds of miles long and travel very fast and for long distances without losing much of their energy.

• You can see a mini tsunami if you throw a large object into the water.
• Tsunamis on the high seas can travel at a speed of 950 kilometers per hour (that is, the speed of a passenger plane).

  The tsunami loses speed as it approaches the ground, but does not lose much of its energy.

What is the size of a tsunami?

• In the open ocean, tsunami waves are very difficult to see. However, as the tsunami wave approaches the ground and goes to a lower depth, the leading edge of the wave slows down and moves back in the waves at the initial speed.

  This causes the water to crash into the pile and causes the wave height to increase. This process is known as "shallow water". When a wave hits the floor, it can behave like a series of surfs or just a powerful wave.

• The tremendous energy of the waves can cause a large amount of water to flow into the depths, far beyond the coastal zone.
• Some of the largest tsunami waves were generated by the Krakatoa volcano in 1883.

  The tsunami reached a height of 37 m. The tsunami reached a height of 64 m or more in 1737 (its influence fell at Cape Lopatka, in northeastern Russia).

• Tsunami waves are different from ordinary waves! Normal waves caused by wind and water moving near the surface.

  In a tsunami, all the water moves from the surface to the bottom of the ocean, which is caused by the movements of water (earthquakes are the cause of this). In the open ocean, tsunamis create little traffic and a great threat to shipping.

• When a tsunami reaches the coast, its wavelength is over 100 km.

  A tsunami can last several hours or even days, depending on the location. This is fundamentally different from the waves we saw on the beach. Typical ocean waves typically last less than a minute and are only 100 meters long.

• The energy from the tsunami is enough to strip the sand of an entire beach, knock down trees, and crush a building.
• People and boats are powerless against the power of the tsunami. The amount of water generated by a tsunami can flood vast areas of normal land.

The most famous tsunami in recent times:

• Solomon Islands April 2, 2007

The earthquake struck in shallow water early in the morning and was soon followed by a tsunami. The waves were up to 10 m high. More than 50 deaths were reported, while thousands of people were left homeless. There are tsunami warnings in Australia and Alaska 15 minutes after the earthquake.

At 6:49 a.m., the tsunami, which caused extensive damage to property and the natural environment, triggered a magnitude 8.0 earthquake and caused the deaths of more than 100 people.

The cause is an earthquake with a magnitude of 8.8.

The epicenter of the earthquake was located 115 km from Concepción. The epicenter of the earthquake was 230 km. This earthquake was the result of movement between the plates in the eastern Pacific and the South American planks. The first waves broke about 34 minutes after the earthquake. Buildings were severely damaged and more than 200 people died.

• Papua New Guinea 17 July 1998

An earthquake measuring 7.0 on the Richter scale just off the northern coast triggered a devastating tsunami.

Waves up to 10 meters were very fast through the villages in the Aitape region. Over 2,000 people were killed and the tsunami caused severe damage to buildings and farmland.

• December 26, 2004 Indian Ocean Tsunami

This tsunami has become one of the most devastating natural disasters in recent years.

The quake that caused it was just west of the Indonesian island of Sumatra and measured 9.0 on the same Richter scale, the world's largest quake in 40 years. The death toll in March 2005 was over 273,000, many of whom are missing.

And here is a series of incredible videos:

Tsunami Thailand 2004

Key words in 2017: Haip, Zashchvar and Eshkere!

Tsunami - what is it? Definition, i.e. translation

tsunami(emphasis on "a") it's a super heavy wave, which usually occurs as a result of a strong underwater earthquake or volcanic eruption.

What is a tsunami, photography and photography of a tsunami. Causes and symptoms of a tsunami

The word "tsunami" is Japanese, composed of "tsu" meaning "bay" and "nas" meaning "wave". With their destructive power, tsunamis can be compared to the impact of a nuclear explosion. Often the effects of an earthquake are much less obvious than the damage caused by a tsunami.

There are examples of the deaths of thousands of people caused by the tsunami, of which the last one came to Southeast Asia in 2004 and claimed the lives of 280,000 people.

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Tsunamis kill thousands of people every year and destroy many homes and infrastructure. Giant waves can be predicted by experts, or they can appear suddenly, which is especially dangerous. About what a tsunami is, about the causes of its occurrence and possible precursors, will be discussed in this article.

Causes of the “wave in the harbor”

“Tsunami” is translated from Japanese as “waves in the harbor”. But the name does not convey all the power and fear that this phenomenon brings. In the open ocean, tsunamis are rarely seen and do not cause such concern. The waves gain their strength and power off the coast and mercilessly sweep away any obstacles in their path.

The causes of tsunamis are:

1. displacement of the seabed during earthquakes;
2. landslides;
3. volcanic eruptions.

When earthquakes occur, one lithospheric plate rises above another. This shift is accompanied by the rise of a large amount of water. As a result of this phenomenon, waves appear on the surface of the water, which can reach 30 meters and be dangerous for the area near the epicenter of the earthquake. But underwater waves are of particular concern. They can move at a speed of 600 - 800 km / h. When this kind of tsunami approaches the shore, their underwater character is transformed into a surface one, but stronger and more powerful.

Earthquakes are the most common cause of tsunamis. Landslides are the second most likely cause. They generate waves of local significance, which do not have a high propagation velocity. But those areas that are near the epicenter can receive waves 20 meters high. The stronger the landslides, the more destructive the force of the tsunami.

A volcanic eruption can also be the cause of giant waves. History will count dozens of such tragic examples.

Damage after the tsunami

The main task in the event of a tsunami is to save the lives of people who are at the epicenter of events. This phenomenon destroys infrastructure facilities, houses, and also leads to such negative events:

1. soil salinization;
2. soil erosion;
3. ship damage.

If the tragedy fell on agricultural land, then a large amount of land will become unusable. It takes more than one month to minimize salinity and eliminate erosion.

In the construction industry, they know how to avoid significant damage from a tsunami. For this, buildings are erected on strong columns. You also need to build the building so that the waves hit its short side, then the impact force will not be so strong.

If it is known in advance about the possibility of a cataclysm, then the moored ships in the port are taken out to the open sea, where the waves will not cause them much harm.

Are there tsunami warning signs?

From a scientific point of view, the forerunners of the appearance of large waves are natural phenomena - earthquakes, landslides, etc. But the difficulty lies in the fact that such cataclysms can occur hundreds of kilometers from the intended place where the tsunami will hit.

Often, before the appearance of a mountain wave, atypical, large ebb tides occur. This should immediately alert and promote the adoption of security measures.

But there is also an unscientific theory that talks about the strange behavior of animals immediately before the disaster. They try to quickly escape from the coastal strip and hide in more elevated places.

Tsunami action plan

In the event that the onset of a tsunami is known in advance, then one should not hesitate, but collect documents, food and the most necessary things. If not all family members are at home at this moment, then you should agree on a meeting place.

Sometimes strong earthquakes generate instant strong waves, so there will be only 10-15 minutes for the training camp. A safe distance is considered to be 2 - 3 km from the coast. It is better to choose hills or high-rise buildings that can withstand the pressure of a significant mass of water as a place for placement.

When the threat of a tsunami becomes clear, the warning system is activated. Sirens and announcements on television and radio will confirm the fears, which should prompt active evacuation actions.

Sometimes it happens that giant waves can collapse after a certain interval of time. It is difficult to predict it, therefore it is necessary not to lose vigilance.

The most destructive tsunamis

The most destructive tsunamis in human history include:

1. Tsunami in the Indian Ocean in 2004, when the waves reached 30 meters. The number of victims reached 230 thousand.
2. Tsunami in Tohuku, where waves reached 40 meters. As a result, there was a catastrophe at the nuclear power plant and a radiation leak.
3. The disaster in Valdivia, which affected the territory of Chile, Hawaii and Japan. 6 thousand people died.
4. A disaster on the island of Java, where many people were injured due to a poor warning system.
5. Tsunami near Tumaco, which killed or went missing about 300 people.

Tsunami is a destructive force that is difficult to predict in advance. That is why in those areas that are prone to this phenomenon, it is necessary to develop a protection system, carry out propaganda and educate the population in the rules of survival.

Tsunami(Japanese) - giant waves with destructive power. They are caused by underwater, or underwater landslides. These phenomena are usually accompanied by a strong tremor transmitted by water to the surface, which is not safe 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 gentle here. But they spread with great speed (up to 1000 km / h). Approaching the shore, they become steeper and higher, acquiring a terrible destructive power. As a result, giant water shafts from 10 to 50 meters high or more can collapse on the coast.

Most often, tsunamis hit the coast, which is associated with the high volcanic activity of this basin (see Volcanoes). Over the past millennium, the Pacific coast has been hit by tsunamis about 1000 times, while on the coasts of the Atlantic and Indian oceans, giant destructive forces have been observed only a few dozen times.

Before the arrival of a tsunami, within 1 to 15 minutes, the water usually recedes from the coast for hundreds of meters, and sometimes for kilometers. The further the water receded from the coast, the greater the height of the tsunami should be expected. The approach of a tsunami can also be known in advance by registering seismic waves that arise during and propagate in water at a speed many times greater than the speed of a tsunami. There is a special warning service that warns residents of the coast in advance of possible danger. People have to leave their homes and climb higher ground to wait out the tsunami. Thanks to this service, the number of victims is decreasing.

The damage caused by a tsunami is many times greater than the consequences caused by the earthquakes themselves. Great destruction was caused by the Kuril tsunami in 1952, the Chilean tsunami in 1960, the Alaska tsunami in 1964, and the wave caused by Krakatau in 1912 bypassed the entire. The Krakatoa eruption is often called the most powerful eruption in human history. There were several strong volcanic explosions at intervals of , the last explosion being the most powerful. Each explosion was accompanied by a tsunami that flooded the coast of Indonesia, and the last one caused a giant wave about 25-35 meters high, which flooded the coast of all nearby islands. Not only the inhabitants, but the whole were washed away from them. In the port on the island of Java, a large ship was torn off the anchor and skidded 3 km inland, to a height of 9 meters above sea level. Waves from the islands of Indonesia through the Sunda Strait spread through