Flood. Tsunami is a catastrophic natural phenomenon

A giant wave never occurs just like that, the main thing is to have an idea of \u200b\u200bthe dangerous regions and take precautions.

Causes of the tsunami

• Tsunamis are caused by earthquakes, but not every earthquake will necessarily cause a tsunami.
• The great Lisbon earthquake of 1755, which killed more than 50 thousand people off the coast of Spain and Portugal, experts associate with the tidal effects of the Moon and the Sun on the earth's crust.
• The 1998 tsunami, which demolished everything in its path in the Papua New Guinea region, was caused by a landslide, the descent of which, in turn, provoked a moderately powerful earthquake ().
• The so-called "meteorological" tsunamis appear against the background of typhoons: after a sharp turn of the typhoon to the side, the formed wave can continue to move on its own (for example, the 2011 tsunami in the area of \u200b\u200bthe English city of Plymouth was caused by a storm in the Bay of Biscay).
• "Exclusive" tsunamis occur as a result of underwater volcanic eruptions (for example, the tsunami of 1883, formed after the eruption of the volcano Krakatoa), the fall of meteorites (in the documentary of the National Geographic channel, tsunami tracks are mentioned that survived in Texas after a meteorite fell 65 million years ago ) and man-made disasters.

Philippines, Malay Archipelago

The Philippine Islands are located in a seismically active area. And where there are earthquakes, there are tsunamis, and it is impossible to predict which of the seven thousand islands will be under attack this year. In 2013, these were the islands of Samar and Leyte, where waves up to 5 meters high claimed the lives of 10 thousand people and left about half a million local residents homeless. And the worst tsunami in the history of the Philippines happened in 1976, when an earthquake in the Cotabato oceanic trench hit the island of Mindanao, killing 8,000 people.

Guizot, Solomon Islands

The Solomon Islands - tiny patches of land scattered across the Pacific Ocean - are defenseless against the devastating force of the tsunami, which was confirmed in 2007, when the cities of Guizot and Noro completely disappeared under water.

Honshu, Japan

In 2012, an earthquake of 7.9 points, which occurred near the Philippine city of Guan, "rolled back" Japan with a tsunami a little more than half a meter high, covering the metropolitan region and Fukushima prefecture. Do not compare with the truly horrific destruction of 2011, when after the earthquake of magnitude 9, dubbed the "Great Earthquake of East Japan," came a tsunami up to 40 meters high, flooding an area with a total area of \u200b\u200b561 square kilometers.

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

Maldives

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

More dangerous than waves

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

Phuket, Thailand

A magnitude 9 underground earthquake brought death and destruction to the Thai island of Phuket in 2004. Despite the fact that the epicenter of the earthquake was in the Indian Ocean near the island of Sumatra, the subsequent tsunami reached the shores of Indonesia, Thailand, Sri Lanka, India and even South Africa. Three waves crashed in turn, numerous buildings, local residents and tourists were under water.

Hilo, Hawaii

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

Alaska, USA

Alaska had two powerful tsunamis in a row at once: in 1957 and 1958, giant waves covered the Andreanova Islands and Lituya Bay, respectively. In 1958, the shock of the wave was of such force that an entire strip of land was actually destroyed - the La Gaussian spit.

Kamchatka, Russia

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

Iquique, Chile

On May 22, 1960, near the Chilean city of Valdivia, there was an earthquake of magnitude 9.5, the largest earthquake in modern human history. And of course, the tsunami was not without: in addition to the damage caused directly to the Chilean coast by the 20-meter wave, it reached Alaska, the shores of the Kuril Islands, Japan and swept the Hawaiian city of Hilo, taking about 6 thousand people into the ocean. In 2014, residents of the port town of Iquique were evacuated, where after an earthquake of 8.2 points a two-meter tsunami wave came.

Acapulco, Mexico

Despite the fact that the 7.2 magnitude earthquake in April 2014 did not cause a tsunami, the Mexican resorts of Acapulco and Zihuatanejo are under constant threat of a sudden arrival of a killer wave. So if the ocean has suddenly receded from the coast - it's time to run.

Tsunami statistics

What to do if "covered"

• If you are in the coastal zone and feel an earthquake, leave the coast within 15-20 minutes.
• If you have not felt an earthquake, you can guess about the approaching tsunami by the strong ebb.
• While the tsunami is approaching, in no case do not waste your time: do not go down to look at the exposed seabed, do not shoot the wave on camera. Immediately look for a hill of at least 40 meters in height, preferably warning others about the danger, without sowing panic.
• If you are in a building (for example, a hotel) and there is no time left to search for a hill, go up to the upper floors of the building and barricade the windows and doors. Take a safe place: there should be no potentially dangerous objects near you (for example, cabinets that can fall, or mirrors that can break).
• If you cannot find a hill, try to hide behind any obstacle that is significant to the water (for example, a strong tall tree or large stone) and catch on to it so that you are not carried away by the water flow into the ocean.
• If a tsunami caught you on the open sea (for example, you were on a ship and you were thrown into the water by a wave), do not panic, take a breath, group up and cover your head with your hands. Having emerged to the surface, get rid of wet clothes as soon as possible and find any object that you can catch on (in 2004, in Thailand, one of the survivors managed to swim out, clinging to the tail of a crocodile, and the other - to a python).
• After the elements have raged off, do not return to the sea for 2-3 hours: a tsunami is a series of waves.

Photo: thinkstockphotos.com, flickr.com

Tsunamis are a series of destructive and highly dangerous waves resulting from seismic activity or other similar underwater incidents. Tsunamis have caused an incredible amount of damage in recent years. To survive a tsunami, you must be prepared, alert and calm. This article outlines the steps you need to know and follow to help you survive tsunami in the future.

Steps

Part 1

Become aware of potential hazards in advance. It is important to know in advance if there is a risk of a tsunami where you live. You are probably in danger if:

• Your home, school, or place of work is in the waterfront.
• Your home, school, or workplace is located in flat or slightly hilly terrain and near zero altitude. If you are not aware of how high above sea level your home, school and place of work are, find out. Some local authorities use altitude as the hazard level.
• There are warning signs indicating the area's susceptibility to tsunamis.
• Local authorities have released information on the potential threat of a tsunami.
• The natural boundaries of the sea, such as embankments and dunes, have been leveled for the development of the area.

1. Find out if your coastal region has been hit by tsunamis in the past. Go to the library or send a request to your local administration. FEMA (Federal Emergency Management Agency) has a website where you can learn about flood hazards online.

   Collect essential supplies in an easily accessible place. In the event of a tsunami (or other natural disaster) approaching, you will most likely need several items to survive, and quickly. It is extremely useful to get your essentials and survival kit well in advance:

   • Pack your essentials. Food, water, and a first aid kit are the bare minimum. Leave the set in a prominent, easily accessible place known to all household members. In addition, it will not hurt to leave a raincoat or other raincoat for each person near the set of essentials.
   • Assemble your personal survival kit for each family member, as well as a common set with shared things. Include the necessary medications for each family member. Don't forget vital things for your pets.

2. Develop an evacuation plan. To be in any way useful, an evacuation plan must be prepared in advance. When designing it, you should consider your family, place of work, school, and the wider community. If necessary, start developing a mass evacuation plan if your county does not have one. Take the lead in developing such a plan, and involve local authorities and other residents. The lack of an evacuation plan and warning systems puts you, your family and your entire community at increased risk of injury and death during and after the tsunami. Some of the mandatory items that must be present in every evacuation plan:

   Pay close attention to government warnings. If the local authorities take the time to report the danger, you should listen. Find out how they will warn the public about the danger so that you do not make a mistake and do not ignore the voiced warnings. Share this information with your family, friends, neighbors, and others. If the local authority publishes brochures, runs a website, or uses another source of information, call to distribute copies of the brochures or ask the local authority to do so.

Part 3

Throw away all your belongings. In the event of a tsunami, save lives, not things. Attempts to collect your belongings at the cost of precious time can hinder your salvation. Grab a set of essentials, warm clothes, family and leave immediately. Tsunami survivors acted quickly and generally did not try to save property.

Move inland and climb higher ground. The first thing you should do is move away from the coast, lagoons and other bodies of water towards higher elevations, and even hills or mountains. Don't stop until you've moved 3.2 kilometers inland or 30 meters above sea level.

Climb high. If you are trapped and unable to leave the shore, head up. This is certainly not the best solution, as the building can collapse, but if you have no other choice, choose a tall, sturdy, reliable building and climb it. Climb as high as you can, even to the roof.

Climb a sturdy tree. As a last resort, if you are trapped and unable to go inland or climb a tall building, find a strong and tall tree and try to climb it as high as you can. There is a danger that the tsunami will knock the tree down, so use this hideout only if other options are not available. The more powerful the tree, the higher you can climb it, the more comfortable it will be to rest on its branches (you can sit on the tree for many hours) and the more chances you will have to survive.

Such a phenomenon as a tsunami is as old and indomitable as the ocean. Eyewitness accounts of the terrible waves passed from mouth to mouth over time became legends, and about 2,000-2,500 years ago, written evidence began to appear. Among the probable reasons for the disappearance of Atlantis, which happened about 10,000 years ago, some of the researchers also call giant waves.

The word "tsunami" came to us from the Land of the Rising Sun. It is Japan that is most affected by the tsunami on the planet. She felt the dire consequences of the tsunami, which took many thousands of lives and caused enormous material damage. Tsunamis occur most often in the Pacific Ocean. In Russia, the Far Eastern shores - Kamchatka, the Kuril and Commander Islands and, in part, Sakhalin - are subject to regular attacks by giant waves.

What is a tsunami? A tsunami is a giant wave that captures a huge amount of water and raises it to great heights. Such waves are found in oceans and seas.

The occurrence of a tsunami

What can make ordinary water transform into such a destructive phenomenon of nature, endowed with a truly hellish power?

Tsunamis are long and high waves generated as a result of a powerful impact on the entire water column in the ocean or other body of water.

A common cause of catastrophic tsunamis is activity that occurs in the interior of the Earth. For the most part, water monsters provoke underwater earthquakes, so the study of this destructive phenomenon became possible only after the science of seismology appeared. A direct dependence of the wave strength on the strength of the earthquake was recorded. This is also influenced by the depth at which the shock occurred. Thus, only waves generated by high-energy earthquakes with a magnitude equal to or greater than 8.0 have significant destructive power.

Observations show that tsunamis occur when an area of \u200b\u200bthe sea or ocean surface is unexpectedly displaced in a vertical direction after the corresponding area of \u200b\u200bthe seabed is also displaced. Experts understand by tsunamis the so-called long-period (that is, far from each other) sea gravitational waves that suddenly appear in the seas and oceans precisely as a result of earthquakes, the centers of which are under the bottom.

The ocean floor shudders with colossal energy and produces huge faults and cracks that lead to subsidence or elevation of significant areas of the bottom. As if a giant underwater ridge directs the entire volume of water from the bottom to the surface itself, in all directions from the hearth. Oceanic water at the very surface may not absorb this energy at all, and vessels passing through them may simply not notice the serious disturbance of the waves. And in the depths, a future catastrophe begins to gain momentum and at breakneck speed rushes to the nearest shores.

Tsunamis also arise from explosions of underwater volcanoes, and as a result of bottom landslides. Coastal landslides, caused by the fall of a huge mass of rock into the water, can also cause a tsunami. Tsunamis with foci at great depths usually have a great destructive force. In addition, tsunamis are caused by water surges in bays caused by typhoons, storms and strong tides, which, as you can see, can explain the origin of the Japanese word "tsunami", which translates as "big wave in the harbor."

Giant waves have great speed and enormous energy, and therefore are capable of being thrown far out onto land. When approaching the shore, they deform and, rolling onto the shore, produce enormous destruction. In the open ocean, water monsters are low, not exceeding the heights of 2-3 m during the strongest earthquakes, but at the same time they have a considerable length, sometimes reaching 200-300 km, and an incredible propagation speed.

Approaching the coast, depending on the coastal bottom topography and the shape of the coastline, giant waves can grow up to several tens of meters. Getting into a shallow coastal zone, the wave changes - its height increases and, at the same time, the steepness of the leading front increases. When approaching the shore, it begins to overturn, creating a foaming, bubbling, high-altitude water stream crashing onto the shore. In such cases, river mouths are quite dangerous, along which monstrous waves can penetrate into the depths of the territory for a distance of several kilometers.

Tsunami - aftermath

1946, April 6 - the city of Hilo on the island of Hawaii experienced the full power of the disturbance of the water element. Residential buildings and administrative buildings were overturned, asphalted roads and beaches disappeared, the railway bridge was moved 300 meters upstream, and boulders weighing several tons were scattered throughout the devastated area. This was the result of a displacement of the ocean floor that occurred at a distance of 4,000 km from Hilo, in the Aleutian Islands.

The jolt gave rise to a series of tsunamis that swept across the Pacific Ocean at a speed of over 1,100 km / h, reaching a height of 7.5 to 15 m. The water element with all its fury pounced on the land and literally tore everything that it managed to embrace with its foamy embrace. Waves of this kind travel in all directions from the point where they appeared, at large intervals, but at an alarming speed. While the distance between normal sea waves is about 100 m, tsunami wave crests follow one another at intervals from 180 km to 1200 km. Therefore, the passage of each such wave is accompanied by a deceptive lull.

That is why, when the first wave in Hilo subsided, many residents descended to the shore to understand the scale of the destruction, and were washed away by the next giant wave. The eyewitness account said:

“The tsunami waves, steep and eddy, rushed to the shore. Between the ridges, the water receded from the coast, exposing reefs, coastal silt accumulations and the bottom of the bay up to 150 meters or more beyond the usual coastline. The water rolled back swiftly and violently, with a hiss, hiss and a crash. In several places, houses were washed away into the sea, in some places even huge rocks and concrete blocks were carried over the reefs. The people, along with their belongings, were carried out to sea, and only a few of them were rescued several hours later with the help of boats and life rafts dropped from aircraft. "

If the speed of a simple wind wave is capable of reaching 100 km / h, then tsunami waves move at the speed of a jet plane - from 900 to 1500 km / h. The lethal effect of the elements is determined not only by the power of the shock that generated the tsunami, but also by the terrain along which the giant wave is traveling, and the distance from the coast.

Of course, they are more dangerous on gentle coasts than on steep ones. When the bottom has cliffs, the oncoming waves will not rise to a sufficient height, but, hitting a gentle shore, they often reach the height of a six-story building or more. When these waves enter the bay or inlet in the form of a funnel, each of them brings a violent flood onto the shore. The height of the wave decreases only in closed expanding bays with a narrow entrance, and when it enters the river, the wave increases in size, increasing its destructive power.

The activity of a volcano in the water column gives an effect that can be compared with a strong earthquake. The greatest of all known giant waves was caused by the powerful eruption of the Krakatoa volcano in Indonesia in 1883, when a huge mass of rock was thrown into the air at a height of several kilometers and turned into a dust cloud that circled our planet three times.

Sea waves rushing one after another, up to 35 m high, drowned over 36,000 inhabitants of the nearby islands. They circled the entire globe and were spotted in the English Channel a day later. A military vessel, located off the coast of Sumatra, threw 3.5 km inland, where it got stuck in a thicket 9 m above sea level.

Another stunning case of an unusually high wave was recorded on July 9, 1958. After the earthquake in Alaska, a mass of ice and earth rocks with a volume of about 300 million cubic meters. m collapsed into the narrow and long bay of Lituya, causing a colossal wave splash on the opposite side of the bay, reaching almost 60 meters in height on certain parts of the coast. At that time, there were three small fishing boats in the bay.

“Despite the fact that the disaster took place 9 km from the ship's anchorage,” says an eyewitness, “everything looked terrible. Before the eyes of the shocked people, a huge wave rose up, engulfing the foot of the northern mountain. Then she swept across the bay, stripping trees from the slopes of the mountains, destroying the recently abandoned camp site of climbers; falling like a water mountain on the island of Cenotaphia, it swallowed up the old hut and, in the end, rolled over the highest point of the island, which was 50 m above sea level.

The wave spun Ulrich's ship, which, losing control, rushed at the speed of a galloping horse towards the Swanson and Wagner ships, still at anchor. To the horror of the people, the wave broke the anchor chains and dragged both ships like splinters, forcing them to overcome the most incredible journey that once fell to the lot of fishing vessels. Below the ship, Swanson said, they saw the tops of 12-meter trees and cliffs the size of a house. The wave literally threw people across the island into the open sea. "

Over the centuries, tsunamis have been the cause of terrible world catastrophes.

1737 - a case of a giant wave on the Kamchatka coast is described, when the waves washed away almost everything that was in the flooded zone. The small number of casualties was due only to the small number of residents.

1755 - due to the fault of a water monster, the city of Lisbon was completely wiped off the ground, the death toll was more than 40,000 people.

1883 - Tsunami caused colossal damage to the shores of the Indian Ocean, the death toll is more than 30,000.

1896 - the water element hit the shores of Japan, the death toll is more than 25,000.

1933 - The coast of Japan was damaged again, more than a thousand buildings were destroyed, 3,000 people died.

1946 - a powerful tsunami caused huge damage to the islands and the coast near the Aleutian Gap; total loss of more than $ 20 million.

1952 - the enraged ocean pounced on the northern coast of Russia, and although the waves were no more than 10 meters high, the damage was enormous.

1960 - the coast of Chile and surrounding territories suffered from the raid of giant waves, the damage was more than $ 200 million.

1964 - The Pacific coast is attacked by a tsunami that destroyed over $ 100,000 worth of buildings, roads and bridges.

In recent years, it has been established that giant waves can cause even "space guests" - meteorites that did not have time to burn up in the earth's atmosphere. Perhaps a few tens of millions of years ago, the fall of a giant meteorite led to a tsunami, which led to the death of the dinosaurs. Another, quite banal reason, may be the wind. He is able to cause a large wave only under the right circumstances - the air pressure must be correct.

However, the most important thing is that a person is capable of provoking a "man-made" tsunami himself. This is exactly what the Americans proved in the middle of the 20th century, having experienced an underwater nuclear explosion, which caused huge underwater disturbances and, as a result, the appearance of monstrous high-speed waves. Be that as it may, even now man cannot predict for sure the appearance of a tsunami and, what is even more terrible, stop it.

Tsunamis are huge sea waves that occur most often as a result of a strong underwater earthquake, when the bottom topography changes rapidly. It acts on the water like a huge piston, raising or lowering large masses of water, which scatter in all directions and form waves. Less commonly, a tsunami occurs as a result of the eruption of underwater or island volcanoes, when large masses of earth rocks fall into the water and underwater landslides.

In the open ocean, tsunami waves propagate at speeds of up to 1000 kilometers per hour. But there they are very shallow, since the wavelength (distance between the crests) reaches 100-300 kilometers, and the height from the bottom to the top is only a few meters, and therefore are not dangerous for navigation. When waves emerge in shallow water, near the coastline, their speed sharply decreases to 50-100 kilometers per hour, and the height increases. Off the coast, tsunamis can reach several tens of meters. The highest waves, up to 30-40 meters, are formed at steep shores, in wedge-shaped bays and at promontories protruding far into the ocean. Coastal areas with closed bays are less hazardous.

Tsunami warning system
The Tsunami Warning System (TWS) in the Pacific Ocean includes 25 states, including Russia, whose coastal regions are affected by the impact of the tsunami.

The Far East tsunami warning service is inter-regional and consists of three regional services: Kamchatka, Sakhalin regions and Primorsky Krai. In the Kamchatka region, tsunami warning is carried out by the tsunami station of the Kamchatka Territorial Administration for Hydrometeorology and Environmental Monitoring and the seismic station of the Institute of Physics of the Earth of the Russian Academy of Sciences.

The Pacific Tsunami Warning Center (TCNC) is located in the Hawaiian Islands of the United States in Honolulu.

Remote earthquake warning
When a strong earthquake occurs in the Pacific Ocean, the Pacific Center informs all TWS members of the time, coordinates and strength of the earthquake. The first information about the tsunami comes from sea level observation stations located in the immediate vicinity of the epicenter of the earthquake. If confirmation of the formation of waves is received, then in the event of a devastating tsunami approach and to bring the operational services to a state of readiness, the TTSPC sends a warning.

The tsunami station, after analyzing this information and with a real threat of tsunami to Kamchatka, announces the alarm.

Near earthquake warning
In the event of a strong nearby earthquake off the coast of Kamchatka and a possible threat of a tsunami, the seismic station announces an alarm and transmits it according to the notification scheme. The tsunami station spreads this message throughout the region, as well as beyond, calculates the tsunami parameters (the height and time of arrival of the waves), analyzes the information about the observed heights of their waves received from hydrometeorological stations, and transmits the alarm clearing. The tsunami station also transmits information about the height of waves on the peninsula to the TCPC, on the basis of which the Center makes an assessment of the tsunami hazard to other regions of the Pacific Ocean.

• Signs of a tsunami threat:
  
  
  • a strong earthquake with a magnitude of 6 points or more - when vibrations of the earth's surface interfere with walking, buildings stagger, pendant lamps swing strongly, dishes fall and break, objects fall from shelves, furniture may move. Strong fluctuations last 20 seconds or more;
  • a sudden rapid departure of the water from the coast for a considerable distance and the bottom drying out, while the sound of the surf stops (do not try to go down to the water to check this!). The further the sea recedes, the higher the tsunami waves can be;
  • rapid drop in sea level at high tide or rise at low tide;
  • unusual drift of ice and other floating objects, formation of cracks in the fast ice;
  • huge uplifts at the edges of stationary ice and reefs, the formation of swells, currents.
• Your family's action plan.
• In case of evacuation, you need to keep ready a flashlight, matches, some food, spare clothes along with documents, packed in a backpack.
• How to get to the nearest safe area.
• In populated areas, civil defense forces and other rescue teams will try to save your life. Help them in everything.

What to do in case of a tsunami threat

• If you are out of earshot of a warning or in hard-to-reach coastal areas, then if you find signs of a threat, remember that tsunami waves can reach the coast 15-20 minutes after the start of an earthquake. During this time, protective measures must be taken immediately:
  
  
  • it is necessary to go from the coast to the depths of the land to a hill, where the height above sea level is 30-40 meters. If you are on the shore of a closed bay, then this height must be at least 5 meters; it is necessary to leave the coast up the slopes, and not along the river valleys, since the tsunami penetrates the farthest into the land through the rivers;
  • in the absence of a hill nearby, it is necessary to leave the coast for at least 2-3 kilometers.
• If within 1-2 hours after a strong earthquake the waves did not hit the coast, then the tsunami, as a rule, is no longer threatened.
• You should not return to the shore after the first wave earlier than 3 hours, since the first wave is usually followed by others, with the second and third waves reaching the greatest strength.
• Vessels in coastal waters, standing in an open roadstead or in a bay with a wide entrance, and even more so at berths, should go into the ocean beyond the 50-meter isobath; keep course - perpendicular to the coastline.
• If there is a warning system in your area, wait for the alarm clearing signal.

The rules of behavior during a tsunami should be known to everyone who lives in the area where this natural phenomenon can occur. It is always worth remembering that it is fraught with the most destructive consequences.

What is a Tsunami?

The main thing to remember is that if you follow the rules of behavior during a tsunami, you will save the life of yourself and your loved ones.

After all, this global It represents waves of enormous height that appear due to a powerful underwater earthquake. This usually happens when the bottom topography changes. It acts on the water like a huge piston that lifts and drops large masses of water. Scattering to the sides, they form destructive waves.

Sometimes there are others For example, it can appear due to the eruption of island, less often underwater volcanoes, as well as the simultaneous collapse of large masses of earth rocks into the water. This happens with underwater landslides.

Spread

The rules for a tsunami should be well remembered by everyone, because this natural disaster spreads very quickly. In the open ocean, the speed of a tsunami wave can reach thousands of kilometers. But there they are not as dangerous as on the coast, because they are flatter.

The distance between the ridges can range from one hundred to three hundred kilometers. And the height from the sole to the top is only a few meters. Therefore, tsunamis almost never pose a danger to ships and vessels. First of all, coastal residents should know the rules of behavior during a tsunami.

The element is coming

When approaching the coast, the speed of the waves drops sharply, to about several tens of kilometers per hour. But the height, on the contrary, increases. In shallow waters, the height of a tsunami can rise to forty meters. It is especially dangerous near steep banks, as well as in wedge-shaped bays, near capes protruding far into the ocean.

Also, a tsunami can penetrate inland, moving along river valleys. The boron phenomenon is formed in their channels. This is the name of a high water shaft, which moves upstream. The coastal areas with closed bays are the least dangerous for the impact of tsunamis.

Where do tsunamis occur?

It is now known for certain that the rules of conduct during a tsunami are most relevant for the inhabitants of the Pacific coast. After all, it is in this ocean that about 80% of the most powerful earthquakes occur. Therefore, the coast and Kamchatka are considered to be the most exposed to this element. Here, most of the residents clearly know the rules of conduct in the event of a tsunami threat. Even if you don't live in these places, you need to remember them if you go to travel along the eastern coast of Russia.

Not far from these places there is a tsunamigenic zone, from where the most powerful waves come. It is located in the Aleutian and Kuril-Kamchatka troughs. Information about the tsunami in Kamchatka, which occurred in 1737, has survived to this day.

Notification system

When it becomes known that an earthquake has occurred in the Pacific Ocean, the Pacific Center sends the corresponding information to all tsunami warning services. It immediately becomes known about the coordinates and strength of the earthquake, as well as the probability of a tsunami and its estimated strength.

The first to know about the approaching tsunami at sea level observation stations. They are located in the immediate vicinity of the epicenter of the earthquake. When a confirmation of the formation of waves of anomalous height is received, the residents of the areas that they may affect are warned, all operational services are put on alert. It is especially important to know the tsunami rules of conduct in these moments.

When it becomes obvious that there is a real threat of high wave propagation, an alarm is announced. All operational services receive the corresponding messages. In the Kamchatka Territory, this is done with the help of a special OXION system. This modern system operates in fourteen of the most tsunami-prone communities in Kamchatka. Operational services immediately bring information to the public. For this, there is, in particular, radio broadcasting points, sirens, loudspeakers are listed briefly, point by point, the rules of behavior during a tsunami.

Tsunami Threats

It is important not only to be guided by the messages of the operational rescue services, but also to be aware of the signs that may indicate the approach of this element.

The real threat of a tsunami exists when a powerful earthquake (at least 6 points) occurs. It is not difficult to define it. The vibration of the earth's surface is so strong that it is difficult for a person to walk, buildings stagger, pendant lamps swing in apartments, dishes fall out of cabinets and break, objects fall from shelves, even powerful furniture can move around the house or office. Such strong fluctuations should last for at least 20 seconds.

Another sign of an approaching tsunami is the sudden departure of water from the coast for a considerable distance. In this case, the bottom is exposed. Remember, the further the sea recedes, the higher and stronger the tsunami waves can be. It is also worth worrying if the sea level is too low at high tide and too high at low tide, the ice begins to drift in an unusual way, cracks form in the fast ice, and floating objects move along an abnormal trajectory. In addition, it is worth paying attention to the formation of currents, reverse faults at the edges of stationary ice and reefs.

How to prepare for a tsunami?

In order for the tsunami not to catch you by surprise, you must always have at hand in an easily accessible place the items necessary in case of an emergency evacuation. These are matches, a small amount of food, a flashlight, documents, spare clothes. All of this should be packed into a secure backpack or waterproof bag.

Also, you always need to evaluate in what ways and ways you can quickly get to a safe place.

Tsunami Action

You should follow the rules of conduct during a tsunami so as not to get hurt. In coastal settlements, having received an alarm, you should immediately leave your homes and offices. It is necessary to leave the premises in accordance with the evacuation plan.

If you find yourself in the zone of hearing a warning or in hard-to-reach areas, remember that a tsunami can reach the coast within 10-20 minutes after the start of an earthquake. This is the time you have to take the necessary protective measures.

You need to quickly leave the coast inland. Best of all on a hill, so that the height above sea level is at least 30-40 meters. If you are in a closed bay, then the height may be limited to five meters. From the coast, you should go along the slopes, and not along the river valleys.

If there is no hill in the area, you need to move away from the coast for at least two to three kilometers. If two hours have passed after the earthquake, and the waves have not hit the shore, most likely the tsunami threat has passed. But it is better to wait until the alarm is cleared if there is a warning system in your area.

If the tsunami wave has reached the coast, you should return to the coast no earlier than three hours later. Indeed, after the first wave, several more often follow.

Vessels in coastal waters must sail into the open ocean keeping a course perpendicular to the coastline.