Long and high waves. The biggest waves in the world

When I read about the wave height caused by the tsunami in 1958, I couldn’t believe my eyes. I checked it once, twice. It's the same everywhere. No, they probably made a mistake with the comma, and everyone is copying each other. Or maybe in units of measurement?
Well, how could it be otherwise, do you think there could be a wave from a tsunami 524 meters high? HALF A KILOMETER!
Now we will find out what really happened there...

Here's what an eyewitness writes:

“After the first shock, I fell out of bed and looked towards the beginning of the bay, where the noise was coming from. The mountains trembled terribly, stones and avalanches rushed down. And the glacier in the north was especially striking; it is called the Lituya glacier. Usually, it is not visible from where I was anchored. People shake their heads when I tell them that I saw him that night. I can't help it if they don't believe me. I know that the glacier is not visible from where I was anchored in Anchorage Bay, but I also know that I saw it that night. The glacier rose into the air and moved forward until it became visible. He must have risen several hundred feet. I'm not saying it was just hanging in the air. But he was shaking and jumping like crazy. Large pieces of ice fell from its surface into the water. The glacier was six miles away, and I saw large chunks falling off it like a huge dump truck. This continued for some time - it is difficult to say how long - and then suddenly the glacier disappeared from view and a large wall of water rose above this place. The wave went in our direction, after which I was too busy to say what else was happening there.”

On July 9, 1958, an unusually severe disaster occurred in Lituya Bay in southeastern Alaska. In this bay, which extends more than 11 km into the land, geologist D. Miller discovered a difference in the age of trees on the hillside surrounding the bay. Based on tree rings, he estimated that over the past 100 years, waves with a maximum height of several hundred meters have occurred in the bay at least four times. Miller's conclusions were viewed with great distrust. And so, on July 9, 1958, a strong earthquake occurred on the Fairweather fault north of the bay, causing the destruction of buildings, the collapse of the coast, and the formation of numerous cracks. And a huge landslide on the mountainside above the bay caused a wave of record height (524 m), which swept at a speed of 160 km/h across the narrow, fjord-like bay.

Lituya is a fjord located on the Fairweather Fault in the northeastern part of the Gulf of Alaska. It is a T-shaped bay 14 kilometers long and up to three kilometers wide. The maximum depth is 220 m. The narrow entrance to the bay is only 10 m deep. Two glaciers descend into Lituya Bay, each of which is about 19 km long and up to 1.6 km wide. During the century preceding the events described, waves over 50 meters high had already been observed in Lituya several times: in 1854, 1899 and 1936.

The 1958 earthquake caused a subaerial rockfall at the mouth of the Gilbert Glacier in Lituya Bay. This landslide caused more than 30 million cubic meters of rock to fall into the bay and create a megatsunami. This disaster killed 5 people: three on Hantaak Island and two more were washed away by a wave in the bay. In Yakutat, the only permanent settlement near the epicenter, infrastructure was damaged: bridges, docks and oil pipelines.

After the earthquake, a study was carried out of a subglacial lake located northwest of the bend of the Lituya Glacier at the very beginning of the bay. It turned out that the lake dropped by 30 meters. This fact served as the basis for another hypothesis of the formation of a giant wave more than 500 meters high. Probably, during the glacier's descent, a large volume of water entered the bay through an ice tunnel under the glacier. However, the runoff of water from the lake could not be the main cause of the megatsunami.

A huge mass of ice, stones and earth (volume of about 300 million cubic meters) rushed down from the glacier, exposing the mountain slopes. The earthquake destroyed numerous buildings, cracks appeared in the ground, and the coastline slid. The moving mass fell on the northern part of the bay, filled it up, and then crawled onto the opposite slope of the mountain, tearing off its forest cover to a height of more than three hundred meters. The landslide generated a giant wave that literally swept Lituya Bay towards the ocean. The wave was so great that it swept entirely over the entire sandbank at the mouth of the bay.

Eyewitnesses to the disaster were people on board the ships that dropped anchor in the bay. The terrible shock threw them all out of their beds. Jumping to their feet, they could not believe their eyes: the sea rose. “Giant landslides, raising clouds of dust and snow in their path, began to run along the slopes of the mountains. Soon their attention was attracted by an absolutely fantastic sight: the mass of ice of the Lituya glacier, located far to the north and usually hidden from view by the peak that rises at the entrance to the bay, seemed to rise above the mountains and then majestically collapsed into the waters of the inner bay. It all seemed like some kind of nightmare. Before the eyes of the shocked people, a huge wave rose up and swallowed the foot of the northern mountain. After that, she swept across the bay, tearing trees off the mountain slopes; falling like a water mountain onto the island of Cenotaph... rolled over the highest point of the island, rising 50 m above sea level. This entire mass suddenly plunged into the waters of the narrow bay, causing a huge wave, the height of which apparently reached 17-35 m. Its energy was so great that the wave rushed furiously across the bay, sweeping the slopes of the mountains. In the inner basin, the impact of the waves on the shore was probably very strong. The slopes of the northern mountains facing the bay were bare: where there had once been dense forest there were now bare rocks; This pattern was observed at altitudes of up to 600 meters.

One longboat was lifted high, easily carried across the sandbar and dropped into the ocean. At that moment, when the longboat was carried over the sandbank, the fishermen on it saw standing trees beneath them. The wave literally threw people across the island into the open sea. During a nightmare ride on a giant wave, the boat pounded against trees and debris. The longboat sank, but the fishermen miraculously survived and were rescued two hours later. Of the other two longboats, one successfully withstood the wave, but the other sank, and the people on it went missing.

Miller found that the trees growing at the upper edge of the exposed area, just below 600 m above the bay, were bent and broken, their fallen trunks pointing towards the top of the mountain, but the roots were not torn from the soil. Something pushed these trees up. The enormous force that accomplished this could not have been anything other than the top of a gigantic wave that swept over the mountain that July evening in 1958.”

Mr. Howard J. Ulrich, in his yacht, which is called "Edri", entered the waters of Lituya Bay about eight in the evening and anchored in nine meters of water in a small cove on the southern shore. Howard says that suddenly the yacht began to rock violently. He ran out onto the deck and saw how in the northeastern part of the bay the rocks began to move due to the earthquake and a huge block of rock began to fall into the water. About two and a half minutes after the earthquake, he heard a deafening sound from the destruction of rock.

“We definitely saw that the wave came from Gilbert Bay, just before the earthquake ended. But at first it was not a wave. At first it was more like an explosion, as if the glacier was splitting into pieces. The wave grew from the surface of the water, at first it was almost invisible, who would have thought that then the water would rise to a height of half a kilometer.”

Ulrich said that he observed the entire process of development of the wave, which reached their yacht in a very short time - something like two and a half to three minutes from the time it could first be noticed. “Since we didn’t want to lose the anchor, we pulled out the entire anchor chain (about 72 meters) and started the engine. Halfway between the northeastern edge of Lituya Bay and Cenotaf Island, a thirty-meter-high wall of water could be seen that stretched from one shore to the other. When the wave approached the northern part of the island, it split into two parts, but after passing the southern part of the island, the wave became one again. It was smooth, only there was a small ridge on top. When this mountain of water approached our yacht, its front was quite steep and its height was from 15 to 20 meters. Before the wave arrived at the place where our yacht was located, we did not feel any drop in water or other changes, with the exception of a slight vibration that was transmitted through the water from tectonic processes that began to operate during the earthquake. As soon as the wave approached us and began to lift our yacht, the anchor chain began to crack loudly. The yacht was carried towards the southern shore and then, on the reverse course of the wave, towards the center of the bay. The top of the wave was not very wide, from 7 to 15 meters, and the trailing front was less steep than the leading one.

As the giant wave swept past us, the surface of the water returned to its normal level, but we could see a lot of turbulence around the yacht, as well as random waves six meters high that moved from one side of the bay to the other. These waves did not create any noticeable movement of water from the mouth of the bay to its northeastern part and back.”

After 25-30 minutes the surface of the bay calmed down. Near the banks one could see many logs, branches and uprooted trees. All this rubbish slowly drifted towards the center of Lituya Bay and towards its mouth. In fact, during the entire incident, Ulrich did not lose control of the yacht. When the Edri approached the entrance to the bay at 11 pm, a normal current could be observed there, which is usually caused by the daily ebb of ocean water.

Other eyewitnesses to the disaster, the Swenson couple on a yacht called the Badger, entered Lituya Bay around nine in the evening. First, their ship approached Cenotaf Island, and then returned to Anchorage Bay on the northern shore of the bay, not far from its mouth (see map). The Svensons anchored at a depth of about seven meters and went to bed. William Swenson's sleep was interrupted by strong vibrations from the yacht's hull. He ran to the control room and began to time what was happening. A little over a minute after William first felt the vibration, and probably just before the end of the earthquake, he looked towards the northeastern part of the bay, which was visible against the backdrop of Cenotaph Island. The traveler saw something that he initially mistook for the Lituya glacier, which rose into the air and began to move towards the observer. “It seemed like this mass was solid, but it jumped and swayed. In front of this block, large pieces of ice were constantly falling into the water.” After a short time, “the glacier disappeared from view, and instead of it a large wave appeared in that place and went in the direction of the La Gaussi spit, just where our yacht was anchored.” In addition, Svenson noticed that the wave flooded the shore at a very noticeable height.

When the wave passed Cenotaf Island, its height was about 15 meters in the center of the bay and gradually decreased near the shores. She passed the island approximately two and a half minutes after she was first seen, and reached the yacht Badger another eleven and a half minutes (approximately). Before the wave arrived, William, like Howard Ulrich, did not notice any drop in water level or any turbulent phenomena.

The yacht "Badger", which was still at anchor, was lifted by a wave and carried towards the La Gaussie spit. The stern of the yacht was below the crest of the wave, so that the position of the vessel resembled a surfboard. Svenson looked at that moment at the place where the trees growing on the La Gaussy spit should have been visible. At that moment they were hidden by water. William noted that above the tops of the trees there was a layer of water equal to approximately two times the length of his yacht, about 25 meters. Having passed the La Gaussi spit, the wave subsided very quickly.

In the place where Swenson's yacht was moored, the water level began to drop, and the ship hit the bottom of the bay, remaining afloat not far from the shore. 3-4 minutes after the impact, Swenson saw that water continued to flow over the La Gaussie Spit, carrying logs and other debris from forest vegetation. He wasn't sure it wasn't a second wave that could have carried the yacht across the spit into the Gulf of Alaska. Therefore, the Svenson couple left their yacht, moving onto a small boat, from which they were picked up by a fishing boat a couple of hours later.

There was a third vessel in Lituya Bay at the time of the incident. It was anchored at the entrance to the bay and was sunk by a huge wave. None of the people on board survived; two were believed to have died.

What happened on July 9, 1958? That evening, a huge rock fell into the water from a steep cliff overlooking the northeastern shore of Gilbert Bay. The collapse area is marked on the map in red. The impact of an incredible mass of stones from a very high altitude caused an unprecedented tsunami, which wiped out from the face of the earth all life that was located along the entire coast of Lituya Bay right up to the La Gaussi spit. After the wave passed along both shores of the bay, there was not only no vegetation left, but even no soil; there was bare rock on the surface of the shore. The damaged area is shown in yellow on the map.

The numbers along the shore of the bay indicate the height above sea level of the edge of the damaged land area and approximately correspond to the height of the wave that passed here.

What causes the appearance of most waves in the oceans and seas, about the destructive energy of waves and about the most gigantic waves and the largest tsunamis that man has ever seen.

The highest wave

The formation of waves in the ocean follows certain patterns.

The height and length of the wave depend on the wind speed, the duration of its influence, and the area covered by the wind. There is a correspondence: the greatest height of a wave is one-seventh of its length. For example, a strong breeze generates waves up to 3 meters high, an extensive hurricane - on average up to 20 meters. And these are truly monstrous waves, with roaring foam caps and other special effects.

The highest normal wave of 34 meters was recorded in the Agulhas Current (South Africa) in 1933 by sailors on board the American ship Ramapo. Waves of this height are called “rogue waves”: even a large ship can easily get lost in the gaps between them and die.

In theory, the height of normal waves can reach 60 meters, but such waves have not yet been recorded in practice.

In addition to the usual wind origin, there are other mechanisms of wave formation. The cause and epicenter of the birth of a wave can be an earthquake, a volcanic eruption, a sharp change in the coastline (landslides), human activity (for example, nuclear weapons testing) and even the fall of large celestial bodies - meteorites - into the ocean.

The biggest wave

The worst tsunamis are caused by significant disturbances in the topography of the seabed, such as tectonic faults or shifts, due to which billions of tons of water begin to abruptly move tens of thousands of kilometers at the speed of a jet aircraft. Disasters occur when this entire mass slows down on the shore, and its colossal energy first goes to increase in height, and ultimately collapses onto the land with all its power, a wall of water.

The most tsunami-hazardous places are bays with high banks. These are real tsunami traps. And the worst thing is that a tsunami almost always comes suddenly: in appearance, the situation at sea can be indistinguishable from low tide or high tide, an ordinary storm, people do not have time or do not even think about evacuating, and suddenly they are overtaken by a giant wave. Not many places have developed a warning system.

Territories with increased seismic activity are areas of particular risk in our time. No wonder the name of this natural phenomenon is of Japanese origin.

The worst tsunami in Japan

Another of the highest waves in Japanese history hit the western island of Hokkaido in 1741 as a result of a volcanic eruption; its height is approximately 90 meters.

The biggest tsunami in the world

And the record holder for wave height is named “Lituya”. This tsunami, which swept through Lituya Bay in Alaska at a speed of 160 km/h in 1958, was triggered by a giant landslide. The wave height was estimated at 524 meters.

Meanwhile, the sea is not always dangerous. There are “friendly” seas. For example, not a single river flows into the Red Sea, but it is the cleanest in the world. .
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The most common cause of waves in oceans and seas is wind: gusts of air move surface layers of water at a certain speed. Thus, the wind can accelerate the wave at a speed of 95 km/h, and the raised water column can reach 300 meters in length. Such waves are capable of covering gigantic distances, but, as a rule, wave energy is extinguished in the ocean, being consumed long before land. When the wind subsides, the waves in the ocean become smaller and smoother.

Patterns of wave formation

The length and height of the wave depend not only on the wind speed. The influence of the duration of exposure to wind is also great, and it also matters how much of the territory was covered by it. There is a natural correspondence: the maximum wave height is 1/7 of its length. For example, a breeze with a strength above average creates waves whose height reaches 3 meters, a hurricane, which has a large area, raises waves to approximately 20 m.

Formation of a large wave

In 1933, sailors of the American ship Ramapo in the South African Agulhas Current noted the highest normal wave - it reached a height of 34 m. Waves of this height are popularly called "rogue waves", since even a large ship can easily fall through and get lost in the distances between their ridges. Theoretically, the height of such ordinary waves can reach 60 m, but in practice such waves have never been recorded.

In addition to the normal, that is, wind-driven origin of waves, other causes of wave generation are known:

• earthquake
• volcanic eruption
• large meteorites falling into the ocean
• landslides leading to a sharp change in the coastline
• nuclear weapons testing or other human activity

Tsunami

Tsunamis have the largest waves. In essence, it is a serial wave caused by a certain impulse of enormous power. Tsunami waves are quite long; gaps between peaks can reach more than 10 km. For this reason, a tsunami in the open ocean is not a great danger, since the height of the waves rarely reaches 20 cm, only in some (record) cases they can reach 1.5 m. But the speed of a tsunami develops enormously - the waves travel at a speed of 800 km/h. In the open sea, such waves are almost impossible to notice from the ship. Tsunami waves acquire their monstrous strength as they approach the coastline. Reflecting from the shore, the waves are compressed in length, but their destructive energy does not disappear anywhere. As a result, the wave amplitude - their height - increases. Of course, such waves are much more dangerous than wind waves, since they reach much higher heights.

The most terrifying tsunamis are caused by significant disturbances in the topography of the ocean floor. These can be tectonic shifts or faults, during which billions of tons of water move at the speed of a jet plane over enormous distances (tens of thousands of kilometers). And this happens suddenly, immediately. A catastrophe is inevitable when a multibillion-dollar mass of water reaches the shore. Then the colossal energy of the waves is first directed to increase the amplitude, and then hits the coast with an entire powerful wall of water.

Bays with high shores are most often susceptible to dangerous tsunamis. Such places are real traps for serial waves. What is characteristic and at the same time scary is that a tsunami almost always strikes suddenly, visually the sea can be the same as during low tides, high tides or an ordinary storm, so people do not even think about timely evacuation. Unfortunately, special warning systems for the approach of giant waves have not been developed everywhere.

Seismically active areas are also tsunami risk zones. The word “tsunami” itself is of Japanese origin, since earthquakes are very frequent here and waves of different scales and sizes constantly attack the islands. There are also real giants among them, and they lead to human casualties. The 2011 earthquake, which occurred in the east of Honshu Island, generated a powerful tsunami up to 40 m high. Japan has never known such earthquakes. The disaster had horrific consequences: the monstrous waves dealt severe blows along the entire eastern coast of the island, claiming the lives of over 15 thousand people along with the earthquake; several thousand people are considered missing to this day.

A large-scale disaster on the islands of Java and Sumatra in 2004 turned into a tsunami, which was generated by a powerful earthquake in the Indian Ocean. According to various sources, from 200 to 300 thousand people died - that’s 1/3 of a million. Today, the Indian Ocean tsunami is recognized as the most destructive in the world.

The record holder for wave amplitude was tsunami "Lituya" which happened in 1958. It swept across Lituya Bay in Alaska at a speed of 160 km/h. The cause of the world's highest tsunami was a gigantic landslide. The wave height reached 524 m.

At the end of December 2004, one of the most powerful earthquakes in the last half century occurred near the island of Sumatra, located in the Indian Ocean. Its consequences turned out to be catastrophic: due to the displacement of lithospheric plates, a huge fault was formed, and a large amount of water rose from the ocean floor, which, at a speed reaching one kilometer per hour, began to rapidly move throughout the Indian Ocean.

As a result, thirteen countries were affected, about a million people were left without a roof over their heads, and more than two hundred thousand were killed or missing. This disaster turned out to be the worst in human history.

Tsunamis are long and high waves that appear as a result of a sharp displacement of the lithospheric plates of the ocean floor during underwater or coastal earthquakes (the length of the shaft is from 150 to 300 km). Unlike ordinary waves that appear as a result of the impact of a strong wind on the water surface (for example, a storm), a tsunami wave affects water from the bottom to the surface of the ocean, which is why even low-level water can often lead to disasters.

It is interesting that for ships located in the ocean at this time, these waves are not dangerous: most of the disturbed water is located in its depths, the depth of which is several kilometers - and therefore the height of the waves above the surface of the water ranges from 0.1 to 5 meters. Approaching the coast, the back of the wave catches up with the front, which at this time slows down slightly, grows to a height of 10 to 50 meters (the deeper the ocean, the larger the swell) and a crest appears on it.

It should be taken into account that the approaching shaft develops the highest speed in the Pacific Ocean (it ranges from 650 to 800 km/h). As for the average speed of most waves, it ranges from 400 to 500 km/h, but there have been cases when they accelerated to speeds of up to a thousand kilometers (the speed usually increases after the wave passes over a deep-sea trench).

Before hitting the coast, the water suddenly and quickly moves away from the shoreline, exposing the bottom (the further it recedes, the higher the wave will be). If people do not know about the approaching disaster, instead of going as far from the shore as possible, they instead run to collect shells or pick up fish that did not have time to go to sea. And just a few minutes later, a wave that arrived here at enormous speed does not leave them the slightest chance of salvation.

It must be taken into account that if a wave rolls onto the coast from the opposite side of the ocean, the water does not always recede.

Ultimately, a huge mass of water floods the entire coastline and goes inland to a distance of 2 to 4 km, destroying buildings, roads, piers and leading to the death of people and animals. In front of the shaft, clearing the way for the water, there is always an air shock wave, which literally explodes buildings and structures that are in its path.

It is interesting that this deadly natural phenomenon consists of several waves, and the first wave is far from the largest: it only wets the coast, reducing the resistance for the following waves, which often do not arrive immediately, and at intervals of two to three hours. The fatal mistake of people is their return to the shore after the first attack of the elements has left.

Reasons for education

One of the main reasons for the displacement of lithospheric plates (in 85% of cases) is underwater earthquakes, during which one part of the bottom rises and the other sinks. As a result, the ocean surface begins to oscillate vertically, trying to return to the initial level, forming waves. It is worth noting that underwater earthquakes do not always lead to the formation of a tsunami: only those where the source is located a short distance from the ocean floor, and the shaking was at least seven points.

The reasons for the formation of a tsunami are quite different. The main ones include underwater landslides, which, depending on the steepness of the continental slope, are capable of covering enormous distances - from 4 to 11 km strictly vertically (depending on the depth of the ocean or gorge) and up to 2.5 km if the surface is slightly inclined.

Large waves can be caused by huge objects falling into the water - rocks or blocks of ice. Thus, the largest tsunami in the world, the height of which exceeded five hundred meters, was recorded in Alaska, in the state of Lituya, when, as a result of a strong earthquake, a landslide came down from the mountains - and 30 million cubic meters of stones and ice fell into the bay.

The main causes of tsunamis also include volcanic eruptions (about 5%). During strong volcanic explosions, waves are formed, and water instantly fills the vacated space inside the volcano, as a result of which a huge shaft is formed and begins its journey.

For example, during the eruption of the Indonesian volcano Krakatoa at the end of the 19th century. The “rogue wave” destroyed about 5 thousand ships and caused the death of 36 thousand people.

In addition to the above, experts identify two more possible causes of a tsunami. First of all, this is human activity. For example, in the middle of the last century, the Americans carried out an underwater atomic explosion at a depth of sixty meters, causing a wave about 29 meters high, although it did not last long and fell, having covered a maximum of 300 meters.

Another reason for the formation of a tsunami is the fall of meteorites with a diameter of more than 1 km into the ocean (the impact of which is strong enough to cause a natural disaster). According to one version of scientists, several thousand years ago it was meteorites that caused the strongest waves that became the causes of the largest climate disasters in the history of our planet.

Classification

When classifying tsunamis, scientists take into account a sufficient number of factors of their occurrence, including meteorological disasters, explosions and even ebbs and flows, and low wave surges with a height of about 10 cm are included in the list.
By shaft strength

The strength of the shaft is measured by taking into account its maximum height, as well as how catastrophic the consequences it caused and, according to the international IIDA scale, there are 15 categories, from -5 to +10 (the more victims, the higher the category).

By intensity

According to intensity, “rogue waves” are divided into six points, which make it possible to characterize the consequences of the disaster:

1. Waves with a category of one point are so small that they are recorded only by instruments (most people do not even know about their presence).
2. Two-point waves are capable of slightly flooding the shore, so only specialists can distinguish them from the fluctuations of ordinary waves.
3. The waves, which are classified as force three, are strong enough to throw small boats onto the coast.
4. Force four waves can not only wash large sea vessels ashore, but also throw them onto the coast.
5. Point five waves are already acquiring catastrophe proportions. They are capable of destroying low buildings, wooden buildings, and causing casualties.
6. As for force six waves, the waves that wash up on the coast completely devastate it along with the adjacent lands.

By number of victims

Based on the number of deaths, five groups of this dangerous phenomenon are distinguished. The first includes situations where no deaths were recorded. The second - waves that resulted in the death of up to fifty people. Shafts belonging to the third category cause the death of fifty to one hundred people. The fourth category includes “rogue waves,” which killed from one hundred to a thousand people.

The consequences of a tsunami belonging to the fifth category are catastrophic, since they entail the death of more than a thousand people. Typically, such disasters are typical for the waters of the deepest ocean in the world, the Pacific, but they often occur in other parts of the planet. This applies to the disasters of 2004 near Indonesia and 2011 in Japan (25 thousand dead). “Rogue waves” have also been recorded in history in Europe, for example, in the middle of the 18th century, a thirty-meter wave hit the coast of Portugal (from 30 to 60 thousand people died during this disaster).

Economic damage

As for the economic damage, it is measured in American dollars and calculated taking into account the costs that must be allocated for the restoration of the destroyed infrastructure (lost property and destroyed houses are not taken into account, because they relate to the country’s social expenses).

Economists distinguish five groups based on the size of losses. The first category includes waves that did not cause much harm, the second - with losses of up to 1 million dollars, the third - up to 5 million dollars, and the fourth - up to 25 million dollars.

Damage from waves, classified as group five, exceeds 25 million. For example, losses from two major natural disasters, which occurred in 2004 near Indonesia and in 2011 in Japan, amounted to about $250 billion. It is also worth taking into account the environmental factor, since the waves, which led to the death of 25 thousand people, damaged a nuclear power plant in Japan, causing an accident.

Disaster recognition systems

Unfortunately, rogue waves often appear so unexpectedly and move at such high speeds that it is extremely difficult to determine their appearance, and therefore seismologists often fail to cope with the task assigned to them.

Basically, disaster warning systems are built on the processing of seismic data: if there is a suspicion that an earthquake will have a magnitude of more than seven points, and its source will be located on the ocean (sea) floor, then all countries that are at risk receive warnings of approaching huge waves.

Unfortunately, the 2004 disaster occurred because almost all surrounding countries did not have an identification system. Despite the fact that about seven hours passed between the earthquake and the surging shaft, the population was not warned of the approaching disaster.

To determine the presence of dangerous waves in the open ocean, scientists use special hydrostatic pressure sensors that transmit data to a satellite, which allows them to quite accurately determine the time of their arrival at a particular point.

How to survive during a disaster

If it so happens that you find yourself in an area where there is a high probability of deadly waves occurring, you must remember to follow the forecasts of seismologists and remember all the warning signals of an approaching disaster. It is also necessary to find out the boundaries of the most dangerous zones and the shortest roads along which you can leave the dangerous territory.

When you hear a signal warning of approaching water, you should immediately leave the danger area. Experts will not be able to say exactly how much time there is to evacuate: it could be a couple of minutes or several hours. If you do not have time to leave the area and live in a multi-story building, then you need to go up to the top floors, closing all the windows and doors.

But if you are in a one- or two-story house, you need to immediately leave it and run to a tall building or climb some hill (as a last resort, you can climb a tree and cling tightly to it). If it so happens that you did not have time to leave a dangerous place and found yourself in the water, you need to try to free yourself from shoes and wet clothes and try to cling to floating objects.

When the first wave subsides, it is necessary to leave the dangerous area, since the next one will most likely come after it. You can return only when there are no waves for about three to four hours. Once at home, check the walls and ceilings for cracks, gas leaks and electrical conditions.

The largest wave in the world was recorded on July 9, 1958 in Alaska. Wave 524 meters high struck Lituya Bay.

The giant wave was formed as a result of the earthquake and subsequent landslide. The power of the earthquake was 7.9 points, according to some sources 8.3 points (this was the strongest earthquake in the previous 50 years in this region). From a height of 1100 meters, 300 million cubic meters of rock, ice and stones fell onto the bay. The speed of the resulting wave was 160 km/h, it practically destroyed the La Gaussi spit, which was in the path of the “giant,” and the largest wave in the world also uprooted trees.

At that time, there were three fishing ships in the bay, which were also destroyed. By luck, the crews of the two ships managed to escape. 2 hours after the incident, they were picked up by a rescue ship near Lituya Bay. However, the crew of the third vessel, consisting of two people, failed to escape; their bodies were never discovered.

In second place among the largest waves on Earth is 250 meter wave, formed on May 18, 1980 on Spirit Lake in Washington state (USA). The event began with an earthquake that collapsed part of the rock from the mountainside, as a result of which the hot liquid inside the volcano turned into steam and an explosion occurred, equal in power to 20 million tons of TNT.

In third place in the list of the most gigantic waves in the world we can put wave 100 meters high, which was recorded in 1792 in Japan. It was formed as a result of the collapse of part of Mount Unzen, the collapse occurred due to a powerful earthquake (6.4 points). A giant wave covered a nearby settlement. About 15 thousand people died.

Another tragedy associated with huge waves occurred on October 9, 1963 at the Vajont dam in Italy (Belluno province). Big wave 90 meters high was formed as a result of the collapse of a huge rock mass with an area of ​​2 square meters in the reservoir. km. A giant wave moved through the lower-lying areas at a speed of about 10 m/s, washing away everything in its path. According to various sources, from 2 to 3 thousand people died, several settlements were completely destroyed.

According to many scientists, the largest waves in the world will be formed not as a result of earthquakes, but as a result of the collapse of large mountain ranges on the coast or near water bodies. Scientists have already compiled a list of possible rock collapse areas and have identified 4 main places:

1) Hawaiian Islands. Experts believe landslides from local volcanoes could cause waves up to 1 kilometer in height.

2) British Columbia (Canada). Some geologists believe that part of Mount Breckenridge could collapse into Harrison Lake, creating a large wave that could wash away the tourist town of Harrison Hot Springs (95 kilometers from Vancouver)

3) Canary Islands. Particular attention of scientists (in particular the English volcanologist William McGuire, the American seismologist Stephen Ward and others) is attracted here by the island of La Palma with its chain of Cumbre Vieja volcanoes. Scientists say that as a result of the earthquake, a mountain range with an area of ​​500 cubic km could collapse, which could create the largest wave in the world, more than 1 kilometer high, which would spread in a westerly direction. Predominantly impact the east coast of South and North America. Upon reaching cities such as Boston, Miami, New York, etc. The wave height can range from 20 to 50 meters.

4) Cape Verde Islands (Cape Verde). Local steep cliffs can also pose a great danger.

There is also an interesting and still little-studied phenomenon in the world called “Rogue Waves”. These are huge single waves, the height of which ranges from 20 to 34 meters. The first officially recorded case of a rogue wave occurred on the Dropner oil platform on January 1, 1995, near the Norwegian coast. Its height was 25.6 meters.

It is interesting that rogue waves appear out of nowhere, unlike tsunamis that are caused by landslides and earthquakes. It is believed that rogue waves arise due to their transformation while moving across the ocean, as well as the peculiarities of their own dynamics.

A feature of a rogue wave is also that it exerts much greater pressure on an object (ship, oil platform, etc.). One sq. a meter of surface experiences a pressure of 100 tons, whereas a normal wave 12 meters high exerts a pressure of 12 tons. One can imagine what a rogue wave could do to a ship, considering that most ships can only withstand 15 tons.