Wild waves: the sea monsters that science did not know

A single wave that crashed on the tall pillars of an oil drilling rig in the North Sea a little less than twenty years ago, devoured all the cards

For many years, scientists and oceanographers believed that they understood ocean waves very well. The mathematical models developed for other waves, such as sound waves or electromagnetic waves, were also seamlessly integrated into the models that explained the phenomenon of waves in the sea. A wave, in the end, is simply a disturbance spreading in space - energy that is transferred from place to place. The mathematical formulas that explained the wave phenomenon were suitable for a very wide variety of phenomena and allowed researchers and forecasters to develop models for predicting the height of the waves in the sea, their direction and speed. But precisely when it seemed that everything was clear, understandable and known - precisely then a single wave arrived, which smashed against the tall pillars of an oil drilling rig in the North Sea a little less than twenty years ago, and devoured all the cards.

Over the years there have been many reports from sailors who told of huge waves, monstrous wild waves that appeared out of nowhere in the middle of the sea and hit their ships with tremendous force. The waves described in these stories rose to heights of thirty meters and more, like ten-story buildings. These stories, passed from word of mouth in sailors' pubs and during long shifts on the command bridge, spoke of a huge 'pit' that suddenly opened in the middle of the sea, tens of meters deep, and immediately following it appeared a huge wall of water, an almost vertical wall that no ship could climb. A ship hit by such a wild wave usually broke up and sank immediately, with a suddenness that did not leave enough time for the sailors to run to their lifeboats, and they went down with it into the depths.

The scientists tended to underestimate these stories. They saw them as chisabettes, fairy tales sailors tell each other to pass the time. They had every reason in the world not to believe the stories about the monstrous waves. The scientific mathematical models specifically stated that the maximum height of the waves that may be created as a result of the activity of the wind on the surface of the water, is twelve to fifteen meters at the most, and all the evidence and proofs showed with certainty that this theory is correct. A wave of thirty meters is possible, according to the formulas, but the probability of its existence is very low - maybe one in thirty thousand years.

In 1978, the ship 'Munich' left for a routine voyage from Bremen, Germany to the United States. The Munich was the splendor of the German merchant fleet: huge, two hundred and sixty meters long, equipped with the best of the latest technology. No ordinary storm in the Atlantic could even tickle the Munich, and her sophisticated radars scanned the horizon to great distances for dangers such as icebergs or collisions with other ships.

At three in the morning, on the twelfth of December, an SOS message was received from Munich. The message was picked up by a Greek merchant ship that was sailing in the area, and it passed it on to other ships and the rescuers on the coast. Within a few hours, a rescue and search force was organized that included dozens of ships and aircraft, but the Munich was not found. The great ship went down to the depths with a crew of twenty-eight sailors on board.

Much mystery surrounds the circumstances of Munich's disappearance. The weather was quite stormy but not unusually dangerous, and the sudden sinking indicated that the whole event was very violent and rapid. The mystery only increased when searchers discovered one of the Munich lifeboats floating, empty, on the surface of the ocean. An examination of the life raft revealed that it was not lowered into the water in an orderly manner by the crew, but was thrown into the sea following a blow it received. The pins that connected the raft to the ship were crooked and broken as if they had taken a tremendous blow. But while operating, the lifeboat was suspended in the air at a height of twenty meters above the water. What mighty force was able to rise to such a height and then strike the Munich with such force that it blew the raft off the spot, and probably sank the entire merchant ship?

On the first of January, 1995, hurricane-force winds blew over the waters of the North Sea -off the coast of Norway- and raised waves that reached a height of up to twelve meters. On the Draufner oil rig, the workers were not particularly worried - the rig was designed and built so that such waves would not endanger it. At three o'clock in the afternoon, an order was given to all the workers who were walking around on the deck of the rig to enter the structure so as not to be damaged by the strong wind, and no one volunteered to stay to watch the stormy sea.

This is also the reason why no one noticed the monstrous wave that hit the rig at twenty minutes past three, a wave nearly twenty meters high. The rig stands on a series of pillars, so the wave did not cause significant damage, except for a few thin metal beams that were bent and in fact we might not have known about it at all - if it weren't for a special laser meter that was placed on the rig to measure the height of the waves below it. This laser gauge did its job faithfully, and when the rig engineers checked the wave record they were amazed to see the huge jump in the wave height graph. According to any accepted engineering model, the wave measured that day was almost impossible: it should appear no more than once every ten thousand years.

But the laser meter was accurate in all other measurements before and after the wave hit, and was completely normal throughout the day. The scientists who examined the measurement could not, simply could not, ignore the data in their hands. After decades and centuries of fairy tales and seafarers' chizebats, the fact of the existence of these monstrous waves was now undeniable.

Where, then, did the huge wave that hit the Darufner rig come from?

The oceanographers, the researchers of the oceans and seas, know a number of natural phenomena that may cause the formation of giant waves, and have begun to examine and rule them out one by one. A tsunami, for example, is a very familiar phenomenon. A tsunami wave is caused by the sudden displacement of huge amounts of water in the ocean. The most well-known and common cause is an earthquake, but it is not the only one: meteorite impact in water, underwater nuclear tests. Both mudslides and volcanic eruptions can cause tsunami waves, with huge amounts of material spilling into the sea at once.

But the possibility that the wave that hit the Darufner rig was a tsunami was ruled out immediately. The huge waves that we are used to associate with the tsunami phenomenon, are manifested only near the coast. In the middle of the sea, as in the case of the oil rig, tsunami waves do not look like tsunami waves at all. Far from the coast, these are very low waves, barely a meter or two, and their wavelength - the distance between the top of the wave and its bottom - can reach several hundred kilometers. I mean, on a ship in the middle of the sea you wouldn't feel like a tsunami hit you at all. Only when the wave reaches the shore does it change: first the bottom of the wave arrives, then the sea seems to retreat and disappear. A few minutes later, the peak of the wave arrives - and when it arrives, it doesn't stop coming! Because the wave is so long, it looks like the sea just overflows and the wave goes on and on.

Another possibility, then, is a tidal wave, Tidal Bore in English - one of the most fascinating natural phenomena in the world. Tides occur slowly, and the water rises and falls over hours. But in a very small number of places on Earth, special geographical conditions can cause the tide to appear all at once as a wave front or a series of very high waves.

Tidal waves are of great interest to scientists, but they are even more interesting to the surfing population. For surfers, tidal waves are almost ideal: they arrive every day at predetermined times, and there are tidal waves that you can surf on for a distance of ten kilometers. I use the word 'almost' here again, as tidal waves have certain disadvantages. The tidal waves in the Poruroca River in Brazil attract many surfers, but they also attract to them - this time involuntarily - all kinds of creatures from the Amazon jungles that drift into the river - such as crocodiles, anacondas, jaguars and spiders, and all kinds of other things that have a tendency to turn the Surfing for a Darwinian experience-something.

But there are no tidal waves in the heart of the ocean, and therefore this possibility is ruled out outright. The scientists suddenly realized that the solution would be a completely new model, a new theory. The first step in developing the new model was, of course, gathering information. The researchers went back and re-examined the information received over the years from wave measuring buoys and returns from radars on the coast - and counted hundreds and thousands of wild waves. Now it was also possible to open the history books and better understand maritime disasters that have so far remained unexplained, such as the event known as the 'Mystery of the Flannan Islands'.

In 1899 a new lighthouse was inaugurated on this remote group of islands in the north of Scotland, about twenty nautical miles off the coast. Three people were stationed at the lighthouse whose job it was to operate the lighthouse and maintain it. About a year after the lighthouse was established, like every week, a supply ship arrived at the islands to equip the guards - but the island was empty. All three guards disappeared without a trace, leaving behind signs of haste: unworn storm suits, a chair that had fallen to the side in the kitchen.

An inspection of the lighthouse revealed surprising damage: a box that stood at a height of about thirty-three meters was broken, a metal safety rail was completely bent and a rock weighing close to a ton was moved from its place. A researcher who examined the disaster suggested that a large wave, or a series of huge waves washed away the island and the guards - but since a wave of such a height was considered impossible, many assumptions and theories were put forward over the years: starting with a fight that broke out between the guards and ending in murder and suicide, through kidnapping by spies Strangers and even mysterious sea monsters devoured the three. Following the revelations about the wild waves, the accepted explanation today is that two of the guards were working near the beach, and the third guard noticed a huge wave approaching them. He hurried to run to them to warn them, not stopping to take his coat or pick up the chair he dropped - but the wave washed him away too, and drowned all three of them.

A review of past data, along with satellite photographs and other information, soon revealed that there are areas on the globe that are prone to disasters, with a particularly high concentration of wild waves. Particularly dangerous are areas where waves moving in a certain direction meet a sea current moving straight towards them, as occurs not far from the coast of South Africa.

But the problem was that wild waves appeared everywhere, and not only in areas where currents and waves meet. It was still necessary to explain where they came from and how, perhaps, they could be predicted. As of today, there is no single theory that is agreed upon by all scientists. In a rough division, the theories regarding the formation of wild waves are divided into two: linear versus non-linear.

The linear theories hold that a wild wave is the result of a sum of waves. This is the principle meaning of the word 'linear' - if we take a ten-meter-high wave, and add it to another ten-meter-high wave, we will get a new twenty-meter-high wave. This phenomenon may occur when a fast wave series chases and catches up with a slower wave series.

The linear theories are not perfect, because they require very certain conditions to create wild waves, conditions that are possible and are quite rare in the open sea. The non-linear theories, on the other hand, take a completely different approach. They rely on equations taken from the world of quantum mechanics, and try to include them in the chaos of the open sea as well. The Schrödinger equation, for example, is a very important equation in quantum mechanics and it describes the electrons in an atom as waves moving around the nucleus. A version of this equation, known as the nonlinear Schrödinger equation, is particularly effective for applications in optics and, it turns out, for analyzing the motion of ocean waves. According to this equation there are situations where completely normal waves may start to 'suck' energy from the waves around them. They begin to grow and intensify at the expense of the other waves, which become lower and lower. The result is the same 'pit of water' that is obtained before such a wild wave.

As mentioned, all research on wild waves is still in its infancy, and no one knows for sure how, when and where they are created. As in the case of the 'Titanic', nature proves to us again that we are not as big, strong and wise as we sometimes tend to think ourselves. At least for the foreseeable future, the vast expanses of the oceans will continue to be hostile and difficult for us, just as they have been since ancient times. The sailors in their ships can't afford, yet, to put down the binoculars. They must continue to scan the horizon and look for the wild waves, and maybe more sea monsters unknown to science.

* This article is taken from the show's script.Making history!', a bi-weekly podcast about the history of science and technology.