As storm Eunice moves away from France, we learn that the ocean is now unleashed: a record wave has been observed off the coast of Canada. It rose in November 2020, but it has only now been discovered in the scientific data. Details from Mathilde Fontez, editor-in-chief of the scientific magazine Epsiloon.
franceinfo: Mathilde, this 18-meter wave off Vancouver, interested physicists?
Mathilde Fontez: That’s what they call a rogue wave. A special, legendary wave. The phenomenon has been reported by sailors for hundreds of years.
The famous explorer and naval officer Dumont d’Urville, for example, was mocked at the beginning of the 19th century for having brought back from his travels the description of these waves: nothing to do with the rollers that delight surfers. There, we are talking about a wall of water, very straight, which rises suddenly, and which reaches heights much higher than the surrounding waves.
And finally, it is not a fantasy. Do these waves really exist?
It’s neither a fantasy nor a nightmare, it’s very real yes. The proof, therefore, with this wave measured 7 kilometers off Vancouver by a swell buoy: 17.6 meters suddenly – a 7-storey building – in a very calm sea.
It rose on November 17, 2020, but Canadian specialists have only just found it in the data. They publish a detailed study of it this week. And that allows them to explain, finally, how it is formed. Why such a monster can suddenly arise.
Is this the first time that we really measure this type of wave?
It’s actually the fourth wave. A first had been measured near an oil platform in the North Sea, in 1995. A wave of 26 meters, in a swell of 12 meters. It was she who had for the first time proved that the phenomenon is not a legend. And two others had been measured in the 2000s.
From there, physicists were able to start doing real studies: they tried to reproduce the phenomenon in a basin – a first experiment, carried out at the University of Oxford, succeeded in 2019. And they modeled the phenomenon to simulate it with numerical studies – by mobilizing a lot of computing power.
That’s what the Canadian team did with the Vancouver wave?
Yes, they did a digital study. And what they see is that the wave is formed by a phenomenon called “constructive interference”: waves are waves. And it happens that several trains of waves which come from different directions, which circulate at different speeds, are added by chance, at a precise place. So that’s how the sea suddenly rises.
The mystery of the rogue waves is solved. And that allows you to start making statistics: researchers estimate that a wave like that of Vancouver occurs every 1300 years. This is little. But on an ocean scale, that’s one in 10,000 waves that would be a rogue wave.
Which means that any ship is likely to come across one on its way. It is estimated that 22 cargo ships have disappeared at sea, or have been severely damaged in 25 years by rogue waves. It’s not just a sea bass legend anymore…