The Hokusai Wave is a famous wood-cut print created by the Japanese artist Katsushika Hokusai around 1831. The proper Japanese name for the picture is Kanagawa-oki-nami-ura which translates to something like ‘Behind a wave off-shore from Kanagawa’. The work was part of a collection called ‘Thirty-six views of Mount Fuji’.
The Hokusai Wave is one of the world’s most well-known images of a wave, and has been intensely studied both from an artistic and from a scientific point of view. It has been used to sell the image of a wave by thousands of different people and companies, including, unmistakably, the major influence for the logo of the clothing giant Quiksilver. It has also been used to symbolize the tsunami in popular culture, and even in some textbooks. However, as I’ll explain later, it is now almost certain that it wasn’t a tsunami that Hokusai intended to portray.
Although the picture is spatially dominated by the wave, the main subject is intended to be Mount Fuji. Hokusai cleverly keeps the viewer’s attention focused on Mount Fuji, despite it being much smaller than the wave in the picture. The boats in the picture are typical transport vessels of the time, called Oshiokuri-bune, which carried fish and other goods up and down the coast. The tiny oarsmen are cowering against the giant wave, too frightened to look up at it. The diminutive size of these figures compared with the wave was clearly meant to demonstrate how vulnerable people like these were against the force of the sea.
The Hokusai Wave has been used by scientists as one of the first examples of an artwork that displayed self-similarity, or fractals. The ‘fingers’ around the tips of the wave, are a similar shape to the wave itself. You could imagine zooming in further and finding ever-smaller versions of same shape. Of course, this may have just been intended to give the wave a more frightening aspect, but some experts have suggested that Hokusai subconsciously ‘fractalized’ his work, and that Japanese culture in general has a high degree of self-similarity about it.
The idea that the Hokusai Wave was supposed to be a tsunami is something that was probably invented fairly recently. According to some people, the misconception might have simply arisen from the fact that the words ‘tsunami’ and ‘Hokusai’ are both Japanese.
However, in a recent paper published in Notes and Records of the Royal Society, Julyan Cartwright and Hisami Nakamura provide more than enough ideas to convince anyone that the wave definitely wasn’t supposed to be a tsunami. Firstly, they point out that the wave is too big to be a tsunami in that particular area. Tsunamis have hit there in the past, but the largest run-up (the height of water reached by the wave on the shore) ever measured was little more than two metres. The Hokusai wave, if you compare it with the size of the boats, would produce a much higher run-up than that. Of course, the painting is just an invention, so the artist could have been imagining some catastrophic future event, or he could have simply exaggerated it for no apparent reason.
What is probably more convincing than the height of the wave is its shape. The wavelength of a tsunami (the distance between the front and the back) is typically hundreds of times greater than that of a normal wave. Out in deep water, tsunamis are often only one or two metres high, but thousands of metres long. If the Hokusai Wave were a tsunami it wouldn’t be anywhere near as steep as the wave in the picture unless it was really close to the shore. Cartwright and Nakamura suggest that, if this were the case, Hokusai would have included the shoreline in the picture, which he didn’t. Also, Hokusai’s waves tend to take on an ‘A-frame’ appearance, which is particularly un-tsunami-like. A-frames can also be seen in earlier wave paintings by Hokusai.
So, whether the Hokusai Wave was meant to be a normal wind-generated wave, or just something that Hokusai imagined, we shall never know for sure. What is pretty certain though, is that he wasn’t thinking of a tsunami when he drew it.
The experts, in their analysis and dissection of this piece of work, have found many features, such as fractals, that appear decades or even centuries before those things were thought of scientifically. From a surfer’s perspective, we can see that the profile of the wave is very similar to the way we might draw a classic surfing wave nowadays, almost three centuries later. It contains a deep trough in front of the wave and a pitching lip, just about to form a tube. In fact, the wave face has the shape of a classic deep-water break such as Sunset Beach in Hawaii. How did he know?