The superstitions and the great respect that sailors show to the unfathomable ocean are understandable. It remains that great unknown containing unexpected surprises and dangers. It is true that some phenomena can be predicted in advance thanks to known physical patterns and processes, but others may manifest themselves more abruptly and unexpectedly.
Ernest Shackleton, the great Antarctic explorer, knew this well. In 1916, when his ship Endurance ran aground on the polar ice and sank, the adventurer and the rest of the crew headed for South Georgia in a lifeboat1, 2. To his misfortune, the danger did not end there. “For God’s sake, hold on! It’s got us!!” he cried out in terror as he watched an uncrossable wall of water unstoppably bearing down on them2. Fortunately, the boat survived the impact and they were able to reach land safely. Shackleton thus became a witness to a rogue wave1, 2.
It is estimated that these titans of the ocean can reach 30 meters in height under favorable conditions1. Until recently, these were considered mere legends and the ravings of superstitious sailors, but the so-called New Year’s Wave shattered the uncertainty. A 25-meter-high mass slammed into the Draupner oil platform in the North Sea on January 1, 1995, hence the name1.
Rogue waves can be defined as those whose crest-to-valley height is more than twice the average height of the highest third of waves in a sample3. They are relatively unexpected and are therefore studied through laboratory simulations and remote monitoring. The main driver of this phenomenon would be the strong winds that favor energy accumulation as the wave travels1, but there are other mechanisms that would also play a role, such as ocean currents1, 3, as well as many others whose importance has not yet been fully clarified. When one of these waves moves in the opposite direction to that of a current, the wave slows down and gains height and power3. Another possible mechanism proposed is the interaction and superposition of linear waves3, 4. All these phenomena respond to linear mechanics, according to which the final result is the exact sum of the individual results derived from the components that constitute the phenomenon3, 4. However, advances in knowledge have made it possible to discern the important role of nonlinear mechanisms, i.e. when the result obtained is greater than the sum of the individual components3, 4. Thus, when two nonlinear waves (also called solitons) coincide, the combined height of the generated wave is greater than the sum.
With all this in mind, some scientists have looked at one of Japan’s best-known artistic manifestations: The Great Wave off Kanagawa, the masterpiece of Katsushika Hokusai. It is still common to compare the image with a tsunami, but its characteristics make the hypothesis of the rogue wave more plausible.
This work was composed between 1831 and 1833. It depicts a group of fishermen about to be crushed by a huge mass of water that is already breaking. In the background, the sacred Mount Fuji can be timidly distinguished. In fact, this work is part of a collection of 46 prints (Thirty-six Views of Mount Fuji, to which he eventually added 10 more) in which the mountain is the real protagonist3, 4. The Great Wave was widely accepted in Western artistic circles and was a great source of inspiration for modernism and for artists such as Vincent van Gogh (you will surely find similarities between The Great Wave and The Starry Night) or Gustav Klimt among many others3, 4.
Compared to boats and fishermen, the wave height has been estimated to be around 10-12 meters3. The scene was located somewhere 3 km offshore within Tokyo Bay4. In this context, such a size could be associated with a rogue wave. Another reason why the association with a tsunami would be unrealistic is its morphology: tsunamis are not that large and their wavelength is considerably longer in the open ocean3, 4. Therefore, what Hokusai would have depicted through his hypertrophied ability to render nature with an astonishing level of realism would be a monstrous rogue wave.
REFERENCES
Kotze, P. (2021). A merced de las olas colosales. Muy Interesante, 482, 86-93.
Shackleton, E. (1999). South. The Endurance Expedition. London: Penguin.
Cartwright, J.H.E., Nakamura, H. (2009). What kind of a wave is Hokusai’s Great Wave off Kanagawa? Notes Rec. R. Soc., 63, 119-135. https://doi.org/10.1098/rsnr.2007.0039
Dudley, J.M., Sarano, V., Dias, F. (2013). On Hokusai’s Great Wave off Kanagawa: localizations, linearity and a rogue wave in sub-Antarctic waters. Notes Rec. R. Soc., 67, 159-164. https://doi.org/10.1098/rsnr.2012.0066
