Monsters of the Deep

Rogue waves, or killer waves, are abnormally high and deadly waves that can emerge unpredictably in open seas and along shorelines. They pose an imminent deadly threat to everyone from colossal liners and pleasure yachts to seafarers and vacationers. Scientists from the HSE campus in Nizhny Novgorod Efim Pelinovsky and Ekaterina Didenkulova have assembled a catalogue of such phenomena that occurred in the World Ocean from 2011 to 2018, identifying the areas where they are frequently documented and inflict the most substantial damage.

From Disbelief to Recognition

Sailors have long told stories about huge 30-meter waves that could suddenly descend on a ship and sink it. However, few people truly believed such stories, as sailors and fishermen were ascribed a tendency to exaggerate, and it was hard to even accept the existence of such extraordinary waves.

But in 1980, this phenomenon was documented off the coast of Durban, South Africa, by an eyewitness. Philippe Lijour, first mate of the supertanker Esso Languedoc, recalled: 'We were in a storm, and the tanker was running before the sea. This amazing wave came from the aft and broke over the deck... It was special, much bigger than the others'.

The wave was higher than the ship's masts, which stood about 25 metres above sea level—meaning the wave could have towered 30 metres high. The tanker survived, and the wave was photographed. After that, sailors' accounts started gaining greater credibility.

Two years later, a rogue wave claimed the Ocean Ranger,the world's largest semi-submersible oil rig at the time. The vessel, which was 121 metres long, 103 meters high (the size of a 35-storey building), and had twelve 20-ton anchors, was destroyed on February 14–15, 1982. A 27-meter wall of water smashed the windows and flooded the control room, causing the stabiliser systems to fail. The rig then capsized and sank, killing all 84 people on board.

Thirteen years later, on January 1, 1995, a 26-metre rogue wave hit the Draupner platform in the North Sea. It was the first rogue wave to be recorded by scientific instruments. The existence of such waves was finally recognised by scientists, and studies of this phenomenon began.

What Are They?

Following the Draupner disaster, extensive research on rogue waves has been undertaken through diverse approaches, encompassing full-scale measurements, computational experiments, and the development of physical and mathematical models. In English-language literature, various names have been attributed to this phenomenon, including rogue wave, freak wave, monster wave, episodic wave, killer wave, extreme wave, and abnormal wave. Oceanologists have devised an altitude criterion to describe these waves:

A rogue wave is defined as a wave more than twice the height of the significant wave height, which is the average of the highest one-third of waves at a given location.

These waves are also characterised by their abrupt onset and dissipation, along with their immense energy and relatively short lifespan, typically lasting from a few minutes to several dozen seconds. According to scientists, rogue waves should not be confused with tsunamis, which possess distinct characteristics and are formed through entirely different mechanisms.

Where Do They Come From?

After years of extensive research, the primary mechanisms behind the occurrence of exceptionally large waves have been identified. They include:

 interference, where regular waves overlap as a result of currents colliding with winds or waves converging from opposite directions along reefs or islands

 modulation instability, characterised by the spontaneous amplification in space and time of perturbations in the amplitude and phase of an almost monochromatic wave propagating through a nonlinear medium or dynamic system, without any loss of energy

 dispersion focusing, where waves 'play catch-up', causing the fastest and longest waves to overtake the shorter ones, resulting in interactive effects

Can They Be Predicted?

The primary challenge lies in accurately predicting rogue waves. Two approaches have been proposed:

 detecting a wave using instruments positioned at a certain distance from the location of interest. By accurately forecasting the wave's behaviour in advance, specialised services can mitigate the impact of a potential collision, eg evacuate individuals from the deck or alter the ship's course accordingly.

 determining the marine conditions in which anomalies are most likely to occur, including specific bathymetry (bottom relief), convergence of currents with swell waves, and interactions with the shoreline. Furthermore, specific water regions can be identified where the rogue wave generation mechanisms are particularly strong, so that vessels may strategically navigate around these areas and avoid potential hazards. Individuals need to be warned about coastal areas in particular, where there can be a risk of fatality.

Naming and Categorising Rogue Waves

It was previously believed that 30-meter colossal waves were extremely rare, occurring once every 10,000 years. This theory, however, was disproven in the early 2000s. As part of the MAXWAVE project, the European Space Agency (ESA) deployed two satellites to monitor the ocean surface. The satellite data produced astonishing results: within just a three-week span, over 10 individual waves with heights surpassing 25 meters were observed in various locations across the globe.

Over time, the occurrence of rogue waves has been registered with greater frequency, making it necessary to organise and systematise the collected data. The US National Oceanic and Atmospheric Administration (NOAA) compiled eyewitness accounts spanning from 1498 to 2007. Another work documented the events of 2013, and a paper by Russian researchers analysed cases from 2005.

A comprehensive catalogue encompassing the entire World Ocean was created for the period 2006–2010. Subsequently, more specific catalogues emerged, focusing on particular years or certain water areas. Efim Pelinovsky and Ekaterina Didenkulova continued their global-scale efforts, systematically documenting cases in the World Ocean from 2011 to 2018.

The Magnitude of Disaster

'The collected data primarily consists of eyewitness accounts rather than direct measurements,' explains Didenkulova. 'Nevertheless, the documented events closely align with the criteria attributed to rogue waves, including their height, sudden occurrence, and resulting damage.'

The catalogue compiled by the scientists includes 210 individual cases. The waves have been classified into three distinct types:

 deep-water waves occurring at depths exceeding 50 metres

 shallow-water waves occurring at depths less than 50 metres

 coastal waves characterised by a sudden surge towards the shoreline that sweeps away individuals and coastal structures

The annual count of waves remained relatively consistent, ranging from 20 to 30. Coastal waves were documented significantly more frequently, accounting for 120 instances (57%) throughout the entire period.

Rogue waves in deep/shallow water and on shore (% of cases, 2011–2018)

The study authors attribute the higher frequency of incidents on the shore to factors such as 'the high population density in coastal areas and the extensive use of shorelines, which increase the likelihood of encountering a rogue wave compared to deep-water locations.'

However, in deep-water areas, the loss of lives was more prevalent. Between 2011 and 2018, deep-water incidents accounted for approximately 49% of recorded fatalities. During this period, a total of 210 wave attacks resulted in:

 386 deaths

 184 people injured

 50 vessels damaged

 24 vessels sunk

Damage from rogue waves, 2011–2018

Risk Area

The catalogue, which relies on eyewitness accounts rather than direct measurements, is acknowledged by the researchers to be approximate. Nonetheless, these statistics not only reveal the characteristics of the phenomenon but also highlight the most hazardous water areas in the World Ocean.

The researchers have mapped the locations where rogue waves have occurred and inflicted damage, the most notable of them being the coastlines of the USA, the Caribbean Sea, Europe, Australia, and New Zealand.

Map of rogue waves, 2011–2018

No specific locations were marked in certain territories, such as Latin America or Greenland, during the period 2011–2018. The primary reasons are their relatively low population density and limited oceanic traffic. According to Didenkulova, 'There are simply too few witnesses in Greenland because people do not spend time on beaches, while maritime traffic is scarce, so there is no reported damage. In contrast, Latin America has a lot of beaches in its coastal regions, and fatalities probably occur. However, fewer reports from Latin America reach the press, and even when they do, the coverage is often not in English, which is the language used for our search.’

Russia's northern coast is another region where awareness of killer waves remains limited due to low vessel traffic, a sparse population, and the ice cover of the sea surface during the winter months. The same generally applies to Russia, where despite its extensive maritime borders, there are relatively few encounters with these oceanic giants. Rogue waves in Russia have been predominantly documented in the Black Sea and the Okhotsk Sea, and along the coasts of Sakhalin and Kamchatka.
IQ
 

Study authors:

Ekaterina Didenkulova, Candidate of Physical and Mathematical Sciences; Senior Research Fellow, Laboratory of Topological Methods in Dynamics, Faculty of Informatics, Mathematics, and Computer Science, HSE Nizhny Novgorod

Efim Pelinovsky, Doctor of Physical and Mathematical Sciences; Professor, Senior Research Fellow, International Laboratory for Dynamical Systems and Applications, Faculty of Informatics, Mathematics, and Computer Science, HSE Nizhny Novgorod

 

Author: Svetlana Saltanova, June 23, 2023