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RTD info logoMagazine on European Research N° 42 - August 2004   
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NATURAL HAZARDS
Title  Rogue waves

Sometimes towering to a height of 30 metres, and seemingly coming from nowhere, 'rogue waves' (1) are genuine monsters of the seas. Over the past 20 years, about 200 vessels of over 200 metres in length have been sunk or damaged by an encounter with these freaks of nature which have claimed the lives of 540 sailors. The multidisciplinary team working on the MaxWave European project is now trying to understand how these waves are formed, to analyse their potential to harm, and to suggest an appropriate warning system. It is hoped that shipyards will be able take these data into account to strengthen the resistance of ships and offshore platforms. 

© Technical University Berlin
© Technical University Berlin
Those who have encountered them describe them as 'walls of water’. Their pyramid shape immediately marks them out from an ordinary wave. When the explorer Jules Dumont d'Urville spoke of what he had seen when he returned from a voyage to the South Seas, in the 19th century, he was greeted with jibes and scepticism. But when, during World War Two, a US aircraft carrier was almost split into two by one of them, the rogue waves suddenly became much more real. Similar stories told by sailors have since been gathered and compared. In 1989, the Derbyshire, 300 metres long, sank, not at the centre but on the edge of a typhoon, no doubt due to one of these 'pyramid' waves. In 1994, the yachtswoman Isabelle Autissier capsized off the coast of New Zealand when she hit one of these monsters which she estimated to be 35 metres high. A year later, off the Norwegian coast, it was the Draupner oil platform which was battered by an 18-metre wave that appeared out of nowhere in a zone without currents and in an otherwise normal sea. Rare but capricious, freak waves can appear in deep waters or coastal zones, alone or in series (the Three Sisters).


Help from above

When and how do such phenomena occur?(2) Exactly how much damage can they do? How can shipbuilders provide protection against their devastating effects? These are the major questions which the MaxWave project, supported by the EU, is seeking to answer.

The German research centre GKSS is coordinator of this partnership of oceanographic institutes and technical universities, meteorologists and shipbuilding engineers. In pooling their knowledge of fundamental oceanography, statistical data on recorded events, and the recordings of the new observation tools provided by satellites and networks of 'intelligent' buoys, their objective is to improve both warning systems (in particular the Global Maritime Distress Safety System) and technical resistance to these rogue waves. 

One of the project's first achievements was to exploit the mass of satellite data able to provide a broader picture of the instances of this phenomenon. In 2002, the team from the German DLR (Deutsches Zentrum für Luft und Raumfahrt) aerospace centre started by drawing a map of these extreme waves on the basis of 30 000 radar recordings obtained by the ERS 2  and continued with the much more numerous and higher-resolution pictures from the Ensivat satellite. Although it is true to say that these waves seem to have a predilection for the seas west of Cape Horn and south of the Cape of Good Hope, they can rise up just about anywhere.  

Atypical vertical energy
Another key aspect of the project is the study of phenomena related to the formation and size of these freak waves. Using digital models, Berlin's Technical University carried out a study of the physics of giant waves. Our knowledge of their origin – and atypical behaviour – is much more detailed today. While all 'traditional' waves build over four or five days before melting or breaking on the coastline, the 'maxi’ waves concentrate a vertical energy. One possible explanation is that 'young' waves quickly reproduce and build, their height becoming the sum of these and other waves whose path they cross. This dynamic, confirmed by modelling, has been simulated in test basins and shows that the interaction between a number of waves which meet and cross can engender a new and abnormal wave.

This series of photographs shows a simulation of the effect of this famous New Year wave on a model ship. It was carried out in a wave tank built by the Berlin Technical University.    © Technical University Berlin
This series of photographs shows a simulation of the effect of this famous New Year wave on a model ship. It was carried out in a wave tank built by the Berlin Technical University.
© Technical University Berlin


The results of the MaxWave project are currently being circulated to and used by the maritime community, not just in Europe but worldwide. 

The point lying between the values 200 and 400 on this graph corresponds to the giant 'New Year wave’ which hit the Draupner oil rig in the Norwegian waters of the North Sea on 1 January 1995. It consisted of a wall of around twenty metres high in a sea where the average wave height was 12 metres.    © Technical University Berlin
The point lying between the values 200 and 400 on this graph corresponds to the giant 'New Year wave’ which hit the Draupner oil rig in the Norwegian waters of the North Sea on 1 January 1995. It consisted of a wall of around twenty metres high in a sea where the average wave height was 12 metres.
© Technical University Berlin


(1) Also known as 'freak waves'.
(2) Extreme waves should not be confused with the violent waves known as tsunamis. The latter are caused by seismic activity on the seabed, triggering a movement of water which grows as it approaches the coast. 


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