Rogue waves are also referred to as freak waves or killer waves by sailors, and as extreme storm waves by researchers. Unlike tsunamis, which are considered shallow water waves, they are deep water wind waves, because they are generated by the wind, and have a restoring gravitational force.
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Rogue waves are characterized by heights more than twice the size of the waves surrounding them, with directions different from that of the wind and other nearby waves. They are also unusual because of their ability to achieve extreme heights. Normal ocean waves typically average heights of no more than 12 to 15 meters ( 39 to 49 feet), even in storms. Rogue waves however, can be much higher, and it is not unusual for them to be 80 to 100 feet. For a while they have been thought to be myths only, despite having been observed by sailors throughout the ages.
They were also once thought to be uncommon, occurring over a period of thousands of years, but this has been found to be false. More recently, it was speculated that there were about ten rogue waves in existence every year. However, ten of them were once spotted in a three week period, contradicting this belief. More importantly, satellites have now shown that they are a frequent, natural occurrence that happens not only during fierce storms but also in calm seas, and they are known to suddenly appear without any warning.
Rogue waves are no respecters of geography; incidents have been recorded in the North Atlantic, the South Atlantic, the Pacific, the Antarctic, and the South Indian Ocean. They are most common in the latter, particularly around South Africa.
In part two, we will look at rogue wave disasters on the sea and dry land.
