Rogue Waves
With that movie coming out this weekend, it only seems appropriate that we should catch up on our reading on rogue waves, or as they are more dramatically described in some circles, freak waves:
Freak waves, also known as rogue waves or monster waves, are relatively large and spontaneous ocean surface waves which can sink even large ships and ocean liners. In oceanography, they are more concisely defined as waves that are more than double the significant wave height (SWH), which is itself defined as the mean of the largest third of waves in a wave record.
Once thought to be only legendary, they are now known to be a natural (although relatively rare) ocean phenomenon. Anecdotal evidence from mariners' testimonies and damages inflicted on ships suggested they occurred; however, their scientific measurement was only positively confirmed following measurements of a freak wave at the Draupner oil platform in the North Sea on January 1, 1995. During this event, minor damage was inflicted on the platform, confirming that the reading was valid.
It is common for mid-ocean storm waves to reach 7 metres (23 feet) in height, and in extreme conditions such waves can reach heights of 15 metres (50 feet). However, for centuries maritime lore told of the existence of vastly more massive waves — veritable monsters up to 30 metres (100 feet) in height (approximately the height of a 12-story building) — that could appear without warning in mid-ocean, against the prevailing current and wave direction, and often in perfectly clear weather. Such waves were said to consist of an almost vertical wall of water preceded by a trough so deep that it was referred to as a "hole in the sea"; a ship encountering a wave of such magnitude would be unlikely to survive the tremendous pressures of up to 100 tonnes/m2 (980 kPa) exerted by the weight of the breaking water, and would almost certainly be sunk in a matter of seconds. Usual ship design allows for rounded storm waves up to 15 m and pressures around 15 tonnes/m2 (147 kPa) without damage, and up to twice that if some deformation is allowed for, which is about a wave of twenty metres.
Scientists long dismissed such stories, asserting that mathematical models indicated that ocean waves of greater than 15 metres in height were likely to be rare "once in 10,000 years" events. However, satellite imaging has in recent years confirmed that waves of up to 30 metres in height are much more common than mathematical probability would predict based on a linear model of wave size. In addition, pressure readings from buoys moored in the Gulf of Mexico at the time of Hurricane Katrina also indicate the presence of such large waves at the time of the storm. In fact, they seem to occur in all of the world's oceans many times every year. This has caused a re-examination of the reason for their existence, as well as calling into serious question many long-accepted principles of maritime engineering.
So there you have it. It could happen.