Everything about Freak Waves totally explained
Rogue waves, also known as
freak waves,
monster waves,
extreme waves or
hundred year waves, are relatively large and spontaneous
ocean surface waves that are a threat even to large
ships and
ocean liners. In
oceanography, they're more precisely defined as waves whose height is more than twice the
significant wave height (SWH), which is itself defined as the mean of the largest third of waves in a wave record. Therefore rogue waves are not necessarily the biggest waves found at sea; they are, rather, surprisingly large waves for a given sea state. A wave, such as the one that probably caused the loss of the RV
Ballena in Southern California, was a rogue wave that occurred in a rather calm sea state. Such a wave is nevertheless very small compared to the largest waves recorded by instrumented buoys, with significant wave height.
Once thought to be only legendary, they're now known to be a natural 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 the "
Draupner wave", a rogue 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.
In the course of Project MaxWave, researchers from the GKSS Research Centre, using data collected by
ESA satellites, identified a large number of radar signatures that have been portrayed as evidence for rogue waves. Further research is under way to develop better methods of translating the radar echoes into sea surface elevation, but at present this technique isn't proven.
Freak waves have been cited in the media as a likely source of the sudden, inexplicable disappearance of many ocean-going vessels. However, although this is a credible explanation for unexplained losses, there's to date little clear evidence supporting this hypothesis nor any cases where the cause has been confirmed, and the claim is contradicted by information held by
Lloyd's Register. One of the very few cases in which evidence exists that
may indicate a freak wave incident is the 1978 loss of the freighter
MS München, detailed below. In February 2000, a British oceanographic research vessel sailing in the
Rockall Trough west of Scotland encountered the largest waves ever recorded by scientific instruments in the open ocean, with a SWH of and individual waves up to .
History
It is common for mid-ocean storm waves to reach in height, and in extreme conditions such waves can reach heights of .
However, for centuries maritime
folklore told of the existence of vastly more massive waves — veritable monsters up to in height (approximately the height of a 10-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 980
kPa (142 psi) exerted by the weight of the breaking water, and would almost certainly be sunk in a matter of minutes.
Many years of research have confirmed that waves of up to in height are much more common than mathematical
probability theory would predict using a
Rayleigh distribution of wave heights. 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 reconsideration of the implications for ocean-going
ship design.
Rogue waves are also known to occur on the inland
Great Lakes, which are more like large inland seas. Perhaps most famously such inland freak waves are believed, according to some reconstructions, to be responsible for the sinking of the in November 1975 (see below). However, other causes have been advanced, and the matter is far from settled.
A rogue wave isn't the same as a
tsunami. Tsunamis are mass displacement generated waves which propagate at high speed and are more or less unnoticeable in deep water; they only become dangerous as they approach the shoreline and don't present a threat to shipping (the only ships lost in the
2004 Asian tsunami were in port). A rogue wave, on the other hand, is a spatially and temporally localized event that most frequently occurs far out at sea.
Occurrence
The MaxWave project studied the ocean surface with radar over a 3-week period in 2001. Researchers took 30,000 images each of a 10 km × 5 km (6.2 mi x 3.1 mi) section of ocean in that time, resulting in a total imaged area of 1.5 million square kilometres (580,000 sq mi). Giant waves were detected in ten of these, amounting to one per . A short-lived wave in a section of ocean this size is an extremely rare occurrence in its own right.
Causes
The phenomenon of rogue waves is still a matter of active research, so it's too early to say clearly what the most common causes are or whether they vary from place to place. The areas of highest predictable risk appear to be where a strong
current runs counter to the primary direction of travel of the waves; the area near
Cape Agulhas off the southern tip of Africa is one such area. However, since this thesis doesn't explain the existence of all waves that have been detected, several different mechanisms are likely, with localised variation. Suggested mechanisms for freak waves include the following:
- Diffractive focusing — According to this hypothesis, coast shape or seabed shape directs several small waves to meet in phase. Their crest heights combine to create a freak wave.
- Focusing by currents — Storm forced waves are driven into an opposing current. This results in shortening of wavelength, causing shoaling (for example, increase in wave height), and oncoming wave trains to compress together into a rogue wave. and Miles provide some insight into the problem, though it still remains a tricky one.
The spatio-temporal focusing seen in the NLS equation can also occur when the nonlinearity is removed. In this case, focusing is primarily due to different waves coming into phase, rather than any energy transfer processes. Further analysis of rogue waves using a fully nonlinear model by R.H. Gibbs (2005) brings this mode into question, as it's shown that a typical wavegroup focuses in such a way as to produce a significant wall of water, at the cost of a reduced height.
There are three categories of freak waves:
"Walls of water" travelling up to through the ocean
"Three Sisters", groups of three waves
Single, giant storm waves, building up to fourfold the storm's waves height and collapsing after some seconds
A research group at the Umeå University, Sweden in August 2006 showed that normal stochastic wind driven waves can suddenly give rise to monster waves. The nonlinear evolution of the instabilities was investigated by means of direct simulations of the time-dependent system of nonlinear equations.
Applications
The possibility of the artificial stimulation of rogue wave phenomena, has attracted research funding from DARPA, an agency of the United States Department of Defense. Bahram Jalali and other researchers at UCLA studied microstructured optical fibers near the threshold of soliton supercontinuum generation and observed rogue wave phenomena. After modeling the effect, the researchers announced that they'd successfully characterized the proper initial conditions for generating rogue waves in any medium.
Reported encounters
On the 11th March 1861 at midday the lighthouse on Eagle Island (External Link
), off the West coast of Ireland was struck by the sea smashing 23 panes, washing some of the lamps down the stairs, and damaging the reflectors with broken glass beyond repair. In order to damage the uppermost portion of the lighthouse, water would have had to surmount a seaside cliff measuring 40 m (133 feet) and a further 26 m (87 feet) of lighthouse structure.
On December 15, 1900, three lighthouse keepers mysteriously disappeared from the Flannan Isles Lighthouse in the Outer Hebrides of Scotland. Although there were no surviving witnesses, a rogue wave has been theorized to be responsible.
On 10 October 1903, was only four hours out of New York when, at 2:30 p.m., the ship was struck by a freak wave. The wave was reported to be at least high and struck the ship on the port side. The wave carried away part of the fore bridge and smashed the guardrail stanchions. There were a number of first-class passengers sitting in deck chairs close to the bridge and they caught the full force of the water. One passenger was fatally injured and several other passengers were hurt.
The Blue Anchor Line luxury steamer SS Waratah, a ship of 16,000 tons, disappeared without trace south of Durban in July 1909. No survivors and no wreckage of any kind was found. The most plausible theory for her disappearance is that she encountered a rogue wave which either caused her to capsize or flooded her cargo holds, sinking her almost instantly.
In 1933 in the North Pacific, the U.S. Navy oiler encountered a huge wave. The crew triangulated its height at .
In 1942 while carrying 15,000 American troops from Scotland during a gale, was broadsided by a wave and nearly capsized. Queen Mary listed briefly about 52 degrees before the ship slowly righted herself.
In 1966, the Italian liner Michelangelo was steaming toward New York City when a giant wave tore a hole in its superstructure, smashed heavy glass above the waterline, and killed a crewman and two passengers.
The six-year-old, 37,134-ton barge carrier was lost at sea in 1978. At 3 a.m. on 12 December 1978 she sent out a garbled mayday message from the mid-Atlantic, but rescuers found only "a few bits of wreckage." This included an unlaunched lifeboat, stowed above the water line, which had one of its attachment pins "twisted as though hit by an extreme force." The Maritime Court concluded that "bad weather had caused an unusual event." It is thought that a large wave knocked out the ship's controls (the bridge was sited forward), causing the ship to shift side-on to heavy seas, which eventually overwhelmed it. Although more than one wave was probably involved, this remains the most likely sinking due to a freak wave.
The, which sank with all hands off Japan in 1980, is the largest British vessel ever lost at sea. Some now believe it to have been sunk by a rogue wave.
The Ocean Ranger (North Atlantic, 1981), a semi-submersible mobile offshore drilling unit sank with all hands after a rogue wave flooded the platform's ballast control room.
Draupner wave (North Sea, 1995): The freak wave first confirmed with scientific evidence, it had a maximum height of .
(North Atlantic, 1995),, during bad weather in the North Atlantic. » The Master said it "came out of the darkness" and "looked like the White Cliffs of Dover." Newspaper reports at the time described the cruise liner as attempting to "surf" the near-vertical wave in order not to be sunk.
On November 4, 2000, Channel Islands Sanctuary research vessel R/V Ballena was hit by a rogue and capsized near Point Conception in Santa Barbara, California. The ship was long, and the wave estimated at high. Although the two USGS crew members were trapped briefly inside the ship, they were rescued by the captain and all three managed to swim to shore. The boat, operated by NOAA at the time, was a total loss.
and Caledonian Star (South Atlantic, 2001) encountered freak waves. Bridge windows on both ships were smashed, and all power and instrumentation lost.
Norwegian Dawn, (three waves in succession, off the coast of Georgia, 16 April, 2005): » "The sea had actually calmed down when the 21 meter wave seemed to come out of thin air… Our captain, who has 20 years on the job, said he never saw anything like it."
"The water exerted enough force to shear off the welds for the aluminum rail supports on the [ninthand tenth level] balconies of two cabins, allowing the teak balcony rails to break loose and crash into the cabin windows. The broken glass filling the drains compounded the water damage by allowing a large amount of water to enter the two cabins and damage the carpets in 61 other cabins. The ship’s operating at reduced speed when the waves hit probably limited the damage."
Aleutian Ballad, (Bering Sea, 2005) » Footage of a rogue wave appears in an episode of Deadliest Catch. The wave cripples the vessel, causing the boat to tip onto its side. The boat manages to right itself; some of the crew suffers minor injuries. One of the only video recordings of a Rogue Wave.
Norwegian Spirit, (off the coast of Tortola, January 2006)
Brittany Ferries' was struck by a wave estimated at between 40 and 50 feet in height during a Force 9 gale in the Bay of Biscay on 21 May 2006.
In March 2007, Holland America's cruise ship was hit by a tall rogue wave in the Antarctic segment around the tip of South America.
April 14, 2008 off South Africa - freak wave hit tourists diving to see sharks.
It has also been suggested that these types of waves may be responsible for the loss of several low-flying aircraft, namely U.S. Coast Guard helicopters on Search and Rescue missions.
Loss estimates
A widely spread claim that around 200 large ships have been sunk in recent years by 'freak' waves has never been substantiated.Rogue waves in popular culture
The film Poseidon from 2006 explores the capsizing of an ocean liner by a rogue wave and the struggle of passengers to survive. The film is a remake of The Poseidon Adventure from 1972, itself an adaptation of Paul Gallico's novel, which was published in 1969. In the original novel and film, the ship was hit by a tsunami, which raised some criticism since these are only a few inches high in open sea and could never overturn a vessel. A 2005 remake addressed this issue by substituting a terrorist attack.
New York alternative rock band Brand New references rogue waves in "Play Crack The Sky", a track on their second album, Deja Entendu. The exact line is "They call them rogues, they travel fast and alone; one hundred foot faces of God's good ocean gone wrong."
Rogue Wave is the name of an indie rock band from Oakland, California.
In the final minutes of The Perfect Storm (2000), a massive rogue wave appears just as the title storm of the movie appears to be dying down, and finally destroys and sinks the Andrea Gail fishing boat and her six crew. Though Sebastian Junger's 1997 book of the same title was largely presented as a non-fiction account, there's no evidence that the boat encountered or was destroyed by a rogue wave.Further Information
Get more info on 'Freak Waves'.
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