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Bonjour,
J'attends vos boulets de canons sceptiques sur un documentaires effectués il y a quelques années sur le thème du triangle des Bermudes....en comparant réalités vs légendes.
Notez que mes approches sont souvent empiriques étant peu doué pour les développements longs et fastidieux.
SEA LEGENDS! reality vs legends where does the truth stand?
The Bermuda Triangle is well known but over in the Eastern Hemisphere there's a similar area of Pacific Ocean known as the Dragon's Triangle. The region starts from western Japan and runs to a point in the ocean at approximately 145 degrees east latitude, then turns west-southwest to the islands of Guam and Yap, then west to Taiwan and back up to Japan to the north-northeast. Like the Bermuda Triangle, the region is known for ship and airplane disappearances, freak storms, misbehaving instruments and other unusual activity — even UFOs.
The Dragon's Triangle is so named according to an ancient Chinese myth, which tells of dragons that live deep beneath the surface, whose movement can suddenly churn up waves, whirlpools, thick fog and sudden storms. (The Japanese refer to it as Ma-no Umi: the Sea of the Devil.) Both this region and the Bermuda Triangle sit upon upon an agonic line, an area where magnetic north and true north align. Such areas are known to cause wild readings in compasses and other instruments. The similarities don't end there: both spots also mark nodal points in the sea, where major surface and tidal currents converge and turn, and they're both located on the eastern edges of continental shelves. Both areas are also volcanically active; in the Dragon's Triangle, volcanic islands have been known to appear and disappear over the course of a few weeks or months.
During World War II, countless Japanese warships and planes were lost in the Triangle, and in the years after the war the Japanese government studied the area to determine what had happened. In 1952, the Kaio Maru No. 5, the research vessel sent to investigate, vanished without a trace with 22 crewmen and nine scientists on board.
UFO sightings are common in the Dragon's Triangle stretching back centuries.
so myth or reality: how do these world class vanish into thin air?which myteries lie in back of these disappearances? ROGUE WAVES? SEA MONSTERS?UFO? tidal waves?
lets check case by case myths and rational explanations , and some highly fascinating videolinks to clear examples of the dangers lying in the waters for superyacht will illustrate this article.
ROGUE WAVES
french helicopter carrier JEANNE D ARC , some 400 miles south of japan was,suddenly striked by the "three sisters" , the legendary superwaves that french navigator dumont d urville had stated encountering in the south seas and for which he was mocked till his life ended.
three freak waves just appeared out of nowhere and struck the ship forward as it had time enough to change course betwenn the 60 feet waves separated each by 100 meters.no great damage was done as the excellent reaction was possible as immediately spotted .the mystery here lies in the fact that the freaks were only approximately 800 meters large wheras other such waves are witnessed to have no end on either side of horizon.
la jeanne d arc et les trois glorieuses
http://www.ifremer.fr/web-com/molagnon/jpo2000/_images/glorieuses.pdf
a yacht was caught in a freak wave by normal weather in the following video link i invite you to look at; one can see a 10 meter wave appear out of the blue and slam the superyacht forward while deckies are working on front bow.without having the supersize of the previous example of helicopter carrier jeanne d arc , this shows a clear example of how freaky these rogue waves can be.
https://www.youtube.com/watch?v=szk83cONAqM
in the following internet link , one can observe the effects of a superrogue wave which specialists estimate to be at least 18 to 23 meters slam sideways a fishing ship stuck in a storm off the aleutian archipelago
http://opilia.vodpod.com/video/49142-rogue-wave-hits-aleutian-ballad
oceans claim on average one ship a week, often in mysterious circumstances. With little evidence to go on, investigators usually point at human error or poor maintenance but an alarming series of disappearances and near-sinkings, including world-class vessels with unblemished track records, has prompted the search for a more sinister cause and renewed belief in a maritime myth: the wall of water. Waves the height of an office block. Waves twice as large as any that ships are designed to ride over.
These are not tsunamis or tidal waves, but huge breaking walls of water that come out of the blue. Suspicions these were fact not fiction were roused in 1978, by the cargo ship München. She was a state-of-the-art cargo ship. The December storms predicted when she set out to cross the Atlantic did not concern her German crew. The voyage was perfectly routine until at 3am on 12 December she sent out a garbled mayday message from the mid-Atlantic. Rescue attempts began immediately with over a hundred ships combing the ocean.
The ship was never found. She went down with all 27 hands. An exhaustive search found just a few bits of wreckage, including an unlaunched lifeboat that bore a vital clue. It had been stowed 20m above the water line yet one of its attachment pins had twisted as though hit by an extreme force. The Maritime Court concluded that bad weather had caused an unusual event. Other seafarers could not help but consider the possibility of a mythical freak wave.
Freak waves are the stuff of legend. They aren't just rare, according to traditional views of the sea, they shouldn't exist at all. Oceanographers and meteorologists have long used a mathematical system called the linear model to predict wave height. This assumes that waves vary in a regular way around the average (so-called 'significantwave height. In a storm sea with a significant wave height of 12m, the model suggests there will hardly ever be a wave higher than 15m. One of 30m could indeed happen - but only once in ten thousand years.
Except they do happen with startling frequency. Since 1990, 20 vessels have been struck by waves off the South African coast that defy the linear model's predictions. And on New Year's Day, 1995 a wave of 26m was measured hitting the Draupner oil rig in the North Sea off Norway. Concerned shipping operators wanted to know what was going on. The largest wave marine architects are required to accommodate in the design strength calculations is 15m from trough to crest. If that assumption were to be proved false, the whole world shipping industry would face some very tough choices.
What could cause such extreme waves? Curious about the spate of South African incidents, oceanographer Marten Grundlingh plotted the strikes on thermal sea surface maps. All the ships had been at the edge of the Agulhas Current, the meeting point of two opposing flows mixing warm Indian Ocean water with a colder Atlantic flow. Radar surveillance by satellite confirmed that wave height at the edge of this current could grow well beyond the linear model's predictions, especially if the wind direction opposed the current flow.
Problem solved: the answer was just to avoid certain ocean currents in certain weather conditions. There was nothing freakish about large waves; the mariners' myth was an explicable phenomenon. To science, this was one that didn't get away.
Unfortunately, ocean currents could not explain two near disastrous wave strikes in March 2001. Once more two reputable ships, designed to cope with the very worst conditions any ocean could throw at them, were crippled to the point of sinking. The Bremen and Caledonian Star were carrying hundreds of tourists across the South Atlantic. At 5am on 2 March the Caledonian Star's First Officer saw a 30m wave bearing down on them.
It smashed over the ship, flooding the bridge and destroying much of the navigation and communication equipment. The Caledonian Star limped back to port, her crew and passengers grateful that the engines had kept running, despite the onslaught.
Just days earlier, the cruise liner Bremen had been less fortunate. 137 German tourists were aboard when she too faced an awesome wall of water in the South Atlantic. The impact knocked out all the instrumentation and all power, leaving them helpless in the tumultuous sea. Unable to maintain her course into the waves, there was a real risk the ship could go down and they knew none of the passengers would survive in lifeboats in such freezing conditions. With emergency power only, the crew battled to restart the engines. When they eventually succeeded, it opened the door to a very lucky escape.
No current could have created such huge waves. There is none in that part of the Atlantic. Clearly, there was another effect investigators needed to find. Except someone already had: it existed (on paper at least) in the world of quantum physics. Al Osborne is a wave mathematician with 30 years experience devising equations to describe open ocean wave patterns. Quantum physics has at its heart a concept called the Schrodinger Equation, a way of expressing the probability of something happening that is far more complex than the simple linear model. Al's theory is based on the notion that in certain unstable conditions, waves can steal energy from their neighbours. Adjacent waves shrink while the one at the focus can grow to an enormous size. His modified Schrodinger Equation had been rejected in the past as implausible, but with research attention centred on analysing these rogue waves - including global satellite radar surveillance by the new European Remote Sensing Satellite - data began to emerge backing his case. When Al came across the New Year's Day 1985 wave profiles from the Draupner oil rig, he saw his mathematical model played out in the real world.
Al's work - if correct - suggests that there are two kinds of waves out on the high seas; the classical undulating type described by the linear model and an unstable non-linear monster - a wave that at any time can start sucking up energy from waves around it to become a towering freak. The consequences for ship design could be stark.
Currently the biggest wave factored into most ship design is smooth, undulating and 15m high. A freak wave is not only far bigger, it is so steep it is almost breaking. This near-vertical wall of water is almost impossible to ride over - the wave just breaks over the ship. According to accident investigator, Rod Rainey, such a wave would exert a pressure of 100 tonnes per square metre on a ship, far greater than the 15 tonnes that ships are designed to withstand without damage. It's no wonder that even ships the size of the huge freighter München can sink without trace.
SEA MONSTERS
The chief witnesses in this amazing yet little-remembered encounter were experienced British naturalists, Fellows of the Zoological Society of London best known for their work in ornithology. Their account of "a creature of most extraordinary form and proportions" is recorded in the 1906 edition of the Society's Proceedings and in Nicoll's 1908 book Three Voyages of A Naturalist.
On December 7, 1905, at 10:15 AM, Nicoll and Meade-Waldo were on a research cruise aboard the yacht Valhalla. Fifteen miles east of the mouth of Brazil's Parahiba River, Nicoll spotted a large dorsal fin which "resembled that of no fish I had previously seen."
Nicoll turned to his companion and asked, "Is that the fin of a great fish?" Meade-Waldo looked. The fin was cruising past them about a hundred yards from the yacht. Meade-Waldo described it as "dark seaweed-brown, somewhat crinkled at the edge." The visible part of the fin was roughly rectangular, about six feet long and eighteen inches to two feet high.
Meade-Waldo turned his binoculars on the object, and immediately a head on a long neck rose from the water in front of the frill. He estimated the neck was "about the thickness of a slight man's body, and from 7 to 8 feet was out of the water; head and neck were all about the same thickness."
The head had a very turtle-like appearance, as also the eye," Meade-Waldo wrote of the incident. It moved its head and neck from side to side in a peculiar manner: the color of the head and neck was dark brown above, and whitish below-almost white, I think."
The neck threw up a significant wave where it entered the water, and Nicoll noted that, "Below the water we could indistinctly see a very large brownish-black patch, but could not make out the shape of the creature."
Nicoll added, "This creature was an example, I consider, of what has been so often reported, for want of a better name, as the 'great sea-serpent.'"
In a 1929 letter to sea-serpent writer Rupert T. Gould, Meade-Waldo added that "I will never forget poor Nicoll's face of amazement when we looked at each other after we had passed out of sight of it." Gould gave the case a very thorough treatment in his meticulous if partisan book, The Case for the Sea-Serpent, published in 1930.
The original sighting lasted for several minutes. The Valhalla drew away from the creature, and the yacht was traveling under sail and could not come about to pursue. At 2:00 AM on December 8th, however, three crewmembers saw what appeared to be the same animal, almost entirely submerged, overtaking and passing the Valhalla at a speed of about nine knots.
That, in brief, is the story of the most important sighting in the long and controversial history of the sea-serpent.
So what did the witnesses see?
Skeptics often explain sea-monster reports as misidentifications of known animals, floating debris, etc. Very often, they are undoubtedly correct. On this report, however, the response from skeptics was a deafening silence. Neither then nor since has a "non-monstrous" explanation been offered.
There is no logical reason to doubt that the observers saw an unknown marine animal. The observing conditions were perfect and the witnesses highly qualified. It would be hard to wish for better testimonial evidence.
Horror sea legends are making the rounds about unsuspecting yachts sinking in mid-ocean after striking a floating container, or running into a floating log off the Canadian coast and shattering their hull.
one skipper recals another skipper wrtiting him an email explaining he came "across something yesterday that makes every single-hander shudder -- a huge steel floating mooring buoy for a ship, covered with tires, just cut loose and drifting around. Jim popped his head out of the cockpit just in time to see this massive thing go by. If he had hit it square on, it could have been a serious situation.”"That's one of my biggest worries, hitting a large solid object, particularly lost shipping containers. I once read a report about how many lost containers were floating around in the ocean at any one time and it was a scary number. Hit one of those at speed and there's a good chance you're going down.”this shows some level of danger but is only finally a floating buoy.
whatabout those legendary semi sumerged containers or floating logs as one can see them in the last issue of the crew report in the ocean travellers editorial of a superyacht cruising up in finland?
research revealed that containers are not built to float. They are weather-tight to keep out the elements of wind and spray, but not water-tight. Consequently, nearly all of them sink almost immediately. Their ventilation openings prevent air from being trapped inside. If a container does continue to float after being lost overboard it would be a rare occurrence caused by the buoyancy of the cargo that it happens to contain. Since many things are shipped packed in Styrofoam the cargo could be buoyant enough to float the container for a period of time. However, while Styrofoam seems to be bulky when we unpack our latest computer, it is actually full of great voids. If you break up the Styro it all fits in a little bag. Consequently, in each packing crate there is not enough styrofoam to float the heavy object being shipped, much less the steel shipping container. So except in rare cases, the truth is that as the cardboard and paper packing becomes waterlogged there would soon be insufficient buoyancy remaining in the Styrofoam to keep a container afloat after a day or two.
According to USA Today, industry experts estimate that anywhere from 2,000 to 10,000 containers fall off ships each year, less than 1 percent of the number of containers sent by sea annually but representing a huge cost to those who lose cargo to the ocean.
There are a total of 97,745,706 square nautical miles of ocean worldwide, so even if all containers that are lost annually each stayed afloat for an average of one week, then on any given day there would be only 38 containers floating in the world’s oceans.
Looking at it another way, there would be only one floating container in each piece of ocean the size of EUROPE.
On the other hand, floating logs, or dead heads seem to be a clear and present danger sighted by almost every pleasure boater of wide experience. several persons who struck dead heads only tell of damage to their boat, bent propellers, scratches to the hull, and none speak of catastrophic collisions, sinking or death.
Most floating logs would strike a boat hull at an angle and glance off with a loud and scary thump. Also floating logs tend to lie across the direction of the swell pattern, spending most of their time in the troughs of the waves. Consequently, if you are not plowing directly into the waves or heading directly downwind which is never a good course, you will strike any floating log with a glancing blow, which won’t do more damage than a large scratch. Most floating logs escape from log booms and are already dressed for the mill with roots or branches already trimmed off. The only floating log to actually fear is a huge tree washed out to sea in a storm with a heavy rock filled root ball which might be floating vertically just below the surface. That vertical submerged tree, when struck, would not glance off and might hole your bottom. Similarly a broken off piling that had some concrete or other weight on one end causing it to float vertically, could also become a nearly immovable object. But, even here the damage may be merely negligible.
a commercial captain was operating a large dinner cruise vessel on the San Francisco Bay iwhen he hit such a floating piling in a vertical position. This occurred off Ayala Cove in over 100-feet of water, and he was making about 6 knots with his steel hulled, 185-foot ship. The bow struck the piling a glancing blow, and the piling was pushed down by the ship’s bow, leaving only a scratch on the hull. Then, the piling resurfaced under the ship’s shaft where it caused the stuffing box to start leaking. The only result was a significant leak in the propeller shaft stuffing box, which the bilge pump could easily handle. All of this was easily repaired, but did require a drydocking. No one was even knocked down or injured by the collision, and the dinner cruise continued unabated, but with the bilge pump coming on and off more than normal.a sea serpent or nessie? no difference these are legends but reality of open water monsters as dangerous floating unidentified objects are real.
Since the days of early civilization many thousands of ships have sunk and/or disappeared in waters around the world due to navigational and other human errors, storms, piracy, fires, and structural/mechanical failures. Aircraft are subject to the same problems, and many of them have crashed at sea around the globe. Often, there were no living witnesses to the sinking or crash, and hence the exact cause of the loss and the location of the lost ship or aircraft are unknown. A large number of pleasure boats travel the waters between Florida and the Bahamas. All too often, crossings are attempted with too small a boat, insufficient knowledge of the area's hazards, and a lack of good seamanship.
To see how common accidents are at sea, you can examine some of the recent accident reports of the united states National Transportation Safety Board for ships and aircraft. One of the aircraft accident reports concerns an in-flight engine failure and subsequent ditching of a Cessna aircraft near Great Abaco Island in the Bahamas on 13 July 2003. This is the type of accident that would likely have been attributed to mysterious causes in the Bermuda Triangle if there had been no survivors or other eyewitnesses of the crash.
A significant factor with regard to missing vessels in the Bermuda Triangle is a strong ocean current called the Gulf Stream. It is extremely swift and turbulent and can quickly erase evidence of a disaster. The weather also plays its role. Prior to the development of telegraph, radio and radar, sailors did not know a storm or hurricane was nearby until it appeared on the horizon. For example, the Continental Navy sloop Saratoga was lost off the Bahamas in such a storm with all her crew on 18 March 1781. Many other US Navy ships have been lost at sea in storms around the world. Sudden local thunder storms and water spouts can sometimes spell disaster for mariners and air crews. Finally, the topography of the ocean floor varies from extensive shoals around the islands to some of the deepest marine trenches in the world. With the interaction of the strong currents over the many reefs the topography of the ocean bottom is in a state of flux and the development of new navigational hazards can sometimes be swift.
It has been inaccurately claimed that the Bermuda Triangle is one of the two places on earth at which a magnetic compass points towards true north. Normally a compass will point toward magnetic north. The difference between the two is known as compass variation. The amount of variation changes by as much as 60 degrees at various locations around the World. If this compass variation or error is not compensated for, navigators can find themselves far off course and in deep trouble. Although in the past this compass variation did affect the "Bermuda Triangle" region, due to fluctuations in the Earth's magnetic field this has apparently not been the case since the nineteenth century.
We know of no US Government-issued maps that delineate the boundaries of the Bermuda Triangle. However, general maps as well as nautical and aviation charts of the general area are widely available in libraries and from commercial map dealers.the us coast guards position on the bermuda triangle is the following,
The Bermuda Triangle or Devil’s Triangle is a mythical geographic area located off the southeastern coast of the United States. It is noted for an apparent high incidence of unexplained losses of ship, small boats, and aircraft.
The Coast Guard does not recognize the existence of the so-called Bermuda Triangle as a geographic area of specific hazard to ships or planes. In a review of many aircraft and vessel losses in the area over the years, there has been nothing discovered that would indicate that casualties were the result of anything other than physical causes. No extraordinary factors have ever been identified.
TIDAL WAVES
another danger for yachting is while at cay with sea surges or tsunamis: what are the dangers in the prevalent yachting hotspots around the world to top those dangers already clearly identified here above as concerning sea devil and bermuda triangle.
we have all seen clearly that even a waeship at anchor off a coast where a tsunami hits is a toy in the hands of the devil.
what risks exist in both med and caribbean? here is the viewpoint of a bahamas paper concerning the possibility of a tsunami and supertsunami strike in that country.
The Bahamas islands, all of which are low-lying, would take the full brunt of the mega-tsunamis and be completely swamped. The damage would be almost incalculable, both socially and economically.
As the earthquake and tsunami death toll in the Far East rose over 63,000 yesterday, the Bahamas was given a worrying reminder of what could happen if a volcano in the Canary Islands ever erupts and splits.
In fact, such a calamity could have an even greater impact than the current crisis in the Indian Ocean, where giant waves have taken more than 44,000 lives at the latest count.
For the waves created by a major eruption of Cumbre Vieja on La Palma could reach 330 feet high, devastating not only the west African coast, but also the eastern seaboard of the United States and the entire Caribbean region.
The Bahama islands, all of them low-lying, would take the full brunt of the mega-tsunamis and be completely swamped. The damage would be almost incalculable, both socially and economically.
Seismologist Stuart Sipkin stressed over the weekend that the Canary Islands tsunami scenario is the least likely of those that could occur in future. The Pacific is a much likelier location for a disaster of this kind because of the huge faults running through California and around the southern Alaskan coast.
Impact
But it can never be ruled out. And the Bahamas can learn from the devastating impact of the Sumatra earthquake by having an early warning system in place, and the means to get people off the beaches and out of harm´s way.
There is no doubt that the Sumatra tragedy, which has destroyed lives in countries all round the Indian Ocean, would have had less impact if even a rudimentary warning system had been in place.
As it turned out, thousands of people were actually on the beaches and in waterfront cafes when the waves crashed inland in countries like Thailand and Sri Lanka. Entire communities were simply washed away, and the complete death toll may never be known.
If Cumbre Vieja ever erupts and splits, with millions of tons of rock and earth plunging into the sea, the Bahamas and Florida will have roughly nine hours to brace themselves before the mega-tsunamis start to come ashore.
All the way across the Atlantic, the waves would gather a frightening momentum, moving at around 500mph and gaining height as they neared the coast.
As they drew close, water would be sucked from the shallow Bahamian beaches, exposing huge areas of seabed, leaving millions of fish to flounder in the sand and coral.
Then the water would crash inland with horrific power, washing away everything in its path.
In the Maldives, which took a hard hit from the Sumatra disaster, whole islands are said to have disappeared under massive walls of water. If Cumbre Vieja ever blows its top, the Bahamas, along with Haiti, the Dominican Republic and the entire Antilles chain, will take an even heavier hit.
However, the Bahamas, unlike many islands in the Caribbean basin, has no high ground on which people could take refuge. The best chance of escape would be to get into the highest and strongest buildings around, or fly out of the country during the limited time available before the waves hit.
Simon Day, of the Benfield Greig Hazard Research Centre at London University, said the Canary Islands volcano is not erupting at present. So the short-term and medium-term risks were “negligible’.
But he said Cumbre Vieja should be monitored closely for any signs of activity so that emergency services could plan an effective response.
“Eruptions of Cumbre Vieja occur at intervals of decades to a century or so and there may be a number of eruptions before its collapse,’ said Day.
“Although the year-to-year probability of a collapse is therefore low, the resulting tsunami would be a major disaster with indirect effects around the world.’
The problem with Cumbre Vieja is that it contains a deep, near vertical flawline which any future volcanic activity could expand into a chasm. Once this fissure widens significantly, it is in great danger of splitting the mountain in two, sending a massive volume of rock into the sea.
The energy released by such an occurrence would be equal to the electricity consumption of the entire United States during a six-month spell, according to scientists.
Collapse
The landslide itself would create a 3,000 feet high dome of water tens of miles wide. This would then collapse and rebound. In just ten minutes, the first tsunami would have moved 155 miles.
The west Saharan coast would be first to be hit, with 330-foot waves crashing ashore. Florida and the Caribbean, including the Bahamas, would have to brace themselves for 165-foot waves some eight or nine hours later.
Waves striking Europe would be smaller, but Spain, Portugal, Britain and France would all be affected. Without proper warnings, the death toll could be even higher than that of the current disaster in Asia.
A research study into the possibility of a Cumbre Vieja eruption warned that mega-tsunamis would push sea water many miles inland in the United States, causing trillions of dollars in damage.
The one encouraging factor for the Bahamas and the eastern US is that the Atlantic is much less susceptible to the tectonic plate activity that usually causes tsunamis. The Cumbre Vieja volcano is, however, potentially just as deadly as more conventional upheavals like quakes and tremors.
Tectonic
Bob Morton, research geologist at the US geological survey centre in St Petersburg, Florida, said the likelihood of tectonic activity in this area was very low - comparable, odds-wise, to an asteroid striking the state. The mid-Atlantic region is relatively benign with Cumbre Vieja one of the few potential flashpoints.
Robert Weisberg, professor of physical oceanography at the University of Florida, said tsunamis were born of undersea earthquakes, volcanic eruptions or submarine landslides.
“You get movement at the base of the ocean, which causes water to move,’ he said, “It´s like throwing a stone into a lake. Waves propagate away from the disturbance going very, very fast. From the epicentre to somebody´s beach takes a short period of time.’
In the Caribbean itself, the Puerto Rico Trench is a potential source of trouble, though this 27,000-feet deep undersea fissure has not produced a significant quake since 1946, when 1,800 people died in north-east Hispaniola.
In 1918, a tsunami killed 91 people in north-west Puerto Rico and in 1867 a 25-foot wave in the Virgin Islands killed five people. Since the 1940s, however, the Trench has been silent.
The closest thing to a Florida tsunami in recent memory was a rogue wave in Daytona 13 years ago.
The 18-foot monster injured 20 people and damaged 10 cars. It was later linked to thunderstorms from the Georgia coast.
As with most natural disasters, tsunamis offer few consolations, only powerful reminders that mankind is relatively helpless in the face of catastrophes which are beyond its control.
However, the Bahamas would do well in future to keep one ear cocked for news of Cumbre Vieja, the slumbering peak in the Canaries which clears its throat every decade or so.
If it ever erupts and blows skywards, with one side of the mountain falling into the sea, we know that trouble is on its way.
the devastating tsunamis of december 2004 in south east asia have shown us spectacular and horrifying images of a cataclysmic seismic event which don t necessarily help analysis of the happenings.for a professional yachtsmen standpoint , the photo hereunder clearly shows the steps of this tsunami when hitting the coast.the photo is the record of a depth analyzer from a yacht anchored out a few hundred meters off the tsunami striked beach .
the phenomenon lasts an hour.it starts with a 3 meter regression of the sea in ten minutes , then gains them back and then goes up an extra 3 meters in six minutes. between the time one notices waters lowering and the time the first wave strikes about eight minutes go by: time enough for an average person to walk half a mile.
like all tidal waves, it s a succession of oscillations of which the first isn t the most powerful.getting out of harms way starts when a more powerful wave to the first one strikes.
the incredible point to this recording is that the yacht wasn t damaged as ten meters depth was enough to allow the waves to slip under the boat.as the followwing photo shows us the phuket port right after the tidal wave , one can see boats peacefully anchored off a devastated coastline.
any potential tsunami risks in provence or italian riviera?
we ve seen that they can really strike anywhere so long as seismic activity is present underwater.however the scenario of tidal waves is very remote in this part of the world as the ocean volume in western med , the underwater faults and the tectonic displcement are far of those present in the pacific or indian ocean.so waves the size of december 2004 in asia arent really possible.
however this phenomenon has striked the french riviera twice per century on the past two hundred years.the latest remembered by many locals in Nice was end of year 1979 when a third of the airport fell to the bottom of the sea along with billions of tons of soil and stone creating a quake which in turn has turned to a 4 meter wave which struck the coast betwen menton and theoule killing one in antibes at la salice beach and injuring many more.in 1564 a n earthquake in the nice region was followed by a tidal wave which a witness in antibes states "left the entire port dry , then water came back powerfully leveling different stores" being of course above the remparts!
J'attends vos boulets de canons sceptiques sur un documentaires effectués il y a quelques années sur le thème du triangle des Bermudes....en comparant réalités vs légendes.
Notez que mes approches sont souvent empiriques étant peu doué pour les développements longs et fastidieux.
SEA LEGENDS! reality vs legends where does the truth stand?
The Bermuda Triangle is well known but over in the Eastern Hemisphere there's a similar area of Pacific Ocean known as the Dragon's Triangle. The region starts from western Japan and runs to a point in the ocean at approximately 145 degrees east latitude, then turns west-southwest to the islands of Guam and Yap, then west to Taiwan and back up to Japan to the north-northeast. Like the Bermuda Triangle, the region is known for ship and airplane disappearances, freak storms, misbehaving instruments and other unusual activity — even UFOs.
The Dragon's Triangle is so named according to an ancient Chinese myth, which tells of dragons that live deep beneath the surface, whose movement can suddenly churn up waves, whirlpools, thick fog and sudden storms. (The Japanese refer to it as Ma-no Umi: the Sea of the Devil.) Both this region and the Bermuda Triangle sit upon upon an agonic line, an area where magnetic north and true north align. Such areas are known to cause wild readings in compasses and other instruments. The similarities don't end there: both spots also mark nodal points in the sea, where major surface and tidal currents converge and turn, and they're both located on the eastern edges of continental shelves. Both areas are also volcanically active; in the Dragon's Triangle, volcanic islands have been known to appear and disappear over the course of a few weeks or months.
During World War II, countless Japanese warships and planes were lost in the Triangle, and in the years after the war the Japanese government studied the area to determine what had happened. In 1952, the Kaio Maru No. 5, the research vessel sent to investigate, vanished without a trace with 22 crewmen and nine scientists on board.
UFO sightings are common in the Dragon's Triangle stretching back centuries.
so myth or reality: how do these world class vanish into thin air?which myteries lie in back of these disappearances? ROGUE WAVES? SEA MONSTERS?UFO? tidal waves?
lets check case by case myths and rational explanations , and some highly fascinating videolinks to clear examples of the dangers lying in the waters for superyacht will illustrate this article.
ROGUE WAVES
french helicopter carrier JEANNE D ARC , some 400 miles south of japan was,suddenly striked by the "three sisters" , the legendary superwaves that french navigator dumont d urville had stated encountering in the south seas and for which he was mocked till his life ended.
three freak waves just appeared out of nowhere and struck the ship forward as it had time enough to change course betwenn the 60 feet waves separated each by 100 meters.no great damage was done as the excellent reaction was possible as immediately spotted .the mystery here lies in the fact that the freaks were only approximately 800 meters large wheras other such waves are witnessed to have no end on either side of horizon.
la jeanne d arc et les trois glorieuses
http://www.ifremer.fr/web-com/molagnon/jpo2000/_images/glorieuses.pdf
a yacht was caught in a freak wave by normal weather in the following video link i invite you to look at; one can see a 10 meter wave appear out of the blue and slam the superyacht forward while deckies are working on front bow.without having the supersize of the previous example of helicopter carrier jeanne d arc , this shows a clear example of how freaky these rogue waves can be.
https://www.youtube.com/watch?v=szk83cONAqM
in the following internet link , one can observe the effects of a superrogue wave which specialists estimate to be at least 18 to 23 meters slam sideways a fishing ship stuck in a storm off the aleutian archipelago
http://opilia.vodpod.com/video/49142-rogue-wave-hits-aleutian-ballad
oceans claim on average one ship a week, often in mysterious circumstances. With little evidence to go on, investigators usually point at human error or poor maintenance but an alarming series of disappearances and near-sinkings, including world-class vessels with unblemished track records, has prompted the search for a more sinister cause and renewed belief in a maritime myth: the wall of water. Waves the height of an office block. Waves twice as large as any that ships are designed to ride over.
These are not tsunamis or tidal waves, but huge breaking walls of water that come out of the blue. Suspicions these were fact not fiction were roused in 1978, by the cargo ship München. She was a state-of-the-art cargo ship. The December storms predicted when she set out to cross the Atlantic did not concern her German crew. The voyage was perfectly routine until at 3am on 12 December she sent out a garbled mayday message from the mid-Atlantic. Rescue attempts began immediately with over a hundred ships combing the ocean.
The ship was never found. She went down with all 27 hands. An exhaustive search found just a few bits of wreckage, including an unlaunched lifeboat that bore a vital clue. It had been stowed 20m above the water line yet one of its attachment pins had twisted as though hit by an extreme force. The Maritime Court concluded that bad weather had caused an unusual event. Other seafarers could not help but consider the possibility of a mythical freak wave.
Freak waves are the stuff of legend. They aren't just rare, according to traditional views of the sea, they shouldn't exist at all. Oceanographers and meteorologists have long used a mathematical system called the linear model to predict wave height. This assumes that waves vary in a regular way around the average (so-called 'significantwave height. In a storm sea with a significant wave height of 12m, the model suggests there will hardly ever be a wave higher than 15m. One of 30m could indeed happen - but only once in ten thousand years.
Except they do happen with startling frequency. Since 1990, 20 vessels have been struck by waves off the South African coast that defy the linear model's predictions. And on New Year's Day, 1995 a wave of 26m was measured hitting the Draupner oil rig in the North Sea off Norway. Concerned shipping operators wanted to know what was going on. The largest wave marine architects are required to accommodate in the design strength calculations is 15m from trough to crest. If that assumption were to be proved false, the whole world shipping industry would face some very tough choices.
What could cause such extreme waves? Curious about the spate of South African incidents, oceanographer Marten Grundlingh plotted the strikes on thermal sea surface maps. All the ships had been at the edge of the Agulhas Current, the meeting point of two opposing flows mixing warm Indian Ocean water with a colder Atlantic flow. Radar surveillance by satellite confirmed that wave height at the edge of this current could grow well beyond the linear model's predictions, especially if the wind direction opposed the current flow.
Problem solved: the answer was just to avoid certain ocean currents in certain weather conditions. There was nothing freakish about large waves; the mariners' myth was an explicable phenomenon. To science, this was one that didn't get away.
Unfortunately, ocean currents could not explain two near disastrous wave strikes in March 2001. Once more two reputable ships, designed to cope with the very worst conditions any ocean could throw at them, were crippled to the point of sinking. The Bremen and Caledonian Star were carrying hundreds of tourists across the South Atlantic. At 5am on 2 March the Caledonian Star's First Officer saw a 30m wave bearing down on them.
It smashed over the ship, flooding the bridge and destroying much of the navigation and communication equipment. The Caledonian Star limped back to port, her crew and passengers grateful that the engines had kept running, despite the onslaught.
Just days earlier, the cruise liner Bremen had been less fortunate. 137 German tourists were aboard when she too faced an awesome wall of water in the South Atlantic. The impact knocked out all the instrumentation and all power, leaving them helpless in the tumultuous sea. Unable to maintain her course into the waves, there was a real risk the ship could go down and they knew none of the passengers would survive in lifeboats in such freezing conditions. With emergency power only, the crew battled to restart the engines. When they eventually succeeded, it opened the door to a very lucky escape.
No current could have created such huge waves. There is none in that part of the Atlantic. Clearly, there was another effect investigators needed to find. Except someone already had: it existed (on paper at least) in the world of quantum physics. Al Osborne is a wave mathematician with 30 years experience devising equations to describe open ocean wave patterns. Quantum physics has at its heart a concept called the Schrodinger Equation, a way of expressing the probability of something happening that is far more complex than the simple linear model. Al's theory is based on the notion that in certain unstable conditions, waves can steal energy from their neighbours. Adjacent waves shrink while the one at the focus can grow to an enormous size. His modified Schrodinger Equation had been rejected in the past as implausible, but with research attention centred on analysing these rogue waves - including global satellite radar surveillance by the new European Remote Sensing Satellite - data began to emerge backing his case. When Al came across the New Year's Day 1985 wave profiles from the Draupner oil rig, he saw his mathematical model played out in the real world.
Al's work - if correct - suggests that there are two kinds of waves out on the high seas; the classical undulating type described by the linear model and an unstable non-linear monster - a wave that at any time can start sucking up energy from waves around it to become a towering freak. The consequences for ship design could be stark.
Currently the biggest wave factored into most ship design is smooth, undulating and 15m high. A freak wave is not only far bigger, it is so steep it is almost breaking. This near-vertical wall of water is almost impossible to ride over - the wave just breaks over the ship. According to accident investigator, Rod Rainey, such a wave would exert a pressure of 100 tonnes per square metre on a ship, far greater than the 15 tonnes that ships are designed to withstand without damage. It's no wonder that even ships the size of the huge freighter München can sink without trace.
SEA MONSTERS
The chief witnesses in this amazing yet little-remembered encounter were experienced British naturalists, Fellows of the Zoological Society of London best known for their work in ornithology. Their account of "a creature of most extraordinary form and proportions" is recorded in the 1906 edition of the Society's Proceedings and in Nicoll's 1908 book Three Voyages of A Naturalist.
On December 7, 1905, at 10:15 AM, Nicoll and Meade-Waldo were on a research cruise aboard the yacht Valhalla. Fifteen miles east of the mouth of Brazil's Parahiba River, Nicoll spotted a large dorsal fin which "resembled that of no fish I had previously seen."
Nicoll turned to his companion and asked, "Is that the fin of a great fish?" Meade-Waldo looked. The fin was cruising past them about a hundred yards from the yacht. Meade-Waldo described it as "dark seaweed-brown, somewhat crinkled at the edge." The visible part of the fin was roughly rectangular, about six feet long and eighteen inches to two feet high.
Meade-Waldo turned his binoculars on the object, and immediately a head on a long neck rose from the water in front of the frill. He estimated the neck was "about the thickness of a slight man's body, and from 7 to 8 feet was out of the water; head and neck were all about the same thickness."
The head had a very turtle-like appearance, as also the eye," Meade-Waldo wrote of the incident. It moved its head and neck from side to side in a peculiar manner: the color of the head and neck was dark brown above, and whitish below-almost white, I think."
The neck threw up a significant wave where it entered the water, and Nicoll noted that, "Below the water we could indistinctly see a very large brownish-black patch, but could not make out the shape of the creature."
Nicoll added, "This creature was an example, I consider, of what has been so often reported, for want of a better name, as the 'great sea-serpent.'"
In a 1929 letter to sea-serpent writer Rupert T. Gould, Meade-Waldo added that "I will never forget poor Nicoll's face of amazement when we looked at each other after we had passed out of sight of it." Gould gave the case a very thorough treatment in his meticulous if partisan book, The Case for the Sea-Serpent, published in 1930.
The original sighting lasted for several minutes. The Valhalla drew away from the creature, and the yacht was traveling under sail and could not come about to pursue. At 2:00 AM on December 8th, however, three crewmembers saw what appeared to be the same animal, almost entirely submerged, overtaking and passing the Valhalla at a speed of about nine knots.
That, in brief, is the story of the most important sighting in the long and controversial history of the sea-serpent.
So what did the witnesses see?
Skeptics often explain sea-monster reports as misidentifications of known animals, floating debris, etc. Very often, they are undoubtedly correct. On this report, however, the response from skeptics was a deafening silence. Neither then nor since has a "non-monstrous" explanation been offered.
There is no logical reason to doubt that the observers saw an unknown marine animal. The observing conditions were perfect and the witnesses highly qualified. It would be hard to wish for better testimonial evidence.
Horror sea legends are making the rounds about unsuspecting yachts sinking in mid-ocean after striking a floating container, or running into a floating log off the Canadian coast and shattering their hull.
one skipper recals another skipper wrtiting him an email explaining he came "across something yesterday that makes every single-hander shudder -- a huge steel floating mooring buoy for a ship, covered with tires, just cut loose and drifting around. Jim popped his head out of the cockpit just in time to see this massive thing go by. If he had hit it square on, it could have been a serious situation.”"That's one of my biggest worries, hitting a large solid object, particularly lost shipping containers. I once read a report about how many lost containers were floating around in the ocean at any one time and it was a scary number. Hit one of those at speed and there's a good chance you're going down.”this shows some level of danger but is only finally a floating buoy.
whatabout those legendary semi sumerged containers or floating logs as one can see them in the last issue of the crew report in the ocean travellers editorial of a superyacht cruising up in finland?
research revealed that containers are not built to float. They are weather-tight to keep out the elements of wind and spray, but not water-tight. Consequently, nearly all of them sink almost immediately. Their ventilation openings prevent air from being trapped inside. If a container does continue to float after being lost overboard it would be a rare occurrence caused by the buoyancy of the cargo that it happens to contain. Since many things are shipped packed in Styrofoam the cargo could be buoyant enough to float the container for a period of time. However, while Styrofoam seems to be bulky when we unpack our latest computer, it is actually full of great voids. If you break up the Styro it all fits in a little bag. Consequently, in each packing crate there is not enough styrofoam to float the heavy object being shipped, much less the steel shipping container. So except in rare cases, the truth is that as the cardboard and paper packing becomes waterlogged there would soon be insufficient buoyancy remaining in the Styrofoam to keep a container afloat after a day or two.
According to USA Today, industry experts estimate that anywhere from 2,000 to 10,000 containers fall off ships each year, less than 1 percent of the number of containers sent by sea annually but representing a huge cost to those who lose cargo to the ocean.
There are a total of 97,745,706 square nautical miles of ocean worldwide, so even if all containers that are lost annually each stayed afloat for an average of one week, then on any given day there would be only 38 containers floating in the world’s oceans.
Looking at it another way, there would be only one floating container in each piece of ocean the size of EUROPE.
On the other hand, floating logs, or dead heads seem to be a clear and present danger sighted by almost every pleasure boater of wide experience. several persons who struck dead heads only tell of damage to their boat, bent propellers, scratches to the hull, and none speak of catastrophic collisions, sinking or death.
Most floating logs would strike a boat hull at an angle and glance off with a loud and scary thump. Also floating logs tend to lie across the direction of the swell pattern, spending most of their time in the troughs of the waves. Consequently, if you are not plowing directly into the waves or heading directly downwind which is never a good course, you will strike any floating log with a glancing blow, which won’t do more damage than a large scratch. Most floating logs escape from log booms and are already dressed for the mill with roots or branches already trimmed off. The only floating log to actually fear is a huge tree washed out to sea in a storm with a heavy rock filled root ball which might be floating vertically just below the surface. That vertical submerged tree, when struck, would not glance off and might hole your bottom. Similarly a broken off piling that had some concrete or other weight on one end causing it to float vertically, could also become a nearly immovable object. But, even here the damage may be merely negligible.
a commercial captain was operating a large dinner cruise vessel on the San Francisco Bay iwhen he hit such a floating piling in a vertical position. This occurred off Ayala Cove in over 100-feet of water, and he was making about 6 knots with his steel hulled, 185-foot ship. The bow struck the piling a glancing blow, and the piling was pushed down by the ship’s bow, leaving only a scratch on the hull. Then, the piling resurfaced under the ship’s shaft where it caused the stuffing box to start leaking. The only result was a significant leak in the propeller shaft stuffing box, which the bilge pump could easily handle. All of this was easily repaired, but did require a drydocking. No one was even knocked down or injured by the collision, and the dinner cruise continued unabated, but with the bilge pump coming on and off more than normal.a sea serpent or nessie? no difference these are legends but reality of open water monsters as dangerous floating unidentified objects are real.
Since the days of early civilization many thousands of ships have sunk and/or disappeared in waters around the world due to navigational and other human errors, storms, piracy, fires, and structural/mechanical failures. Aircraft are subject to the same problems, and many of them have crashed at sea around the globe. Often, there were no living witnesses to the sinking or crash, and hence the exact cause of the loss and the location of the lost ship or aircraft are unknown. A large number of pleasure boats travel the waters between Florida and the Bahamas. All too often, crossings are attempted with too small a boat, insufficient knowledge of the area's hazards, and a lack of good seamanship.
To see how common accidents are at sea, you can examine some of the recent accident reports of the united states National Transportation Safety Board for ships and aircraft. One of the aircraft accident reports concerns an in-flight engine failure and subsequent ditching of a Cessna aircraft near Great Abaco Island in the Bahamas on 13 July 2003. This is the type of accident that would likely have been attributed to mysterious causes in the Bermuda Triangle if there had been no survivors or other eyewitnesses of the crash.
A significant factor with regard to missing vessels in the Bermuda Triangle is a strong ocean current called the Gulf Stream. It is extremely swift and turbulent and can quickly erase evidence of a disaster. The weather also plays its role. Prior to the development of telegraph, radio and radar, sailors did not know a storm or hurricane was nearby until it appeared on the horizon. For example, the Continental Navy sloop Saratoga was lost off the Bahamas in such a storm with all her crew on 18 March 1781. Many other US Navy ships have been lost at sea in storms around the world. Sudden local thunder storms and water spouts can sometimes spell disaster for mariners and air crews. Finally, the topography of the ocean floor varies from extensive shoals around the islands to some of the deepest marine trenches in the world. With the interaction of the strong currents over the many reefs the topography of the ocean bottom is in a state of flux and the development of new navigational hazards can sometimes be swift.
It has been inaccurately claimed that the Bermuda Triangle is one of the two places on earth at which a magnetic compass points towards true north. Normally a compass will point toward magnetic north. The difference between the two is known as compass variation. The amount of variation changes by as much as 60 degrees at various locations around the World. If this compass variation or error is not compensated for, navigators can find themselves far off course and in deep trouble. Although in the past this compass variation did affect the "Bermuda Triangle" region, due to fluctuations in the Earth's magnetic field this has apparently not been the case since the nineteenth century.
We know of no US Government-issued maps that delineate the boundaries of the Bermuda Triangle. However, general maps as well as nautical and aviation charts of the general area are widely available in libraries and from commercial map dealers.the us coast guards position on the bermuda triangle is the following,
The Bermuda Triangle or Devil’s Triangle is a mythical geographic area located off the southeastern coast of the United States. It is noted for an apparent high incidence of unexplained losses of ship, small boats, and aircraft.
The Coast Guard does not recognize the existence of the so-called Bermuda Triangle as a geographic area of specific hazard to ships or planes. In a review of many aircraft and vessel losses in the area over the years, there has been nothing discovered that would indicate that casualties were the result of anything other than physical causes. No extraordinary factors have ever been identified.
TIDAL WAVES
another danger for yachting is while at cay with sea surges or tsunamis: what are the dangers in the prevalent yachting hotspots around the world to top those dangers already clearly identified here above as concerning sea devil and bermuda triangle.
we have all seen clearly that even a waeship at anchor off a coast where a tsunami hits is a toy in the hands of the devil.
what risks exist in both med and caribbean? here is the viewpoint of a bahamas paper concerning the possibility of a tsunami and supertsunami strike in that country.
The Bahamas islands, all of which are low-lying, would take the full brunt of the mega-tsunamis and be completely swamped. The damage would be almost incalculable, both socially and economically.
As the earthquake and tsunami death toll in the Far East rose over 63,000 yesterday, the Bahamas was given a worrying reminder of what could happen if a volcano in the Canary Islands ever erupts and splits.
In fact, such a calamity could have an even greater impact than the current crisis in the Indian Ocean, where giant waves have taken more than 44,000 lives at the latest count.
For the waves created by a major eruption of Cumbre Vieja on La Palma could reach 330 feet high, devastating not only the west African coast, but also the eastern seaboard of the United States and the entire Caribbean region.
The Bahama islands, all of them low-lying, would take the full brunt of the mega-tsunamis and be completely swamped. The damage would be almost incalculable, both socially and economically.
Seismologist Stuart Sipkin stressed over the weekend that the Canary Islands tsunami scenario is the least likely of those that could occur in future. The Pacific is a much likelier location for a disaster of this kind because of the huge faults running through California and around the southern Alaskan coast.
Impact
But it can never be ruled out. And the Bahamas can learn from the devastating impact of the Sumatra earthquake by having an early warning system in place, and the means to get people off the beaches and out of harm´s way.
There is no doubt that the Sumatra tragedy, which has destroyed lives in countries all round the Indian Ocean, would have had less impact if even a rudimentary warning system had been in place.
As it turned out, thousands of people were actually on the beaches and in waterfront cafes when the waves crashed inland in countries like Thailand and Sri Lanka. Entire communities were simply washed away, and the complete death toll may never be known.
If Cumbre Vieja ever erupts and splits, with millions of tons of rock and earth plunging into the sea, the Bahamas and Florida will have roughly nine hours to brace themselves before the mega-tsunamis start to come ashore.
All the way across the Atlantic, the waves would gather a frightening momentum, moving at around 500mph and gaining height as they neared the coast.
As they drew close, water would be sucked from the shallow Bahamian beaches, exposing huge areas of seabed, leaving millions of fish to flounder in the sand and coral.
Then the water would crash inland with horrific power, washing away everything in its path.
In the Maldives, which took a hard hit from the Sumatra disaster, whole islands are said to have disappeared under massive walls of water. If Cumbre Vieja ever blows its top, the Bahamas, along with Haiti, the Dominican Republic and the entire Antilles chain, will take an even heavier hit.
However, the Bahamas, unlike many islands in the Caribbean basin, has no high ground on which people could take refuge. The best chance of escape would be to get into the highest and strongest buildings around, or fly out of the country during the limited time available before the waves hit.
Simon Day, of the Benfield Greig Hazard Research Centre at London University, said the Canary Islands volcano is not erupting at present. So the short-term and medium-term risks were “negligible’.
But he said Cumbre Vieja should be monitored closely for any signs of activity so that emergency services could plan an effective response.
“Eruptions of Cumbre Vieja occur at intervals of decades to a century or so and there may be a number of eruptions before its collapse,’ said Day.
“Although the year-to-year probability of a collapse is therefore low, the resulting tsunami would be a major disaster with indirect effects around the world.’
The problem with Cumbre Vieja is that it contains a deep, near vertical flawline which any future volcanic activity could expand into a chasm. Once this fissure widens significantly, it is in great danger of splitting the mountain in two, sending a massive volume of rock into the sea.
The energy released by such an occurrence would be equal to the electricity consumption of the entire United States during a six-month spell, according to scientists.
Collapse
The landslide itself would create a 3,000 feet high dome of water tens of miles wide. This would then collapse and rebound. In just ten minutes, the first tsunami would have moved 155 miles.
The west Saharan coast would be first to be hit, with 330-foot waves crashing ashore. Florida and the Caribbean, including the Bahamas, would have to brace themselves for 165-foot waves some eight or nine hours later.
Waves striking Europe would be smaller, but Spain, Portugal, Britain and France would all be affected. Without proper warnings, the death toll could be even higher than that of the current disaster in Asia.
A research study into the possibility of a Cumbre Vieja eruption warned that mega-tsunamis would push sea water many miles inland in the United States, causing trillions of dollars in damage.
The one encouraging factor for the Bahamas and the eastern US is that the Atlantic is much less susceptible to the tectonic plate activity that usually causes tsunamis. The Cumbre Vieja volcano is, however, potentially just as deadly as more conventional upheavals like quakes and tremors.
Tectonic
Bob Morton, research geologist at the US geological survey centre in St Petersburg, Florida, said the likelihood of tectonic activity in this area was very low - comparable, odds-wise, to an asteroid striking the state. The mid-Atlantic region is relatively benign with Cumbre Vieja one of the few potential flashpoints.
Robert Weisberg, professor of physical oceanography at the University of Florida, said tsunamis were born of undersea earthquakes, volcanic eruptions or submarine landslides.
“You get movement at the base of the ocean, which causes water to move,’ he said, “It´s like throwing a stone into a lake. Waves propagate away from the disturbance going very, very fast. From the epicentre to somebody´s beach takes a short period of time.’
In the Caribbean itself, the Puerto Rico Trench is a potential source of trouble, though this 27,000-feet deep undersea fissure has not produced a significant quake since 1946, when 1,800 people died in north-east Hispaniola.
In 1918, a tsunami killed 91 people in north-west Puerto Rico and in 1867 a 25-foot wave in the Virgin Islands killed five people. Since the 1940s, however, the Trench has been silent.
The closest thing to a Florida tsunami in recent memory was a rogue wave in Daytona 13 years ago.
The 18-foot monster injured 20 people and damaged 10 cars. It was later linked to thunderstorms from the Georgia coast.
As with most natural disasters, tsunamis offer few consolations, only powerful reminders that mankind is relatively helpless in the face of catastrophes which are beyond its control.
However, the Bahamas would do well in future to keep one ear cocked for news of Cumbre Vieja, the slumbering peak in the Canaries which clears its throat every decade or so.
If it ever erupts and blows skywards, with one side of the mountain falling into the sea, we know that trouble is on its way.
the devastating tsunamis of december 2004 in south east asia have shown us spectacular and horrifying images of a cataclysmic seismic event which don t necessarily help analysis of the happenings.for a professional yachtsmen standpoint , the photo hereunder clearly shows the steps of this tsunami when hitting the coast.the photo is the record of a depth analyzer from a yacht anchored out a few hundred meters off the tsunami striked beach .
the phenomenon lasts an hour.it starts with a 3 meter regression of the sea in ten minutes , then gains them back and then goes up an extra 3 meters in six minutes. between the time one notices waters lowering and the time the first wave strikes about eight minutes go by: time enough for an average person to walk half a mile.
like all tidal waves, it s a succession of oscillations of which the first isn t the most powerful.getting out of harms way starts when a more powerful wave to the first one strikes.
the incredible point to this recording is that the yacht wasn t damaged as ten meters depth was enough to allow the waves to slip under the boat.as the followwing photo shows us the phuket port right after the tidal wave , one can see boats peacefully anchored off a devastated coastline.
any potential tsunami risks in provence or italian riviera?
we ve seen that they can really strike anywhere so long as seismic activity is present underwater.however the scenario of tidal waves is very remote in this part of the world as the ocean volume in western med , the underwater faults and the tectonic displcement are far of those present in the pacific or indian ocean.so waves the size of december 2004 in asia arent really possible.
however this phenomenon has striked the french riviera twice per century on the past two hundred years.the latest remembered by many locals in Nice was end of year 1979 when a third of the airport fell to the bottom of the sea along with billions of tons of soil and stone creating a quake which in turn has turned to a 4 meter wave which struck the coast betwen menton and theoule killing one in antibes at la salice beach and injuring many more.in 1564 a n earthquake in the nice region was followed by a tidal wave which a witness in antibes states "left the entire port dry , then water came back powerfully leveling different stores" being of course above the remparts!
