Posted on 05/14/2002 9:37:13 AM PDT by gcallah
Did anyone watch the Discovery channel on MegaTsunamis over the weekend? Basically, a huge chunk of the island of La Plama in the Canaries is in danger of collapsing into the sea, which would set off a tidal wave washing 12 miles inland on the east coast of the US.
I've heard from a contact in the Army that there are serious worries that bin Laden could try to set off a nuke on La Palma that would trigger the collapse.
Should Discovery have been allowed to show this? Should the US station troops on La Palma?
The experts on the program presented speculative numbers - I found it interesting, but not all that credible.
Also, I have not read about tsunamis much, but my impression is that this is a shock wave (this is why it propagates much faster than the regular waves), so no permanent displacement of water is necessary.
Good point. You folks in the Islands would be in a world of hurt a big one came through.
Lol
No biggy, after all it's the blue zone, isn't it? ;-)
If you'll buy that I'll throw the Golden Gate in free....
This coming from an ex-smokers so please no flames. Puff to your hearts content.
It's pretty much a shallow-water sinusoidal wave as it crosses the ocean, i.e., it's wavelength is markedly greater than ocean depth. In the middle of the ocean, the wave would be many kilometers long and only a meter or so high. Such a wave travels at about the square root of the product of ocean depth and the acceleration of gravity. Deep ocean = high speed.
As the wave approaches shore, ocean depth decreases and the wave "piles up" because the leading edge of it has to slow down. All the water that had been spread out over many kilometers piles into a wave only a few 100 meters long. The result is your "shock wave" or breaking wave that can be 100 meters high.
From this site:
Appalling as the World Trade Center bombing was, it's absolutely nothing compared to the apocalyptic event that is yet to come. Somewhere over the next stretch of time, New Yorkers will have to deal with a HUGE tidal wave of biblical proportions. Meet the La Palma Megatsunami -- and shiver.
Try to surf this: a wave almost twice as tall as the Empire State Building, and traveling faster than an airplane, at a breathtaking 700 kilometers per hour. Enough to give you the creeps, right? Well, it should. For the question is not if such a massive wave will one day slosh across the oceans -- but when.
And there's more disturbing news. If the Doomsday Wave kicks in, it'll be end of story for the US East Coast. New York City: gone. Boston: washed away. Florida, Miami, the Bahamas -- all history. Oh, several hundreds of years may pass before the Super Wave rolls in. But on the other hand, it could happen next month as well.
It all starts with a faint rumbling of the earth, thousands of miles away. Near the African shore, the volcanic island of La Palma will rumble with seismic activity, announcing yet another eruption of the Cumbre Vieja volcano on the southern half of the island. But this time, the unstable western flank of the volcano doesn't hold. A huge chunk of the island simply breaks off and drops into the Atlantic Ocean. Plunge! No; PLUNGE!
Immediately, up rises a tsunami. And not just a tsunami: the sea is pushed up something like 650 meters, as 500 billion tons of rock and debris hit the ocean. Witnesses to the event will see how a massive wall of water towers up and starts sloshing westwards across the Atlantic, at the astonishing speed of over 700 kilometers per hour. Destination: US East Coast.
Now that will bring about some stress on the other side of the Atlantic. New Yorkers and millions of other inhabitants of the US coastal region will hear about it on the radio: within eight hours, the entire east coast will be splashed away! Hundreds of millions of Americans will get the hell out to escape the wet cataclysm, turning every city and every road in the area into total chaos.
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Some people will hope the Megatsunami will just break down by itself. But the La Palma tsunami isn't just the next dull wave. It will pass storms unscathed, and bombs won't do it much harm either. You see, the Megatsunami we're dealing with is an endless wall of water that stretches out across the entire Atlantic! Not exactly the kind of wave that easily breaks down.
Then, after eight hours, the incredible happens. At the US shore, all water suddenly recedes, as it is `sucked up' by the wave to come. You will be able to see the bottom of the ocean for hundreds of meters ahead. But your attention will be caught by something else: this huge wall of water, that's moving in on you a lot faster than you think might be good for your health.
As it closes in on the steep coast, the tsunami will grow and grow some more, until it is perhaps several hundreds of meters high. Seconds later, it impacts. With unimaginable force, billions of gallons of water slam into the coastal areas. Skyscrapers snap, bridges are ripped to pieces and outside the cities, forests and villages are swept away. And obviously, if you're still around, it's only likely you're killed in the whole show. The La Palma wave will push twenty kilometers into the land: since the wave is so long, more and more water will be pushed land inwards, until the entire wave has finally rolled onto the shore.
Next, the water mass withdraws. With unimaginable force, the wave is sucked back into the ocean, dragging with it everything and everyone it encounters. So one moment you're high and dry; only minutes later, you find yourself floundering in the Atlantic, well away from the shore. In effect, the tsunami will wash the coastal area clean. And although it won't really bring about the end of life on our planet, millions will die -- not to mention the total disruption of the world when the urban heart of America is swept away.
And by the way, the Americans aren't the only ones affected. More southwards, the Middle and Southern Americas will be struck. Calculations show Europe will suffer as well. The southern part of England will be inundated. Parts of the low lying Netherlands will be flooded. Some parts of the French and Spanish coasts will be severely hit. In Europe too, many thousands will die.
Like almost every apocalyptic scenario described here on Exit Mundi, the one with the tidal wave is nothing really special in Earth's history. You see, it's quite normal for a volcanic island to collapse every once and a while. That's why on several occasions in our prehistoric past, giant killer waves rolled over the seas, bringing about doom and destruction everywhere they hit land (see table).
| Ohau island, Hawaii | Many times in history, big chunks of Hawaii plummeted into the sea. The biggest event occurred 2 million years ago, when a piece of rock ten times as big as the Mount Everest broke off the island of Ohau. Result: a HUGE tsunami, hundreds of meters high and tens of kilometers long. |
| Cape Verde island | 80,000 years ago, the west coast of Africa was rinsed clean, as another massive tsunami hit it at nearly full force. One hour earlier, a massive chunk of the Cape Verde island had plunged into the sea. |
| Réunion island | 4,000 years ago, the island of Réunion in the Indian Ocean snapped in half. Another megatsunami popped up. Several hours later, it slammed into the coasts of Australia. |
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And La Palma? Only recently scientists realised that the ideal conditions for the next landslide exist on the island. Actually, in 1949, an eruption of the Cumbre Vieja almost triggered the La Palma disaster. The volcano erupted, the weaker half of the island dropped down four meters -- and halted. It was only in the nineties geologists realised what a close call it really was.
No-one knows if the island is able to withstand the next volcanic eruption. Gladly, we'll know several weeks in advance the Cumbre Vieja is about to go berserk again. But then again, will our governments take the warnings of the geologists serious enough if it gets that far? Will they be willing to evacuate the entire US East Coast and large parts of Europe, following the advice of only a handful of scientists? Somehow, Exit Mundi doubts it. Perhaps the killer wave will take us by surprise after all.
500 feet? Try 500 meters (1640 feet)!
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Flush! - By the time the La Palma wave hits the US, it is `only' something like 50-80 meters high -- and twenty kilometers long.