World leaders were today urged to wake up to the threat from a collapsing mountain which at any moment could unleash a massive tidal wave on the east coast of North America.
By John von RadowitzA chunk of a volcano in the Canary Islands the size of the Isle of Man is on the brink of falling into the sea, a leading expert warned.
Scientists believe it could break away when the Cumbre Vieja volcano in La Palma next erupts.
If that happened a giant tsunami, or massive wave, reaching heights of more than 500 feet would be sent racing across the Atlantic at the speed of a passenger jet.
Around nine hours later it would hit the Caribbean islands and the east coasts of Canada and the US.
After travelling 4,000 miles the wave would be lower and wider but still 20 metres ? 50 metres (66ft ? 164ft) high.
Stretching for many miles, it would home in on estuaries and harbours and sweep up to 20 miles inland, destroying everything in its path.
Boston, New York, Washington DC and Miami would be virtually wiped off the map and tens of millions of people killed.
Leading expert Professor Bill McGuire today said close monitoring might at best provide two weeks warning of the disaster.
But although the danger had been known about since the 1990s, no-one was keeping a proper watch on the mountain.
The two or three seismographs left to pick up signs of movement in the rock were not capable of detecting a looming eruption weeks in advance.
?What we need now is an integrated volcanic monitoring set up to give maximum warning of a coming eruption,? said Prof McGuire, director of the Benfield Grieg Hazard Research Centre at University College London.
?The US government must be aware of the La Palma threat. They should certainly be worried, and so should the island states in the Caribbean that will really bear the brunt of a collapse.
?They?re not taking it seriously. Governments change four to five years and generally they?re not interested in these things.?
A monitoring station equipped to look deep into the heart of the mountain and spot the early signs of an eruption might cost hundreds of thousands of dollars, said Prof McGuire.
In comparison, the US was spending four million dollars (?2.2 million) a year scouring the skies for kilometre-sized asteroids which were much less of a threat.
Speaking at a briefing in London, Prof McGuire said the mountain could split apart literally the next time the volcano erupts.
Cumbre Vieja last erupted in 1949. The next eruption could occur this year, or not for the next 1,000 years.
Any evacuation plan would have to be based on the forecast of an eruption, since once the collapse happened it would be too late.
Yet it could be a false alarm. Several eruptions could come and go before one of them sent the mountain side crashing into the sea in a matter of minutes.
Prof McGuire acknowledged that the decision to depopulate the eastern seaboard of the US would not be an easy one.
?I don?t honestly know how we handle that,? he said. ?As scientists all we should really do is advise people of what we think the risks are.?
The wave-front from the collapse would spread out in a crescent, striking the west African coast with a wall of water more than three hundred feet high in two to three hours.
Its northern side would also brush against Europe. Within three to four hours, a 33ft high wave would smash into the south coast of England, causing immense damage.
Unlike a normal wave, the tsunami would not break rapidly but just keep coming, said Prof McGuire.
?You?re not talking about the destruction of the UK economy, but very serious damage along the south coast,? he said.
Trying to stop the mountain collapsing was simply out of the question, he said.
He had done a calculation which showed it would take 35 million years to dig out the dangerous part of the volcano and move it away.
