Today forty million Americans live and work on the east coast of the United States without suspecting that an incredible phenomenon could well destroy the entire region, from New York to Miami, one of the most densely populated places in the world. Scientists have now found evidence that a colossal wave will one day devastate the coast of America. It will be far bigger than any normal tidal waves, or tsunami. It is what scientists call a mega-tsunami.
Unlike the tsunamis with which the Japanese are familiar and which have entirely seismic causes, the mega-tsunami would be triggered by huge rocks falling into the sea from the Cumbre Vieja volcano in the Canaries.
If the Cumbre Vieja were to collapse as one single block it would create a giant mega-tsunami with an initial wave height of 650 metres and a wavelength of 30-40 kilometres travelling westwards across the Atlantic with speeds up to 720 kilometres an hour towards America.
Mark Hedgecoe leads this investigation, which includes accounts, interviews with scientists, archive footage and computer- generated imges to help viewers get to grips with this astonishing idea.