Scientist says governments are ignoring threat of a piece of rock as big as the Isle of Man crashing into the Atlantic.
When - Professor McGuire says it is not a matter of if - the rock plunges into the ocean it will trigger giant waves called mega-tsunamis.
Travelling at speeds of up to 560mph, the huge walls of water will tear across the ocean and hit islands and continents, leaving a trail of destruction.
Mega-tsunami waves are much longer than the ones we are used to.
"When one of these comes in, it keeps on coming for 10 to 15 minutes," Prof McGuire said.
"It's like a huge wall of water that just keeps coming."
Computer models of the island's collapse show the first regions to be hit, with waves topping 100 metres (330ft), will be the neighbouring Canary Islands. Within a few hours the west coast of Africa will be battered with similar-sized waves.
Between nine and 12 hours after the island collapses, waves between 20 and 50 metres high will have crossed 4,000 miles of ocean to crash into the Caribbean islands and the eastern seaboard of the US and Canada.
The Guardian - full story