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2001 when they published a scientific paper that modelled the future collapse of the Cumbre Vieja and the passage of the resulting tsunamis across the Atlantic. Within two minutes of the landslide entering the sea, Ward and Day show that –for a worst case scenario involving the collapse of 500 cubic kilometres of rock –an initial dome of water an almost unbelievable 900 metres high will be generated, although its height will rapidly diminish. Over the next 45 minutes a series of gigantic waves up to 100 metres high will pound the shores of the Canary Islands, obliterating the densely inhabited coastal strips, before crashing onto the African mainland. As the waves head further north they will start to break down, but Spain and the UK will still be battered by tsunamis up to 7 metres high. Meanwhile, to the west of La Palma, a great train of prodigious waves will streak towards the Americas. Barely six hours after the landslide, waves tens of metres high will inundate the north coast of Brazil, and a few hours later pour across the low-lying islands of the Caribbean and impact all down the east coast of the United States. Focusing effects in bays, estuaries, and harbours may increase wave heights to 50 metres or more as Boston, New York, Baltimore, Washington, and Miami bear the full brunt of Vulcan and Neptune’s combined assault. The destructive power of these skyscraper-high waves cannot be underestimated. Unlike the wind-driven waves that crash every day onto beaches around the world, and which have wavelengths (wave crest to wave crest) of a few tens of metres, tsunamis have wavelengths that are typically hundreds of kilometres long. This means that once a tsunami hits the coast as a towering, solid wall of water, it just keeps coming –perhaps for ten or fifteen minutes or more –before taking the same length of time to withdraw. Under such a terrible onslaught all life and all but the most sturdily built structures are obliterated.
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Bill McGuire (Global Catastrophes: A Very Short Introduction (Very Short Introductions;Very Short Introductions;Very Short Introductions))