Last Spring, the BBC Horizon programme aired a show dedicated to the possible consequences of a massive landfall in the Canary Islands. A conclusion was reached that suggested a massive tidal wave or Tsunami would be created and could race across the Atlantic at speeds of 800km/h and reach the USA and Caribbean as a 150 foot ‘wall of water’. At the time, nothing was mentioned of possible consequences in the British Isles. A report was released more recently, detailing possible affects in Britain.
La Palma is one of the smaller Canary Islands, its geographical structure is made up of two volcanoes, one dormant and one active. The active one is the Cumbre Vieja and this is where the problem has arisen. Natural pockets of water inside the Cumbre Vieja could be superheated by molten rock and the force of the resulting steam could literally break one side of the Island away. It has now been revealed that if this were to happen, the massive landslide would cause a tidal wave that could reach the shores of Scilly as a 40-foot wave.
Scilly and the South West peninsular would bear the brunt of the impact.
However, Scilly is used to 40-foot waves. On exposed rocks, like Scilly Rock in the Norrad Rocks, waves have been seen this high before. In fact, Scilly Rock, which is about 40-feet high, has been seen totally submerged under waves. Though the tsunami will be travelling faster than normal waves, and coming from a different direction, it still should leave Scilly pretty much as it was.
Waves cannot be any taller than they are deep, so if they are in 20-feet of water, they can only support being 20-feet high. This will also rule out total devastation of Scilly, due to our shallow waters.
The wave will be far more devastating to the American continent.
Scientists cannot say when this wave will strike. It revolves around the active volcano in the Canary Islands, which erupts, on average, every 200 years, and the last eruption was in 1949. But the landslide may not occur on the next eruption, it may take up to six explosions, by which time Scilly may have submerged due to global warming, anyway.