Could an eruption of El Hierro in the Canary Islands lead to a megatsunami that would threaten the eastern coast of the United States or elsewhere?
Islands of volcanic origin, such as the Canaries, have an especially large potential for triggering a tsunami. That the Canaries constitute a danger was shown 300 000 years ago when a part of the island El Hierro slid into the sea, triggering a mega-tsunami which carried rocks as high as a house for many hundreds of metres into the interior of the east coast of what is today the USA. The danger of a similar island collapse is seen by scientists particularly at the island of La Palma in the Canaries. Here, following a volcanic eruption in 1949 almost half of the mountain range of 20 km moved westwards towards the sea, leaving a large tear in the volcanic basalt. In the event of a fresh eruption, a huge part of the volcano could loosen itself due to differences in the types of rock and diverse water deposits within the now active volcano. As a result, the densely populated east coast of America would be massively threatened. According to a computer simulation by Stephen N. Ward and Simon Day, a tsunami (purple-red on the graphics) would rush across the Atlantic if the slopes of the Cumbre Vieja.volcano were to collapse into the sea.
Knowing that the recent major tsunami in Japan traveled 4.000 miles across the Pacific to produce an approximate 3 foot tsunami on some areas of the US west coast, the approximate ratio was 10:1 as the wave reached the US coastline. There are many factors that are at work to determine tsunami height, and this is highly over-simplifying the formula – the point is that if this were to be a similar case on the US east coast, which is 3,000 miles from the Canary Islands, the tsunami height could be 30 to 40 feet – while some suggest even higher.
There are voices talking about an 'over-hyped' thread:
But researchers taking part in a three-week research cruise aboard Southampton Oceanography Centre's research ship, the RRS Charles Darwin, say the threat is far lower than previous warnings would suggest.
Doug Masson, who has been researching Canary Islands landslides for 20 years, says the models are a worst-case scenario. Ref3