Volcano’s collapse caused mega-tsunami (800 feet) 240 meters high – study

October 2015 – WEST AFRICA – The sudden collapse of a volcano caused a tsunami that created waves up to 240 meters (800ft) high 73,000 years ago, scientists have discovered. The mega-tsunami took place near the Cape Verde islands off west Africa when the slopes of the volcano gave way – a process known as a “flank collapse” – and some experts fear a similar collapse could present a real threat today, especially around volcanic islands.

The lead scientist, Dr Ricardo Ramalho, now at Bristol University, and his team at Columbia University in New York, said: “Our point is that flank collapses can happen extremely fast and catastrophically, and therefore are capable of triggering giant tsunamis. They probably don’t happen very often. But we need to take this into account when we think about the hazard potential of these kinds of volcanic features.”

The sudden collapse of a volcano caused a tsunami that created waves up to 240 metres (800ft) high 73,000 years ago, scientists have discovered. The mega-tsunami took place near the Cape Verde islands off west Africa when the slopes of the volcano gave way – a process known as a “flank collapse” – and some experts fear a similar collapse could present a real threat today, especially around volcanic islands. The lead scientist, Dr Ricardo Ramalho, now at Bristol University, and his team at Columbia University in New York, said: “Our point is that flank collapses can happen extremely fast and catastrophically, and therefore are capable of triggering giant tsunamis. They probably don’t happen very often. But we need to take this into account when we think about the hazard potential of these kinds of volcanic features.”

The boulders, weighing up to 770 tonnes, matched marine-type rocks ringing the island’s shores and were quite unlike the volcanic terrain on which they were found. By calculating the energy needed to hurl the boulders such a distance, the scientists were able to estimate the size of the wave. Their findings are reported in the journal Science Advances. Prof Bill McGuire, a tsunami expert from University College London, believes such mega-tsunami events occur once every 10,000 years. He said: “Nevertheless, the scale of such events, as the Fogo study testifies, and their potentially devastating impact, makes them a clear and serious hazard in ocean basins that host active volcanoes.” –Guardian