Scientists working off west Africa in the Cape Verde Islands have found evidence that the sudden collapse of a volcano there tens of thousands of years ago generated an ocean tsunami that dwarfed anything ever seen by humans.
The researchers say an 800-foot wave engulfed an island more than 30 miles away. The study could revive a simmering controversy over whether sudden giant collapses present a realistic hazard today around volcanic islands, or even along more distant continental coasts. The study appears today in the journal Science Advances.
“Our point is that flank collapses can happen extremely fast and catastrophically, and therefore are capable of triggering giant tsunamis,” said lead author Ricardo Ramalho, who did the research as a postdoctoral associate at Columbia University’s Lamont-Doherty Earth Observatory, where he is now an adjunct scientist. “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 apparent collapse occurred some 73,000 years ago at the Fogo volcano, one of the world’s largest and most active island volcanoes. Nowadays, it towers 2,829 meters (9,300 feet) above sea level, and erupts about every 20 years, most recently last fall. Santiago Island, where the wave apparently hit, is now home to some 250,000 people.