Researchers working in the Cape Verde islands off the coast of West Africa have made an interesting discovery: some tens of thousands of years ago, a giant volcano in the region collapsed during eruption, producing an enormous landslide that in turn generated what appears to be one of the biggest ocean tsunamis in the history of our planet. Reaching a height of up to 840 feet, the fierce waves drowned an island over 30 miles away. The study, the scientists believe, raises questions regarding whether such a catastrophic event could occur in today’s world.
Located on the island of Fogo, the 9,300-foot-tall volcano in question is currently one of the world’s largest active volcanoes. According to the researchers, some 73,000 years ago, the volcano collapsed while erupting, generating a massive tsunami that in turn submerged the neighboring Santiago Island. The study was recently published in the Science Advances journal. Speaking about the findings, Ricardo Ramalho, a researchers at Columbia University’s Lamont Doherty Earth Observatory and the study’s first author, said:
Our observations therefore further demonstrate that flank collapses may indeed catastrophically happen and are capable of triggering tsunamis of enormous height and energy, adding to their hazard potential… we need to take this into account when we think about the hazard potential of these kinds of volcanic features.
The team stumbled upon the discovery while working on the Santiago island several years ago. At 650 feet above the sea level, the scientists came across huge boulders, weighing around 770 tons each, which were later found to be the same as the marine rocks present along the island’s shoreline. As the researchers point out, this was likely the doing of a giant wave that must have hurled the heavy stones up the hill. To calculate the size of these waves, the team measured the amount of energy that would have been required to move the rocks against gravity.
Upon studying the isotopes of helium present on the boulders’ surface, the researchers concluded that the rocks had been in the open for the last 73,000 years. At present, the scientific world is divided as to whether volcanoes can collapse suddenly, and subsequently produce megatsunamis. The current study provides concrete evidence of the evidence. Ramalho added:
It doesn’t mean every collapse happens catastrophically. But it’s maybe not as rare as we thought.