Megatsunamis with waves that can submerge the Statue of Liberty and reach nearly as high as the Eiffel Tower may seem to appear only in movies. Scientists, however, have found evidence that these are real.
In a new study, researchers reported that 73,000 years ago, the partial collapse of Fogo Volcano in the Cape Verde islands off Africa's coast happened so fast it triggered a tsunami so powerful it brought rocks, some as big as delivery vans, to Santiago Island, which lies 34 miles from Fogo.
Study researcher Ricardo Ramalho, from Columbia University's Lamont-Doherty Earth Observatory and colleagues found that the boulders were made of marine rock while the surrounding terrain was composed of young volcanic rock.
Only one force is powerful enough to bring 700-ton rocks 800 feet above from where they are originally located, a megatsunami. The researchers studied the isotopes on rock surfaces and were able to date the boulders back to the same time when the large flank from Fogo fell off the coast.
Fossils of marine animals that were scattered thousands of feet above sea level also hint of a massive wave that brought marine creatures on the high plateau.
The researchers said that the 40 cubic mile rock that collapsed from Fogo dropped all at one and generated an 800-foot wave.
For comparison, the Eiffel Tower in Paris stands at 984 feet without the antenna. The Statue of Liberty in New York, which stands 305 feet from ground to torch, could have been easily engulfed by the gigantic wave.
"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." The researchers wrote in their study published in the journal Science Advances on Oct. 2.
As for the possibility of the catastrophic event happening again in the future, Ramalho said that the phenomenon is what scientists refer to as "very low frequency, very high impact event," which means that the possibility of them happening again is very small.
While such an event does not happen very often, the impact could be catastrophic. Ramalho said that it is important to take this into account when thinking about the potential threats associated with flank collapses.
"Due to their very low frequency, we estimate that the probability for them to happen again is very small," Ramalho said. "But they may and will happen nevertheless, at some point in time. And since their impact can be absolutely devastating, we need to be vigilant and improve our society's resilience to their possible occurrence."
