The dense vegetation of Isla de Mona, an uninhabited speck in the Caribbean, hides car or truck-sized boulders studded with corals. Experts very first noted recognizing them in the early 1990s, but the peculiar rocks slipped back again into obscurity right before any person investigated their origin. Now scientists have revisited these behemoths and concluded that enormous tsunami waves, launched by an underwater landslide, heaved them from the sea.
Quite a few of the boulders are obvious from the air, but most are hard to arrive at from the floor, says Bruce Jaffe, an oceanographer at the Pacific Coastal and Marine Science Center in Santa Cruz, Calif. He recollects selecting his way close to the island’s poisonous vegetation, such as one particular that can result in blistering and short term blindness. “We’ve talked about likely back with hazmat satisfies,” he suggests.
In the course of two journeys, the researchers visited additional than 50 boulders. The most significant was extra than eight meters lengthy, and the rocks were being strewn about a broad spot up to 800 meters inland. A storm likely would not have deposited them so far from the shoreline, Jaffe suggests a highly effective tsunami should have been concerned. Ricardo Ramalho, a geologist at the University of Lisbon, who was not involved in the investigation, agrees: “I would find it shocking if it was the operate of a storm,” he says.
Crew member Pedro Israel Matos Llavona, a geoscientist at the University of Massachusetts Amherst, pored around maps of the close by seafloor and found evidence of one thing that could have brought on these a tsunami: a jagged melancholy just about 4 kilometers vast, the relic of a long-ago underwater landslide. Matos Llavona simulated the landslide and identified it would have despatched 10-meter-large tsunami waves crashing onto Isla de Mona—with enough drive to heave lots of-ton boulders far inland. The researchers offered these effects at the 2020 American Geophysical Union Tumble Meeting.
Next the team ideas to pinpoint extra of these boulders by traveling a drone to detect the heat that they emit just after a working day in the sunshine. The scientists suggest that tracing how the rocks are scattered may possibly enable experts detect tsunami signatures in other places.