THE Falkland Islands are at risk from tsunamis caused by underwater landslides, according to new research.
Scientists from Heriot-Watt University and the British Geological Survey found evidence of prehistoric submarine landslides in the Falkland Trough. The landslides are all in the same location and the report – published in the Marine Geology journal – found the Subantarctic Front, a branch of one of Earth’s strongest currents, was behind the formation of the landslides.
The landslides came from a drift that formed when strong currents, up to 50 million cubic metres of water per second, pushed sediment high up on the continental slope, at 400-1000 metres underwater.
A tipping point would then occur and cause a landslide.
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Sediment has been accumulating again at the site, named Burdwood Drift by the researchers, where the seabed is so steep it will collapse again – but they can’t tell when.
Most large tsunamis, such as the Indian Ocean Boxing Day tsunami in 2004, or the 2011 event in Japan, were caused directly by large earthquakes. But landslides have also triggered tsunami waves, including the 1998 Papua New Guinea tsunami, the prehistoric Storegga landslide that inundated Scotland around 8000 years ago and most recently in 2018, on Sulawesi in Indonesia.
Dr Uisdean Nicholson, a sedimentary geologist at Heriot-Watt University, said: “We used seismic data to see the differences in the density of the offshore sediments.
“This allowed us to image the sedimentary bodies beautifully in three dimensions, similar to an ultrasound scan of the Earth.”
Once the team located the submarine landslides, they used numerical modelling to test whether they could have generated hazardous tsunamis, and to calculate whether future landslides would pose a risk to the Falkland Islands to the north.
Professor David Tappin of the British Geological Survey said: “The landslides found in the Falkland Trough aren’t recent, but it’s another example of submarine landslides in a location where we wouldn’t have expected to find them.”
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