Scientists have discovered the cause of giant underwater landslides in Antarctica which they believe could have generated tsunami waves that stretched across the Southern Ocean.
An international team of researchers, led by
Dr Jenny Gales from the University of Plymouth, uncovered layers of weak, fossilised and biologically-rich sediments hundreds of metres beneath the seafloor.
These formed beneath extensive areas of underwater landslides, many of which cut more than 100 metres into the seabed.
Writing in Nature Communications, the scientists say these weak layers – made up of historic biological material – made the area susceptible to failure in the face of earthquakes and other seismic activity.
They also highlight that the layers formed at a time when temperatures in Antarctica were up to 3°C warmer than they are today, when sea levels were higher and ice sheets much smaller than at present.
With the planet currently going through a period of extensive climate change – once again including warmer waters, rising sea levels and shrinking ice sheets – researchers believe there is the potential for such incidents to be replicated.
Through analysing the effects of past underwater landslides, they say future seismic events off the coast of Antarctica might again pose a risk of tsunami waves reaching the shores of South America, New Zealand and South East Asia.
The landslides were discovered in the eastern Ross Sea in 2017 by an international team of scientists during the Italian ODYSSEA expedition.
Scientists revisited the area in 2018 as part of International Ocean Discovery Program (IODP) Expedition 374, where they collected sediment cores extending hundreds of meters beneath the seafloor.
By analysing those samples, they found microscopic fossils which painted a picture of what the climate would have been like in the region millions of years ago and how it created the weak layers deep under the Ross Sea.