- Future seismic events off the coast of Antarctica could again pose a risk of tsunami waves reaching the coasts of South America, New Zealand and Southeast Asia.
Weak layers of sediment identified under the Southern Ocean seafloor crumbled in past episodes as the oceans warmed and Antarctic ice sheets receded. With the planet currently undergoing a period of extensive climate change, again including warmer waters, rising sea levels and shrinking ice sheets, the authors of the finding, led by the University of Plymouth, believe there is a possibility of for such incidents to recur.
Through analysis of the effects of past submarine landslides, they say that future seismic events off the coast of Antarctica could again pose a risk of tsunami waves reaching the coasts of South America, New Zealand and Southeast Asia. These sediment layers formed beneath extensive areas of submarine landslides, many of which cut more than 100 meters into the seafloor.
Writing in Nature Communications, the scientists say these weak layers, made up of historical biological material, made the area susceptible to faulting from earthquakes and other seismic activity. They also note that the layers formed at a time when temperatures in Antarctica were up to 3°C warmer than today, when sea levels were higher and the ice sheets were much smaller than they are today. .
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 the International Ocean Discovery Program (IODP) Expedition 374, where they collected sediment cores extending hundreds of meters below the sea floor.
By analyzing those samples, they found microscopic fossils that painted a picture of what the climate in the region would have been like millions of years ago and how it created the weak layers in the depths of the Ross Sea.