Scientists discover cause of giant underwater landslides in antarctica

Scientists have made a significant discovery regarding the cause of enormous underwater landslides in Antarctica. They believe that these landslides could have generated far-reaching tsunami waves throughout the Southern Ocean.

An international team of researchers has unearthed layers of vulnerable, fossilized sediments teeming with biological material, located hundreds of meters beneath the ocean floor. These sediments formed under extensive regions of underwater landslides, some of which penetrated over 100 meters into the seabed.

According to a publication in Nature Communications, the scientists explain that these weak layers, consisting of historical biological remnants, rendered the area highly susceptible to failure in the presence of seismic activity such as earthquakes.

The researchers also note that these layers were established during a period when Antarctica experienced temperatures up to 3°C warmer than the present, leading to higher sea levels and smaller ice sheets compared to today.

Given the ongoing significant climate changes, including rising sea levels, warmer waters, and shrinking ice sheets, the scientists believe there is a potential for similar incidents to occur again. By studying the effects of past underwater landslides, they suggest that future seismic events off the coast of Antarctica could pose a risk of tsunami waves reaching the shores of South America, New Zealand, and Southeast Asia.

Professor Rob McKay (Director of the Antarctic Research Centre at Victoria University of Wellington and co-chief scientist of IODP Expedition 374) and Dr Jenny Gales (Lecturer in Hydrography and Ocean Exploration at the University of Plymouth) examine the half-section of a core recovered from the Antarctic seabed. Credit: Justin Dodd

In 2017, a team of international scientists participating in the Italian ODYSSEA expedition discovered the landslides in the eastern Ross Sea.

The scientists returned to the area in 2018 as part of the International Ocean Discovery Program (IODP) Expedition 374. During this expedition, they collected sediment cores that extended deep beneath the sea floor, spanning hundreds of meters.

Through the analysis of these sediment samples, the researchers uncovered microscopic fossils that provided insights into the climate conditions that prevailed in the region millions of years ago. These findings helped explain the formation of the weak layers beneath the Ross Sea.

Dr. Jenny Gales, a Lecturer in Hydrography and Ocean Exploration at the University of Plymouth and a member of the IODP Expedition 374, led the recent study.

Dr. Gales emphasized the significance of submarine landslides as a major geohazard capable of triggering tsunamis and causing substantial loss of life. Additionally, such landslides can result in the destruction of critical infrastructure, including subsea cables, leading to significant economic and social impacts.

The preservation of sediments beneath the sea floor provided invaluable information, enabling the researchers to elucidate the causes of historical landslides in the region and assess the potential impact of similar events in the future. The study underscores the urgent need to enhance our understanding of how global climate change may affect the stability of these regions and the potential for future tsunamis.

Drilling into the seabed of the Ross Sea during International Ocean Discovery Program (IODP) Expedition 374 to recover one of the hundreds of cores which helped scientists assess the cause of historic landslides. Credit: Laura de Santis

Professor Rob McKay, the Director of the Antarctic Research Centre at Victoria University of Wellington and co-chief scientist of IODP Expedition 374, expressed that the primary objective of their drilling project in 2018 was to comprehend the impact of a warming climate and oceans on Antarctica’s melting ice sheets in the past, with the aim of better understanding their future response. However, the discovery of the significant submarine landslides and scarps by Dr. Gales and her colleagues during the previous year’s mapping efforts came as a revelation. It became evident that the climate changes they were studying through drilling directly correlated to these large-scale submarine landslide events. This unexpected connection highlights a potential hazard that merits further investigation.

Laura De Santis, a researcher at the National Institute of Oceanography and Applied Geophysics in Italy and co-chief scientist of IODP Expedition 374, explained that the sediment cores they examined were obtained as part of the long-standing international sea floor scientific drilling project, IODP. Over its 50-year history, the project has aimed to explore Earth’s history, encompassing topics such as ocean currents, climate change, marine life, and mineral deposits, through the study of sediments and rocks beneath the sea floor.

Jan Sverre Laberg from The Arctic University of Norway, Tromsø, emphasized that giant submarine landslides have occurred in both the southern and northern high-latitude continental margins, including Antarctica and the Norwegian continental margins. Further knowledge about these events in Antarctica would also be relevant for assessing submarine geohazards off the coast of Norway.

Dr. Amelia Shevenell, an Associate Professor of Geological Oceanography at the University of South Florida, College of Marine Science, underscored the importance of scientific ocean drilling and marine geology in comprehending past climate change and identifying regions vulnerable to natural hazards, thereby informing infrastructure decisions. Given that large landslides along the Antarctic margin can potentially trigger tsunamis with far-reaching effects, it is crucial to conduct marine geological and geophysical feasibility studies early on in the development process. Such studies are vital for the success of projects aiming to install submarine cables for improved communication from Antarctic research bases, as they help identify potential risks before countries invest in and rely on such communication infrastructure.

Source: University of Plymouth

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