Project Background
This project aims to determine the currently unknown submarine geohazard risk of the sub-Antarctic South Sandwich Islands (SSI; Fig.1) in terms of earthquake, submarine landslide and tsunami generation, allowing future geohazard assessment. The SSI are one of the last truly wild areas of the planet, lying deep in the ‘furious fifties’; some of the stormiest seas on Earth. The archipelago is an arc of active volcanic islands and is incredibly remote and inhospitable. One of the largest ever recorded earthquakes in the South Atlantic (Mw 8.2) occurred in the SSI in 2021; this caused a global spreading tsunami that reached nearly every ocean basin. Tsunamis are significant, often catastrophic events with wide-reaching socio-economic consequences, including destroying human life, coastal and seafloor infrastructure. Submarine landslides often generate the largest and most destructive tsunamis, for example, the 1998 submarine landslide-generated tsunami in Papua New Guinea killed 2200 people. The potential hazard associated with submarine landslides is often overlooked owing to a lack of repeat seafloor bathymetric data, especially in remote locations, making it difficult to assess their causes and involvement in tsunami generation. While repeat seafloor mapping pre- and post-event is rare, results can be groundbreaking.
This project offers a unique, time-sensitive, and societally important opportunity to assess the future geohazard risk of the South Sandwich Islands where the geological setting raises significant concerns over tsunami generation. Previous mapping by the RRS James Clark Ross in 2007 and 2010 provide a pre-earthquake baseline seafloor map. Repeat bathymetric survey (including an expedition scheduled in 2025) over parts of the SSI volcanic flanks will determine the impacts of recent earthquake activity and constrain the drivers behind slope failure, crucial for assessing risks posed by future slope instability.
