The fastest and furthest-travelling flows on Earth: New insights from direct monitoring of deep-sea hazards

Despite covering two thirds of our planet, the ocean remains largely unmonitored with respect to the diversity of natural hazards that can occur in the deep sea. These hazards represent some of the largest processes on Earth and include underwater landslides that dwarf their onshore equivalents, avalanches of sand and mud (called turbidity currents) that can transport huge volumes of sediment for 1000s of kilometres into the deep-sea, and submerged volcanoes that can trigger seafloor flows that travel at >100 km/hour. Our first understanding of these hazards came from damage to seafloor infrastructure such as telecommunications cables and the impacts on coastal communities of the tsunamis they created. Reliance on seafloor and coastal infrastructure is ever-growing; hence understanding these hazards is increasingly important. For example, >99% of all digital data traffic worldwide is now carried via a network of 1.4 million km of seafloor cables. This presentation shares new insights into the largest and furthest travelling flows on the planet based on novel direct monitoring and damage to critical infrastructure in deep sea sites from the Congo Canyon (West Africa), the Whittard Canyon (North Atlantic), and Hunga Volcano (South Pacific), and outlines some lessons learned to design more resilient infrastructure to ensure continuity in global connectivity.