NERC-NSTC: Erosion in the deep ocean - the impact of the Kuroshio Current on the continental shelf and slope of Taiwan

The global 'conveyor belt' of ocean currents are an important part of Earth's climate system, transporting heat and nutrients around the global oceans. They also transport large volumes of sediments and re-deposit these in large drifts in the deep oceans. These sediments then provide an important archive of the current systems that produced them, as well as changing temperatures and environmental conditions. In recent years, we have increasingly recognized that the large-scale eddies in the Earth's large surface currents, such as the Gulf Stream, also play an important role in the deep ocean. These eddies, which are equivalent to cyclones in the atmosphere, are concentrated at ocean fronts, and can cause deep erosion of the seabed - many hundreds of metres deep in some cases.

The Kuroshio Current is one of these important surface current systems (associated with a front), that is a fundamental part of the ocean circulation system of the Pacific. Our recent work to the south of Taiwan, and offshore Japan, shows that this is a highly dynamic system which interacts with the complex seabed at an active margin (where two tectonic plates are colliding), deeply eroding and re-distributing sediment.

In this project, we aim to understand the effect of the Kuroshio Current offshore Taiwan. We will use seismic reflection data, multibeam bathymetry data (proving high-resolution seabed maps) and core samples, to understand the impact of the current in a number of areas. We will specifically test how the current interacts with elevated tectonic ridges and whether it is capable of eroding deep channels across the continental shelf and slope. We will then investigate hazards associated with this deep erosion, including whether the removal of sediment from the plate boundary changes the stress state in the area, potentially with implications for earthquake magnitude and frequency - something that has never previously been tested - and whether the current destabilizes the continental slope, leading to underwater landslides and tsunamis.

This project will also allow us to develop a new, long-term partnerships between our institutions in the UK, Germany and Taiwan, to expand this work in the future. The Kuroshio Current is relatively understudied but it is the ideal natural laboratory to understand the impact of ocean currents on continental margins, and address fundamental new questions about the links between the oceans and deep earth processes that have a major impact on human populations.