PhD studentship: The Weakest Link: Triggering of giant submarine landslides

This PhD studentship is now open for applications. For more information and to apply follow this link.

Description of the project:

Giant landslides and sediment avalanches on the seafloor are a demonstrated hazard to seafloor infrastructure (e.g. internet cables and oil pipelines) as well as being the key mechanism by which terrestrial sediment is transported thousands of kilometres before ultimate burial in the deep sea. Our understanding of these landslides and avalanches, from how seafloor slopes fail to how the flows evolve is limited because we know little about the material properties (i.e. the rheology) of the sands, silts and clays that make up the seafloor in the deep sea. Understanding these properties will lead to a better understanding of where and why landslides and avalanches occur, how such flows evolve and therefore enable better modelling capabilities. This will ultimately inform, where to locate and how to protect seafloor infrastructure; how such flows interact with seafloor habitats and how sediment is transported in our oceans.

This project will establish the composition and rheology of seafloor sediments from a wide variety of environments from seafloor channels and canyons, open slopes and deep sea fans. This will be achieved by making use of samples from deep sea sediment cores that have been collected from all over the world and are housed in the British Ocean Sediment Core Research Facility (BOSCORF) at the National Oceanography Centre, Southampton. The composition of the sediments will be established using X-ray diffraction and the grain size will be established using a laser particle analyser.  The main method of research will be to generate a highly controlled flow over ‘miniature seafloors’ using a rheometer. The first step will be to determine the rheological properties of the sediment suspension. These rheological properties will then be correlated to the sediment composition and grain size. Following on from this, customised rheometer setups with optical access will be used to perform controlled perturbations of the sediment sample. These experiments will investigate how laminar but potentially unsteady flow conditions can generate stable sediment structures and where their point of failure is using image analysis techniques.

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