Assessment of the hydrogeology of the upper Nankai subduction prism, using borehole geophysical and drilling data from the NanTroSEIZE project.

Active faults have been investigated through several scientific drilling projects, like the Integrated Oceanic Discovery Program (IODP). The Nankai accretionary prism is the locus of the NanTroSEIZE project which was the focus of many IODP expeditions (among which expedition 314, 315, 316, 319, 333, 348 and 358).

The objective of the internship is to use this extensive pre-existing dataset to explore the hydraulic properties of the prism, especially of the several active splay faults, which represent a high tsunami hazard. To do so, we will use and improve the innovative strategy developed during the PhD of Joshua Pwavodi. We use in-situ drilling data, especially the mud pressure data recorded downhole, to investigate the continuous variation in hydraulic properties along the borehole. This will provide a high-resolution pressure and permeability profiles, and characterise the structure of the fault and refine its hydromechanical model.