FEC Recovery for Co-Chief Scientist duties of Dr Lisa McNeill for IODP Expedition 319

Subduction zones, where two tectonic plates converge, generate the largest magnitude earthquakes on earth and also commonly generate accompanying tsunami waves. These natural hazards can impact both regions local to the earthquake source and distant communities. The 2004 Indian Ocean tsunami and earthquake provided a recent dramatic example of the potential impact of these hazards. Our understanding of the earthquake process has significantly advanced in the last few decades with improvements in the technology for recording earthquake waves. But opportunities to directly sample and take measurements within the fault zones which generate these earthquakes are rare and require complex technology. The Nankai subduction zone of Japan has a long record of past earthquakes and tsunami and has been the focus of geological and geophysical studies over the last 2 decades. As a result, it is probably the best understood subduction system in the world. However, the challenge of directly sampling and monitoring the earthquake-generating fault system is yet to be achieved and the process of earthquake initiation and rupture is still relatively poorly understood. The NanTroSEIZE experiment has been launched within the Integrated Ocean Drilling Program (IODP) specifically to sample, measure and monitor all parts of the subduction zone fault system, including the deeper parts (~ 6-7 km below the seafloor) of the system where the earthquake rupture takes place. The experiment is a long term project staged over a period of years. The project started with drilling into the relatively shallow (<1.5 km) parts of the subduction zone and fault systems. This stage directly sampled sediment and rock materials and took in situ measurements of the properties of the sediments including the shallow fault zones. IODP Expedition 319, the expedition which this proposal relates to, is the first expedition of Stage 2 and is the first to employ 'riser' drilling technology - this technology will be used for the deep drill holes by allowing greater control on conditions and stability of the borehole at depth. A variety of methods will be used to measure sediment, rock and fault properties during Expedition 319 at two sites within different parts of the subduction zone system: Samples of borehole sediments and rocks; Measurements of sediment-rock properties from tools in the borehole; In situ measurements of properties, such as pressure of fluids within the sediments and the magnitude of the strain that the rocks-sediments are under as the two tectonic plates converge; Measurements of rock properties around and below the borehole, including the main fault generating the earthquakes, by using a second ship to send seismic signals to borehole instruments; Installation of sensitive instruments within one of the boreholes to measure temperature and pressure changes within a fault zone over several years; Preparation of the boreholes for future installation of more complicated monitoring instruments, including seismometers which will record earthquakes, strain and tiltmeters which will measure how the rocks and sediments deform, and pressure and temperature to indicate if and when fluids are moving along the fault systems; These measurements will contribute to the overall NanTroSEIZE goals of understanding how earthquake-generating fault systems develop and behave and how they generate earthquakes.