High velocity friction experiments. In this study, new samples recovered by IODP (Integrated Ocean Drilling Program) Exp. 362 from incoming Indian plate sediments will be used to investigate the frictional behavior of these sediments en-route to the plate boundary interface. The UK IODP Moratorium award will be used to achieve 5 Strategic Objectives: SO 1 - identify the characteristics of the sedimentary sections to optimize the sampling strategy for friction experiments based upon onboard sedimentology, petrology, geochemistry and in-situ logging profiles. This objective will benefit from the Exp. 362 Science Party work carried out during the cruise. SO 2 - acquire a quantitative data set of the mineral assemblages, fluid permeability, and porosity for each sample. SO 3 - measure their frictional dependence on slip, slip rate, slip velocity, and normal stress by performing experiments on the collected samples under deformation conditions typical of earthquakes using the high velocity rock friction apparatus SHIVA. SO 4 - monitor gas emission, humidity, and temperature variations during friction experiments using mass spectrometry, temperature and humidity measurements with the sensors installed on the rotary shear apparatus. SO 5 - analyse the experimental fault rock material using a multidisciplinary approach that involves microstructural analysis, mineralogy, and petrology so that proxy records may be reconstructed for plate interface seismic slip. Validate these against the seismological record. The ultimate goal is to incorporate the actual physical properties of the Sumatra-Andaman incoming sedimentary section within an improved theoretical earthquake rupture propagation model. This research will develop a new approach to the assessment of extreme near-trench tsunamogenic slip based on the analysis of incoming plate sediments. This approach is also applicable to other plate-boundary megathrusts (e.g. Japan Trench, Barbados). Future studies can also consider possible lateral variations in the lithological composition of the incoming plate/subduction plate boundary material.
