FRICTIONAL PROCESSES OF SMECTITE-RICH GOUGES AT HIGH SLIP RATES

The determination of frictional processes of smectite-rich gouges at high slip rates (~1 m/s) is important to understand the unusually large coseismic slip in the shallower part of tsunamogenic megathrusts (e.g. 2011 Tohoku earthquake) and the mechanics of catastrophic landslides (e.g. 1963 Vajont landslide). At present, only rotary shear apparatuses can reproduce simultaneously the slip and slip rates of these natural events. I will present here new frictional data obtained with two rotary shear machines. Experiments were performed on natural gouges from the Vajont slide, and on selected monomineralic smectite gouges and smectite-quartz mixtures. Deformed and undeformed powders will be investigated with x-ray powder diffraction (Rietveld method), scanning and transmission microscopes. The final and most challenging goals of my thesis are the understanding of the frictional processes triggered in smectite-rich gouges at high slip rates and the formulation of an empirical law to describe them.

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