Proceedings of the 12th International INQUA meeting on paleoseismology, active tectonic and archaeoseismology

220 PATA Days 2024 The microstructural analysis also reflected a strong correlation between deformation styles and mineralogical. At sub-seismic sliding velocity (v = 10 µm/s), phyllosilicate-rich gouges (>49%) predominantly exhibit distributed deformation across the entire layer thickness and develop an S-C fabric (Fig. 4A). Conversely, samples containing less than 38% of phyllosilicates developed Y-B-P-R fabrics with localized deformation in principal slip zones (PSZs) with thickness of a few tens of microns (Fig. 4B). We identified the operation of both ductile and brittle processes at low sliding velocities (<300 µm/s), such as cataclastic flow, kinking development, dilation cracks, boudinage development, and foliation development. We propose viscous-low-frictional flow as the deformation mechanism operating at low strain rates during interseismic stages. Fig. 3: a) Representative fault reactivation experiment, showing normal stress reduction vs shear stress. Reactivations (red star = dynamic failure) occur close to failure envelope (Black line). b) Last 7 minutes of reactivation experiment showing dynamic rupture (Sample MF14; granular minerals- rich gouge), and oscillatory motion (Sample PPF10; Illite+muscovite-rich gouge). c) High- velocity experiment displaying curves of friction coefficient versus slip (m) during the seismic velocity slip pulse of 1 m/s (purple line).