Granular Controls on Periodicity of Stick-Slip Events: Kinematics and Force-Chains in an Experimental Fault

摘要: It is a long-standing question whether granular fault material such as gouge plays major role in controlling dynamics seismicity and slip-periodicity. In both natural experimental faults, materials resist shear accommodate strain via interparticle friction, fracture toughness, fluid pressure, dilation, rearrangements. Here, we isolate the effects of particle rearrangements on deformation through laboratory experiments. Within sheared photoelastic aggregate at constant volume, simultaneously visualize particle-scale kinematics forces, latter taking form force-chains. We observe stick-slip associated force drops during an overall strengthening zone. This regime provides insight into rheology conditions periodicity, may be qualitatively analogous to slip that accompanies longer term interseismic faults. Of particular note observation increasing packing density increases stiffness decreases damping (increases time-scales) events. At relatively loose density, displacements events follow approximately power-law distribution, opposed exponential distribution higher density. The system exhibits switching between quasi-periodic aperiodic behavior all densities. Higher densities favor behavior, with time interval than difference time-scale reflected force-chain dynamics: reorganizations are Our experiments conceptually link observations current models for dynamics. find consistent driven harmonic oscillator model provided by effective viscosity, shear-transformation-zone, jamming, crackling noise theories provide patterns localization deformation.