This lecture covers the dynamics of crack propagation in bimaterials, faults, and avalanche releases, focusing on different crack loading modes, crack speed regimes, and experimental observations. It also discusses the impact of in-plane shear experiments and laboratory earthquake experiments on fault behavior. Moreover, it delves into the process of snow avalanche release, including slab tensile failure, sliding, and the dynamics of friction. The lecture concludes with insights into micro branching instability in gels and glass, exploring the crack tip velocity and the principles governing the direction of crack propagation.