Rock Mechanics A type of deformation on faults called slow slip releases similar amounts of energy as earthquakes, but without the familiar and frightening shaking. Leeman et al. use clever laboratory observations to investigate how faults might have a full range of behaviors ranging from slow slip to earthquake. They quantify the transition from silent to audible behavior in their simulated fault with a critical stiffness parameter, which depends on the frictional stability of the system. The result suggests that there exists a universal framework for understanding the range of slip behavior on natural faults. Nat. Commun. 10.1038/ncomms11104 (2016).