Figure 2: Spectrum of fault slip behaviour.
From: Laboratory observations of slow earthquakes and the spectrum of tectonic fault slip modes
(a) Friction data for experiments (p43XX run numbers) at different effective shear-loading stiffness k′=k/σn′. Friction data are offset vertically for clarity. The emergence of slow stick–slip occurs at lower shear displacement, and stick–slip amplitude increases, for higher normal stress experiments. The spikes in friction at 13–15 mm are due to frictional aging caused by brief pauses in shearing to reset displacement transducers. (b) Details of friction (solid line) and velocity (dashed) during a stick–slip event with a peak slip velocity of ≈80 μm s−1, only a few times that of the background loading velocity of 10 μm s−1. (c) Stick–slip events have systematically longer duration at lower normal stresses. Slip accelerates more slowly and event durations are correspondingly longer than at higher normal stress.
