Slow, aseismic slip (such as slow slip and surface creep) is now recognized as the glue at tectonic plate boundaries that holds the earthquake cycle together. Since the first observations of surface creep along the San Andreas plate boundary more than 50 years ago, advances in geophysical instrumentation and innovative observational approaches have revealed that faulting at major plate boundaries covers a broad spectrum of slip modes, from fast earthquake ruptures to intermittent slow slip.

Today, the continuous GPS record and satellite imagery reveal the jerky, intermittent nature of aseismic slip. The pattern that is emerging suggests that slow slip at plate boundaries and surface creep on major transform faults is not a steady, continuous process as once thought, but is rather a complex spatiotemporal cluster of interacting aseismic transients. I will present observations of aseismic slip rate variations from seconds to decades. These results suggest that slow slip is much more similar to earthquake slip than previously acknowledged, with strong implications on our understanding of the dynamics of active faults.