Precursors of catastrophic failure in intermittent creep landslides: a frictional evolution perspective
Slow-moving landslides are widespread and potentially highly hazardous, yet no clear physical criterion exists to determine whether they evolve from creep to catastrophic failure. Here, ring shear experiments are integrated with long-term in situ monitoring to elucidate the key processes governing shear zone response to transient pore pressure perturbations. It is found that, before catastrophic failure, landslides typically pass through a metastable state characterised by pore pressure-induced slip pulses superimposed on long-term creep. This metastable state can be activated under diverse hydro-mechanical conditions, where intensifying slip pulses and progressive shear zone dilation erode the system’s rate-strengthening capacity. Once a critical threshold is crossed, the system enters sustained acceleration – a key precursor to the transition from creep to catastrophic failure. Furthermore, the rate-and-state friction framework provides a physical basis for shear zone creep, and embedding the proposed critical friction threshold curve as an instability criterion offers a more robust means of assessing landslide hazard under dynamic pore pressure perturbations.