Modeling the Onset of Earthquake-Triggered Landslides on Slip Surfaces Governed by Rate-And-State Friction

Earthquake-triggered landslides are a severe hazard and contribute to landscape evolution. To understand their process and controlling factors, we model the onset of seismically-triggered slip on pre-existing slip surfaces governed by laboratory-based rate-and-state friction, including wave propagation effects. Through numerical simulations and theoretical analysis, we identify how friction properties, landslide thickness and incident wave attributes (frequency, duration, amplitude) control slope stability. We find that the frictional state variable tracks the cyclic fatigue of the slip surface, its progressive weakening with each wave cycle. Wave propagation effects introduce two regimes depending on frequency relative to the two-way travel time across the landslide thickness: the stability criterion is well approximated by a threshold on incident peak acceleration at low frequencies, and on peak velocity at high frequencies. We derive analytical approximations, validated by simulations, suitable to apply the model to evaluate landslide stability under arbitrary input motions.