Endo-exo framework for a unifying classification of episodic landslide movements: Implications for forecasting catastrophic failures.

Landslides exhibit intermittent downslope movements over days to years before a possible collapse, commonly boosted by external events like precipitation. The origins of these episodic movements and their relation to final instability remain unclear. We propose a novel "endo-exo" theory capturing the interplay between exogenous stressors such as rainfall and endogenous damage-healing processes. We predict four types of episodic dynamics, defined by the disturbance source (endogenous or exogenous) and criticality level (subcritical or critical), each with distinct power law exponent but all governed by a single parameter [Formula: see text] . These predictions are tested on the Preonzo landslide, whose sporadic activities align with the classification with [Formula: see text] . We find that its final collapse is preceded by an increased frequency of medium-to-large velocities over 1 to 2 months, signaling the transition into a catastrophic regime. Our research suggests that landslides may not permanently operate at a critical state, with major implications for forecasting catastrophic failures.