Catastrophic landslides can generate rich seismic signatures that reveal both their preparatory phases and their dynamic failure processes. At Costa Rica’s IrazÅLu volcano, we document days-to-weeks of evolving precursory signals preceding the December 2014 and August 2020 flank collapses, including a progressive increase in repeating low-frequency events (LFEs) and lowperiod tremor that intensifies as failure approaches. These observations, synthesized from dense local networks and retrospective analyses, indicate a transition from quasi-stable to unstable sliding within a deforming, fluid-affected hillslope—analogous to fault weakening prior to earthquake nucleation. The repeating character and spectral content of the LFEs suggest episodic aseismic slip and/or fluid pressurization in damage zones acting as “stick-slip” asperities that load the slope to failure, offering a quantitative basis for near-real-time anticipation. Building on these results, we report ongoing near-field monitoring of the Aguas Zarcas rockslide complex in north-central Costa Rica with a compact array of nodal seismometers. Continuous recordings there capture families of LFEs and emergent tremor during rainfall and pore-pressure transients, supporting a unified framework in which landslide precursors map the evolution of effective stress toward runaway acceleration. Together, the IrazÅLu and Aguas Zarcas case studies demonstrate that (i) LFE rate changes and repeating-event statistics are actionable indicators for shortterm landslide forecasting, and (ii) landslides provide accessible natural laboratories for probing earthquake nucleation physics—linking frictional weakening, fluid coupling, and rupture initiation across scales. Our findings motivate operational landslide early-warning strategies that fuse LFE detection, template matching, and trend analysis with hydrometeorological inputs, while also informing constitutive models of fault and slope failure that explicitly incorporate damage and fluids.

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