Seismic Signature and Numerical Modeling of the 2017 Rainfall-Induced Landslide in Villa Santa Lucía (Patagonia), Chile

Abstract On 16 December 2017, a catastrophic rainfall-induced landslide struck Villa Santa Lucía in Chilean Patagonia, causing 22 fatalities and widespread destruction. Despite extensive post-event studies, the precise timing of failure initiation and its dynamic evolution remain poorly constrained. Here, we combine regional seismic observations, flow numerical modeling, and meteorological data to reconstruct the onset, dynamics, and triggering conditions of this event. Seismic records constrain the onset to ∼12:03 UTC and reveal a short-lived (∼2 min) signal dominated by 1–10 Hz energy, associated with the initial collapse and rapid acceleration of the mass, during which most seismic energy is radiated. Numerical modeling reproduces the observed inundation area and indicates that the full landslide process lasted tens of minutes, reflecting a transition toward slower, less seismically efficient flow downstream. The absence of detectable seismic precursors, together with extreme rainfall before the event, suggests a sudden failure once critical subsurface conditions were reached. The strong contrast between the rapid seismic onset and the longer propagation times highlights the potential of seismic observations for early warning, as seismic waves propagate much faster than the landslide itself. These results emphasize the value and complementary role of seismic data, modeling, and meteorological observations in reconstructing landslide dynamics, linking failure to hydrometeorological forcing, and improving hazard assessment in mountainous regions.