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<p>Dam formation and failure are secondary hazards of landslides. In 2005, a rockslide–debris avalanche on the western slope of the Santa Cruz Mountain Range (Central Andes, San Juan Province, Argentina) dammed the Santa Cruz River, forming Los Erizos Lake. The subsequent collapse of the lake generated an outburst flood that caused infrastructure damage up to 250&#xa0;km downstream. Nearly two decades later, we reassess slope instability in the same area by analyzing potential failure scenarios using remote sensing techniques. Displacements were derived using Persistent Scatterer Interferometry (PS-InSAR) in Line-of-Sight (LOS) geometry and optical image correlation (COSI-Corr). Three active areas were identified. Scenario 1, the most active sector, exhibits cumulative horizontal displacements of approximately 15–36&#xa0;m over the 2016–2024 period, while an independently tracked point shows ~ 20&#xa0;m of displacement. The area lacks interferometric coherence in the InSAR analysis, likely due to displacement rates exceeding the detectable range of C-band InSAR and/or surface decorrelation. Scenario 2, located along the upper scarp and influenced by permafrost conditions, shows measurable deformation detected by PS-InSAR, with LOS velocities reaching up to − 14.5&#xa0;mm/year (ascending) and − 67&#xa0;mm/year (descending), where negative values indicate motion away from the satellite. The deformation patterns are broadly consistent with the magnitude and direction inferred from optical image correlation. Scenario 3 also exhibits cumulative displacements up to ~ 15&#xa0;m; however, similarly to Scenario 1, it shows limited interferometric coherence, restricting the InSAR-based analysis. For Scenario 1, the unstable volume is estimated at ~ 15.36 × 10⁶ m<sup>3</sup>, representing a significant hazard to downstream infrastructure and population. The scenario analysis identifies the upslope sector of the 2005 landslide headscarp (Scenario 1) as the most dynamic area and the main potential source of future large-scale failure. These findings highlight the importance of continuous multi-sensor monitoring to detect precursory deformation and reduce the risk of future landslide-induced damming and outburst flooding.</p>

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Potential failure scenarios in the Santa Cruz range, Argentina: 20 years after a natural dam collapse

  • 期刊论文

  • 发表日期：

    2026年5月26日

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  • Romina Solorza,
  • Ivanna Penna,
  • Carla Tapia Baldis,
  • Gökhan Aslan,
  • John Dehls,
  • Pierrick Nicolet,
  • Michel Jaboyedoff

摘要

Dam formation and failure are secondary hazards of landslides. In 2005, a rockslide–debris avalanche on the western slope of the Santa Cruz Mountain Range (Central Andes, San Juan Province, Argentina) dammed the Santa Cruz River, forming Los Erizos Lake. The subsequent collapse of the lake generated an outburst flood that caused infrastructure damage up to 250 km downstream. Nearly two decades later, we reassess slope instability in the same area by analyzing potential failure scenarios using remote sensing techniques. Displacements were derived using Persistent Scatterer Interferometry (PS-InSAR) in Line-of-Sight (LOS) geometry and optical image correlation (COSI-Corr). Three active areas were identified. Scenario 1, the most active sector, exhibits cumulative horizontal displacements of approximately 15–36 m over the 2016–2024 period, while an independently tracked point shows ~ 20 m of displacement. The area lacks interferometric coherence in the InSAR analysis, likely due to displacement rates exceeding the detectable range of C-band InSAR and/or surface decorrelation. Scenario 2, located along the upper scarp and influenced by permafrost conditions, shows measurable deformation detected by PS-InSAR, with LOS velocities reaching up to − 14.5 mm/year (ascending) and − 67 mm/year (descending), where negative values indicate motion away from the satellite. The deformation patterns are broadly consistent with the magnitude and direction inferred from optical image correlation. Scenario 3 also exhibits cumulative displacements up to ~ 15 m; however, similarly to Scenario 1, it shows limited interferometric coherence, restricting the InSAR-based analysis. For Scenario 1, the unstable volume is estimated at ~ 15.36 × 10⁶ m3, representing a significant hazard to downstream infrastructure and population. The scenario analysis identifies the upslope sector of the 2005 landslide headscarp (Scenario 1) as the most dynamic area and the main potential source of future large-scale failure. These findings highlight the importance of continuous multi-sensor monitoring to detect precursory deformation and reduce the risk of future landslide-induced damming and outburst flooding.