InSAR-Based Deformation Monitoring of High-Fill Engineered Landslides: A Case Study at Panzhihua Airport, Southwest China

High-fill engineered landslides challenge infrastructure safety in mountainous regions, particularly where geological settings interact with human activity. This study investigated a landslide at Panzhihua Airport, Southwest China, using multi-track Sentinel-1 data with a Time-Series InSAR framework. This methodology innovatively combines multi-orbit LOS (Line of Sight) deformation retrieval through InSAR processing, 2D deformation vector decomposition (vertical + slope-parallel directions), and spatiotemporal correlation analysis with geological structure and rainfall patterns. Results show: (i) In the airport area, the average LOS deformation rates for the runway and surrounding buildings are 3.58 mm/year and − 1.37 mm/year, indicating stability, while the landslide area to the northeast decreases to -37.07 mm/year and − 12.75 mm/year, suggesting active sliding. (ii) Deformation in the landslide area was spatially heterogeneous, with vertical settlement (max. 45.3 mm/year) at the rear, and creeping (max. 53.61 mm/year) at the front of the fill body. (iii) The displacement time series revealed a clear correlation between vertical deformation and rainfall. During the first two uplift cycles, the expansion volume showed a strong correlation with rainfall, with a Pearson correlation coefficient (PCC) value exceeding 0.9 in some regions. These findings provide insights for managing secondary deformation risks on large-scale fill slopes for early warning system development in similar geo-engineered environments.