MONITORING OF SURFACE LANDSLIDES USING INSAR AND PSI TIME SERIES, MONJES BLANCOS SECTOR, PEHUENCHE PASS, MAULE REGION.

This study applies the Persistent Scatterer Interferometry (PSI) technique to analyze surface displacements associated with mass-wasting processes along km 134.7–136.8 of International Route 115-CH, Paso Pehuenche, Maule Region, Chile. A total of 253 Sentinel-1 images were processed for both orbital geometries (253 ascending and 253 descending) between 2015 and 2024, identifying 27 persistent scatterers located exclusively over hydrothermally altered zones. Results reveal vertical displacement rates ranging from 3.43 to 5.48 mm/year (uplift) and horizontal rates from -6.50 to -8.43 mm/year (westward). Maximum cumulative displacements reached 66 mm vertically and -77.9 mm horizontally. Temporal analysis shows a correlation between periods of higher precipitation and increased displacement rates. The concentration of persistent scatterers over hydrothermally altered materials confirms that these zones act as coherence refuges in mountainous volcanic environments. The PSI methodology proved effective in overcoming temporal decorrelation limitations in complex terrain, establishing a baseline for continuous monitoring of natural hazards along strategic bioceanic corridors