Post-failure evolution analysis of a rainfall-triggered landslide by Multi-Temporal Interferometry SAR approaches integrated with geotechnical analysis

Abstract

Persistent Scatterers Interferometry (PSI) represents one of the most powerful techniques for Earth’s surface deformation processes’ monitoring, especially for long-term evolution phenomena. In this work, a dataset of 34 TerraSAR-X StripMap images (October 2013-October 2014) have been processed by two PSI techniques - Coherent Pixel Technique-Temporal Sublook Coherence (CPT-TSC) and Small Baseline Subset (SBAS) - in order to study the evolution of a slow-moving landslide which occurred on February 23, 2012 in the Papanice hamlet (Crotone municipality, southern Italy) and induced by a significant rainfall event (185 mm in three days). The mass movement caused structural damage (buildings’ collapse), and destruction of utility lines (gas, water and electricity) and roads. In The results showed analogous displacement rates (30-40 mm/yr along the Line of Sight –LOS - of the satellite) with 41 respect to the pre-failure phase (2008-2010) analyzed in previous works. 42 Both approaches allowed to detect the landslide-affected area, however the higher density of targets identified by 43 means of CPT-TSC enabled to analyze in detail the slope behavior in order to design possible mitigation interventions. 44 For this aim, a slope stability analysis has been carried out, considering the comparison between groundwater 45 oscillations and time-series of displacement. Hence, the crucial role of the interaction between rainfall and 46 groundwater level has been inferred for the landslide triggering. In conclusion, we showed that the integration of 47 geotechnical and remote sensing approaches can be seen as a best practice to support stakeholders to design remedial 48 works.