Integration of field investigations and remote sensing techniques for the assessment of landslide activity and damage

The aim of the PhD thesis was to look for a relationship between the landslide-induced damage recorded on structures and facilities based on the results of several field campaigns and kinematic parameters quantitatively estimated by remote sensing techniques. Investigations were developed on two test sites: a deep-seated landslide in Colle Lapponi-Piano Ovetta in municipality of Agnone (Molise region, southern Italy) and the landslides affecting the southwestern sector of Volterra (Tuscany region, central Italy). First of all, a re-enactment of the evolution of both landslides were conducted, by means of 3D reconstructions based on historical aerial series of images and the analysis of Persistent Scatterers of ERS1/2, ENVISAT and COSMO-SkyMed satellites. The 3D Points Clouds and models were developed on several sets of aerial historical images dating from different years starting from 1945 and 1954 for Agnone and Volterra, respectively. To better understand the morpho-evolutionary stages, a qualitative assessment of changes of volume were made combining the oldest and the latest 3D reconstructed Points Clouds. This interpretation, even if qualitative and not quantitative, can be helpful for understanding possible effects of future reactivations and as a support to realize mitigation plans, susceptibility maps and other useful for the local administrators. The Persistent Scatterers were used to monitor the evolution in recent years, up to 2015. Then, for both case studies, the damage was revealed on structures and facilities by several field surveys and classified by means of five literature damage categorizations. During their application, some drawbacks and benefits of the methodologies were carried out and a new approach to improve the categorization of the damage on structures, facilities and ground surfaces was developed. This was conceived in two subsequent phases: i) a classification to use during the field campaign to quantify the severity of cracks and fractures on structures, facilities and ground surfaces; ii) an a posteriori ranking to apply on the entire structure, involving the extension of damage classes, performed by a cell-grid matrix. Furthermore, a damage recording scheme, useful for the recognition of cracks and fractures during the field surveys, was proposed. A critical comparison between the results obtained applying the different classification approaches, then followed. Buildings and facilities, for both sites, were categorized using also kinematic parameters such as velocity and maximum displacement measured along the Line Of Sight, derived by A-DInSAR, and their absolute values re-projected along the steepest local slope. Once characterized and categorized all structures and facilities of both sites of interest, a correlation between the surveyed damage classes and the deriving parameters by satellite were looked for. The investigation was carried to understand the behaviour of entire structures, subject to displacements. The first analysis was conducted on the Agnone test site where for several constructions an upper regression line between damage categories and velocity reprojected along the slope was recognized. Some outlayers were identified, mainly for low damage levels, then singularly Integration of field investigations and remote sensing techniques for the assessment of landslide activity and damage investigated. To assess the reliability of all the structures, a matrix involving damage and velocity along the slope parameter acquired by ENVISAT and COSMO-SkyMed sensors was developed in order to obtain a classification. To validate the correlation and the reliability matrix the same procedure was applied to the Volterra site. Once asserted the validity of the relation between the velocity reprojected along the steepest slope and the classes of damage also for this area, the reliability matrix was applied on the constructions of the Volterra site. In this way, the relation between the displacement occurred during the period covered by ENVISAT and COSMO-SkyMed shows how the surveyed damage construction are related to the displacement. Some areas where damage occurred in the 2000 shows high reliability with ENVISAT recorded velocity, while others structures exhibits high reliability with COSMO-SkyMed data. The results were interesting because they highlight the fact that for some construction there is correlation between velocity of displacement of the entire structure and affecting damage; for others, instead, the high damage is related to the differential settlement and not necessarily to a high rate of displacement velocity.