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The study is part of a larger project that involves the analysis of recently identified Deep-Seated Gravitational Slope Deformation (DSGSD) in Sicily which have been sub-divided according to the geological framework in light of the new geological data about the regional setting. Here are presented the first results of a multidisciplinary study of a DSGSD recently identify in Mount San Calogero area (Northern Sicily). The study was performed by means of different approaches including conventional methods (field surveys) and the Differential Interferometry Synthetic Aperture Radar (DInSAR) technique. The geological and geomorphological analyses were carried out to investigate slopes dynamic, and DInSAR analysis were integrated to obtain, for the first time in this area, displacement rates of the DSGSD. The identified deformation patterns show the effective movement of homogeneous rock mass that constitutes the Mount San Calogero, characterized by the gravitational morphostructures and evidence of slopes deformation, as well as the shallow landslides detected in the foothill area. Furthermore, the distribution of the Persistent Scatterers (PS) points shows a clear convergence with the main tectonic lineaments of the area, thereby emphasizing the role of the structural setting in the DSGSD's development.

Slow-moving landslides are a natural hazard which affects wide areas in the world and often are cause of significant damage to structures and infrastructures. Analysis of landslide evolution and of their interaction with existing man-made structures plays a key role in risk prevention and mitigation activities. To this purpose, a considerable interest towards innovative approaches has grown among the scientific community and land management institutions. In this work, Synthetic Aperture Radar data acquired by C-band and X-band sensors, combined with numerical analyses, have been successfully applied as a tool to detect spatial and temporal landslide-induced effects, in terms of deformations and structural behavior of a building affected by ground instability. Such approach has been applied to Moio della Civitella urban settlement (Salerno province, Italy), whose whole territory is interested by several slow-moving landslides. In detail, performance of a masonry building aggregate and the efficacy of restoration works have been investigated through an integrated assessment of displacement time-series pre- and post-repair intervention, and structural analysis performed with numerical code. Historical DInSAR data have permitted firstly the interpretation of building displacement time-series corresponding to pre- and post-works configurations; subsequently, the analysis of interpolated interferometric products has allowed to define gradient maps of vertical and horizontal displacements and to identify part of aggregate which can suffer a greater susceptibility to damage as a consequence of deformation gradients. Finally, the comparison of satellite and numerical data showed a substantial agreement with local failures and damage surveyed, thus confirming the capability of DInSAR technique to investigate building performance where no in situ displacement measurements were available. Research funded by the Campania Region through Regional Law n. 5/2002, year 2008 – Project “La pericolosità delle frane intermittenti in formazioni strutturalmente complesse; analisi comparata dei parametri geologici, mineralogici e geotecnici” (CUP_E64G08000060002) – Scientific manager: prof. Domenico Calcaterra. Part of this work was partially supported by the Spanish Ministry of Economy, Industry and Competitiveness (MINECO), the State Agency of Research (AEI) and the European Funds for Regional Development (FEDER) under projects TEC2017-85244-C2-1-P and TIN2014-55413-C2-2-P and the Spanish Ministry of Education, Culture and Sport under project PRX17/00439.

Landslides are frequent events that may cause human casualties and injuries as well as damage to urban and man-made structures, with extensive loss of economic resources. For this reason, landslide mapping is a primary tool for hazard and risk assessment. Italian Ministry of Environment, thanks to great availability and functionality of Synthetic Aperture Radar (SAR) data promoted the Not-ordinary Plan of Environmental Remote Sensing (Piano Straordinario di Telerilevamento Ambientale, PST-A in Italian) in 2008, as to constitute a national database of active or potential instability phenomena affecting the Italian territory, based on the exploitation of interferometric products (ERS and ENVISAT). In this paper, the PST-A-3 is described. A procedure based on the integration of engineering-geological approaches and SAR interferometry data belonging to COSMO-SkyMed constellation (100 frames 40 × 40 km) has been here implemented over 7,400 km 2 of the Italian territory. First, landslides have been mapped by field geologists, defining type and state of activity. Simultaneously to field surveys, remote sensing data have been analyzed as to detect areas with considerable displacement registered by the satellite. Both products have been overlaid, also quantifying the coincidence between the events reported according to the two detection methodologies and subtracting those landslide not recordable by the satellite, finally obtaining an updated landslide inventory map with 4,522 newly detected phenomena. Therefore, PST-A-3 proves to be a valuable system for local authorities, in order to provide a contribution to risk management but also for the forecasting of landslide events, as testified by two case studies selected. Thanks to the PST-A experience, the use of such strategy to other countries could represent a valid contribution to land management at worldwide scale.

Kinematic characterization of a landslide at large, small, and detailed scale is today still rare and challenging, especially for long periods, due to the difficulty in implementing demanding ground surveys with adequate spatiotemporal coverage. In this work, the suitability of space-borne synthetic aperture radar sub-pixel offset tracking for the long-term monitoring of the Slumgullion landslide in Colorado (US) is investigated. This landslide is classified as a debris slide and has so far been monitored through ground surveys and, more recently, airborne remote sensing, while satellite images are scarcely exploited. The peculiarity of this landslide is that it is subject to displacements of several meters per year. Therefore, it cannot be monitored with traditional synthetic aperture radar differential interferometry, as this technique has limitations related to the loss of interferometric coherence and to the maximum observable displacement gradient/rate. In order to overcome these limitations, space-borne synthetic aperture radar sub-pixel offset tracking is applied to pairs of images acquired with a time span of one year between August 2011 and August 2013. The obtained results are compared with those available in the literature, both at landslide scale, retrieved through field surveys, and at point scale, using airborne synthetic aperture radar imaging and GPS. The comparison showed full congruence with the past literature. A consistency check covering the full observation period is also implemented to confirm the reliability of the technique, which results in a cheap and effective methodology for the long-term monitoring of large landslide-induced movements.

This paper presents the results of an investigation on a Deep Seated Gravitational Slope Deformation (DSGSD), previously only hypothesized by some authors, affecting Bisaccia, a small town located in Campania region, Italy. The study was conducted through the integration of conventional methods (geological-geomorphological field survey, air-photo interpretation) and an Advanced-Differential Interferometry Synthetic Aperture Radar (A-DInSAR) technique. The DSGSD involves a brittle lithotype (conglomerates of the Ariano Irpino Supersynthem) resting over a Structurally Complex Formation (Varycoloured Clays of Calaggio Formation). At Bisaccia, probably as a consequence of post-cyclic recompression phenomena triggered by reiterated seismic actions, the rigid plate made up of conglomeratic sediments resulted to be split in five portions, showing different rates of displacements, whose deformations are in the order of some centimeter/year, thus inducing severe damage to the urban settlement. A-DInSAR techniques confirmed to be a reliable tool in monitoring slow-moving landslides. In this case 96 ENVIronmental SATellite-Advanced Synthetic Aperture Radar (ENVISAT-ASAR) images, in ascending and descending orbits, have been processed using SUBSOFT software, developed by the Remote Sensing Laboratory (RSLab) group from the Universitat Politècnica de Catalunya (UPC). The DInSAR results, coupled with field survey, supported the analysis of the instability mechanism and confirmed the historical record of the movements already available for the town.

An integrated system to analyze slope instabilities over vast areas through the intercomparison of measurements obtained by in-situ and persistent scatterer (PS) interferometry processing of satellite synthetic aperture radar (SAR) data, is here introduced and tentatively named landslide detection integrated system (LaDIS).The persistent scatterer pair (PSP) SAR interferometry technique has been used to process high-resolution SAR images acquired in the 2008–2011 time span by the COSMO-SkyMed satellite constellation, available in a 40 km × 40 km study area in the Palermo Province (Sicily region—Italy). Derived displacement rate estimates from COSMO-SkyMedPS measurements have been analyzed in approximately 10% of the study area for landslide research. Within this area, according to the official landslide inventory map, extremely slow to very slow landslides are dominant, being favored by the presence of heterogeneous clay formations characterized by poor mechanical properties. To prove COSMO-SkyMedPS displacement rates an engineering-geological approach was adopted, tailored to allow a continuous and rapid updating of landslide-inventory maps; to this aim a detailed geological field work has been performed. To guarantee an independent assessment, field surveys have been carried out without sharing information derived from PS data. Almost half (49%) of the active unstable areas identified through COSMO-SkyMedPS measurements were confirmed by the field work. In an additional 26% of cases the greater sensitivity of the satellite has allowed to identify movements, even if very slow, that did not show superficial evidence. A confirmation of the great potentialities of the latest generation of satellite systems also comes from the comparison with the current official landslide-inventory map, updated in 2006. Among the 58% of the total PS measurements that have been used to contour the landslides “in remote”, 84.3% falls outside the polygons of the failures detected in the existing maps, which implies a significant percentage of data to be associated to new landslides or extension of pre-existing landslides. Advantages and drawbacks of exploiting COSMO-SkyMed X-band SAR data to study landslides over wide areas through the proposed approach are finally discussed.

This work presents a Differential SAR Interferometry (DInSAR) analysis of slow-moving landslides in Costa della Gaveta (southern Italy) exploiting the improved spatial density of radar targets provided by the novel Intermittent SBAS (ISBAS) algorithm. Several landslides occurred in this area over the past decade, producing a ground displacement of several centimeters and causing unsafe road and rail traffic conditions. In the 2.4 km2 study area, ISBAS analysis of TerraSAR-X data acquired in 2010–2011 has shown the presence of sixteen phenomena with a southeastern main direction of motion. The DInSAR results agree with both the magnitude and the deformation mechanisms that were mapped during field observations and reported in the geotechnical literature.

This paper presents the application of Differential Synthetic Aperture Radar (SAR) interferometry (DInSAR) algorithms for the precise monitoring of earth dams ground deformation. The test site selected for this study is the Conza Dam, located in the southern Apennines (Italy), very close to the epicenter of the big earthquake (M-w = 6.9) which took place on November 23th, 1980, striking the Irpinia region. Among the multiple advanced DInSAR techniques developed by the SAR community during the last decade, this work uses the so-called SUBSOFT software, developed by the Remote Sensing Laboratory (RSLab) group from the Universitat Politecnica de Catalunya (UPC), which is based on the use of Coherent Pixels Technique (CPT) algorithm. The analysis is carried out using 51 ENVIronmental SATellite-Advanced Synthetic Aperture Radar (ENVISAT-ASAR) images, corresponding to the period from 29th of November 2002 to the 30th of July 2010. In this framework, ground displacements recorded by a network of conventional ground-based sensors are also available for the same temporal span. Indeed, the embankment dam is well instrumented to measure internal settlements by means of cross-arms placed in six different cross-sections, and superficial displacements by means of targets for precise leveling. A statistical analysis has been performed to carry out a better comparison between the measurements obtained with the conventional field sensors and the interferometric data. The high agreement between final DInSAR displacements and in-situ instrumental data, demonstrates the reliability of such technique for the precise monitoring of civil infrastructures, and concretely, in dams with a high exposure factor and its consequent risk.