Diego Di Martire

From ERS-1/2 to Sentinel-1: two decades of subsidence monitored through A-DInSAR techniques in the Ravenna area (Italy)

Land subsidence due to underground resources exploitation is a well-known problem that affects many cities in the world, especially the ones located along the coastal areas where the combined effect of subsidence and sea level rise increases the flooding risk. In this study, 25 years of land subsidence affecting the Municipality of Ravenna (Italy) are monitored using Advanced Differential Interferometric Synthetic Aperture Radar (A-DInSAR) techniques. In particular, the exploitation of the new Sentinel-1A SAR data allowed us to extend the monitoring period till 2016, giving a better understanding of the temporal evolution of the phenomenon in the area. Two statistical approaches are applied to fully exploit the informative potential of the A-DInSAR results in a fast and systematic way. Thanks to the applied analyses, we described the behavior of the subsidence during the monitored period along with the relationship between the occurrence of the displacement and its main driving factors.

A-Differential Synthetic Aperture Radar Interferometry analysis of a Deep Seated Gravitational Slope Deformation occurring at Bisaccia (Italy)

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.

A new approach for landslide-induced damage assessment

ABSTRACT The accurate evaluation of landslide-induced damage is a necessity for planning of proper and effective mitigation measures. It requires the implementation of field investigations to identify structural failures to more effectively trace landslide boundaries. Many methods have been proposed to classify landslide-induced damage of buildings. The existing methods demonstrate several advantages and drawbacks depending on the parameters considered, as lack of some important features and difficulties in applicability. A new classification approach of landslide-induced damage of facilities is proposed, which specifically focuses on assessing of damage degree and its relationship to the ground motion intensity and impact severity. The new approach is designed in two steps: a chart utilized during surveys to quantify cracks on structures and ground surface; an a posteriori ranking of structures performed using a cell-grid matrix. Furthermore, a damage recording scheme useful for field surveying is proposed. This approach considers several parameters derived from different existing methodologies by smoothing out drawbacks and homogenizing the considered features. The resulting approach provides a new procedure of landslide-induced damage assessment adoptable in case of private dwellings, as it does not require internal accessibility, and it is exploitable for different landslide events and for different kinds of structures and facilities.

Intermittent small baseline subset (ISBAS) InSAR analysis to monitor landslides in Costa Della Gaveta, Southern Italy

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.

Integrated monitoring network for the hazard assessment of slow-moving landslides at Moio della Civitella (Italy)

Aiming at a deeper comprehension of landslide geological and geotechnical model, territorial monitoring is of utmost importance. The integration of conventional and innovative monitoring techniques allows to obtain the most precise and up-to-date information at reasonable costs. This paper focuses on the case study of Moio della Civitella (Salerno Province, Italy) where, starting from 2007, an integrated monitoring network was implemented to detect the state of activity of some landslides affecting the urban centre.

Assessment of landslide-induced damage to structures: the Agnone landslide case study (southern Italy)

Landslides are among the most important and frequent natural calamities that cause severe socio-economic and human losses. After earthquakes, landslides are responsible for the greatest number of casualties and the largest amount of damage to man-made structures. On average, southern Italy is affected by a high spatial density of landslides due to its complex geological setting, which often predisposes it to slope instability phenomena under both natural and anthropogenic influences. Structurally complex formations are widespread in the southern Apennines and are characterized by high heterogeneity and very poor mechanical properties. Thus, these formations represent one of the main factors contributing to the predisposition of slopes to landsliding. In this paper, landslide-induced damage was investigated and analyzed in an area within the municipality of Agnone (Molise region), which is affected by a complex landslide that involves a structurally complex formation. The approaches used were based on six different methods that have previously been described in the literature, and a comparison of the results was made. Data regarding the damage, which consists largely of cracks observed in buildings and at the ground, were compiled through field surveys. The results were critically analyzed to note the advantages and constraints of each classification scheme. The aim of the work was to apply and compare different approaches in order to test the best and most accurate procedures for assessing damage due to landslides at the scale of individual buildings as well as to provide an objective assessment of the degree of landslide damage to structures and facilities.

A New Statistical Approach for Landslide Susceptibility Assessment in the Urban Area of Napoli (Italy)

The city of Napoli, Italy is an interesting case study for landslide susceptibility assessment, due to its complex interactions between landslides and anthropic fabric. In fact, despite the long history of slope instabilities, the urban evolution, often illegal, disregarded the high landslide propensity of the hillsides and occupied unsafe lands, exposing the population to a high level of risk. This study focuses on three municipality districts of the city, Soccavo, Pianura and Arenella, over which impends the Camaldoli Hill, the most prominent Phlegraean peak (458 m a.s.l.), where more than 300 landslides of the 1300 events recorded from 1850 to date in the Napoli municipality landslide geodatabase, occurred. In this paper the landslide susceptibility assessment has been carried out applying the Maximum Entropy method (MaxEnt). The results have been critically validated using Boyce index and, eventually, compared to the official map provided in the Hydro-geomorphological Setting Plan (HSP) redacted by the competent governmental agency (River Basin Authority) by means of a semi-statistical approach already in use by the research group.

Multivariate Statistical approach vs. Deterministic physically based model for landslide susceptibility assessment

We present a comparison between the results of two landslide susceptibility analyses approaches: multivariate (Logistic Regression) and deterministic–physically based (SHALSTAB). In order to assess the Landslide Susceptibiliy Index, five different predisposing factors to landslide occurrence (slope, aspect, land cover, distance to streams and rocky scarps) for the first one and material density, material friction angle, material hydraulic transmissivity, bulk cohesion and depth to potential shear plane for the second have been set up respectively.Two different sectors of the urban area of the Phlegraean Fields, within the municipalities of Naples and Pozzuoli, have been selected for the application of the two methodologies: the Agnano Plain hillslopes (slope maximum elevation: 190 m a.s.l.) and the Astroni volcano (max. elev.: 253 m a.s.l.). The results have been compared and tested (ROC/AUC curves) allowing further considerations about the benefits and the constraints of each model.

Using Data from Multiple SAR Sensors in Landslide Characterization: Case Studies from Different Geomorphological Contexts in Italy

An application of Differential Interferometry SAR (DInSAR) technique based upon C- and X-band SAR imagery is here presented. The aim of this study was to assess SAR technology’s applicability and reliability for landslide detection and monitoring. To this purpose, two test sites have been selected, both located in Italy, which are affected by slow-moving landslides: Rovegliana, falling within the North-Eastern sector of Italian Alps, and Varco d’Izzo, which belongs to the Southern Apennines. Results from C-band (ERS and EnviSat) and X-band (COSMO-SkyMed and TerraSAR-X) imagery data allowed to identify several unstable areas previously undetected for the Rovegliana site, while the state of activity of Varco d’Izzo landslides was confirmed.

Landslide-Related PS Data Interpretation by Means of Different Techniques

Two different techniques aimed at assessing deformation data related to slow-moving landslides are here discussed, both being based upon Persistent Scatterer Interferometry. To this scope, a case-study from Calitri, Campania region, Italy is dealt with, represented by a large complex landslide re-activated by the 23 November 1980 M=6.9 earthquake. Through the first technique, ascending and descending geometry dataset have been used, creating synthetic PS and vertical and easting displacement maps. The second procedure consisted in a morphometric decomposition of the velocity vector for each PS with respect to the maximum downhill slope angle and slope aspect. The results from both techniques were finally compared and discussed.