Dario Peduto

Geometric and kinematic characterization of landslides affecting urban areas: the Lungro case study (Calabria, Southern Italy)

The geometric and kinematic characterization of landslides affecting urban areas is a challenging goal that is routinely pursued via geological/geomorphological method and monitoring of ground displacements achieved by geotechnical and, more recently, advanced differential interferometric synthetic aperture radar (A-DInSAR) data. Although the integration of all the above-mentioned methods should be planned a priori to be more effective, datasets resulting from the independent use of these different methods are commonly available, thus making crucial the need for their standardized a posteriori integration. In this regard, the present paper aims to provide a contribution by introducing a procedure that, taking into account the specific limits of geological/geomorphological analyses and deep/surface ground displacement monitoring via geotechnical and A-DInSAR data, allows the a posteriori integration of the results by exploiting their complementarity for landslide characterization. The approach was tested in the urban area of Lungro village (Calabria region, southern Italy), which is characterized by complex geological/geomorphological settings, widespread landslides and peculiar urban fabric. In spite of the different level of information preliminarily available for each landslide as result of the independent use of the three methods, the implementation of the proposed procedure allowed a better understanding and typifying of the geometry and kinematics of 50 landslides. This provided part of the essential background for geotechnical landslide models to be used for slope stability analysis within landslide risk mitigation strategies.

Subsidence monitoring in Sarno urban area via multi‐temporal DInSAR technique

In this study Differential Interferometric Synthetic Aperture Radar (DInSAR) is used to investigate the effects of a subsidence phenomenon – related to groundwater withdrawal –on ancient low‐rise masonry buildings located in the urban area of Sarno, Italy. ERS‐1/2 SAR data from 1992 to 2002 were analysed and results were validated with geodetic data. The results encourage future developments for study and use of the multi‐temporal DInSAR technique in the mitigation of subsidence risk.

Detection and monitoring of facilities exposed to subsidence phenomena via past and current generation SAR sensors

The identification of facilities in areas affected by subsidence phenomena represents a fundamental activity in processes dealing with land management. For this kind of phenomena, the analyses may be hampered by the lack of official subsidence zoning maps because of the wide extension of the affected areas. This is mainly due to the costs necessary for measurements and surveys to be carried out via conventional in?situ techniques which can turn out to be unaffordable for the authorities in charge of land management. In this regard, during the last decade the use of remote sensing data, such as medium resolution synthetic aperture radar (SAR) images processed via differential interferometry algorithms (DInSAR), has proven its benefits for the detection and monitoring of facilities (i.e., buildings and infrastructures) in subsiding areas. Currently, the improved resolution and coverage of the ultimate generation SAR sensors seem very promising for consequence analyses of facilities, although displacement time series are still limited for long-term studies. In this paper, analyses of DInSAR data acquired via both medium (ERS-ENVISAT) and high (COSMO-SkyMed) resolution sensors are carried out over a densely urbanized flat area in southern Italy so as to show how the appropriate use of DInSAR data at different scales can valuably help in the detection and monitoring of damageable facilities.

Combined use of statistical and DInSAR data analyses to define the state of activity of slow-moving landslides

Statistical analyses have been often used for landslide susceptibility zoning at small to medium scale when relevant base and thematic maps are available. Since the beginning of the last decade, images remotely acquired by spaceborne Synthetic Aperture Radar (SAR) and processed via Differential SAR Interferometry (DInSAR) proved extremely useful for non-invasive and non-destructive monitoring of displacements of the topographic surface. The present paper proposes an original procedure for the definition of the state of activity of slow-moving landslides via the combined use of multivariate statistical analyses and DInSAR data. The procedure is based on the following essential elements: distinction between terrain units used for computational purposes and the final zoning units; independent statistical and DInSAR analyses and activity models leading to first-level state of activity zoning maps; a consistency model between statistical and DInSAR analyses; two confidence and combination models leading, respectively, to second- or third-level state of activity zoning maps. The application in a test area including 19 municipalities in southern Italy, where slow-moving landslides are widespread and accurately mapped by using geomorphological criteria, allowed the generation of the three above-mentioned levels of zoning maps. The results were successfully crosschecked by exploiting a different DInSAR dataset and the results of previous works based on the use of slow-moving landslide-induced damage to facilities surveys.

Empirical fragility and vulnerability curves for buildings exposed to slow-moving landslides at medium and large scales

Slow-moving landslides yearly induce huge economic losses worldwide in terms of damage to facilities and interruption of human activities. Within the landslide risk management framework, the consequence analysis is a key step entailing procedures mainly based on identifying and quantifying the exposed elements, defining an intensity criterion and assessing the expected losses. This paper presents a two-scale (medium and large) procedure for vulnerability assessment of buildings located in areas affected by slow-moving landslides. Their intensity derives from Differential Interferometric Synthetic Aperture Radar (DInSAR) satellite data analysis, which in the last decade proved to be capable of providing cost-effective long-term displacement archives. The analyses carried out on two study areas of southern Italy (one per each of the addressed scales) lead to the generation, as an absolute novelty, of both empirical fragility and vulnerability curves for buildings in slow-moving landslide-affected areas. These curves, once further validated, can be valuably used as tools for consequence forecasting purposes and, more in general, for planning the most suitable slow-moving landslide risk mitigation strategies.

The Use of DInSAR Data for the Analysis of Building Damage Induced by Slow-Moving Landslides

The paper aims at checking the contribution that DInSAR data, processed via different algorithms, can provide to the analysis of damages recorded to buildings located in slow-moving landslide affected areas. For this purpose, an urban area in Calabria region, southern Italy, was selected due to the availability of both DInSAR data since 1992 and historic information concerning damage data recorded via municipal ordinances. The combination of DInSAR data and the results of supplementary damage surveys allowed the preliminary investigation of a cause (maximum velocity)—effect (damage) relationship which, once validated, can be valuably used for damage analysis and forecasting.

Conventional and Innovative Techniques for the Monitoring of Displacements in Landslide Affected Area

This work shows a methodological approach for the joint use of geological and geomorphological studies and conventional/innovative monitoring data in densely urbanized areas at landslide risk. The methodology is applied to a test area in the Calabria region (southern Italy) extensively affected by several active landslides involving urban areas. These landslides have been studied and monitored via ground-based techniques for many years. In the study area the comparison and interpretation of DInSAR data with geomorphological studies and inclinometric monitoring has been carried out. The results obtained, thanks to the validation of remote sensed data via ground-truths, provide a further step towards the integrated use of DInSAR data within landslide risk mitigation strategies.

Analysis of building vulnerability to slow-moving landslides via A-DInSAR and damage survey data

The paper presents a procedure for the analysis of building vulnerability to slow-moving landslides via A-DInSAR and damage survey data. For this purpose, a test site in Calabria region (southern Italy) affected by slow-moving landslides, which over the time caused severe damage to buildings, was selected. The availability of remote sensing data such as those derived from the processing of Synthetic Aperture Radar images via Advanced Differential Interferometry techniques (A-DInSAR) and information concerning damage severity suffered by the facilities, collected by in situ damage surveys, allowed investigating the cause (differential settlement)—effect (damage) relationship. Then, empirical fragility curves for both reinforced concrete and masonry buildings were generated. These latter, once further validated, can be valuably used for damage analysis and forecasting purposes and framed within procedures for risk analysis and management over urban landslide-affected areas.

Potentialities of the use of spaceborne radar systems in the monitoring of structures and infrastructures

The processing of data acquired by Synthetic Aperture Radar (SAR) with advanced methods based on multidimensional imaging opens new perspectives in the monitoring of facilities in built environment. The availability of data acquired by recent meter-resolution satellite SAR sensors allows precise monitoring of even single buildings and infrastructures, therefore valuably helping in the detection and monitoring of exposed facilities. This paper deals with the potentialities offered by the use of SAR data in the framework of the built environment monitoring by discussing results obtained by the processing of Cosmo-Skymed data.

Geology, slow-moving landslides, and damages to buildings in the Verbicaro area (north-western Calabria region, southern Italy)

ABSTRACT This paper presents a mass movement inventory map at 1:5000 scale of the Verbicaro area (about 13 km2) located in the Calabria region (southern Italy). The Main Map results from the visual interpretation of aerial photographs, multi-temporal geomorphological field surveys, and field investigations of damage suffered by buildings. Some 53% of the study area is affected by a total of 252 landslides, comprising different types, state of activity, and size. The mapped landslides, mainly complex type, involve low-grade metamorphic rocks; among these, 15% are active and slow-move on pre-existing sliding surfaces. Moreover, out of 492 surveyed buildings, 347 are located on landslide-affected areas and experienced damages covering a broad range of severity levels. The Main Map can represent a useful tool for authorities in charge of land-use planning and urban management and can be used to pursue landslide risk analyses.