Francesca Bozzano

The Large Salcito Landslide Triggered by the 2002 Molise, Italy, Earthquake

The 2002 Molise, Italy, earthquake triggered a deep planar earthslide about 38 km away from the epicenter, mainly involving scaly clay shales and related weathered material. Based on site investigations and borehole data, the inferred depth of the sliding surface is between 30 and 50 meters below ground level, indicating an involved volume of about 40⋅106 m3. The complex geological setting, the generated excess pore water pressure, and possible local seismic response are thought to have been the primary contributing factors.

Basin Scale Assessment of Landslides Geomorphological Setting by Advanced InSAR Analysis

An extensive investigation of more than 90 landslides affecting a small river basin in Central Italy was performed by combining field surveys and remote sensing techniques. We thus defined the geomorphological setting of slope instability processes. Basic information, such as landslides mapping and landslides type definition, have been acquired thanks to geomorphological field investigations and multi-temporal aerial photos interpretation, while satellite SAR archive data (acquired by ERS and Envisat from 1992 to 2010) have been analyzed by means of A-DInSAR (Advanced Differential Interferometric Synthetic Aperture Radar) techniques to evaluate landslides past displacements patterns. Multi-temporal assessment of landslides state of activity has been performed basing on geomorphological evidence criteria and past ground displacement measurements obtained by A-DInSAR. This step has been performed by means of an activity matrix derived from information achieved thanks to double orbital geometry. Thanks to this approach we also achieved more detailed knowledge about the landslides kinematics in time and space.

Landslide phenomena in the area of Pomarico (Basilicata–Italy): methods for modelling and monitoring

Abstract This paper takes into consideration landslide phenomena in the clayey slopes facing the built-up area of Pomarico which is situated in the southern part of the “Fossa Bradanica”, in Basilicata (Italy). Based on the great number of geologic, geomorphologic and historic informations a geotechnical model of the slope was built. Particular attention has been paid to define the geotechnical parameters of the soil and which mechanical models are to be used. The studies point out a correlation between the water level in the detritus cover and the stability condition of the slope showing that phenomena at first located at the foot of the slope spread quickly towards its summit as the piezometric height increases.

Forecasting methods for landslides interacting with infrastructures

Few years ago, during the start-up works for the realization of a tunnel entrance, a shallow translational landslide occurred. Following this event detailed engineering-geological surveys of the slope were performed and an integrated monitoring system, including also a Terrestrial SAR Interferometer (TInSAR), was built. Based on the time series of displacement semi-empirical approach was applied to the anchored bulkheads. Simultaneously an engineering-geology model was devised for a stress–strain numerical analysis which was performed by the finite difference code FLAC 6.0.

Imaging Multi-Age Construction Settlement Behaviour by Advanced SAR Interferometry

This paper focuses on the application of Advanced Satellite Synthetic Aperture Radar Interferometry (A-DInSAR) to subsidence-related issues, with particular reference to ground settlements due to external loads. Beyond the stratigraphic setting and the geotechnical properties of the subsoil, other relevant boundary conditions strongly influence the reliability of remotely sensed data for quantitative analyses and risk mitigation purposes. Because most of the Persistent Scatterer Interferometry (PSI) measurement points (Persistent Scatterers, PSs) lie on structures and infrastructures, the foundation type and the age of a construction are key factors for a proper interpretation of the time series of ground displacements. To exemplify a methodological approach to evaluate these issues, this paper refers to an analysis carried out in the coastal/deltaic plain west of Rome (Rome and Fiumicino municipalities) affected by subsidence and related damages to structures. This region is characterized by a complex geological setting (alternation of recent deposits with low and high compressibilities) and has been subjected to different urbanisation phases starting in the late 1800s, with a strong acceleration in the last few decades. The results of A-DInSAR analyses conducted from 1992 to 2015 have been interpreted in light of high-resolution geological/geotechnical models, the age of the construction, and the types of foundations of the buildings on which the PSs are located. Collection, interpretation, and processing of geo-thematic data were fundamental to obtain high-resolution models; change detection analyses of the land cover allowed us to classify structures/infrastructures in terms of the construction period. Additional information was collected to define the types of foundations, i.e., shallow versus deep foundations. As a result, we found that only by filtering and partitioning the A-DInSAR datasets on the basis of the above-mentioned boundary conditions can the related time series be considered a proxy of the consolidation process governing the subsidence related to external loads as confirmed by a comparison with results from a physically based back analysis based on Terzaghi’s theory. Therefore, if properly managed, the A-DInSAR data represents a powerful tool for capturing the evolutionary stage of the process for a single building and has potential for forecasting the behaviour of the terrain–foundation–structure combination.

Mechanism of the Montescaglioso Landslide (Southern Italy) Inferred by Geological Survey and Remote Sensing

Montescaglioso village is located in southern Italy (Matera, Basilicata region), on a hill top, at about 350 m a.s.l., along the left bank of the Bradano River. Several landslides involved this area, some of them classified as relict; the latest one occurred on December 3rd, 2013 on the south-western slope of Montescaglioso hill. A review of the geological setting of this slope is presented, aimed at defining the failure mechanism of the slope. Sub-pixel cross-correlation analysis based on SAR images was performed to infer the co-failure displacement pattern and A-DInSAR was carried out to detect the spatial-temporal deformational pattern before and after the failure. The field surveys confirmed the main role played by geological setting in structurally constraining the landslide mechanism and its complex kinematic, featured by three main distinct “kinematic blocks” with different direction of movement. The 3rd December landslide has been recognized as a partial reactivation along a slope affected by a long-lasting sequence of landslides, the last one triggered by a transient action.

Lesson learned from the pre-collapse time series of displacement of the Preonzo landslide (Switzerland)

In this paper a back-analysis of the 2012 Preonzo landslide (Switzerland) collapse is presented. Failure Forecasting Methods (FFMs) have been applied to the pre-collapse time series of displacement obtained by TInSAR (Terrestrial Synthetic Aperture Radar Interferometry). Then, the time series of displacement have been resampled in order to simulate the satellite InSAR (Synthetic Aperture Radar Interferometry) acquisition. The aim is to investigate the potential and the limitations of satellite InSAR monitoring technique for forecasting purposes. Specifically, the low temporal frequency of data acquisition and the ambiguity phase constraints have been accounted for. The achieved results suggest that satellite InSAR technique could be an effective tool for forecasting purposes, even if some issues have still to be faced.

Analysis of a Subsidence Process by Integrating Geological and Hydrogeological Modelling with Satellite InSAR Data

This paper focuses on a multidisciplinary study carried out in an urban area affected by subsidence. The area is located about 20 km east of Rome (Italy) and is affected by dewatering processes mainly linked to quarry activities. Furthermore, compressible soils are locally present immediately below the ground level. Persistent Scatterer Interferometric Synthetic Aperture Radar (InSAR) analyses carried out with different approaches on ERS and ENVISAT data were performed. The so reconstructed time series of ground displacements were then coupled and compared with a detailed geological model and the variations over time of piezometric levels. Such data overlay allowed us to better understand and constrain the relation among ground displacement, piezometric variations, geological setting and geotechnical properties of subsoil.

Advanced Characterization of a Landslide-Prone Area by Satellite a-DInSAR

An area of about 15 km2 in Central Italy, severely affected by landslide processes, has been studied by several approaches. Field surveys and multi-temporal aerial photos allowed to frame geomorphological setting and temporal evolution of instability slope processes. Starting from this information, Advanced Differential Interferometric SAR (A-DInSAR) analyses have been performed in order to improve our knowledge of the under study processes in terms of both spatial and temporal evolution and kinematics. A previous feasibility analysis has been carried out to define the suitability of A-DInSAR analysis for every recognized landslide. The adopted method was also useful to identify best available data to perform InSAR analyses in order to detect and measure expected deformation processes. A-DInSAR analyses have been performed with two different approaches: a standard Persistent Scatterers (PS) analysis with linear models to estimate PS velocity over the whole area and local scale analyses on some specific sub-areas with a no-model approach, more appropriate for non-linear deformation detection.

Landslide risk reduction by coupling monitoring and numerical modeling

The importance of the reference engineering-geology model of a slope is a concept well established in the scientific and technical community facing on large in frastructures. The engineering-geology model is in fact a fundamental informative layer to understand and predict the structure-slope interactions and to design stabilization countermeasures. Such an issue has a relevant role in the case of unstable slopes: at this regard the Vajont case history represents a worldwide reference. Engineering-geology models can be validated and/or updated by monitoring data. Furthermore, the harmonization of engineering-geology models and monitoring data can be achieved by the implementation of stress-strain numerical models, that represent a validating tool for the engineering-geology models,