Building Deformation Assessment by Means of Persistent Scatterer Interferometry Analysis on a Landslide-Affected Area: The Volterra (Italy) Case Study

Abstract

Abstract:In recent years, space-borne InSAR (interferometric synthetic aperture radar) techniques have shown their capabilities to provide precise measurements of Earth surface displacements for monitoring natural processes. Landslides threaten human lives and structures, especially in urbanized areas, where the density of elements at risk sensitive to ground movements is high. The methodology described in this paper aims at detecting terrain motions and building deformations at the local scale, by means of satellite radar data combined with in situ validation campaigns. The proposed approach consists of deriving maximum settlement directions of the investigated buildings from displacement data revealed by radar measurements and then in the cross-comparison of these values with background geological data, constructive features and on-field evidence. This validation permits better understanding whether or not the detected movements correspond to visible and effective damages to buildings. The method has been applied to the southwestern sector of Volterra (Tuscany region, Italy), which is a landslide-affected and partially urbanized area, through the use of COSMO-SkyMed satellite images as input data. Moreover, we discuss issues and possible misinterpretations when dealing with PSI (Persistent Scatterer Interferometry) data referring to single manufactures and the consequent difficulty of attributing the motion rate to ground displacements, rather than to structural failures.

A-DInSAR Monitoring of Landslide and Subsidence Activity: A Case of Urban Damage in Arcos de la Frontera, Spain

“…The higher spatial resolution and less revisiting time of this satellite would be suitable to measure the differential deformation of different sectors of single buildings. Angular distortions caused by differential settlement processes, where only vertical displacement is assumed, could be investigated [24,26]. Furthermore, it can be used as a tool to monitor possible displacements after remedial stabilization solutions have been carried out.…”

“…Even though high spatial resolution sensors, i.e., TerraSAR-X or CosmoSkyMed, are the most adequate for studying urban areas [22][23][24], the Synthetic Aperture Radar (SAR) images are acquired under request, and thus no images might be available to study past events. On the other hand, several works have demonstrated the usefulness of C-band SAR images acquired by medium spatial resolution sensors such as ERS and ENVISAT satellites to monitor urban structures [22,[25][26][27][28].…”

A GIS-Based Procedure for Landslide Intensity Evaluation and Specific risk Analysis Supported by Persistent Scatterers Interferometry (PSI)

“…The outcropping terrains are mainly Miocene-Pliocene clayey and sandy marine formations (respectively "Blue Clays" and "Villamagna sands") that represent the sedimentary filling of the basin. Calcarenites and limestones close the marine sedimentary succession and constitute the tableland on which Volterra city was built [37]. Fine and coarse detritic sediments (e.g., conglomerates and breccias), developed in lacustrine or lagoonal cycles or in a continental fluvial-deltaic environment are also present.…”

Mapping Vulnerable Urban Areas Affected by Slow-Moving Landslides Using Sentinel-1 InSAR Data

“…Notti et al [22] found a relationship between the severity of damage, the duration of ground deformation and the age of buildings. Bianchini et al [21] concluded that building damage was mainly controlled by the combination of terrain morphology and the type of foundation that had been employed.…”

“…For instance, the use of high-resolution X-band data allows increasing the density of measurements over individual building, and might be of interest for other applications (e.g., estimation of differential settlements for each building, see [21,53]). Additionally, the information provided by our map can be completed by specifying the type of building evaluated (education centres, health facilities) following the requirements for damage and loss data sharing standard for the Sendai Framework for Disaster Risk Reduction [54].…”