Vulnerability Assessment of Buildings due to Land Subsidence using InSAR Data in the Ancient Historical City of Pistoia (Italy)

The launch of the medium resolution Synthetic Aperture Radar (SAR) Sentinel-1 constellation in 2014 has allowed public and private organizations to introduce SAR interferometry (InSAR) products as a valuable option in their monitoring systems. The massive stacks of displacement data resulting from the processing of large C-B and radar images can be used to highlight temporal and spatial deformation anomalies, and their detailed analysis and postprocessing to generate operative products for final users. In this work, the wide-area mapping capability of Sentinel-1 was used in synergy with the COSMO-SkyMed high resolution SAR data to characterize ground subsidence affecting the urban fabric of the city of Pistoia (Tuscany Region, central Italy). Line of sight velocities were decomposed on vertical and E–W components, observing slight horizontal movements towards the center of the subsidence area. Vertical displacements and damage field surveys allowed for the calculation of the probability of damage depending on the displacement velocity by means of fragility curves. Finally, these data were translated to damage probability and potential loss maps. These products are useful for urban planning and geohazard management, focusing on the identification of the most hazardous areas on which to concentrate efforts and resources.This work was supported by the Spanish Ministry of Economy, Industry and Competitiveness (MINECO), the State Agency of Research (AEI) and European Funds for Regional Development (FEDER) under projects AQUARISK (ESP2013-47780-C2-2-R) and TEMUSA (TEC2017-85244-C2-1-P) and STAR-EO (TIN2014-55413-C2-2-P). The first author shows gratitude for the PhD student contract BES-2014-069076. The work was conceived during the research stay of P. Ezquerro and R. Tomás in the Università degli Studi di Firenze and the research stay of G. Herrera in the IGOT Lisbon University, supported by the Spanish Ministry of Education, Culture and Sport under fellowships EEBB-I-18-13014, PRX17/00439 and PRX19/00065, respectively. The S-1 monitoring activity is funded and supported by the Tuscany Region under the agreement “Monitoring ground deformation in the Tuscany Region with satellite radar data.” The authors also gratefully acknowledge TRE ALTAMIRA for having processed the S-1 data. The project was carried out using CSK® Products, © ASI (Italian Space Agency), delivered under the ASI Project Id Science 678 - “High resolution Subsidence investigation in the urban area of Pistoia (Tuscany Region, central Italy). The work is under the framework of the e-shape project, which has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement 820852. This paper is also supported by the PRIMA programme under grant agreement No 1924, project RESERVOIR. The PRIMA programme is supported by the European Union

Integrierte hydrologische und hydrogeologische Modellierung für die Subsidenzanalyse im Becken

Land subsidence, together with landslides and floods, represents one of the main natural hazards that affect several countries all over the world, potentially causing significant damages to buildings and infrastructures. In particular, Firenze-Prato-Pistoia basin has a long experience of ground deformation related to groundwater withdrawal. InSAR satellite data collected since 1992 have revealed the presence of several subsiding areas in the basin, such as the south-eastern portion of Pistoia city. Sentinel-1 persistent scatterer interferometry measurements for 2015–2018 confirmed the long-term subsidence of this area, associated with intense horticulture (plant nurseries). At the same time, Sentinel-1 data revealed the unexpected movement of Pistoia historic center, which has always been considered stable in the past. To identify the complex relationship between aquifer conditions and ground displacement, a hydrogeologic model of the Pistoia aquifers was developed, applying an integrated modelling procedure. This approach was firstly tested in a small pilot basin, to confirm the reliability of the numerical procedure, obtaining promising results. Hydrodynamic-parameter distributions, calibrated and validated by means of Sentinel-1 PSI measurements, suggest that subsidence in Pistoia area is probably related with the combined impacts of groundwater extraction and highly compressible aquitards. To evaluate the potential evolution of ground displacement, numerical simulations were extended until 2050, using regional and global climate model data, analyzing three different pumping-rate scenarios. This, together with damage information of buildings collected on the field, led to the development of several subsidence hazard maps of Pistoia city that display the influence of groundwater extraction in controlling land subsidence in the area. The present study enhances the importance of developing proper groundwater management policies, especially in alluvial aquifers made of fine compressible sediments, in order to sustainably utilize underground freshwater resources and to avoid related side effects. It also emphasizes the role of integrated numerical simulations and the necessity to consider surficial network and groundwater as a unique interacting system, when developing basin scale hydrogeologic analysis.Landabsenkungen stellen eine der wichtigsten Naturgefahren dar, die mehrere Länder auf der Welt betreffen und möglicherweise Schäden an Gebäuden und Infrastruktur verursachen. Das Firenze-Prato-Pistoia-Becken verfügt über langjährige Erfahrung mit Bodenverformungen im Zusammenhang mit der Grundwasserentnahme. InSAR-Satellitendaten, die seit 1992 gesammelt wurden, haben gezeigt, dass im Becken mehrere Absenkungsgebiete vorhanden sind, beispielsweise der südöstliche Teil der Stadt Pistoia. Sentinel-1-Messungen für den Zeitraum 2015–2018 bestätigten die langfristige Absenkung dieses Gebiets, die mit einem intensiven Gartenbau verbunden ist. Gleichzeitig enthüllten Sentinel-1-Daten die unerwartete Bewegung des Zentrums von Pistoia, das in der Vergangenheit immer als stabil angesehen wurde. Um die Beziehung zwischen den Bedingungen des Grundwasserleiters und der Bodenverschiebung zu identifizieren, wurde ein hydrogeologisches Modell der Pistoia-Grundwasserleiter unter Anwendung eines integrierten Modellierungsverfahrens entwickelt. Dieser Ansatz wurde zunächst in einem Pilotbecken getestet, um die Zuverlässigkeit des Verfahrens zu bestätigen und vielversprechende Ergebnisse zu erzielen. Hydrodynamische Parameterverteilungen, die mithilfe von Sentinel-1-Messungen kalibriert und validiert wurden, legen nahe, dass das Absinken im Gebiet von Pistoia wahrscheinlich mit den kombinierten Auswirkungen der Grundwassergewinnung und hochkomprimierbarer Aquitards zusammenhängt. Um die mögliche Entwicklung der Bodenverschiebung zu bewerten, wurden Simulationen bis 2050 erweitert, wobei prädiktive Klimamodelldaten verwendet und drei verschiedene Pumpraten-Szenarien analysiert wurden. Dies führte zusammen mit Schadensinformationen von Gebäuden zur Entwicklung mehrerer Karten der Senkungsgefahr der Stadt Pistoia, die den Einfluss der Grundwassergewinnung auf die Kontrolle der Bodensenkung in der Region zeigen. Die vorliegende Studie unterstreicht die Bedeutung einer angemessenen Grundwassermanagementpolitik, insbesondere bei Schwemmlandgrundwasserleitern aus feinen komprimierbaren Sedimenten, um die unterirdischen Süßwasserressourcen nachhaltig zu nutzen und damit verbundene Nebenwirkungen zu vermeiden. Es unterstreicht auch die Rolle integrierter numerischer Simulationen und die Notwendigkeit, das Oberflächennetz und das Grundwasser als ein einzigartiges Wechselwirkungssystem zu betrachten, wenn hydrogologische Analysen im Beckenmaßstab entwickelt werden

Numerical modeling and characterization of a peculiar flow-like landslide

Abstract Background On March 25th, 2015, a rapid landslide occurred upstream of the village of Gessi-Mazzalasino, in the municipality of Scandiano, affecting two buildings. Rapid landslides, due to their high velocity and mobility, can affect large areas and cause extensive damage. Considering the often unpredictable kinematics of landslides, the post-failure behavior has been studied by many authors to predict the landslide runout phase for hazard assessment. Findings With the aim of characterizing the Gessi-Mazzalasino landslide, field surveys were integrated with the results of laboratory tests. The geometric characteristics (thickness, area and volume) and kinematic aspects of the landslide were estimated by using a laser scanning survey and geomorphological data. To model the landslide and obtain its rheological parameters, a back analysis of the event was performed by means of a depth-averaged 3D numerical code called DAN3D. The results of the back analysis of the landslide propagation were validated with field surveys and velocity estimations along selected sections of the landslide. Finally, potential areas prone to failure or reactivation were identified, and a new simulation was performed that considered the back-calculated rheological parameters. Conclusions Rapid landslides are one of the most dangerous natural hazards and are one of the most frequent natural disasters in the world. Therefore, prediction of post-failure motion is an essential component of hazard assessment when a potential source of a mobile landslide it is located. To assess the risk affecting the area, both numerical and empirical methods have been proposed, in order to predict the runout phase of the phenomenon. For the numerical modelling of the landslide, carried out with DAN-3D code, the best results were obtained by using a Voellmy reological model, with a constant turbulence parameter (ξ) of 250 m/s2 and a friction parameter (μ) comprised between 0.15 and 0.19. The rheological parameters obtained through dynamic back analyses were used to evaluate the propagation phase and the deposition areas of new potential landslides, that could affect the same area of the 25th March 2015 event. The predicted runout length obtained by the DAN3D software was compared to runout lengths predicted by the Corominas (Can Geotech J 33:260–271, 1996), (Nat. Hazards 19, 47-77) and (UNICIV Report, R-416, School of Civil & Environmental Engineering, UNSW, Sydney Australia 2003) empirical relations. All the data confirm that the impact area of possible future events will be smaller than the 2015 event, probably due to the safety measures established after the landslide

Cyclochronology of the Early Eocene carbon isotope record from a composite Contessa Road-Bottaccione section (Gubbio, central Italy)

High-resolution geochemical time series from the composite Contessa Road-Bottaccione (CRBTT) section (central Italy) allows testing the global significance of Early Eocene short- and long-term carbon isotope trends by comparison with available records from oceanic successions. Spectral analysis reveals Milankovitch frequency band fluctuations in the concentration of CaCO3. Extraction of the short- and longeccentricity orbital periodicities from the wt.% CaCO3 record provides a relative cyclochronology for the interval spanning ~ 49.5 Ma to ~ 52.5 Ma corresponding to magnetochron C22r to the top of C24n thus extending the cyclochronology already available from the same section in the interval between ~ 52.0 to ~ 56 Ma, spanning the lower C24r to upper C23r. Recognition of orbitally forced sedimentary cycles, corresponding to the long (405 kyr) and short (100 kyr) eccentricity, allows to test the chemostratigraphic alignment with ODP Site 1258 and ODP Site 1263 records and to obtain a correlation of hyperthermal events to an unambiguous magnetostratigraphic record across the interval corresponding to the Early Eocene Climatic Optimum and to refine the astrochronological interpretation of the Ypresian Stage