Repeated thermal cycles influence rock slope evolution inducing stresses that can initiate and propagate fractures. Ground-Based Interferometric Synthetic Aperture Radar (GBInSAR) monitors the mechanical behavior and superficial displacement, including thermally-induced, useful for precursor displacements detection before landslide onset and collapse. A coupled thermo-mechanical Finite Element Method (FEM) is used to investigate thermal effects on rock slope deformations to (i) understand how slope geometry influences heat flux and stress, (ii) assess thermo-mechanical parameter impact on the thermo-mechanical response, and (iii) simulate slope geometry and aspect effects on system response through different boundary temperature. Finally, simulated FEM superficial displacement maps are compared with GBInSAR measurements from two Italian Alps sites. Results demonstrate that curvature and changes in slope inclination significantly concentrate temperature increments and associated stresses. Specific heat affects both temperature distribution and displacements, while Young's modulus and thermal expansion coefficients influence displacement and stress magnitudes. External temperatures controlled by slope aspect impact movement modes, producing torsional effects, especially for slender features. The numerical predictions and GBInSAR data comparison reveal a strong agreement in displacement distribution, validating the model ability to capture observed deformation patterns. These findings highlight the role of thermal forcing in rock slope deformation and its sensitivity to geometric features and material properties. The results offer valuable insights for monitoring planning, by identifying thermally sensitive areas, for interpreting field data, isolating thermal contributions from total displacements; and for slope stability analysis, by providing a framework to assess thermo-mechanically induced stress and deformation under current and future climatic conditions.

The unexpected collapse of the Marmolada Glacier in the Italian Alps on 3 July 2022, caused 11 fatalities and emphasized the need for a deeper understanding of unstable glaciers. In response, we initiated a radar monitoring campaign to assess the stability of the remaining ice cliff and obtained a near-continuous data set of displacement at sub-hourly resolution and sub-millimeter accuracy. The survey spanned July 4-October 2, covering most of the ablation season and allowing insights into the post-collapse evolution of the potentially unstable scar. Rather than observing downslope motion, our measurements revealed progressive ice cliff backwasting driven by melt, with overall displacements up to 1.2 m on the sun-exposed rim and about three times smaller on the shaded wall. The observed pattern suggests that the wall retreated more slowly than the rim, consistent with typical radiation-driven ice cliff morphologies. Daily backwasting peaked at 53 1 mm on the hottest day and fluctuated with air temperature. Sub-freezing temperatures halted the melt, revealing minor displacements toward the sensor, consistent with ice flow of up to 6 1 mm . Correlation analyses confirmed a strong link between daily backwasting rates and air temperature (Spearman coefficient at the rim). Independent estimates of backwasting from topographic data were consistent with our measurements, demonstrating the potential of terrestrial radar interferometry for studying ice cliff morphodynamics.

The use of radar techniques to perform static (slowly moving) structural measurements is a well known task and most radar systems are limited to this kind of measurements. Recent progresses in this kind of techniques, however, have encouraged researchers to study and develop radar systems capable to perform dynamic measurements. The main advantage consists in the fact that this kind of system is a non-contact one. However, several problems may be encountered when using such a system to perform dynamic measurements. The aim of this work is to provide the validation of the prototype of a radar system (GBInSAR) developed by LiSALab, underlining the advantages and limitations in the use of this technique to perform dynamic measurements. The previous version of this system was usable to investigate phenomena with slow dynamics. The new system was tested imposing harmonic movements to a trihedron and measuring the displacements with the radar and with a set of accelerometers. Frequencies up to 20 Hz and displacements up to 10 + 10 mm were imposed during the tests. The tests were performed using one (shifting) reflecting body and nothing else in the scene and with the shifting reflecting body plus other three static reflecting bodies. A comparison between the results obtained with the two measurement techniques is proposed.

This work presents the operational application of the Ground-Based Interferometric Synthetic Aperture Radar (GBInSAR) data to anticipate the collapse of incandescent volcanic material deposited on crater rims, a poorly understood process that can trigger glowing rock avalanches, often referred to as deposit-derived pyroclastic density currents (PDCs). The results show that this method effectively identifies anomalous periods, assesses the level of instability, and provides timely anticipation of any observed failures. During the 2024 eruption at Stromboli, the system detected a progressive increase in instability corresponding to increased eruptive activity, and provided early warnings of major crater rim collapses. These failures are interpreted as being caused by magma thrust, driven by lava densification and conduit pressurisation by ascending low-density magma. Although effective, the method has limitations in estimating collapse volumes, mainly due to its reliance on empirical area-volume relationships and the challenge of distinguishing between single and multiple failure events. Refinements incorporating improved morphometric data and stability models could improve its predictive capability. GBInSAR provides high-resolution deformation data in real time, enabling effective early warning systems. Since 2003, this approach has proven successful at Stromboli and could be adapted to other active volcanic environments, providing a valuable tool for assessing the instability of hazardous volcaniclastic accumulations and contributing to PDC-related risk mitigation.

Introduction: Sinkholes are ground collapses that can cause significant damage to infrastructure and buildings. Part of the risk represented by sinkholes is related to their abruptness and the difficulty in spotting in advance their exact location within a sinkhole-prone area. For this reason, urban planning informed by an accurate risk mapping and monitoring is one of the most effective ways to reduce the risk.Methods: In this study, we propose a two-folded procedure based on the examination of ground displacement data measured by a ground-based interferometric radar and on the generation of a sinkhole risk zonation map. We examined 11 years' worth of ground displacement data measured by a ground-based interferometric radar to search for sinkhole precursors. The analysis was based on averaged displacement time series retrieved from high-coherence pixels scattered around Camaiore, Italy, a test site where a catastrophic sinkhole occurred in 1995. To generate a sinkhole risk map, we evaluated the susceptibility map as derived from a set of predisposing environmental parameters, the vulnerability derived from the thickness of the sedimentary cover that can be linked to the abruptness of the collapse, and the value of the elements at risk from the Italian Real Estate Market Observatory integrated with land cover information for the non-built up areas.Results: The analysis of ground displacement data revealed that Camaiore had not experienced subsidence relatable to incoming sinkholes in the monitored period. However, few cm of vertical movements, which are well correlated with water table oscillations, have been measured and are expected to be of the same order of magnitude of sinkhole precursor deformations. This implies that a phenomenon of the size and velocity of the 1995 event could have likely been detected before its final collapse. The sinkhole risk map identified specific areas that should be closely monitored using in situ and remote sensing instrumentation.Discussion: The sinkhole risk zonation map generated in this study can be used to inform urban planning and risk management strategies. The study also shows the potential of ground-based interferometric radar to detect sinkhole precursors and the importance of integrating different mitigation approaches. Overall, this study can provide insights for sinkhole risk assessment and management in sinkhole-prone areas.

Ground-based synthetic aperture radar interferometry (GBInSAR) remote sensing technique has been repeatedly proved an effective tool for monitoring built environment affected by structural and geological criticalities. In this paper, it is described how this technique can be successfully applied for early-warning procedures and detection of ongoing deterioration processes on archeological and cultural heritage sites. An integrated approach of GBInSAR and terrestrial laser scanner (TLS) technologies was performed on Volterra test site (Tuscany, Italy), where a sudden collapse of a 35-m wide section of city walls occurred on January 31, 2014. The installed early-warning monitoring system is capable of an accurate and focused real-time displacement detection of the south-western side of the city including walls, buildings, and monuments, thus allowing prompt interventions for citizens safety and conservation purposes. The effectiveness of this alert technique became evident when the precursors of a second impressive wall collapse were clearly detected. From the beginning of the GBInSAR monitoring, we measured a constant displacement velocity of 0.1 mm/h in correspondence to a 15-m high wall sustaining the Acropolis and lying an underground parking. After a sudden increase of velocity values up to 1.7 mm/h, the local authorities were alerted so that they had time to interdict the area to citizens and to take adequate safety countermeasures two days before the collapse.

Recent progresses have encouraged researchers to study and develop radar systems capable to perform dynamic measurements. The aim of this work is to investigate advantages and limitations in the use of this technique to perform dynamic measurements in the presence of multiple reflections, such as the ones generated by large civil structures. To this purpose, a radar system was tested in controlled conditions, imposing harmonic movements to a corner reflector and measuring the displacement. The tests were first performed using only one (shifting) reflecting body to assess the radar ability to perform dynamic measurements. Further tests were performed using one shifting reflecting body plus other three static reflecting bodies to simulate possible multiple reflections. The results obtained with the radar were compared with traditional measurement systems and with numerical simulations. The overall analysis shows how the presence of disturbing elements may cause distortions in the measured signals. The work is intended to warn against the use of this technique without a good a priori knowledge of the observed phenomenon.

Stromboli volcano (Southern Italy) is one of the most monitored volcano in the world with a surveillance network that includes a permanently sited ground-based SAR interferometer (GBInSAR). This work is the review of the GBInSAR data gained from the last decade of monitoring activity. The analysis of the entire dataset of GBInSAR measurements allowed the assessment of the deformation field of the northern part of the summit crater area and the Sciara del Fuoco depression. In detail, the main displacements recognized can be related to different factors: 1) the inflation/deflation respectively immediately before and after each new effusive event; 2) the bulging of localized sectors of the volcano involved in the vent opening; 3) the gravitational sliding of the Sciara del Fuoco infill; 4) the movement of lava flows. Accelerations in this sector are related to sheet intrusions, while the possibility of vent opening, associated with small sliding, or catastrophic flank failure are related to highly overpressurized sheets, able to produce high displacement rate in the Sciara del Fuoco.In the summit crater area, the increases in the displacement rate are related to the pressurization of the shallow conduit system, as the consequence of the variation in the magma level (magmastatic pressure) or to the lateral magma migration (lateral conduit expansion or dike intrusion) in response to the increase of the overpressure component. Fluctuations in the displacement rate in the summit crater area can be related to the magma overturning within the conduit, with the increases in displacement rate during the upwelling of less dense magma, while displacement rate decreases as the degassed magma column is pushed out from the conduit (lava flows or overflows). Instead, the decrease in the displacement rate without coeval lava outpouring could be related to the sink of the degassed magma due to density contrast between the gas-poor and the gas-charged magmas. Using the displacement rate in the summit crater area as a proxy for the variation in the pressure condition in conduit (both magmastatic and overpressure components), thresholds for the crises characterized by the occurrence of overflows (eventually associated with major explosions) and flank effusions (eventually associated with paroxysmal explosions) are identified. Small conduit overpressure will produce overflows (sometimes associated with crater-rim collapses), while large magma overpressure will laterally expand the conduit forming NE-SW striking sheets, feeding eruptive vents at the base of the summit crater area and within the Sciara del Fuoco, generating conditions of instability that can evolve into catastrophic collapse of the instable flank. (C) 2014 Elsevier B.V.

Stromboli volcano (Aeolian Archipelago, Southern Italy) experienced an increase in its volcanic activity from late December 2012 to March 2013, when it produced several lava overflows, major Strombolian explosions, crater-wall collapses pyroclastic density currents and intense spatter activity. An analysis of the displacement of the NE portion of the summit crater terrace and the unstable NW flank of the volcano (Sciara del Fuoco depression) has been performed with a ground - based interferometric synthetic aperture radar (GBInSAR) by dividing the monitored part of the volcano into five sectors, three in the summit vents region and two in the Sciara del Fuoco. Changes in the displacement rate were observed in sectors 2 and 3. Field and thermal surveys revealed the presence of an alignment of fumaroles confirming the existence of an area of structural discontinuity between sectors 2 and 3. High displacement rates in sector 2 are interpreted to indicate the increase in the magmastatic pressure within the shallow plumbing systems, related to the rise of the magma level within the conduits, while increased displacement rates in sector 3 are connected to the lateral expansion of the shallow plumbing system. The increases and decreases in the displacement rate registered by the GBInSAR system in the upper part of the volcano have been used as a proxy for changes in the pressure conditions in the shallow plumbing system of Stromboli volcano and hence to forecast the occurrence of phases of higher-intensity volcanic activity.

Ground-Based Synthetic Aperture Radar Interferometry (GBInSAR) and Terrestrial Laser Scanning (TLS) were purposely integrated to obtain 3D interferometric radar point clouds to facilitate the spatial interpretation of displacements affecting archaeological monuments. The paper describes the procedure to implement this integrated approach in the real-world situations of surveillance of archaeological and built heritage. Targeted tests were carried out on the case study of the Domus Tiberiana sited along the northern side of the Palatino Hill in the central archaeological area of Rome, Italy, and displacements of the monument were monitored over almost one year of acquisition. The GBInSAR – TLS integration provided updated information about the condition of the archaeological structures in relation to their history of instability mechanisms, and did not highlighted a general worsening for the stability of the entire monument. Point-wise and prompt detection of displacement anomalies and/or sudden changes in displacement trends proved the suitability of the method to support early warning procedures, also to evaluate effects on the masonry due to human activities.

(1) Universita degli Studi di Milano Bicocca, Dipartimento di Scienze Geologiche e Geotecnologie, Milano, Italy (federico.agliardi@unimib.it, +39 0264482073), (2) Studio Cancelli Associato, Milano, Italy, (3) Imageo Srl, Torino, Italy, (4) Regione Autonoma Valle d’Aosta, Assessorato OO.PP. Difesa del Suolo e Edilizia Residenziale Pubblica, Dip. Difesa del Suolo e Risorse Idriche, Servizio Geologico, Quart, Aosta, Italy, (5) Ellegi s.r.l., Milano, Italy

The rapid assessment of the evolution of the phenomena which occur during an emergency, along with an all weather and h24 monitoring capability, are probably the main characteristics of a system aimed at optimizing intervention in natural disasters, such as landslide collapses. A few techniques are able to provide all these features remotely, hence assuring safe conditions to operators. This paper reports on an application of the GB-InSAR (Ground-Based Interferometric Synthetic Aperture Radar) technique to monitor a landslide threatening an infrastructure, the A3 motorway in the Calabria Region (Southern Italy), in emergency conditions. Here, it is evaluated how well this technique is able to satisfy these requirements. On 30 January 2009, a mass movement never detected before and located near Santa Trada viaduct caused the closure of that sector of the A3 motorway. The prompt installation of a GB-InSAR permitted to follow and to understand the temporal evolution of the landslide until the end of the emergency and then safely reopen of the motorway. The main steps of the GB-InSAR interferometry data interpretation used in managing this emergency are described and discussed here. In detail, data collected through a continuous acquisition have permitted the division of the unstable area into three smaller zones characterized by different extents of displacement.