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Structural health monitoring (SHM) can support decision makers in structural integrity management by providing information about occurrence of damage and its evolution in time. Recently, due to new Synthetic Aperture Radar (SAR) missions, remote sensing through active satellites provides a promising methodology capable of monitoring infrastructure assets. This paper investigates the use of Multi‐Temporal Synthetic Aperture Radar Interferometry (MT‐InSAR) processing to monitor the structural health of bridges. The full interferometry processing chain is applied using Sentinel‐1 synthetic aperture radar data and a combination of open‐source routines from the Sentinel Application Platform (SNAP) and Stanford Method for Persistent Scatterers (StaMPS). Displacement time‐histories are derived from single look complex products by employing the Persistent Scatterer Interferometry (PSInSAR) technique. The PS‐InSAR technique is applied to study the behavior of a concrete bridge located over the Oglio river in Isola Dovarese, Italy, on which also GNSS receivers are installed. The GNSS data are then used to validate the PS‐InSAR measurements. The effects on PS‐InSAR results of the number of SAR images used as well of the target structure are investigated. [ABSTRACT FROM AUTHOR]

Recently, structures, built on reclamation sites in the Eastern Black Sea region are quite remarkable. As one of them, Şenol Güneş Medical Park Arena Sport Complex, which is located in Akyazı town of Trabzon city, is one of the rare areas in Turkey. It is very important to monitor surface deformations on this type of unfamiliar and very expensive constructions for protecting human life and property and for taking necessary precautions in advance. Persistent Scatterer Interferometry (PSI), based on the analysis of time series of multiple Synthetic Aperture Radar (SAR) data, is an invaluable geodetic tool to measure surface deformations. So, in this study, it is aimed to monitor the surface deformations on the reclamation site between the dates 20/12/2016–28/01/2020 by StaMPS (Stanford Method for Persistent Scatterers)-PSI technique using 96 Sentinel-1 SAR images. For processing, integration of European Space Agency (ESA) SentiNel Application Platform (SNAP) and StaMPS programs are used. After processing, surface deformations are determined as annual velocities (millimeter(mm)/year(y)) of PS points in the reclamation area along the line-of-sight (LOS) direction between the values −9.7 mm/y and 3.9 mm/y with an average standard deviation of 0.7 mm/y. From the results, it is understood that the area demonstrates very heterogeneous deformations rates, which occur on both horizontal and vertical directions because of the diversity and being on the reclamation site of the structures. [ABSTRACT FROM AUTHOR]

Land subsidence problems have become increasingly prominent. Traditional monitoring methods, such as level measurements, have high costs and low efficiency. Permanent scatterer interferometric synthetic aperture radar (PS-InSAR) has several advantages for land subsidence monitoring based on technological innovations. Aimed at resolving the key problems associated with PS-InSAR technology, the accuracy of three external digital elevations models (DEMs, namely, SRTM, ASTER GDEM, and PleiadesDEM) was analysed and compared. We found that the introduction of ground control points can significantly improve the elevation accuracy of DEMs. Herein, we introduce the specific processing steps and selection of the key parameters for IN-SAR data using the StaMPS software. We discuss the differences between IN-SAR technology and levelling measurements as well as the influence that the different external DEMs have on IN-SAR data. Based on 36 scenes of TerraSAR-X images, we obtained results for land deformation monitoring in Taiyuan City using PS-InSAR technology, which provided satisfactory monitoring results. [ABSTRACT FROM AUTHOR]

Abstract The present study comes in the context of tunnel excavation monitoring. To detect and explain the characteristics of ground displacements due to tunnel excavations, a PsInsar processing chain for Sentinel-1 images using S1TBX and StaMPS tools is set up. Then, it is applied to study surface displacements over the line b of Rennes city metro. This study exploits 20 Sentinel-1 images covering Rennes City, France, over a period of 2.5 years. Mean displacement velocity map and displacement time series show that the detected deformations are correlated in space and in time with the excavation works. Although we did not had the possibility to validate PsInsar results by ground truth data (levelling, GNSS), we demonstrate, through this blind experiment, that we can detect a dense PS cover, the feasibility of small displacement scale and rate monitoring using a small set of Sentinel -1 images. To improve these results, we forecast to use a bigger set of images and to compare the result to ground data. [ABSTRACT FROM AUTHOR]

Slow moving landslides are widespread geomorphological features in the Northern Apennines of Italy where they represent one of the main landscape forming processes. The lithology of the Northern Apennines fold and thrust belt is characterized by alternations of sandstone, siltstone and clayshales, also known as flysch, and clay shales with a chaotic block in matrix fabric, which are often interpreted as tectonic or sedimentary mélanges. While flysch rocks with a high pelitic fraction host earthslides that occasionally evolve into flow like movements, earthflows are the dominant landslide type in chaotic clay shales. In the present work, we document the kinematic response to rainfall of landslides in these different lithologies using radar interferometry. The study area includes three river catchments in the Northern Apennines. Here, the Mediterranean climate is characterized by two wet seasons during autumn and spring respectively, separated by dry summers and winters with moderate precipitation. We use SAR imagery from the X-band satellite COSMO SkyMed and from the C-band satellite Sentinel 1 to retrieve spatial displacement measurements between 2009 and 2016 for 25 landslides in our area of interest. We also document detailed temporal and spatial deformation signals for eight representative landslides, although the InSAR derived deformation signal is only well constrained by our dataset during the years 2013 and 2015. In spring 2013, long enduring rainfalls struck the study area and numerous landslide reactivations were documented by the regional authorities. During 2013, we measured higher displacement rates on the landslides in pelitic flysch formations compared to the earthflows in the clay shales. Slower mean velocities were measured on most landslides during 2015. We analyse the temporal deformation signal of our eight representative landslides and compare the temporal response to precipitation. We show that earthslides in pelitic flysch formations accelerate faster than earthflows in chaotic clay shales and reach higher velocities, while the kinematic behaviour of the earthflows can be described as rather steady with only minor accelerations. Although we have no detailed pore pressure measurements for the period of interest, the observed behaviour can be explained in our view by the morphological and hydrological characteristics of the different landslide types. On the one hand landslide material and bedrock in the pelitic flysch rocks are more resistant, which is why slope angles are higher in this lithology. On the other hand, landslides in the pelitic flysch formations have often deeper slip surfaces and landslide material is more permeable. This is why long persistent rainfall is necessary to saturate the landslide material and induce pore pressures that are high enough to trigger displacement. [ABSTRACT FROM AUTHOR]

Synthetic Aperture Radar (SAR) interferometry (InSAR) is used to make measurements of small surface displacements in different situations including ground-settlement, landslides and excavations. We document the deformation history of four dormant deep-seated landslides in the Northern Apennines of Italy that were reactivated by the excavation of a double road tunnel. The tunnel is part of a larger infrastructure project that involves the improvement of the A1 highway which connects Bologna and Florence. The excavation of the tunnel under the landslides' basal shear surfaces started in 2011, and with the advance of the tunnel front, deformation began to occur, causing damages to homes and infrastructures. The tunnel passes under the small villages of Ripoli and Santa Maria Maddalena. The deformation slowed down after the tunnel was completed in November 2014, and low surface displacement rates were registered for the period between October 2014 and June 2016. We show the results of an InSAR analysis designed to measure surface movements between 2003 and 2016. The InSAR displacements are derived from the Envisat, COSMO SkyMed, and Sentinel 1 datasets and cover the main construction phase of the tunnel (2011–2015). A detailed geological and geomorphological mapping of the slope is developed based on the field evidence and on the spatial pattern of surface deformation provided by our InSAR analysis. Together with the map, a new conceptual geological model of the slope in tectonically sheared and weathered flysch is presented. The satellite InSAR data show good agreement with available ground based monitoring data that include inclinometer and GPS-measurements, while small differences occur with respect to deformation time series obtained from a ground-based InSAR instrument. In particular, the InSAR results for the X-Band data of COSMO SkyMed demonstrate the close relationship between the position of the excavation front and the displacement rates of previously dormant landslide deposits. Conversely, the concurrent rainfall does not appear to significantly influence the observed behavior and, if any, had only a minor influence on the displacement history of the investigated landslides. [ABSTRACT FROM AUTHOR]

Differential Interferometric SAR (DInSAR) time-series techniques can be used to derive surface displacement rates with accuracies of 1 mm/year, by measuring the one-dimensional distance change between a satellite and the surface over time. However, the slanted direction of the measurements complicates interpretation of the signal, especially in regions that are subject to multiple deformation processes. The Simultaneous and Integrated Strain Tensor Estimation from Geodetic and Satellite Deformation Measurements (SISTEM) algorithm enables decomposition into a three-dimensional velocity field through joint inversion with GNSS measurements, but has never been applied to interseismic deformation where strain rates are low. Here, we apply SISTEM for the first time to detect tectonic deformation on the Hyblean Foreland Plateau in South-East Sicily. In order to increase the signal-to-noise ratio of the DInSAR data beforehand, we reduce atmospheric InSAR noise using a weather model and combine it with a multi-directional spatial filtering technique. The resultant three-dimensional velocity field allows identification of anthropogenic, as well as tectonic deformation, with sub-centimeter accuracies in areas of sufficient GPS coverage. Our enhanced method allows for a more detailed view of ongoing deformation processes as compared to the single use of either GNSS or DInSAR only and thus is suited to improve assessments of regional seismic hazard. [ABSTRACT FROM AUTHOR]

Abstract: In the last decade, Synthetic Aperture Radar Interferometry (InSAR) has become operational as a technique that allows remote detection of deformation at the Earth''s surface. Analysis of time series of SAR images extends the area where InSAR can be successfully applied and also permits detection of smaller displacements through the reduction of error sources. Stanford Method for Persistent Scatterers (StaMPS) InSAR implementation, which is based on the processing of multi-temporal SAR data, is widely used for ground deformation monitoring. This is due mainly to its proven reliability and freeware distribution among the scientific community. However, some issues can make the interpretation of the results a difficult task: StaMPS supports data processing based on command prompt, which increases the difficulty of usage by users not familiar with the specific programming language that supports StaMPS. Moreover, several visualization tasks are not implemented in the standard approach requiring that each user develop its own code for visualization and interpretation purposes. In this paper, we present viStaMPS, a new visual application developed to enhance the visualization, manipulation and exportation of StaMPS results. The programmed application is developed in Matlab through the Graphical User Interface (GUI) and no coding is required for running it, which avoids any programming language knowledge for standard uses. The included graphical interface is very versatile allowing the user to choose among several features: visualization, manipulation and exportation of data which are not available in the original StaMPS. [Copyright &y& Elsevier]

Abstract: Differential SAR interferometry (DInSAR) is a very effective technique for measuring crustal deformation. However, almost all interferograms include large areas where the signals decorrelate and no measurements are possible. Persistent scatterer interferometry (PS-InSAR) overcomes the decorrelation problem by identifying resolution elements whose echo is dominated by a single scatterer in a series of interferograms. Two time series of 29 ERS-1/2 and 22 ENVISAT ASAR acquisitions of the Granada basin, located in the central sector of the Betic Cordillera (southern Spain), covering the period from 1992 to 2005, were analyzed. Rough topography of the study area associated to its moderate activity geodynamic setting, including faults and folds in an uplifting relief by the oblique Eurasian–African plate convergence, poses a challenge for the application of interferometric techniques. The expected tectonic deformation rates are in the order of ∼1mm/yr, which are at the feasibility limit of current InSAR techniques. In order to evaluate whether, under these conditions, InSAR techniques can still be used to monitor deformations we have applied and compared two PS-InSAR approaches: DePSI, the PS-InSAR package developed at Delft University of Technology (TU Delft) and StaMPS (Stanford Method for Persistent Scatterers) developed at Stanford University. Ground motion processes have been identified for the first time in the study area, the most significant process being a subsidence bowl located at the village of Otura. The idea behind this comparative study is to analyze which of the two PS-InSAR approaches considered might be more appropriate for the study of specific areas/environments and to attempt to evaluate the potentialities and benefits that could be derived for the integration of those methodologies. [Copyright &y& Elsevier]

Landslides are a major threat for population and urban areas. Persistent Scatterer Interferometry (PSI) is a powerful tool for identifying landslides and monitoring their evolution over long periods and has proven to be very useful especially in urban areas, where a sufficient number of PS can be generated. In this study, we applied PS interferometry to investigate the landslide affecting Santo Stefano d'Aveto (Liguria, NW Italy) by integrating classic interferometric techniques with cross-correlation analysis of PS time-series and with geological and geotechnical field information. We used open-source software and packages to process Synthetic Aperture Radar (SAR) images from the Copernicus Sentinel-1A satellite for both ascending and descending orbits over the period 2015–2021 and calculate both the vertical motion and the E-W horizontal displacement. By computing the cross-correlation of the PS time-series, we identified three families of PS with a similarity greater than 0.70. The cross-correlation analysis allowed subdividing the landslide in different sectors, each of which is characterized by a specific type of movement. The geological meaning of this subdivision is still a matter of discussion but it is presumably driven by the geomorphological setting of the area and by the regional tectonics. [ABSTRACT FROM AUTHOR]

The andesitic volcanic island Whakaari (White Island) explosively erupted on 9 December 2019. White Island is a popular tourist destination, and 47 people were on the island at the time. Twenty-one died, and a further twenty-six people suffered injuries. Persistent scatterer (PS) interferometry with synthetic aperture radar (SAR) is a powerful satellite-based remote sensing tool to monitor land deformation associated with volcanic unrest. This study examined deformation on White Island over the eruption period and identified a dome on the crater floor that inflated for 15 months preceding the eruption, consistent with a previous analysis of TerraSAR-X satellite data. Results here show the dome began to collapse after 25 November, about two weeks prior to the eruption. This finding has immediate relevance for ongoing hazard monitoring at White Island and other volcanoes worldwide where sudden dome contraction may presage an eruption. Unlabelled Image • Study shows deformation on White Island leading up to catastrophic 2019 eruption. • Satellite data shows inflation of crater floor for 15 months preceding the eruption. • Crater floor suddenly deflated about 2 weeks prior to the eruption. • Findings have immediate relevance for volcanic hazard monitoring. [ABSTRACT FROM AUTHOR]

The wider Zagreb area is considered one of the few seismically active areas in the Republic of Croatia. During the period 1880–1906, moderate to strong seismic activity with three earthquakes magnitude ML ≥ 6 occurred on the NW-SE striking Kašina Fault and since then, the area has not experienced earthquakes exceeding magnitude ML = 5. In order to estimate the ongoing interseismic strain accumulation along the fault, we analyze Advanced Land Observing Satellite (ALOS) Phased Array L-band SAR (PALSAR) and Environmental Satellite (Envisat)-Advanced Synthetic Aperture Radar (ASAR) datasets acquired over the period 2007–2010 and 2002–2010, respectively. The data were analyzed using small baseline interferometry (SBI) technique and indicate very slow surface deformations in the area, within ±3.5 mm/year, which are in a good agreement with previous geodetic studies. Interseismic strain accumulation analysis was conducted on two 14 km long segments of the Kašina Fault, seismically active in the South and stable in the North. The analysis indicates an ongoing interseismic strain accumulation of 2.3 mm/year on the Southern segment and no detectable strain accumulation on the Northern segment. Taking into consideration the lack of moderate to strong seismic activity in the past 113 years combined with the preliminary geodetic analysis from this study, we can conclude that the Southern segment of the Kašina Fault has the potential to generate earthquake magnitude Mw < 6. [ABSTRACT FROM AUTHOR]