scholarly journals GROUND-BASED & SPACEBORNE SAR INTERFEROMETRIC TECHNIQUES SUPPORTING THE MANAGEMENT OF EMERGENCIES IN THE HEIMDALL PROJECT

Author(s):  
J. A. Navarro ◽  
G. Luzi ◽  
O. Monserrat ◽  
M. Crosetto

Abstract. This paper describes the application of spaceborne and Ground Based radar interferometry as a tool for assisting the management of emergencies related to land movements. The support of the two techniques is carried out integrating some products, using tools available from a software and hardware architecture specifically developed within HEIMDALL, a H2020 project, devoted to providing a multi-hazard Cooperative Management, for Data Exchange, Response Planning and Scenario Building. Deformation maps obtained processing Sentinel-1 SAR images, updated every six days, can provide information over a large area, to be used during the preparedness and recovery phases. Data acquired through a Ground Based SAR system installed in-situ, provide a continuous and discontinuous (periodical) monitoring, aiming at supporting response and recovery phases. The products, in both cases, consist of deformation maps and temporal series, velocity of displacement, obtained through the application of Persistent Scatterer Interferometry (PSI).

2021 ◽  
Author(s):  
Guido Luzi ◽  
José Antonio Navarro ◽  
Anna Barra ◽  
Oriol Monserrat ◽  
Michele Crosetto

<p>This contribution describes the objectives and the tasks carried out within HEIMDALL, a four-years European project (H2020), whose general aim was to assist the management of emergencies related to fires, flooding and land movements. In particular the authors focus on the tools developed in the case of the landslide’s scenario, using spaceborne and Ground Based radar interferometry. The core of the architecture of HEIMDALL is a system platform which collects data obtained through simulation, Earth Observation images and in-situ sensors measurements to provide updated information and support the activities of several actors involved in disaster management (preparedness, response, and recovery). A multi-hazard Cooperative Management, for Data Exchange, Response Planning and Scenario Building is the rationale of the final product. Concerning the landslides case, two products are integrated as external data sources. The first one is a map of the Active Deformation Areas (ADA) detected through the DInSAR processing technique, using a set of SAR images acquired every 6 days by the satellite Sentinel-1, this product allows the identification and characterization of potential landslides at a regional scale. The second one operates at a local scale; it includes deformation maps covering single slopes obtained through a Ground Based SAR system installed in-situ. This last tool is proposed to provide both continuous and discontinuous (periodical) monitoring for the assessment and updating of the scenario of risk (together with model based on meteorological parameters and simulations) and supporting the recovery phase. HEIMDALL guarantees an information access and sharing among the involved stakeholders, including the population and the first responders on the field. The possibility to integrate data coming from different techniques improves the real time understanding of the situation and, by using advanced multi-hazard methods, allows to develop realistic multi-disciplinary scenarios of risk, vulnerability assessment, information sharing and emergency response. The main added value of using the HEIMDALL service platform results in a valuable, direct, situation assessment which can strength the decision tools.</p>


Author(s):  
M. Crosetto ◽  
A. Budillon ◽  
A. Johnsy ◽  
G. Schirinzi ◽  
N. Devanthéry ◽  
...  

A lot of research and development has been devoted to the exploitation of satellite SAR images for deformation measurement and monitoring purposes since Differential Interferometric Synthetic Apertura Radar (InSAR) was first described in 1989. In this work, we consider two main classes of advanced DInSAR techniques: Persistent Scatterer Interferometry and Tomographic SAR. Both techniques make use of multiple SAR images acquired over the same site and advanced procedures to separate the deformation component from the other phase components, such as the residual topographic component, the atmospheric component, the thermal expansion component and the phase noise. TomoSAR offers the advantage of detecting either single scatterers presenting stable proprieties over time (Persistent Scatterers) and multiple scatterers interfering within the same range-azimuth resolution cell, a significant improvement for urban areas monitoring. This paper addresses a preliminary inter-comparison of the results of both techniques, for a test site located in the metropolitan area of Barcelona (Spain), where interferometric Sentinel-1 data were analysed.


2020 ◽  
Vol 12 (19) ◽  
pp. 3145
Author(s):  
Sen Du ◽  
Jordi J. Mallorqui ◽  
Hongdong Fan ◽  
Meinan Zheng

Ground subsidences, either caused by natural phenomena or human activities, can threaten the safety of nearby infrastructures and residents. Among the different causes, mining operations can trigger strong subsidence phenomena with a fast nonlinear temporal behaviour. Therefore, a reliable and precise deformation monitoring is of great significance for safe mining and protection of facilities located above or near the mined-out area. Persistent Scatterer Interferometry (PSI) is a technique that uses stacks Synthetic Aperture Radar (SAR) images to remotely monitor the ground deformation of large areas with a high degree of precision at a reasonable cost. Unfortunately, PSI presents limitations when monitoring large gradient deformations when there is phase ambiguity among adjacent Persistent Scatterer (PS) points. In this paper, an improvement of PSI processing, named as External Model-based Deformation Decomposition PSI (EMDD-PSI), is proposed to address this limitation by taking advantage of an external model. The proposed method first uses interferograms generated from SAR Single Look Complex (SLC) images to optimize the parameter adjustments of the external model. Then, the modelled spatial distribution of subsidence is utilized to reduce the fringes of the interferograms generated from the SAR images and to ease the PSI processing. Finally, the ground deformation is retrieved by jointly adding the external model and PSI results. In this paper, fourteen Radarsat-2 SAR images over Fengfeng mining area (China) are used to demonstrate the capabilities of the proposed method. The results are evaluated by comparing them with leveling data of the area covering the same temporal period. Results have shown that, after the optimization, the model is able to mimic the real deformation and the fringes of the interferograms can be effectively reduced. As a consequence, the large gradient deformation then can be better retrieved with the preservation of the nonlinear subsidence term. The ground truth shows that, comparing with the classical PSI and PSI with unadjusted parameters, the proposed scheme reduces the error by 35.2% and 20.4%, respectively.


2021 ◽  
Vol 13 (11) ◽  
pp. 2072
Author(s):  
Ali Mehrabi ◽  
Saied Pirasteh ◽  
Ahmad Rashidi ◽  
Mohsen Pourkhosravani ◽  
Reza Derakhshani ◽  
...  

Interferometric Synthetic Aperture Radar (InSAR) monitors surface change and displacement over a large area with millimeter-level precision and meter-level resolution. Anar fault, with a length of ~200 km, is located in central Iran. Recent seismological studies on the fault indicated that it is approaching the end of its seismic cycle. Although a large earthquake is imminent, the mechanism of the fault is not well understood. Therefore, understanding and discovering the mechanism of Anar fault remains a challenge. Here, we present an approach of displacement fault analysis utilizing a combination of InSAR data obtained from the persistent scatterer interferometry (PSI) method and 178 Sentinel-1 images (ascending and descending) (2017–2020). We incorporated groundwater samples from 40 wells, radon concentration anomaly mapping, Global Positioning System (GPS), and 3D displacement measurement acquired over four years (2016–2020). We investigated and monitored the deformation of the fault plate’s behavior over the last three years (2017–2020) to explore new evidence and signature of displacement. The results show that the time series analysis in the fault range has an increasing displacement rate in all dimensions. We observed that the line-of-sight (LOS) displacement rate varied from −15 mm to 5 mm per year. Our calculations show that the E–W, N–S, and vertical displacement rates of the fault blocks are 2 mm to −2 mm, 6 mm to −6 mm, and 2 mm to −4 mm per year, respectively. An anomaly map of the radon concentration shows that the complete alignment of the high concentration ranges with the fault strike and the radon concentration increased on average from 23.85 Bq/L to 25.30 Bq/L over these three years. Therefore, we predict rising the radon concentration is due to the increase in activity which resulted in a deformation. Finally, our findings show that the Anar fault is an oblique and right-lateral strike-slip with a normal component mechanism. We validated the proposed method and our results by comparing the GPS field data and PSI measurements. The root mean square error (RMSE) of the PSI measurement is estimated to be 0.142 mm. Based on the supporting evidence and signature, we conclude that the Anar fault activity increased between 2017 and 2020.


2013 ◽  
Vol 1 (5) ◽  
pp. 5365-5402 ◽  
Author(s):  
M. P. Sanabria ◽  
C. Guardiola-Albert ◽  
R. Tomás ◽  
G. Herrera ◽  
A. Prieto ◽  
...  

Abstract. A new methodology is proposed to produce subsidence activity maps based on the geostatistical analysis of persistent scatterer interferometry (PSI) data. PSI displacement measurements are interpolated based on Conditional Gaussian Simulation (CGS) to calculate multiple equiprobable realizations of subsidence. The result from this process is a series of interpolated subsidence values, with an estimation of the spatial uncertainty and a confidence level on the interpolation. These maps complement the PSI displacement map, improving the identification of wide subsiding areas at regional scale. At local scale, they can be used to identify buildings susceptible to suffer subsidence related damages. In order to do so, it is necessary to calculate the maximum differential settlement and the maximum angular distortion for each building of the study area. Based on PSI derived parameters those buildings in which serviceability limit state has been exceeded, and where in situ forensic analysis should be made, can be automatically identified. This methodology has been tested in Orihuela City (SE Spain) for the study of historical buildings, damaged during the last two decades by subsidence due to aquifer overexploitation.


Author(s):  
M. Crosetto ◽  
L. Solari

Abstract. The paper is focused on the Persistent Scatterer Interferometry (PSI) technique. First, it addresses the substantial evolution of PSI in the last twenty years. Three main factors are identified: the availability of SAR images, the development of advanced data processing techniques, and the increase of the computation capability. The paper then addresses the PSI deformation monitoring initiatives at regional and national scale. Finally, in the last section, it is described a pan European deformation monitoring service: the European Ground Motion Service (EGMS).


2019 ◽  
Vol 2019 ◽  
pp. 1-13 ◽  
Author(s):  
Jili Wang ◽  
Weidong Yu ◽  
Yunkai Deng ◽  
Robert Wang ◽  
Yingjie Wang ◽  
...  

More and more synthetic aperture radar (SAR) satellites in orbit provide abundant data for remote sensing applications. In August 2016, China launched a new Earth observation SAR satellite, Gaofen-3 (GF-3). In this paper, we utilize a small stack of GF-3 differential interferograms to map land subsidence in Beijing (China) using the time-series SAR interferometry (InSAR) technique. The small stack of differential interferograms is generated with 5 GF-3 SAR images from March 2017 to January 2018. Orbit errors are carefully addressed and removed during differential InSAR (DInSAR) processing. Truncated singular-value decomposition (TSVD) is applied to strengthen the robustness of deformation rate estimation. To validate the results of GF-3 data, an additional deformation measurement using 26 Sentinel-1B images from March 2017 to February 2018 is carried out using the persistent scatterer interferometry (PSI) technique. By implementing a cross-comparison, we find that the retrieved results from GF-3 images and Sentinel-1 images are spatially consistent. The standard deviation of vertical deformation rate differences between two data stacks is 11.24 mm/y in the study area. The results shown in this paper demonstrate the reasonable potential of GF-3 SAR images to monitor land subsidence.


2018 ◽  
Vol 10 (10) ◽  
pp. 1523 ◽  
Author(s):  
Sina Montazeri ◽  
Fernando Rodríguez González ◽  
Xiao Zhu

Persistent Scatterer Interferometry (PSI) is an advanced multitemporal InSAR technique that is capable of retrieving the 3D coordinates and the underlying deformation of time-coherent scatterers. Various factors degrade the localization accuracy of PSI point clouds in the geocoding process, which causes problems for interpretation of deformation results and also making it difficult for the point clouds to be compared with or integrated into data from other sensors. In this study, we employ the SAR imaging geodesy method to perform geodetic corrections on SAR timing observations and thus improve the positioning accuracy in the horizontal components. We further utilize geodetic stereo SAR to extract large number of highly precise ground control points (GCP) from SAR images, in order to compensate for the unknown height offset of the PSI point cloud. We demonstrate the applicability of the approach using TerraSAR-X high resolution spotlight images over the city of Berlin, Germany. The corrected results are compared with a reference LiDAR point cloud of Berlin, which confirms the improvement in the geocoding accuracy.


2019 ◽  
Vol 11 (8) ◽  
pp. 937 ◽  
Author(s):  
El Hachemi Bouali ◽  
Thomas Oommen ◽  
Rüdiger Escobar-Wolf

Velocity dictates the destructive potential of a landslide. A combination of synthetic aperture radar (SAR), optical, and GPS data were used to maximize spatial and temporal coverage to monitor continuously-moving portions of the Portuguese Bend landslide complex on the Palos Verdes Peninsula in Southern California. Forty SAR images from the COSMO-SkyMed satellite, acquired between 19 July 2012 and 27 September 2014, were processed using Persistent Scatterer Interferometry (PSI). Eight optical images from the WorldView-2 satellite, acquired between 20 February 2011 and 16 February 2016, were processed using the Co-registration of Optically Sensed Images and Correlation (COSI-Corr) technique. Displacement measurements were taken at GPS monuments between September 2007 and May 2017. Incremental and average deformations across the landslide complex were measured using all three techniques. Velocity measured within the landslide complex ranges from slow (> 1.6 m/year) to extremely slow (< 16 mm/year). COSI-Corr and GPS provide detailed coverage of m/year-scale deformation while PSI can measure extremely slow deformation rates (mm/year-scale), which COSI-Corr and GPS cannot do reliably. This case study demonstrates the applicability of SAR, optical, and GPS data synthesis as a complimentary approach to repeat field monitoring and mapping to changes in landslide activity through time.


Author(s):  
M. Crosetto ◽  
N. Devanthéry ◽  
M. Cuevas-González ◽  
O. Monserrat ◽  
B. Crippa

Abstract. Persistent Scatterer Interferometry (PSI) is a remote sensing technique used to measure and monitor land deformation from a stack of interferometric SAR images. The main products that can be derived using the PSI technique are the deformation maps and the time series of deformation. In this paper, an approach to apply the PSI technique to a stack of Sentinel-1 images is described. Moreover, the problems encountered during the processing are detailed and an explanation of how they were dealt with is provided. Finally, Sentinel-1 deformation maps and time series obtained over the metropolitan area of Mexico DF are shown.


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