Calculations of Earth Surface Deformation Due to Oil Extraction in Southern Iraq Using DInSAR

Reconnaissance to characterisation of land subsidence due to groundwater overdraft and oil extraction in and around Mehsana City, Gujarat, India by long-term hybrid differential interferometric SAR technique

In this study, elevation change and surface morphology of CookE2, one of the most active subglacial lakes in East Antarctica, were analyzed by using Differential Interferometric Synthetic Aperture Radar (DInSAR) and a newly adapted Time-Segmented Persistent Scatterer Interferometric Synthetic Aperture Radar (TS-PSInSAR) techniques. Firstly, several DInSAR pairs were used to study the surface morphology of the subglacial lake during the rapid discharge event in 2007 and the subsequent recharge in 2010 by using ALOS PALSAR data and the continuous recharge from 2018 to 2020 by using Sentinel-1 SAR data. For time-series observation from 2018 to 2020, however, simple integration of DInSAR deviates largely from the satellite altimeter data because errors from the horizontal flow of the surrounding ice field or atmospheric phase accumulate. Conventional PSInSAR deviates from the altimeter data if the LOS displacement exceeds 300 mm, i.e., approximately 1/4 of the slant range resolution of the Sentinel-1 SAR in Interferometric Wide-swath (IW) mode, during the time window. Therefore, a series of Time-Segmented PSInSAR with a 4-month time window could accurately distinguish 1.10 ± 0.01 m/year of highly linear (R2 = 0.99) surface rise rate of CookE2 and 0.63 m/year of horizontal deformation rate of the surrounding ice field from 2018 to 2020.

Land subsidence in Jakarta has been reported by many studies using various geodetic techniques. High exploitation of groundwater is the main factor of increasing land subsidence rate in Jakarta. The impact of land subsidence can be seen in several forms such as the damage on buildings and infrastuctures and the change of surface water pattern flow. This paper presents the update status and analysis of land subsidence of Jakarta Metropolitan Region (Jabodetabek) based on Differential Interferometric Synthetic Aperture Radar (D-InSAR) technique. D-InSAR technique based on interferogram that developed from a coherence technology of active radar imaging. Two images acquired with the same nominal geometry is required to develop interferometry SAR by using phase as a fraction of the wave, and change to distance. The displacement map is the final result of interferometry SAR and external Digital Elevation Model (DEM) required to remove topographic phase. Displacement map using pair of Sentinel data that acquired on March 18, 2017 and March 13, 2018 was successfully developed. The highest rate of land subsidence with 6 cm/year occurred in eastern part and western part of north area of Jakarta, some part in West Jakarta, Central Jakarta, and South Jakarta. The similar rate also occurred in Bekasi City, Bekasi Regency, Depok City, and Tangerang Regency. The moderate rate of land subsidence occurred in Tangerang City and South Tangerang City with 2-3 cm/year. Jakarta Metropolitan Region is a susceptible area of flooding. In this study, land subsidence has a similar pattern with the emergence of flood inundation. Therefore, the increasing of areas with flood inundation is affected by land subsidence. Monitoring of land subsidence rate in Jakarta Metropolitan Region by using D-InSAR Sentinel data is highly required due to high temporal resolution and accurate data especially for flood management and other urban development management, and free access of the data.

Underground mining activities very often cause changes to the surface. Beside the strong influences of active mining, former mining activities with still existing cavities in the underground do influence the surface as well, causing a risk for people and infrastructure. The main risk is induced by sudden falls of the surface. In contrast to surface deformations induced by active mining these deformations are difficult to predict. The risk justifies the monitoring of ground movements in historical mining areas. One technique evaluated is Differential Interferometric Synthetic Aperture Radar (DInSAR). The main difference to other applications of DInSAR is, that location, subsidence rate and spatial extent can just roughly be estimated using related historic information about former mining activities. In addition, the expected character of the subsidence complicates the separation between deformation signal and atmospherical artifacts. In order to get a first idea about the limits of the technique, circular shaped deformation models with different extents and maximum vertical displacements have been modeled and integrated into the DInSAR processing chain. The final results have been evaluated qualitatively and quantitatively in order to get an idea about the detection limits of DInSAR using ERS-1/2 data. The qualitative assessment shows that subsidence cones of circular shape with radii below 400 m cannot be reliably identified in a single interferogram in the investigated case. In the quantitative assessment the highest relative RMS errors between model and result were found for subsidence cones with small radii and small maximum vertical displacements. Furthermore it could be shown that the use of multiple interferograms by applying stacking techniques leads to a better detection limit of the DInSAR method.

Joint analysis of SAR interferometry and electrical resistivity tomography surveys for investigating ground deformation: the case-study of Satriano di Lucania (Potenza, Italy)

The Emilia Romagna Region (N-E Italy) and in particular the Adriatic Sea coastline of Ravenna, is affected by a noticeable subsidence that started in the 1950s, when the exploitation of on and off-shore methane reservoirs began, along with the pumping of groundwater for industrial uses. In such area the current subsidence rate, even if lower than in the past, reaches the -2 cm/y. Over the years, local Authorities have monitored this phenomenon with different techniques: spirit levelling, GPS surveys and, more recently, Differential Interferometric Synthetic Aperture Radar (DInSAR) techniques, confirming the critical situation of land subsidence risk. In this work, we present the comparison between the results obtained with DInSAR and GPS techniques applied to the study of the land subsidence in the Ravenna territory. With regard to the DInSAR, the Small Baseline Subset (SBAS) and the Coherent Pixel Technique (CPT) techniques have been used. Different SAR datasets have been exploited: ERS-1/2, ENVISAT, TerraSAR-X and Sentinel-1. Some GPS campaigns have been also carried out in a subsidence prone area. 3D vertices have been selected very close to existing persistent scatterers in order to link the GPS measurement results to the SAR ones. GPS data were processed into the International reference system and the comparisons between the coordinates, for the first 6 months of the monitoring, provided results with the same trend of the DInSAR data, even if inside the precision of the method.

We investigated the surface deformation of the northern Taiwan area, including the Taipei basin and its surrounding mountainous areas of the last fifteen years using the ERS-1, ERS-2 and ENVISAT SAR images. Although the Taipei basin now is well developed and amenable to research gathering using the Differential Interferometric Synthetic Aperture Radar (DInSAR) technique, the mountainous areas surrounding the basin are densely covered with various vegetation throughout different seasons inducing high noise ratio in interferograms. Therefore the DInSAR technique is ineffective for observation of surface deformations of these areas. As a result, we developed the Persistent Scatterer (PS) InSAR technique to extract the phase signal of the chosen PS points for this study. Our analysis result shows that the atmospheric disturbance and DEM residual can be successfully reduced and the precise information of surface deformation can be effectively obtained by the PSInSAR technique not only in the basin but also in the mountainous areas. Integrating the DInSAR and PSInSAR results, we observed conspicuous deformation events in northern Taiwan including: (1) the slight uplift in the Western Foothills, the Tatun volcanoes, the Linkou Tableland and the Taoyuan area; (2) the subsidence at the border of the Taipei basin; and (3) relative slight uplift rebound in the center of Taipei basin. The displacements along the Shanchiao, Chinshan, and Kanchiao Faults are large enough to be observed; the Taipei, Hsinchuang, and Nankang Faults are too small and cannot be discerned. Further comparison between the DInSAR, PSInSAR, and their corresponding leveling data shows a very coincidental pattern and measurably improves the authenticity of radar interferometry.

One of the enduring facets within contemporary monitoring systems resides in the automation of data processing. This methodology ensures expeditious access to the most current and objectively derived results. Several systems for terrain monitoring have been realised in the last few years, with the leading role of the European Ground Motion Service (EGMS), part of the Copernicus program. Still most of these systems rely on the usage of the advanced Interferometric Synthetic Aperture Radar (InSAR) techniques which are not capable of exploring more dynamic and complex terrain change patterns as those related to underground mining works in Central Europe. A extensive study within the frames of the Polish realisation of the European Plate Observing System (EPOS) project, comprising long term monitoring between the years of 2016 and 2023 revealed the necessity of usage of the classical DIfferential InSAR (DInSAR) for more detailed study of the processes happening in the area of the Upper Silesian Coal Basin (USCB) in Poland. Within the project EPOS-PL+ we have developed an automated system for DInSAR processing of SAR data from Sentinel-1 satellite. The system also includes modules for processing of third party mission X-band data. This processing approach excels in managing significant deformations with reduced coherence, unlike methods relying on stable scatterers. The automated framework encompasses data retrieval, Line of Sight (LOS) deformation computation, trend elimination for atmospheric correction, and assessment of interferogram quality. The final step involves decomposing the LOS deformation into vertical and east-west components.Upon initiation of the application, the user delineates parameters such as the region of interest by a shapefile, the period of study, and ascending and descending orbits. Subsequently, ingress into the Alaska Satellite Facility service repository, and data is procured for subsequent processing utilising the DInSAR method facilitated by the snappy library. This library enables script-based manipulation of the SNAP program using the Python language.The subsequent phase involves detrending the data. Raw 1D deformation maps exhibit discernible trends, primarily attributable to atmospheric variations between successive acquisitions. To overcome this problem, a plane is fitted to the deformation data, and the estimated values are differentially subtracted from the original dataset. This estimation is implemented through two distinct methodologies. The more intricate approach include sthe identification of stable points based on nine coherence maps correlating with the deformation values, followed by the fitting of a plane. The simpler approach involves the fitting of a plane to the entire set of deformation data.The quality check stage involves examining the dataset's pixels for coherence levels exceeding a set threshold (e.g., 0.2). Pixels failing coherence criteria are excluded, and linear interpolation is applied only to selected pixels. This approach minimizes phase unwrapping errors' propagation and effectively removes atmospheric effects in the final analysis. In instances of significant data gaps, the ensemble of adjacent images used for interpolation is expanded to reduce the impact of individual map errors. The enhanced DInSAR data are then projected into 2D components, namely the vertical and east-west (horizontal) dimensions.

Andean plateau in Peru and its World Heritage sites are particularly affected by the impacts of climate change. The sacred Valley Archaeological Site around the city of Cuzco, a UNESCO World Heritage Site, is exposed to significant geological risks due to recurrent landslides induced and worsened by climate change effects that threaten its structural integrity, security and exploitation. The Machu Picchu Historic Sanctuary was built on Upper Permian-Lower Triassic (250–300 Ma) igneous rocks, primarily plutonic, which form the Vilcabamba Cordillera's backbone (from 2000m since 6000m a.s.l.) These intrusive formations, oriented ONO–ESE, constitute the elevated regions of the Eastern Cordillera. The area is dominated by a batholith composed mainly of granite and granodiorite, with medium-textured basic granite prominently outcropping within the citadel. The Machu Picchu site and all the sacred valley of Cuzco its surroundings are characterized by instability phenomena driven by complex geomorphological and structural/tectonic conditions worsened by the effects induced at altitude by the climate change (melting of the permafrost, heavy rainfall and increase in temperature). The above mentioned phenomena are exacerbated by the interplay of primary discontinuity families, resulting in recurring processes such as planar slides, rockfalls, topples, debris slides, debris flows, and avalanches. The present work shows the application of Differential Interferometric Synthetic Aperture Radar (DInSAR) technique to measure slow, non-catastrophic morphological changes with millimeter-scale precision. A previous interferometric satellite analysis work carried out in the early 2000s to test the general stability of the Inca Citadel has been resumed and updated. The analysis captures both long-term and seasonal processes triggered by diverse causative factors, enabling informed planning of mitigation strategies. Specifically, DInSAR data processing was conducted for the Machu Picchu archaeological area and for the wider Cusco area, complemented by direct field surveys to validate the results (November 2024). Multi-temporal SAR images from the Sentinel-1 constellation (C-band radar) were processed using advanced DInSAR techniques to generate ground displacement measurement points. The spatial distribution and correlation of these measurements with slope instability and structural damage were analyzed, revealing ground deformation trends from January 2020 to August 2024. Preliminary results indicate that the citadel exhibits average ground and structural displacement of less than 1 mm/year substantially negligible. However, localized analyses highlight distinct patterns of small-scale displacement in the Grupo de las Tres Puertas with slight brick detachment and in the Upper Plaza and Eastern Citadel sector showing relative subsidence compared to adjacent areas, suggesting potential movements of the eastern flank. Monitoring systems (remote and in situ) are recommended. The use of Sentinel-1 DInSAR data provided critical insights into the interaction between ground displacement and archaeological structures. It facilitated the identification of potentially unstable areas, detected anomalies, and traced ground displacement accelerations over time. Displacement anomalies and weather-climate anomalies over time, highlights the effects of the latter on the spatial-temporal increase of instability phenomena. These findings underscore the utility of DInSAR as a powerful tool for addressing preservation of intervention on CH threatened by slope instability, offering data-driven approaches for damage prevention and site management.

Large urban areas are vulnerable to various geological hazards and anthropogenic activities that affect ground stability—a key factor in structural performance, such as buildings and infrastructure, in an inherently expanding context. Time series data from synthetic aperture radar (SAR) satellites make it possible to identify small rates of motion over large areas of the Earth’s surface with high spatial resolution, which is key to detecting high-deformation areas. Santiago de Chile’s metropolitan region comprises a large Andean foothills basin in one of the most seismically active subduction zones worldwide. The Santiago basin and its surroundings are prone to megathrust and shallow crustal earthquakes, landslides, and constant anthropogenic effects, such as the overexploitation of groundwater and land use modification, all of which constantly affect the ground stability. Here, we recorded ground deformations in the Santiago basin using a multi-temporal differential interferometric synthetic aperture radar (DInSAR) from Sentinel 1, obtaining high-resolution ground motion rates between 2018 and 2021. GNSS stations show a constant regional uplift in the metropolitan area (~10 mm/year); meanwhile, DInSAR allows for the identification of areas with anomalous local subsistence (rates < −15 mm/year) and mountain sectors with landslides with unprecedented detail. Ground deformation patterns vary depending on factors such as soil type, basin geometry, and soil/soil heterogeneities. Thus, the areas with high subsidence rates are concentrated in sectors with fine sedimentary cover and a depressing shallow water table as well as in cropping areas with excess water withdrawal. There is no evidence of detectable movement on the San Ramon Fault (the major quaternary fault in the metropolitan area) over the observational period. Our results highlight the mechanical control of the sediment characteristics of the basin and the impact of anthropogenic processes on ground stability. These results are essential to assess the stability of the Santiago basin and contribute to future infrastructure development and hazard management in highly populated areas.

ABSTRACTIn this paper, we identified recently subsiding areas in Jharia Coalfield, Jharkhand, India from the shorter temporal baseline Radarsat-2 C-band interferometric synthetic aperture radar (InSAR) data pairs of 2012. Although shorter wavelength C-band differential InSAR (DInSAR) is more sensitive to slow deformation and better suited for higher precision land subsidence measurement, the dynamic and adverse land cover in mining areas and resulting temporal decorrelation problem poses a serious problem for DInSAR observation in mining areas. We used smaller temporal baseline data pairs and adopted InSAR coherence-guided incremental filtering with smaller moving windows to highlight the deformation fringes over temporal decorrelation noise. We identified the deformation fringes and validated them based on ground information to prepare the land subsidence map of the coalfield in 2012. Several new, previously unreported subsidence areas were detected in the present study with a total subsiding area of 6.9 km2. The recent incidence of roof collapse on 15 November 2014 at Angar Patra village in Katras region of the coalfield where 45 houses collapsed and 10 people were injured is situated in a highly subsiding vulnerable area as obtained from the present study. Due to spatial discontinuities of InSAR coherence, DInSAR phase unwrapping for the entire study area in one go did not appear feasible. To avoid this problem, we performed DInSAR processing in smaller spatial subsets and unwrapping of the subset interferograms by a ‘minimum cost flow’ algorithm. Subsequently, we plotted unwrapped phase profiles across the deformation fringes and retrieved the maximum deformation phase with respect to background phase and translated them into radar line of sight (LOS) displacement rates. For obtaining the average subsidence rates, we adopted InSAR coherence-weighted LOS displacement rates taking into account the contribution of each data pair as a function of DInSAR phase quality of the fringe areas. Ground-based subsidence measurements by precision levelling were conducted in four test sites that had been undergoing active underground mining during the observation period. We compared space-borne DInSAR-based subsidence rates obtained by the adopted technique with precision levelling measurements. Overall, the results are found to agree well. In the four test sites with gentle to flat topography, land subsidence occurs at slow to moderate rates due to compression of in-filled material (resulting from sand stowing in underground mining), without any evidence of roof collapse. In such cases, the horizontal displacement component is less significant, and overall surface displacement occurs essentially in the vertical direction. However, we assessed the nature of subtle horizontal strain to infer relative shrinkage or dilation of the land surface which could be additive or subtractive to vertical displacement in DInSAR-based LOS displacement.

ABSTRACTBangladesh in the Bengal Delta faces complex environmental issues, including sea‐level rise, coastal flooding, high population density, and widespread poverty. These factors lead to severe land loss, saltwater intrusion, water scarcity, and biodiversity decline, further exacerbated by climate change. These challenges significantly risk groundwater availability and increase the likelihood of natural hazards such as subsidence, landslides, and flooding. This study quantitatively maps the spatial distribution of subsidence in urban and agricultural settings by utilising Differential Interferometric Synthetic Aperture Radar (DInSAR) and Persistent Scatter Interferometric Synthetic Aperture Radar (PSI) techniques with ascending Sentinel‐1 satellite data. We analysed 55 pairs of images with DInSAR and 142 pairs with PSI from March 2017 to October 2022, focusing on five target locations for DInSAR and urban Dhaka for PSI. Findings reveal consistent subsidence in urban Dhaka at an average rate of 16 mm/year, along with semi‐seasonal subsidence variability in five agricultural locations. Specific rates are 7 mm/year in Dhaka, 8 mm/year in both Rajshahi and Mymensingh, and 9 mm/year in Rangpur. Sylhet subsides at a rate of 5 mm/year, potentially linked to the fold and thrust belt and the Dauki Fault. Our research highlights the significant environmental impacts of human activities like groundwater withdrawal and land‐use changes, which contribute to subsidence and groundwater depletion via the Bengal Water Machine. While further study is required to comprehensively understand the relationship between LOS indicated subsidence rates, geological factors, and geomorphological changes, our findings offer crucial insights into the current impacts of climate change and ongoing environmental degradation in the region.

The damage to pipeline infrastructures caused by reactive soils has been a critical challenge for asset owners. Sustainable backfilling materials have recently gained interest to stabilize highly reactive zones as a pre-emptive approach towards sustainability. In this study, two adjacent sections of a sewer pipeline trench in Melbourne, Australia were backfilled with two blends of 100% recycled aggregates. The sites were monitored for ground deformations during October 2020–February 2022 (17 months) using surveying techniques. Interferometric synthetic aperture radar (InSAR) techniques and algorithms were also employed to estimate the ground movements of the sites and surrounding regions. The cross-validation of deformation results achieved from both techniques enabled an in-depth analysis of the effectiveness of the recycled aggregates to address reactive soil issues in urban developments. Observational deformation data and their spatiotemporal variation in the field were satisfactorily captured by the InSAR techniques: differential InSAR (DInSAR), persistent scatterer interferometry (PSI), and small baseline subset (SBAS). The SBAS estimations were found to be the closest to field measurements, primarily due to the analysis of zones without well-defined geometries. This study’s contribution to existing knowledge defines the spatiotemporal influence of sustainable backfill in areas with reactive soil through field data and satellite imaging. The relationship between InSAR techniques and actual field behavior of sustainable backfill can be a baseline for the growing construction that may be challenging to perform field monitoring due to resource constraints.

Differential interferometric synthetic aperture radar (DInSAR) is a novel remote sensing technique to measure earth surface deformation. It is capable of obtaining dense information related to the deformation of a large area efficiently, economically and effectively. Therefore, DInSAR is a promising technology for monitoring the earth surface deformation related to some natural hazardous events, such as earthquake, volcano eruption, land subsidence, landslide. In present study, Conventional DInSAR technique have been applied to a mineral rich zone, coming under the Khetri copper belt, a part of Northern Aravali range of hillocks in India, predominant with mining activities since late 1960’s to address the possibility of deformation phenomena due to hard rock underground metal mining. Four interferometric SAR data sets of Radarsat-2 was used for the study area to address the subsidence/uplift phenomena. Further, results obtained from conventional DInSAR technique using Radarsat-2 data sets compared with results obtained from ground based observation technique for its validity. In both the techniques, deformation results obtained in terms of average subsidence rate in mm (quarterly basis) of points under study within mining zone of Mine-A has well agreed to each other. Further, it has been observed that average subsidence rate in mm (quarterly basis) obtained from space based observation and ground based observation are 5.6 and 6.67, respectively over the points under study in mining zone of Mine-A.

Abstract. The Emilia Romagna Region (N-E Italy) and in particular the Adriatic Sea coastline of Ravenna, is affected by a noticeable subsidence that started in the 1950s, when the exploitation of on and off-shore methane reservoirs began, along with the pumping of groundwater for industrial uses. In such area the current subsidence rate, even if lower than in the past, reaches the -2 cm/y. Over the years, local Authorities have monitored this phenomenon with different techniques: spirit levelling, GPS surveys and, more recently, Differential Interferometric Synthetic Aperture Radar (DInSAR) techniques, confirming the critical situation of land subsidence risk. In this work, we present the comparison between the results obtained with DInSAR and GPS techniques applied to the study of the land subsidence in the Ravenna territory. With regard to the DInSAR, the Small Baseline Subset (SBAS) and the Coherent Pixel Technique (CPT) techniques have been used. Different SAR datasets have been exploited: ERS-1/2, ENVISAT, TerraSAR-X and Sentinel-1. Some GPS campaigns have been also carried out in a subsidence prone area. 3D vertices have been selected very close to existing persistent scatterers in order to link the GPS measurement results to the SAR ones. GPS data were processed into the International reference system and the comparisons between the coordinates, for the first 6 months of the monitoring, provided results with the same trend of the DInSAR data, even if inside the precision of the method.