DInSAR Technique Research Articles

Monitoring the Vulnerability of the Dam and Dikes in Germano Iron Mining Area after the Collapse of the Tailings Dam of Fundão (Mariana-MG, Brazil) Using DInSAR Techniques with TerraSAR-X Data

The Fundão tailings dam in the Germano iron mining complex (Mariana, Brazil) collapsed on the afternoon of 5 November 2015, and around 32.6 million cubic meters of mining waste spilled from the dam, causing polluion with mining waste along a trajectory of 668 km, extending to the Atlantic Ocean. The Sela & Tulipa and Selinha dikes, and the main Germano tailings dam, were directly or indirectly affected by the accident. This work presents an investigation using Advanced-Differential Interferometric Synthetic Aperture Radar (A-DInSAR) techniques for risk assessment in these critical structures during 18 months after the catastrophic event. The approach was based on the integration of SBAS (Small Baseline Subset) and PSI (Persistent Scatterer Interferometry) techniques, aiming at detecting linear and nonlinear ground displacements in these mining structures. It used a set of 48 TerraSAR-X images acquired on ascending mode from 11 November 2015 to 15 May 2017. The results provided by the A-DInSAR analysis indicated an overall stability in the dikes and in the main wall of Germano tailings dam, which is in agreement with in situ topographic monitoring. In addition, it was possible to detect areas within the reservoir showing accumulated values of up to −125 mm of subsidence, probably caused by settlements of the waste dry material due to the interruption of the mining waste deposition, and values up to −80 mm on auxiliary dikes, probably caused by continuous traffic of heavy equipment. The spatiotemporal information of surface displacement of this large mining structure can be used for future operational planning and risk control.

Multiridge Method for Studying Ground-Deformation Sources: Application to Volcanic Environments

Volcanic phenomena are currently monitored by the detection of physical and chemical observations. Generally, the ground deformation field is the most relevant shallow expression of the geometric and physical parameters variations in the magmatic reservoir. In this study, we propose a novel method for the direct estimation of the geometric parameters of sources responsible for volcanic ground deformation detected via the DInSAR technique. Starting with the biharmonic properties of the deformation field, we define an approach based on the Multiridge and ScalFun methods to achieve relevant information about both the positions and shapes of active sources, such as the Mogi source. Our methodology is definitely different from the methods currently used for modeling ground-deformation sources, mainly based on forward or inverse techniques. In fact, (i) it does not require any assumptions about the source type, and (ii) it is not influenced by the distribution of medium elastic parameters or (iii) the presence of high-frequency noise in the dataset. For synthetic cases, we accurately estimate the depth to the source within a 3% error. Finally, we study the real case of the Okmok volcano ground-deformation field and achieve results compatible with those in previous works.

Highway Deformation Monitoring Based on an Integrated CRInSAR Algorithm — Simulation and Real Data Validation

Long-term surface deformation monitoring of highways is crucial to prevent potential hazards and ensure sustainable transportation system safety. DInSAR technique shows its great advantages for ground movements monitoring compared with traditional geodetic survey methods. However, the unavoidable influences of the temporal and spatial decorrelation have brought restrictions for traditional DInSAR on the application for ribbon infrastructures deformation monitoring. In addition, PS and SBAS techniques are not suitable for the area where adequate natural high coherent points cannot be detected. Due to this, we designed an integrated highway deformation monitoring algorithm based on CRInSAR technique in this paper, the processing flow including Corner Reflectors (CR) identification, CR baseline network establishment, phase unwrapping, and time series highway deformation estimation. Both the simulated and real data experiments are conducted to assess and validate the algorithm. In the scenario using simulated data, 10 different noise levels are added to test the performance under different circumstances. The RMSE of linear deformation velocities for 10 different noise levels are obtained and analyzed, to investigate how the accuracy varies with noise. In the real data experiment, part of a highway in Henan, China is chosen as the test area. Six PALSAR images acquired from 22 December 2008 to 09 February 2010 were collected and 12 CR points were installed along the highway. The ultimate time series deformation estimated show that all the CR points are stable. CR04 is undergoing the most serious subsidence, with the maximum magnitude of 13.71[Formula: see text]mm over 14 months. Field leveling measurements are used to assess the external deformation accuracy, the final RMSE is estimated to be [Formula: see text][Formula: see text]mm, which indicates good accordance with the result of leveling.

Advanced SBAS-DInSAR Technique for Controlling Large Civil Infrastructures: An Application to the Genzano di Lucania Dam.

Monitoring surface deformation on dams is commonly carried out by in situ geodetic surveying, which is time consuming and characterized by some limitations in space coverage and frequency. More recently microwave satellite-based technologies, such as advanced-DInSAR (Differential Synthetic Aperture Radar Interferometry), have allowed the integration and improvement of the observation capabilities of ground-based methods thanks to their effectiveness in collecting displacement measurements on many non-destructive control points, corresponding to radar reflecting targets. The availability of such a large number of points of measurement, which are distributed along the whole structure and are characterized by millimetric accuracy on displacement rates, can be profitably adopted for the calibration of numerical models. These models are implemented to simulate the structural behaviour of a dam under conditions of stress thus improving the ability to maintain safety standards. In this work, after having analysed how advanced DInSAR can effectively enhance the results from traditional monitoring systems that provide comparable accuracy measurements on a limited number of points, an FEM model of the Genzano di Lucania earth dam is developed and calibrated. This work is concentrated on the advanced DInSAR technique referred to as Small BAseline Subset (SBAS) approach, benefiting from its capability to generate deformation time series at full spatial resolution and from multi-sensor SAR data, to measure the vertical consolidation displacement of the Genzano di Lucania earth dam.

Estimación del retroceso glaciar en los volcanes Nevado del Ruiz, Tolima y Santa Isabel, Colombia a través de imágenes ópticas y Din-SAR

Se realizó una cuantificación del retroceso glaciar del Volcán Nevado del Ruiz (VNR), Volcán Nevado de Santa Isabel (VNSI) y el Volcán Nevado del Tolima (VNT), utilizando imágenes satelitales Landsat 8 OLI TIRS. Se calcularon índices espectrales y clasificación supervisada de imágenes para diferenciar el límite entre hielo, se utilizó la técnica DinSAR usando imágenes de Radarsat II, específicamente las imágenes de coherencia. Entre 2010 y 2015 la capa de hielo de los volcanes en estudio ha retrocedido 24%, 42% y 60% respectivamente. Las imágenes de coherencia muestran resultados similares que los obtenidos mediante imágenes ópticas. El uso de las imágenes de coherencia puede utilizarse para la delimitación de hielo y roca en zonas glaciares. La ceniza sobre la capa de hielo es un fenómeno particular sobre el casquete glaciar del VNR, lo que complica la delimitación de la superficie glaciar para ese volcán.

MONITORING OF SURFACE SUBSIDENCE OF THE MINING AREA BASED ON SBAS

Abstract. This paper has collected 7 scenes of L band PALSAR sensor radar data of a mine in FengCheng city, jiangxi province, using the Small-baseline Subset (SBAS) method to invert the surface subsidence of the mine. Baselines of interference less than 800m has been chosen to constitute short baseline differential interference atlas, using pixels whose average coherent coefficient was larger than or equal to 0.3 as like high coherent point target, using singular value decomposition (SVD) method to calculate deformation phase sequence based on these high coherent points, and the accumulation of settlements of study area of different period had been obtained, so as to reflect the ground surface settlement evolution of the settlement of the area. The results of the study has showed that: SBAS technology has overcome coherent problem of the traditionality D-InSAR technique, continuous deformation field of surface mining in time dimension of time could been obtained, characteristics of ground surface settlement of mining subsidence in different period has been displayed, so to improve the accuracy and reliability of the monitoring results.

URBAN MONITORING BASED ON SENTINEL-1 DATA USING PERMANENT SCATTERER INTERFEROMETRY AND SAR TOMOGRAPHY

Abstract. 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.

Cooperative monitoring and numerical investigation on the stability of the south slope of the Fushun west open-pit mine

The south slope of the Fushun west open-pit mine in China is geologically complex and is a high-steep rock slope. In recent years, a larger deformation has appeared in the south slope, with the gradual formation of a potential landsliding block that is estimated to be over 300 m3. The east and south boundaries of the block have been identified using different monitoring techniques. However the west boundary has not yet been clearly delineated, a situation which undermines safety assessments and the slope management of the mine. The focus of this was on how the microseismic technology, DInSAR technique and the numerical method are used to determine the shape and formation of the west boundary of the potential sliding block. We found that the upper part of west boundary as determined by numerical simulation is concordant with that determined by microseismic monitoring. The surface deformation area coincides with the DInSAR monitoring results and damage area based on in situ observations. Numerical simulation provides supplementary information on the distribution of stress and the formation process of the west boundary that cannot be observed directly on-site. The microseismic monitoring system was able to capture the progressive rupture of the west boundary during the deformation of the block. The cooperative monitoring strategy together with the numerical simulation can delineate the sliding surface and provide a method for a comprehensive assessment of the slope stability of other similar open-pit mines.

A MULTI-SOURCE DATA APPROACH FOR THE INVESTIGATION OF LAND SUBSIDENCE IN THE KONYA BASIN, TURKEY

Abstract. Groundwater depletion caused by rapid population growth, global climate change, water resources overexploitation is a major concern in many regions of the world. Consequences are not limited to a non-renewable water loss but extend to environmental degradation and geo-hazards risk increase. In areas where excessive groundwater withdrawal occurs, land subsidence induced by aquifer compaction is observed, resulting in severe socio-economic damage for the affected communities. In this work, we apply a multi-source data approach to investigate the fragile environment of Konya plain, central Turkey. The area, which is under strong anthropogenic pressures and faces with serious water-related problems, is widely affected by land subsidence. In order to analyze the spatial and temporal pattern of the subsidence process we use the Small BAseline Subset DInSAR technique to process two datasets of ENVISAT SAR images spanning the 2002–2010 period and to produce ground deformation maps and associated time-series. Results, complemented with meteorological, stratigraphic and piezometric data as well as with land-cover information, allow us to obtain a comprehensive picture of the climatic, hydrogeological and human dynamics of the study area.

Sentinel-1 InSAR data applied to surface deformation in Macaronesia (Canaries and Cape Verde)

The Macaronesia islands (Canary and Cape Verde archipelagos) have experienced intense seismic and volcanic activity that may in the near future put in risk people and goods. It is important to implement measurement strategies to monitor the seismic activity and the surface deformation. Synthetic Aperture Radar interferometry (SAR) has proven to be a useful technique to monitor the surface deformation in wide and remote areas, warning pre-eruption displacements and large-scale mass-wasting, so helping civil protection authorities. In this project, we investigate the applicability of SAR Interferometry (InSAR) for long time deformation monitoring in La Palma and Tenerife (Canary archipelago) and Fogo islands (Cape Verde archipelago). We have applied the advanced interferometric SAR processing based on Persistent Scatterers (PS). The small number of manmade structures on the volcanic areas reduces the density of Persistent Scatterers. Furthermore, the different ascending and descending acquisition geometries give different sets of PSs, with complementary spatial coverage and different line-of sight velocities. The strategy used to overcome the aforementioned problem is based on the combination of 3D GPS velocities with two sets of PS determined from ascending and descending passes. A data set of hundreds of SAR images acquired by Sentinel-1 were interferometrically processed and two sets of PSs, determined from ascending and descending passes, were computed for each island. The images were acquired between 2015 and 2018. In each island, the two PS datasets, were combined to derive the vertical deformation map and further be calibrated with GNSS velocities provided by EUREF continuous operating GNSS stations. The results are analysed and compared with previous results and studies of DInSAR techniques and GPS campaigns.

DInSAR technique for slow-moving landslide monitoring based on slope units

Slow-moving landslides are one of the most widely distributed natural hazards in the world, with severe effects on the stability of structures. However, it is hard to be detected without monitoring method. In this paper, the Differential Interferometric Aperture Radar (DInSAR) technique is used to monitor the slow-moving landslides. But, the standardised procedures for the DInSAR technique are difficult to find the boundaries of landslides. The new segmentation method of slope units with the Digital Elevation Model is proposed. Moreover, the credible zone analysis is established based on slope units to filter the error value and improve the precision of monitoring results. Finally, according to the features of slow-moving landslides, the outcomes of DInSAR technique for slow-moving landslides inventory map are available. The methodology is tested at Wudongde valley area in the North-west China, where the SAR data and natural hazards inventory maps are available. The correctness of monitoring results will be verified.

D-InSAR 기법을 이용한 호남선 고속철도 구간 지반 침하 분석

InSAR 기법은 SAR영상의 간섭을 이용하여 지표의 변위를 측정하는 기술이다. InSAR를 이용한 대표적인 지표변위 관측기법에는 differential InSAR(D-InSAR)와 permanent scatter InSAR(PS-InSAR) 간섭기법이 있다. D-InSAR란 2장의 영상을 각각 master, slave 영상으로 놓고 간섭시키는 기법을 말한다. 이 기법에서는 간섭도로부터 지형의 위상을 제거함으로써 지형과 변위의 두 가지 위상 효과를 분리한다. 본 논문에서는 독일의 Terra SAR-X 위성을 사용하여, 광주~세종시에 이르는 호남선 구간을 6개월 간 촬영한 영상을 D-InSAR 기법으로 분석하였다. 그동안 수행된 D-InSAR 기법을 사용한 연구의 경우 통상적으로 2장의 영상을 사용하였지만, 본 연구에서는 6개월 간 촬영된 총 8장의 영상으로 분석해보고자 한다. 또한 다양한 분석기법을 통하여, 어느 기법이 가장 정밀한 값을 갖는지 비교하여 최적의 D-InSAR 결과물을 도출하고자 하였다.

MINING LAND SUBSIDENCE MONITORING USING SENTINEL-1 SAR DATA

Abstract. In this paper, DInSAR technique was used to monitor land subsidence in mining area. The study area was selected in the coal mine area located in Yuanbaoshan District, Chifeng City, and Sentinel-1 data were used to carry out DInSAR techniqu. We analyzed the interferometric results by Sentinel-1 data from December 2015 to May 2016. Through the comparison of the results of DInSAR technique and the location of the mine on the optical images, it is shown that DInSAR technique can be used to effectively monitor the land subsidence caused by underground mining, and it is an effective tool for law enforcement of over-mining.

Evaluating land subsidence by field survey and D-InSAR technique in Damaneh City, Iran

Based on the data from piezometers, well logs, geophysical surveys and the interferometric synthetic aperture radar (InSAR) technique, this study investigates the main causes of land subsidence in Damaneh City, Iran. The size, openings and direction of fissures were measured by micrometer and compass. The locations of fissures and wall cracks were determined by GPS. The geoelectrical data were used to determine the composition, thickness, depth and shape of lower parts of the aquifer. Groundwater fluctuations were evaluated by available piezometers. The InSAR technique was used to measure land deformation from space and to map the dense changes of surface displacements. The results indicate that the main cause of ground subsidence is the decline of groundwater heads and changes in composition and thickness of compressible lacustrine sediments. The subsidence map obtained from the radar data of ASAR sensor of ENVISAT satellite shows that the subsidence zone is mainly in northern city that is underlain by very thick fine sediments. The subsidence rates from March to December 2005 and from July 2011 to January 2012 are 6.7 and 7.0 cm/a, respectively. The results also show good correlations among the formation of earth features, decline in groundwater head and thickness of fine-grained sediments. We recommend that the groundwater withdrawal for agricultural and industrial sectors should be restricted and urban expansion in the northern part of the city should be constrained.

Minimizing the Residual Topography Effect on Interferograms to Improve DInSAR Results: Estimating Land Subsidence in Port-Said City, Egypt

The accurate detection of land subsidence rates in urban areas is important to identify damage-prone areas and provide decision-makers with useful information. Meanwhile, no precise measurements of land subsidence have been undertaken within the coastal Port-Said City in Egypt to evaluate its hazard in relationship to sea-level rise. In order to address this shortcoming, this work introduces and evaluates a methodology that substantially improves small subsidence rate estimations in an urban setting. Eight ALOS/PALSAR-1 scenes were used to estimate the land subsidence rates in Port-Said City, using the Small BAse line Subset (SBAS) DInSAR technique. A stereo pair of ALOS/PRISM was used to generate an accurate DEM to minimize the residual topography effect on the generated interferograms. A total of 347 well distributed ground control points (GCP) were collected in Port-Said City using the leveling instrument to calibrate the generated DEM. Moreover, the eight PALSAR scenes were co-registered using 50 well-distributed GCPs and used to generate 22 interferogram pairs. These PALSAR interferograms were subsequently filtered and used together with the coherence data to calculate the phase unwrapping. The phase-unwrapped interferogram-pairs were then evaluated to discard four interferograms that were affected by phase jumps and phase ramps. Results confirmed that using an accurate DEM (ALOS/PRISM) was essential for accurately detecting small deformations. The vertical displacement rate during the investigated period (2007–2010) was estimated to be −28 mm. The results further indicate that the northern area of Port-Said City has been subjected to higher land subsidence rates compared to the southern area. Such land subsidence rates might induce significant environmental changes with respect to sea-level rise.

공간적 · 시간적 긴밀도를 고려한 개선된 D-InSAR 기법에 관한 연구

공간적 · 시간적 긴밀도를 고려한 개선된 D-InSAR 기법에 관한 연구

Neotectonic interpretations and PS-InSAR monitoring of crustal deformations in the Fujian area of China

AbstractA neotectonic structural interpretation was conducted in the Fujian Province, west of the Taiwan Strait, by using computer image processing and 3D visualizations to enhance linear structural traces. The major faults in this area can be grouped into two conjugate shear fracture zones, with one trending to the northeast and the other trending to the northwest. PS-InSAR technology uses stable permanent target scatterer points to determine deformation rates and can effectively reduce the influence of spatiotemporal decorrelations and atmospheric anomalies that affect conventional D-InSAR techniques and prevent the formation of interference fringes. This study focuses on the fault zones located in the Quanzhou area of Fujian Province, where the 1604 M7.5–8.0 historic earthquake occurred. In total, 22 scenes of ERS SAR data from 1996 to 1999 were processed using PS-InSAR methods. The results show that the line of sight direction displacement rate of the main fault in the study area is 3–5 mm/yr, which indicates that the faults in this area are still active and subject to earthquake risk.

Principal component analysis of MSBAS DInSAR time series from Campi Flegrei, Italy

Because of its proximity to the city of Naples and with a population of nearly 1 million people within its caldera, Campi Flegrei is one of the highest risk volcanic areas in the world. Since the last major eruption in 1538, the caldera has undergone frequent episodes of ground subsidence and uplift accompanied by seismic activity that has been interpreted as the result of a stationary, deeper source below the caldera that feeds shallower eruptions. However, the location and depth of the deeper source is not well-characterized and its relationship to current activity is poorly understood. Recently, a significant increase in the uplift rate has occurred, resulting in almost 13cm of uplift by 2013 (De Martino et al., 2014; Samsonov et al., 2014b; Di Vito et al., 2016). Here we apply a principal component decomposition to high resolution time series from the region produced by the advanced Multidimensional SBAS DInSAR technique in order to better delineate both the deeper source and the recent shallow activity. We analyzed both a period of substantial subsidence (1993–1999) and a second of significant uplift (2007–2013) and inverted the associated vertical surface displacement for the most likely source models. Results suggest that the underlying dynamics of the caldera changed in the late 1990s, from one in which the primary signal arises from a shallow deflating source above a deeper, expanding source to one dominated by a shallow inflating source. In general, the shallow source lies between 2700 and 3400m below the caldera while the deeper source lies at 7600m or more in depth. The combination of principal component analysis with high resolution MSBAS time series data allows for these new insights and confirms the applicability of both to areas at risk from dynamic natural hazards.

Slopes geometric model: An automatic Pre-DInSAR analysis

Geometric constraints impose one of the limiting factors in successfully applying the DInSAR technique in hilly areas. These limitations are related to the combination of SAR-image characteristics, due to the incidence angle of the sensor during the acquisition, and the properties of the orientation and slope angle. Consequently, a Pre-DInSAR geometric analysis is highly recommended to detect the areas where the DInSAR technique will be feasible. This previous phase implies some GIS software processes. To simplify this process and avoid human errors, we have developed an automatic model created with Model Builder™ ArcGIS software. This paper presents the model as well as an example of its application to an area previously analysed manually in order to validate the model. This pre-DInSAR analysis could increase the success of DInSAR studies and eliminate possible wrong justifications in the areas in which DInSAR results are unfeasible.

DInSAR-Based Detection of Land Subsidence and Correlation with Groundwater Depletion in Konya Plain, Turkey

In areas where groundwater overexploitation occurs, land subsidence triggered by aquifer compaction is observed, resulting in high socio-economic impacts for the affected communities. In this paper, we focus on the Konya region, one of the leading economic centers in the agricultural and industrial sectors in Turkey. We present a multi-source data approach aimed at investigating the complex and fragile environment of this area which is heavily affected by groundwater drawdown and ground subsidence. In particular, in order to analyze the spatial and temporal pattern of the subsidence process we use the Small BAseline Subset DInSAR technique to process two datasets of ENVISAT SAR images spanning the 2002–2010 period. The produced ground deformation maps and associated time-series allow us to detect a wide land subsidence extending for about 1200 km2 and measure vertical displacements reaching up to 10 cm in the observed time interval. DInSAR results, complemented with climatic, stratigraphic and piezometric data as well as with land-cover changes information, allow us to give more insights on the impact of climate changes and human activities on groundwater resources depletion and land subsidence.