Ground Deformation Monitoring Research Articles

Inferring the Creep Settlement Behavior of Rockfill in Reclaimed Lands by Advanced SAR Interferometry and Numerical Modeling: An Example from Arabian Gulf

Satellite Advanced Differential Synthetic Aperture Radar Interferometry (A-DInSAR) is becaming a key-technique for monitoring ground deformations. The potential of A-DInSAR for settlement monitoring is exploited in this paper through the investigation of a reclaimed land in Dubai (UAE). Time histories of displacements were obtained from COSMO-SkyMed satellite images over the period between 2011 to 2016, allowing to derive the long-term deformation of the entire artificial island. Special attention was paid on long-term settlement of the hydraulically-placed rockfill of the peripheral rubble-mound revetments. The A-DInSAR results have been compared with results derived from numerical analyses and with field surveys, proving the relation between observed and modeled displacements. The study has also revealed that rockfill long-term settlement (creep) rate is significantly dependent on the aging (time since placement). In the analyzed time-frame (2011–2016) it has been observed that recently placed rockfill experienced creep rate up to ten times higher than the creep rate measured for similar rockfill structures placed 30 years earlier. Furthermore, it has been demonstrated that static compression by preloading and dynamic or impact densification induced by wave forces proved to have also a significant impact on reducing the creep rate of the rockfill.

Multi-Temporal InSAR Analysis for Monitoring Ground Deformation in Amorgos Island, Greece.

Radar Interferometry is a widely used method for estimating ground deformation, as it provides precision to a few millimeters to centimeters, and at the same time, a wide spatial coverage of the study area. On 9 July 1956, one of the strongest earthquakes of the 20th century in the area of the South Aegean, occurred in Amorgos, with a magnitude of Mw = 7.7. The objective of this research is to map ground deformation in Amorgos island, using InSAR techniques. We conducted a multi-temporal analysis of all available data from 2003 to 2019 by exploiting historical ENVISAT SAR imagery, as well as the dense archive of Sentinel-1 SLC imagery. Persistent Scatterer Interferometry (PS) and Small Baseline Subset (SBAS) methods were implemented. Results of both data-sets indicate a small-scale deformation on the island. A multi-track analysis was implemented on Sentinel-1 data to decompose the line of sight velocities to vertical and horizontal. The central south coast is experiencing horizontal movement, while uplift of a maximum value of 5 mm/y is observed in the southeastern coast. The combination of the good spatial coverage achievable via InSAR, with GPS measurements, is suggested an important tool for the seamless monitoring of Amorgos island towards tectonic hazard estimation.

D-InSAR Analysis of Sentinel-1 Data for Landslide Detection in Northern Morocco, Case Study: Chefchaouen

Land surface displacement caused by landslides is among the most damaging phenomena in northern Morocco. In this paper, we measure ground deformation in the Chefchaouen area which is a zone characterized by geological formations and structurally complex losses that promote instability (landslide, mudflow, block falls, etc.) leading to slow to extremely slow deformation phenomena, which require an interferometric study, using the DinSAR (differential interferometric synthetic Aperture Radar) technique with sentinel 1 images in bance C, which is a powerful tool for the detection and analysis of interferences and monitoring of ground deformations. We worked on four areas of the study area. Its points are provided by the direction of the roads, which generates Interferograms and then deformation maps with precision in mm/year.

Research on ground deformation monitoring method in mining areas using the probability integral model fusion D-InSAR, sub-band InSAR and offset-tracking

With the aim of addressing the problem of accurately monitoring complete deformation fields over mining areas by means of Synthetic Aperture Radar (SAR), this paper proposes a solution to obtain complete deformation fields using the probability integral model to fuse deformation data derived from Differential Interferometric SAR (D-InSAR), sub-band InSAR and offset-tracking. This method is used for small-scale, medium-scale and large-scale deformation monitoring using D-InSAR, sub-band InSAR and offset-tracking, respectively. Finally, the probability integral model is utilized to integrate the three deformation fields, and a complete deformation field with high-accuracy over the study area can be obtained. The method is tested on 13 TerraSAR-X (TSX) images from December 2, 2012 to April 24, 2013 of the working face 52,304 of the Daliuta mining area in Shaanxi province, China. The complete deformation field of the working face during the 113-day mining period is obtained. The results show that during the process of working face advancing, the subsidence basin has been expanding along the direction of excavation. The relationship between the average maximum subsidence rate and the advancing distance of the working face can be described by a quadratic polynomial. It has been also observed that, when the underground mining reaches the full mining condition, the maximum subsidence value does not increase further. The accuracy of the proposed method is verified against the global positioning system field survey data. The root mean square errors in the strike and dip directions are 0.134 m and 0.105 m, respectively. Due to the support provide by the reserved coal pillars, the subsidence value above the reserved coal pillars is smaller.

InSAR technique applied to the monitoring of the Qinghai–Tibet Railway

Abstract. The Qinghai–Tibet Railway is located on the Qinghai–Tibet Plateau and is the highest-altitude railway in the world. With the influence of human activities and geological disasters, it is necessary to monitor ground deformation along the Qinghai–Tibet Railway. In this paper, Advanced Synthetic Aperture Radar (ASAR) (T405 and T133) and TerraSAR-X data were used to monitor the Lhasa–Naqu section of the Qinghai–Tibet Railway from 2003 to 2012. The data period covers the time before and after the opening of the railway (total of 10 years). This study used full rank matrix small baseline subset InSAR (FRAM-SBAS) time-series analysis to analyze the Qinghai–Tibet Railway. Before the opening of the railway (from 2003 to 2005), the Lhasa–Naqu road surface deformation was not obvious, with a maximum deformation of approximately 5 mm yr−1; in 2007, the railway was completed and opened to traffic, and the resulting subsidence of the railway in the district of Damxung was obvious (20 mm yr−1). After the opening of the railway (from 2008 to 2010), the Damxung segment included a considerable area of subsidence, while the northern section of the railway was relatively stable. The results indicate that FRAM-SBAS technology is capable of providing comprehensive and detailed subsidence information regarding railways with millimeter-level accuracy. An analysis of the distribution of geological hazards in the Damxung area revealed that the distribution of the subsidence area coincided with that of the geological hazards, indicating that the occurrence of subsidence in the Damxung area was related to the influence of surrounding geological hazards and faults. Overall, the peripheral surface of the Qinghai–Tibet Railway is relatively stable but still needs to be verified with real-time monitoring to ensure that the safety of the railway is maintained.

SMF-POLOPT: An Adaptive Multitemporal Pol(DIn)SAR Filtering and Phase Optimization Algorithm for PSI Applications

Speckle noise and decorrelation can hamper the application and interpretation of PolSAR images. In this paper, a new adaptive multitemporal Pol(DIn)SAR filtering and phase optimization algorithm is proposed to address these limitations. This algorithm first categorizes and adaptively filters permanent scatterer (PS) and distributed scatterer (DS) pixels according to their polarimetric scattering mechanisms [i.e., the scattering-mechanism-based filtering (SMF)]. Then, two different polarimetric DInSAR (POLDInSAR) phase OPTimization methods are applied separately on the filtered PS and DS pixels (i.e., POLOPT). Finally, an inclusive pixel selection approach is used to identify high-quality pixels for ground deformation estimation. Thirty-one full-polarization Radarsat-2 SAR images over Barcelona (Spain) and 31 dual-polarization TerraSAR-X images over Murcia (Spain) have been used to evaluate the performance of the proposed algorithm. The PolSAR filtering results show that the speckle of PolSAR images has been well reduced with the preservation of details by the proposed SMF. The obtained ground deformation monitoring results have shown significant improvements, about $\times 7.2$ (the full-polarization case) and $\times 3.8$ (the dual-polarization case) with respect to the classical full-resolution single-pol amplitude dispersion method, on the valid pixels’ densities. The excellent PolSAR filtering and ground deformation monitoring results achieved by the adaptive Pol(DIn)SAR filtering and phase optimization algorithm (i.e., the SMF-POLOPT) have validated the effectiveness of this proposed scheme.

An Accurate Method to Correct Atmospheric Phase Delay for InSAR with the ERA5 Global Atmospheric Model

Differential SAR Interferometry (DInSAR) has proven its unprecedented ability and merits of monitoring ground deformation on a large scale with centimeter to millimeter accuracy. However, atmospheric artifacts due to spatial and temporal variations of the atmospheric state often affect the reliability and accuracy of its results. The commonly-known Atmospheric Phase Screen (APS) appears in the interferograms as ghost fringes not related to either topography or deformation. Atmospheric artifact mitigation remains one of the biggest challenges to be addressed within the DInSAR community. State-of-the-art research works have revealed that atmospheric artifacts can be partially compensated with empirical models, point-wise GPS zenith path delay, and numerical weather prediction models. In this study, we implement an accurate and realistic computing strategy using atmospheric reanalysis ERA5 data to estimate atmospheric artifacts. With this approach, the Line-of-Sight (LOS) path along the satellite trajectory and the monitored points is considered, rather than estimating it from the zenith path delay. Compared with the zenith delay-based method, the key advantage is that it can avoid errors caused by any anisotropic atmospheric phenomena. The accurate method is validated with Sentinel-1 data in three different test sites: Tenerife island (Spain), Almería (Spain), and Crete island (Greece). The effectiveness and performance of the method to remove APS from interferograms is evaluated in the three test sites showing a great improvement with respect to the zenith-based approach.

Geodesic monitoring of ground deformations at Klyuchevskoy Volcano in 1978–2014, Kamchatka

Measured values are given - slant distances and elevations between geodetic marks on the northeast slope of Klyuchevskaya volcano for 1978–2014. As a rule, a rise was observed before the secondary and summit eruptions, and the end of the eruptions was accompanied by the lowering of the volcano slope. According to the longest series of observations of vertical displacements from 1979 to 2014. on the “Kirgurich” radial profile, the rise of the volcano slope is determined to increase as it approaches its crater. The maximum displacements occurred two years before the start of the “Predskazannuy” side breakthrough in 1983, and before the summit eruptions of 2003–2004 and 2007. At a distance of 27 km from the crater of the volcano, the vertical displacements become insignificant. It is shown that points located at altitudes from 2000 meters to 3000 meters are subject to deep creep, i.e. sliding down. The displacement rates of such points reached 5–20 cm/year. Significant horizontal displacements of geodetic points occurred near incidental breaks on March 6, 1980 and March 8, 1983. From 1989–1993. until 2014, reductions of all lengths of lines from 5 to 20 mm were observed, which indicated compression of the northeast slope of Klyuchevskaya volcano.

Persistent Scatterers continuous streaming for landslide monitoring and mapping: the case of the Tuscany region (Italy)

The results of the continuous monitoring of ground deformation throughout the Tuscany region using radar images acquired by the Sentinel-1 satellite constellation of the European Space Agency (ESA) are presented here. This new monitoring approach, based on systematic imagery processing and analysis of deformation time series, is discussed at regional (for the entire Tuscany) and at local scale in the context of a case study of the Carpineta landslide, which is a large, active earth slide in the Northern Apennines (Pistoia province). The landslide registered an acceleration during the winter and spring of 2018 as a direct consequence of rainfall and snow melt. The increase in the deformation rate of the landslide, which led to the damage of several buildings, was promptly detected and monitored due to the enhanced temporal repetitiveness offered by the Sentinel-1 constellation. The results demonstrate that advances in satellite sensors, increases in computing capacity and the refinement of processing approaches and data screening tools can contribute to the development of new paradigms in satellite-based monitoring systems. Sentinel-1 data, which are systematically acquired with short revisiting times and then promptly processed, can now be used as a tool for the systematic tracking of ground deformation at the regional scale and for the continuous monitoring of slow and very slow landslides.

Semi-automatic selection of optimum image pairs based on the interferometric coherence for time series SAR interferometry

ABSTRACTTime series synthetic aperture radar (SAR) interferometry (TS-InSAR) has been widely used for monitoring ground deformation. The selection of interferometric image pairs directly affects the quality of the interferograms and the accuracy of deformation monitoring. The Small BAseline Subset (SBAS) method has been widely adopted to form interferograms in TS-InSAR. However, the selection of low-quality interferograms or missed selection of good interferograms due to temporal and/or spatial baselines exceeding the thresholds sometimes occurs in the traditional SBAS method. This letter proposes a new method, namely, the semi-automatic selection of optimum image pairs (SASOIP), based on the interferometric coherence. By quantitatively evaluating the coherence of point targets in a small feature region, the SASOIP results in high-quality interferometric image pairs selected from all possible interferometric combinations for any two SAR images. The SASOIP method can effectively reduce the probability of poor selection and missed selection of quality image pairs. Twenty-nine COSMO-SkyMed SAR images acquired from 27 August 2011, to 29 July 2015, over Tianjin, China, are used to test the proposed algorithm. Validation with 102 levelling data points demonstrates that the accuracy of ground deformation derived from the interferograms by the SASOIP method is 23.13% higher than that based on the SBAS method.

Integrated Monitoring of Volcanic Ash and Forecasting at Sakurajima Volcano, Japan

The Sakurajima volcano is characterized by frequent vulcanian eruptions at the Minamidake or Showa crater in the summit area. We installed an integrated monitoring system for the detection of volcanic ash (composed of remote sensing sensors XMP radars, lidar, and GNSS with different wave lengths) and 13 optical disdrometers on the ground covering all directions from the crater to measure drop size distribution and falling velocity. Campaign sampling of volcanic ash supports the conversion of particle counts measured by the disdrometer to the weight of volcanic ash. Seismometers and tilt/strain sensors were used to estimate the discharge rate of volcanic ash from the vents. XMP radar can detect volcanic ash clouds even under visual difficulty because of weather such as fog or clouds. A vulcanian eruption on November 13 was the largest event at the Sakurajima volcano in 2017; however, the volcanic plume was not visible due to clouds covering the summit. Radar revealed that the volcanic plume reached an elevation of 4.2–6.2 km. Post-fit phase residuals (PPR) from the GNSS analysis increased suddenly after the eruption, and large-PPR paths from the satellites to the ground-based receivers intersected each other at an elevation of 4.2 km. The height of the volcanic plume was also estimated from the discharge rate of volcanic ash to be 4.5 km, which is empirically related to seismic energy and the deflation volume obtained via ground deformation monitoring. Using the PUFF model, the weight of the ash-fall deposit was accurately forecast in the main direction of transport of the volcanic ash, which was verified by disdrometers. For further advances in forecasting of the ash-fall deposit, we must consider high-resolution wind field, shape of volcanic plume as the initial value, and the particle number distribution along the volcanic plume.

Using PS-InSAR with Sentinel-1 Images for Deformation Monitoring in Northeast Algeria

Constantine city, Algeria, and its surroundings have always been affected by natural and human-induced slope instability and subsidence. Neogene clay-conglomeratic formations, which form the largest part of Constantine city, are extremely sensitive to the presence of water, which makes them susceptible to landslides. Fast and accurate identification and monitoring of the main areas facing existing or potential hazardous risks at a regional scale, as well as measuring the amount of displacement is essential for the conservation and sustainable development of Constantine. In the last three decades, the application of radar interferometry techniques for the measurement of millimeter-level terrain motions has become one of the most powerful tools for ground deformation monitoring due to its large coverage and low costs. Persistent scatterer interferometry (PS-InSAR) has a demonstrated potential for monitoring a range of hazard event scenarios and tracking their spatiotemporal evolution. We demonstrate the efficiency of Sentinel-1 data for deformation monitoring in Constantine located in the northeast of Algeria, and how an array of information such as geological maps and ground-measurements are integrated for deformation mapping. We conclude this article with a discussion of the potential of advanced differential radar interferometry approaches and their applicability for structural and ground deformation monitoring, including the advantages and challenges of these approaches in the north of Algeria.

Accuracy of Deformation Rates from Campaign GPS Surveys Considering Extended Observation Session and Antenna Set-Up Errors

GPS campaign measurements are still in use in the monitoring of ground deformation. Campaign measurements are frequently referred to because installing permanent stations are costly, and they cannot be installed at the desired density. Using the data from the International Global Navigation Satellite Systems (GNSS) Service (IGS) permanent GPS stations, the duration, sampling interval, etc. of the campaign measurements can be simulated. Thus, the contribution of the campaign data to the monitoring of the ground deformation can be evaluated. In this study, we carried out an experiment with the aim of determining the deformation of tectonic plates at the selected IGS stations more accurately considering by extending the observation duration to a full 24 h length. We also made an attempt to take into consideration the antenna set up errors developing a scenario referring to the information available in the literature. We have decimated the continuous data of 40 globally scattered IGS stations into monthly intervals between 2012 and 2016 and estimated the deformation rates at the IGS stations from a continuous time series of four years. The continuous time series solutions for those stations were produced by the Jet Propulsion Laboratory (JPL), NASA. We compare velocities (i.e., the deformation rates) determined from GPS campaigns (in which the sampling was performed monthly and four-monthly) with those of the continuous data. The major conclusion of this study is that the vertical velocity estimation accuracy of the GPS campaign measurements had been improved by about 85% by extending the session duration to 24 h. The repetition interval of GPS campaign measurements as per one observation every four months produced only slightly coarser accuracy (i.e., on the average 8% poorer) than those of the measurements repeated once every month.

Delineating ground deformation over the Tengiz oil field, Kazakhstan, using the Intermittent SBAS (ISBAS) DInSAR algorithm

Changes in subsurface pore pressures and stresses due to the extraction of hydrocarbons often cause deformation over oil and gas fields. This can have significant consequences, including ground subsidence, induced seismicity and well failures. Geodynamic monitoring is an important requirement in recognising potential threats in sufficient time for remedial measures to be implemented. Differential interferometric synthetic aperture radar (DInSAR) is increasingly utilised for monitoring ground deformation over oil and gas reservoirs, achieving greater spatial coverage than traditional field-based surveying techniques. However, ground deformation over oil and gas fields can extend regionally into the surrounding rural landscape, where many conventional DInSAR techniques are of limited use due to the dynamic nature of the land cover. The Intermittent Small Baseline Subset (ISBAS) method is an advanced DInSAR technique, which considers the intermittent nature of coherence over dynamic land cover types to obtain markedly more ground motion measurements in non-urban regions. In this study, the ISBAS technique is used to delineate deformation over the super-giant Tengiz oil field in rural Kazakhstan. Analysis of ENVISAT data for 2004–2009 reveals a well-defined bowl subsiding with a maximum rate of −15.7 mm/year, corroborated by independent DInSAR studies and traditional levelling data. Subsequent application of ISBAS to Sentinel-1 data reveals significant evolution of deformation over the field in 2016–2017, with subsidence increasing dramatically to a maximum of -79.3 mm/year. The increased density of measurements obtained using the ISBAS technique enables accurate and comprehensive delineation and characterisation of ground deformation in this rural landscape, without the need for corner reflectors. This enhanced information could ultimately aid reservoir characterisation and management, and improve understanding of the risk posed by ground subsidence and fault reactivation.

Risk Evaluation, Design, Implementation, Instrumentation, and Verification for Crown Pillar Extraction at Pinos Altos Mine

The Santo Nino ore body at Pinos Altos Mine has been in production since 2009 using both open pit and underground mining methods. Between 2015 and 2017, an extensive study evaluated extraction strategy of the Santo Nino crown pillar. The Agnico Eagle project team evaluated geomechanical, operational, safety and economical risks before developing a comprehensive plan to extract the Santo Nino crown pillar by underground stoping. The geomechanical aspects of that study focused on interpreting in situ rock mass conditions and understanding the mechanical and hydrological/hydrogeological mechanisms influencing ground reaction during open pit and underground mine operations to make meaningful forward predictions for crown pillar extraction. Numerical modeling played a significant role in making forward predictions. To minimize uncertainty in those predictions, the model parameters were calibrated using measured pit slope deformations, back analysis of historical slope instabilities and underground observations of rock mass conditions. Ultimately, it was decided that long-hole stoping would be utilized for crown pillar extraction. The pit floor would be used as a drilling horizon, and the upper most level of the underground operations served as the mucking horizon. Various safety and operational risk mitigation strategies were developed and implemented; this included geomechanical monitoring using the in-pit radar system and numerous borehole extensometers installed underground to monitor ground deformations. The calibrated numerical model results provided valuable input for the design of the instrumentation program, and once the crown pillar came into production in late 2017, the instrumentation provided valuable data for model verification and stope design adjustments.

Long-Term Ground Settlements over Mined-Out Region Induced by Railway Construction and Operation

With the rapid development of railway construction and the massive exploitation of mineral resources, many railway projects have had to cross mining areas and their caverns. However, the settlement of the ground surface may cause severe damage to human-built structures and lead to the loss of human lives. The research on ground deformation monitoring over caverns is undoubtedly important and has a guiding role in railway design. Settlement observation points were set up around the mine, establishing a ground subsidence monitoring level network that has been in operation for 11 years. The ground settlement and lateral displacement along the designed railway were studied. A finite element model was established to predict the long-term ground settlements over the mined-out region induced by designed railway embankment construction and train operation. The results show that the predicted ground settlement induced by railway embankment construction is smaller than the ground settlement induced by the mined-out cavity. One train pass-by has an insignificant impact on the safety of train operation. However, when the number of train pass-bys increases to 10,000,000 times and 20,000,000 times, the cumulative deformations of the ground at different depths are quite large, which may affect the safety of the railway operation. Thus, it is necessary to deal with settlement issues when designing railway construction.

Passive radio-frequency identification ranging, a dense and weather-robust technique for landslide displacement monitoring

Ground deformation monitoring at a local scale requires accuracy, along with dense spatio-temporal resolution. Radio-Frequency Identification (RFID) technology is proposed as an alternative to classical geodetic methods for monitoring displacements of a landslide. Passive RFID tags allow for a very dense resolution, both in time and space, at the scale of a 100-m-long surface. By deploying 19 passive RFID tags on a landslide for 5 months, this study validates the technique by comparison with laser total station and wire extensometer data. The accuracy of the RFID technique was 1 cm during normal weather and up to 8 cm during snow events. The results demonstrate that RFID tag tracking can monitor landslide displacements with multiple sensors at low cost, providing dense spatio-temporal data. This technique could potentially be used for other applications such as monitoring volcanic activity, buildings, unstable rocks or snow cover.

An Improved Pre-Processing Algorithm for Resolution Optimization in Galileo-Based Bistatic SAR

Galileo based bistatic synthetic aperture radar (Galileo-BiSAR) is a subclass of passive radar, where the Galileo satellite is used as the transmitter and the receiver can be mounted on a moving vehicle or fixed on the ground. Such scheme is cost-effective and safe, and therefore can be widely used in military areas such as battle monitoring or civil scenarios such as ground deformation monitoring, change detection, etc. However, the drawback of Galileo-BiSAR system lies on the fact that, same with other passive radar, the transmitter and receiver are separately located, which introduces the necessity of pre-processing before further processing such as image formation. The existing pre-processing algorithm for Galileo-BiSAR system was established on the idea that only single band E5b signal is used. Due to its bandwidth of 20MHz, however, the range resolution of resulting image is merely up to 15m, which is not acceptable for most applications. Aimed at improving range resolution, this article proposes a new pre-processing algorithm for Galileo-BiSAR. Rather than employing the single band signal as well as duplicate of transmitting signal as the local reference signal in tradition way, a novel technique of dual matched filtering is proposed for pre-processing. Full simulations of the proposed pre-processing and further image formation were both performed. The results demonstrated the full functionality of the proposed pre-processing algorithm and verified its capability of higher resolution imaging against traditional algorithm. In addition, the paper also highlights its good computational efficiency and performance limitation against noise.

High Spatio-Temporal Resolution Deformation Time Series With the Fusion of InSAR and GNSS Data Using Spatio-Temporal Random Effect Model

High spatio-temporal resolution deformation series can be used to improve the understanding of deformation mechanism, thereby contributing to prevention and control of geological disasters such as mine subsidence, landslide, and earthquake. Among ground deformation monitoring technologies, global navigation satellite system has high temporal resolution but low spatial resolution, and interferometric synthetic aperture radar (InSAR) has high spatial resolution but low temporal resolution. Fusing these two data may generate high spatio-temporal resolution deformation series. Existing fusion methods usually use the bi-direction interpolation, which does not consider the spatio-temporal cross correlation and is computationally extensive. We propose a dynamic filtering fusion model based on the spatio-temporal random effect (a spatio-temporal Kalman filter) model. Experiments with simulated data and real data from the Los Angeles area are conducted to validate this method. Simulated experimental results are compared with truth data and the Los Angeles experiment data results are verified using the leave-one InSAR image-out validation method. The RMS results for them are around 13.8 and 5 mm, respectively, indicating that the proposed method can achieve high accuracy and high spatial-temporal resolution deformation time series.

Development of Continuous Ground Deformation Monitoring System using Sentinel Satellite in the Korea

Development of Continuous Ground Deformation Monitoring System using Sentinel Satellite in the Korea