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The utilization of synthetic aperture radar tomography (TomoSAR) technology for the three-dimensional imaging of urban areas has garnered significant attention. In the case of multi-pass spaceborne TomoSAR, eliminating the atmospheric phase screen (APS) is a critical step. At present, a two-tier network method is widely employed for APS removal from extensive regions. However, challenges persist in the construction of first-tier reference networks using the Delaunay triangulation and bridge reference network methods, such as low network coverage ratios and linear correlation problems associated with near-parallel bridges. Consequently, a notable portion of the inversion results for buildings or artificial structures are either absent or characterized by low accuracy. To fully harness the observational information from all small connecting networks, this study introduces an improved bridge reference network construction method based on a region-growing strategy. This method merges small subnetworks with surrounding reference networks using high-quality bridge connections to maximize the coverage of the largest reference network. To validate the feasibility and effectiveness of the proposed approach, 27 TerraSAR-X images, which were collected in Shenzhen, China were utilized to construct a reference network and estimate building heights. The results clearly indicate that the proposed method effectively overcomes the limitations of existing methods.

Time-series SAR interferometry (InSAR) combining permanent scatterer and distributed scatterer (DS), has been strongly developed in subsidence monitoring. It is known that the Component extrAction and sElection SAR (CAESAR) is a recently presented approach of selecting and filtering scattering mechanisms for DS. This article proposes an improved CAESAR algorithm in InSAR processing. Phase optimization is performed by eigenvalue decomposition and principal component analysis of the coherence matrix that constructed based on the identified homogeneous pixels. In addition, only the interferometric phases with low noise are used to calculate the goodness-of-fit value. The improved method has been tested for subsidence monitoring over a nonurban area located in Xiongxian, China using 25 Sentinel-1A images. The results show that the improved method can provide the high spatial density of deformation measurements with accuracy ensured. Noticeable land subsidence is revealed widely within the north of Xiongxian county, particularly in Daying, Mijiawun and Beishakou towns. [ABSTRACT FROM AUTHOR]

The micro-deformation monitoring radar is usually based on Permanent Scatterer (PS) technology to realize deformation inversion. When the region is continuously monitored for a long time, the radar image amplitude and pixel variance will change significantly with time. Therefore, it is difficult to select phase-stable scatterers by conventional amplitude deviation methods, as they can seriously affect the accuracy of deformation inversion. For different regions studied within the same scenario, using a PS selection method based on the same threshold often increases the size of the deformation error. Therefore, this paper proposes a new PS selection method based on the Gaussian Mixture Model (GMM). Firstly, PS candidates (PSCs) are selected based on the pixels’ amplitude information. Then, the amplitude deviation index of each PSC is calculated, and each pixel’s probability values in different Gaussian distributions are acquired through iterations. Subsequently, the cluster types of pixels with larger probability values are designated as low-amplitude deviation pixels. Finally, the coherence coefficient and phase stability of low-amplitude deviation pixels are calculated. By comparing the probability values of each of the pixels in different Gaussian distributions, the cluster type with the larger probability, such as high-coherence pixels and highphase stability pixels, is selected and designated as the final PS. Our analysis of the measured data revealed that the proposed method not only increased the number of PSs in the group, but also improved the stability of the number of PSs between groups. [ABSTRACT FROM AUTHOR]

Shanghai Pudong International Airport (PDIA), with its east side built along the coast with weak geological conditions, is prone to uneven foundation settlement due to the consolidation and compression of soil and erosion of coastal tides, affecting the safe operation of the airport. Therefore, it is crucial to conduct dynamic subsidence monitoring within the airport, especially in the runway area. 29 scenes of ascending track Sentinel-1A radar images from August 2016 to June 2018 are selected to perform surface deformation inversion based on PS-InSAR and improved SBAS-InSAR for PDIA and its around coastal area. Through cross-validation, the reliability of the time-series InSAR technique for dynamic monitoring of surface deformation of coastal zone infrastructures is confirmed. The results show severely uneven settlement. By combining the monitoring results with the local geological and hydrological dataset, the driving factors of differential deformation of the infrastructures are analyzed, including stratigraphic geological conditions, ground loadings, foundation treatment methods, water erosion, and groundwater level changes. Finally, the time-series deformation characteristics and the causes of PDIA's runway are emphasized based on the PS deformation results. This case provides a reference for the safety management of critical infrastructure in coastal areas using advanced InSAR technique.

In this study, the permanent scatterer InSAR (PS-InSAR) technique was utilized to monitor land subsidence in Asadabad city and the adjoining plains located in the west of Iran using Sentinel-1A satellite images in the 2015–2018 period. Based on the results, the Bad Khoreh area exhibited the maximum subsidence rate of about 224 mm/year among the examined areas in the county in the selected period. Also, the rate of land subsidence had increased from the urban areas toward the plains. Moreover, the processing of underground water level data of piezometric wells in the study area indicates that land subsidence in Asadabad city and the adjacent plains has a direct relationship with the overexploitation of groundwater resources during the 2015–2018 period. Furthermore, subsurface geology and land subsidence were analyzed based on information gathered from eleven wells with a total depth of 614 m. The examination of borehole logs and profiles demonstrated that the areas composed of fine clay and sand had undergone severer subsidence than those composed of coarse-grained sediment due to the greater consolidation and compressibility of the grain sediment. [ABSTRACT FROM AUTHOR]

Shanghai Pudong International Airport (PDIA), with its east side built along the coast with weak geological conditions, is prone to uneven foundation settlement due to the consolidation and compression of soil and erosion of coastal tides, affecting the safe operation of the airport. Therefore, it is crucial to conduct dynamic subsidence monitoring within the airport, especially in the runway area. 29 scenes of ascending track Sentinel-1A radar images from August 2016 to June 2018 are selected to perform surface deformation inversion based on PS-InSAR and improved SBAS-InSAR for PDIA and its around coastal area. Through cross-validation, the reliability of the time-series InSAR technique for dynamic monitoring of surface deformation of coastal zone infrastructures is confirmed. The results show severely uneven settlement. By combining the monitoring results with the local geological and hydrological dataset, the driving factors of differential deformation of the infrastructures are analyzed, including stratigraphic geological conditions, ground loadings, foundation treatment methods, water erosion, and groundwater level changes. Finally, the time-series deformation characteristics and the causes of PDIA's runway are emphasized based on the PS deformation results. This case provides a reference for the safety management of critical infrastructure in coastal areas using advanced InSAR technique. [ABSTRACT FROM AUTHOR]

Several methods allow accurate measurement of terrain surface motions. Global navigation satellite systems (GNSSes) and interferometry with synthetic aperture radar (InSAR) stand out in terms of measurement accuracy among them. In principle, both methods make it possible to evaluate a three-dimensional vector of the motion of points on the terrain surface. In this work, we dealt with the evaluation of motions in the up–down (U–D) and east–west direction (E–W) over underground gas storage (UGS) from InSAR. One crucial step in breaking down PSInSAR line of sight (LOS) measurements to U–D and E–W components is getting time series derived from individual tracks to the same time frame. This is usually performed by interpolation, but we used an innovative approach: we analyzed individual time series using the Lomb–Scargle periodogram (LSP), which is suitable for periodic noisy and irregularly sampled data; we selected the most significant period, created LSP models, and used them instead of the original time series. Then, it was possible to derive time series values for any arbitrary time step. To validate the results, we installed one GNSS receiver in the Tvrdonice UGS test area to perform independent measurements. The results show a good agreement in the evaluation of motions by both methods. The correlation coefficient between horizontal components from both PSInSAR and GNSS was 0.95 in the case of the E–W component, with an RMSE of 1.75 mm; for U–D they were 0.78 and 2.35 mm, respectively. In addition to comparing the motions in the U–D and E–W directions, we also created a comparison by converting GNSS measurements to a line of sight of the Sentinel-1 satellite to evaluate the conformity of InSAR and GNSS measurements. Based on descending track, the correlation coefficient between LOS from both methods is, on average, 0.97, with an RMSE of 2.70 mm. [ABSTRACT FROM AUTHOR]

The detection of multiple interfering persistent scatterers (PSs) using Synthetic Aperture Radar (SAR) tomography is an efficient tool for generating point clouds of urban areas. In this context, detection methods based upon the polarization information of SAR data are effective at increasing the number of PSs and producing high-density point clouds. This paper presents a comparative study on the effects of the polarization design of a radar antenna on further improving the probability of detecting persistent scatterers. For this purpose, we introduce an extension of the existing scattering property-based generalized likelihood ratio test (GLRT) with realistic dependence on the transmitted/received polarizations. The test is based upon polarization basis optimization by synthesizing all possible polarimetric responses of a given scatterer from its measurements on a linear orthonormal basis. Experiments on both simulated and real data show, by means of objective metrics (probability of detection, false alarm rate, and signal-to-noise ratio), that polarization waveform optimization can provide a significant performance gain in the detection of multiple scatterers compared to the existing full-polarization-based detection method. In particular, the increased density of detected PSs at the studied test sites demonstrates the main contribution of the proposed method. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Signal Processing is the property of Journal of Signal Processing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Land subsidence occurs more slowly and gradually in comparison with other natural hazards, such as floods and earthquakes; therefore, it has received much less attention from human communities. However, the subsidence over time causes irreparable damage to the structure of underground aquifers, vital infrastructure such as roads, power lines, and urban structures. In this study, in order to monitor land subsidence in Chahardoli and Qorveh plains located in Hamadan and Kurdistan Provinces, the method of Permanent Scatterer (PS) was used using 59 images of Sentinel satellite in ascending passage and 58 images in descending passage. According to the average displacement of PSs in the region between Hassan Abad Emam and Ahutapeh villages of Asadabad city located in Chahardoli plain of Hamadan Province, displacement in the form of subsidence for Ahutapeh and Hassan Abad Emam villages respectively about -170 and -166 mm was happened in the time period of 2017-2018. Moreover, the research found that the subsidence in the northern part of Chahardoli plain in Hamadan Province is much more than the subsidence in the southern part of Chahardoli plain in Kurdistan Province. In order to find the cause of subsidence, the approach of examining the information of piezometric wells in the region and their changes over time was used. In this regard, it can be concluded that the land subsidence in Qorveh plain and Chahardoli plain of Hamadan and Kurdistan provinces can be attributed to the uncontrolled extraction of groundwater resources.

Ground-based synthetic aperture radar (GB-SAR) has been proved to be one of the cutting-edge techniques for the timely detection of slope failures in both natural and engineered slopes. This paper focuses on the structure deformation monitoring on the dams using GB-SAR data. Temporal sequence data was collected by ground SAR equipment from 29 July to 1 August for the Geheyan dam and the SAR images with high quality were selected through the exhaustive spatial-temporal coherence analysis based on permanent scatterer (PS) theory in this paper. A practical solution for dam structure deformation extraction after the atmospheric effect reduction is proposed in depth. The deformation of the dam spillway gates is greater than that of the dam body monitored by this GB-SAR campaign, and with the increase of the water level in the reservoir area, the displacement increases along the direction of water flow gradually. The surface deformation rate of the dam body is fitted by linear regression analysis, and the interpolated rate results are compared and verified with the plumb line measurements. Finally, the consistency of the dam deformation average rate based on the PS time series analysis technology by GB-SAR and plumb lines is verified in this article, demonstrated the excellent performance of the proposed method for remote multipoint displacement measurements of the dam.

Copyright of Journal of Signal Processing is the property of Journal of Signal Processing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Several methods allow accurate measurement of terrain surface motions. Global navigation satellite systems (GNSSes) and interferometry with synthetic aperture radar (InSAR) stand out in terms of measurement accuracy among them. In principle, both methods make it possible to evaluate a three-dimensional vector of the motion of points on the terrain surface. In this work, we dealt with the evaluation of motions in the up–down (U–D) and east–west direction (E–W) over underground gas storage (UGS) from InSAR. One crucial step in breaking down PSInSAR line of sight (LOS) measurements to U–D and E–W components is getting time series derived from individual tracks to the same time frame. This is usually performed by interpolation, but we used an innovative approach: we analyzed individual time series using the Lomb–Scargle periodogram (LSP), which is suitable for periodic noisy and irregularly sampled data; we selected the most significant period, created LSP models, and used them instead of the original time series. Then, it was possible to derive time series values for any arbitrary time step. To validate the results, we installed one GNSS receiver in the Tvrdonice UGS test area to perform independent measurements. The results show a good agreement in the evaluation of motions by both methods. The correlation coefficient between horizontal components from both PSInSAR and GNSS was 0.95 in the case of the E–W component, with an RMSE of 1.75 mm; for U–D they were 0.78 and 2.35 mm, respectively. In addition to comparing the motions in the U–D and E–W directions, we also created a comparison by converting GNSS measurements to a line of sight of the Sentinel-1 satellite to evaluate the conformity of InSAR and GNSS measurements. Based on descending track, the correlation coefficient between LOS from both methods is, on average, 0.97, with an RMSE of 2.70 mm.

The detection of multiple interfering persistent scatterers (PSs) using Synthetic Aperture Radar (SAR) tomography is an efficient tool for generating point clouds of urban areas. In this context, detection methods based upon the polarization information of SAR data are effective at increasing the number of PSs and producing high-density point clouds. This paper presents a comparative study on the effects of the polarization design of a radar antenna on further improving the probability of detecting persistent scatterers. For this purpose, we introduce an extension of the existing scattering property-based generalized likelihood ratio test (GLRT) with realistic dependence on the transmitted/received polarizations. The test is based upon polarization basis optimization by synthesizing all possible polarimetric responses of a given scatterer from its measurements on a linear orthonormal basis. Experiments on both simulated and real data show, by means of objective metrics (probability of detection, false alarm rate, and signal-to-noise ratio), that polarization waveform optimization can provide a significant performance gain in the detection of multiple scatterers compared to the existing full-polarization-based detection method. In particular, the increased density of detected PSs at the studied test sites demonstrates the main contribution of the proposed method.

National Institute of Earth Physics operates one of the densest real-time regional networks in Eastern Europe for monitoring seismic activity, counting 130 real time seismic station and 22 permanent GNSS stations. The network serves for early warning applications, research studies regarding seismic sources and internal Earth structure, as well as crustal deformation monitoring. In areas that make the object of detailed studies for crustal deformation, additional periodic GNSS stations are installed in monthly surveying campaigns, increasing the coverage of the network. The current study focuses on two regions of interest, Izvoarele-Galați and Black Sea coast, monitored with 9 and 4 GNSS reference points respectively. The Izvoarele-Galați represents an interesting research site because of recent abnormal seismic behaviour, while the Black Sea coast is integrated in a project for a regional early-warning system for marine geohazards. Satellite synthetic aperture radar interferometry is proposed as a complementary monitoring technique that can offer insights regarding surface deformation in addition to information offered by classic techniques such as GNSS and optical levelling.

The micro-deformation monitoring radar is usually based on Permanent Scatterer (PS) technology to realize deformation inversion. When the region is continuously monitored for a long time, the radar image amplitude and pixel variance will change significantly with time. Therefore, it is difficult to select phase-stable scatterers by conventional amplitude deviation methods, as they can seriously affect the accuracy of deformation inversion. For different regions studied within the same scenario, using a PS selection method based on the same threshold often increases the size of the deformation error. Therefore, this paper proposes a new PS selection method based on the Gaussian Mixture Model (GMM). Firstly, PS candidates (PSCs) are selected based on the pixels' amplitude information. Then, the amplitude deviation index of each PSC is calculated, and each pixel's probability values in different Gaussian distributions are acquired through iterations. Subsequently, the cluster types of pixels with larger probability values are designated as low-amplitude deviation pixels. Finally, the coherence coefficient and phase stability of low-amplitude deviation pixels are calculated. By comparing the probability values of each of the pixels in different Gaussian distributions, the cluster type with the larger probability, such as high-coherence pixels and high-phase stability pixels, is selected and designated as the final PS. Our analysis of the measured data revealed that the proposed method not only increased the number of PSs in the group, but also improved the stability of the number of PSs between groups.

Phase analysis based on high-quality pixel (HQP) is crucial to ensure the measurement accuracy of ground-based SAR (GB-SAR). The amplitude dispersion (ADI) criterion has been widely applied to identify pixels with high amplitude stability, i.e., permanent scatterers (PSs), which typically are point-wise scatterers such as stones or man-made structures. However, the PS number in natural scenes is few and limits the GB-SAR applications. This paper proposes an improved method to take HQP selection applied for natural scenes in GB-SAR interferometry. In order to increase the spatial density of HQP for phase measurement, three types of HQPs including PS, quasi-permanent scatter (QPS), and distributed scatter (DS), are selected with different criteria. The ADI method is firstly utilized to take PS selection. To select those pixels with high phase stability but moderate amplitude stability, the temporal phase coherence (TPC) is defined. Those pixels with moderate ADI values and high TPC are selected as QPSs. Then the feasibility of the DS technique is explored. To validate the feasibility of the proposed method, 2370 GB-SAR images of a natural slope are processed. Experimental results prove that the HQP number could be significantly increased while slightly sacrificing phase quality.

In this paper, the synthetic aperture radar (SAR) calibration for low-frequency missions by means of stable point targets is presented. Calibration at low frequency involves the absolute radiometric calibration, the antenna pattern and pointing characterization and validation, and the distortion system parameters' estimation. The use of traditional instrumentation, such as a polarimetric active radar calibrator, a corner reflector, or an active transponder, may be costly and can reduce the time the instrument is used for operational acquisitions. The purpose of this paper is to evaluate the potentiality in calibration of point targets for which the radar cross section and the time stability have been characterized. Given a calibration site, once that a set of the stable point targets have been detected by the analysis of an interferometric stack of SAR acquisitions, they may be used as passive calibrators for the validation of radiometry, elevation antenna pattern, and pointing estimation. We show that, although less targets are expected to be found in P- or L- band than in C- or X-band, a sufficient amount (about 250 targets per acquisition) can provide an accuracy in antenna pattern estimation of about 0.04 dB, if the target accuracy is 0.1 dB at 1◝. [ABSTRACT FROM AUTHOR]

Regions of temperate oceanic climate have historically represented a challenge for the application of satellite-based multi-temporal SAR interferometry. The landscapes of such regions are commonly characterized by extensive, seasonally-variable vegetation coverage that can cause low temporal coherence and limit the detection capabilities of SAR imagery as acquired, for instance, by previous ERS-1/2 and ENVISAT missions. In this work, we exploited the enhanced resolution in space and time of the recently deployed Sentinel-1A/B SAR satellites to detect and monitor ground motions occurring in two study areas in the Republic of Ireland. The first, is a ~1800 km2 area spanning the upland karst of the Clare Burren and the adjacent mantled lowland karst of east Galway. The second, is an area of 100 km2 in Co. Meath spanning an active mine site. The available datasets, consisting of more than 100 images acquired in both ascending and descending orbits from April 2015 to March 2018, were processed by using the Permanent Scatterer approach. The obtained results highlight the presence of small-scale ground motions in both urban and natural environments with displacement rates along the satellite line of sight up to −17 mm/year. Localized subsidence was detected in recently built areas, along the infrastructure (both roads and railways), and over the mine site, while zones of subsidence, uplift, or both, have been recorded in a number of peatland areas. Furthermore, several measured target points indicate the presence of unstable areas along the coastline. Many of the detected movements were previously unknown. These results demonstrate the feasibility of adopting multi-temporal interferometry based on Sentinel-1 data for the detection and monitoring of mm-scale ground movements even over small areas (2) in environments influenced by temperate oceanic climate.

Petra is a famous archaeological Nabataean city, carved out of stone, hidden by towering sandstone mountains in Jordan. Slopes are continuously affected by rock falls and local sliding events, involving volumes from less than 1 m 3 to few hundreds m 3 . To investigate long-term cliff evolution and the impact on monuments, an area of about 50 km 2 , including Petra Archaeological Park and its surroundings, was analysed with the SqueeSAR technique, an advanced Interferometric Synthetic Aperture Radar (InSAR) algorithm. The analysis of 38 satellite radar images, acquired between 2003 and 2010, allowed the identification of about 62,000 Measurement Points (MPs) for which it was possible to estimate the displacement time series along the satellite Line Of Sight (LOS). A close up to relevant monuments and comparison with ground-based geotechnical monitoring was implemented, revealing a major stability against medium-large potential rock falls, detectable with present method. [ABSTRACT FROM AUTHOR]

The Permanent Scatterers Interferometric SAR technique (PSInSAR) is a method that accurately estimates the near vertical terrain deformation rates, of the order of ~1 mm year-1, overcoming the physical and technical restrictions of classic InSAR. In this paper the method is strengthened by creating a robust processing chain, incorporating PSInSAR analysis together with algorithmic adaptations for Permanent Scatterer Candidates (PSCs) and Permanent Scatterers (PSs) selection. The processing chain, called PerSePHONE, was applied and validated in the geophysically active area of the Gulf of Corinth. The analysis indicated a clear subsidence trend in the north-eastern part of the gulf, with the maximum deformation of ~2.5 mm year-1 occurring in the region north of the Gulf of Alkyonides. The validity of the results was assessed against geophysical/geological and geodetic studies conducted in the area, which include continuous seismic profiling data and GPS height measurements. All these observations converge to the same deformation pattern as the one derived by the PSInSAR technique.

Results of a PSInSAR™ project carried out by the Regional Agency for Environmental Protection (ARPA) in Piemonte Region (Northern Italy) are presented and discussed. A methodology is proposed for the interpretation of the PSInSARTM data at the regional scale, easy to use by the public administrations and by civil protection authorities. Potential and limitations of the PSInSARTM technique for ground movement detection on a regional scale and monitoring are then estimated in relationship with different geological processes and various geological environments.

PS detection is the premise of deformation monitoring using PS-DInSAR. Considering strong scattering and stability of PS pixels, this paper proposed a new PS selection method using amplitude threshold and iterative comprehensive coherent coefficient to solve the problems of existing methods such as inapplicability for small dataset. Firstly, PS candidates (PSCs) were selected using amplitude threshold. Then, the true PS pixels were selected by iterative comprehensive coherent coefficient method. The distribution, error rate and precision under different amount of images of several methods were contrasted and analyzed using 23 ERS SAR images covering Shanghai. Theoretical analysis and experimental result show that the proposed method has evident advantages for PS selection of small data set and performs better in the matter of PS distribution, error rate and rationality. The subsidence velocity error between the result of this paper and real measured data is only 1.2717 mm/a, which is precise and credible. [ABSTRACT FROM AUTHOR]

Nowadays, one of the most widespread surface monitoring techniques is synthetic aperture radar interferometry (InSAR), which can be used to measure millimetre-scale deformations by comparing the phase information of satellite images taken a few days to a few years apart. To attain this precision, we need methods that use dozens of radar images and rely on accurate additional information (e.g. satellite positions and meteorological data). There are several limiting spatial and meteorological factors which should be taken into consideration when doing high-precision deformation analysis. Also, due to the relatively high price of these products, a cost optimization is essential before purchasing by taking the above-mentioned aspects into consideration. Here, we give an overview of a new nationwide database intended for this purpose. The paper also summarizes the major advancements and the on-going research done in Hungary in the field of radar interferometry. [ABSTRACT FROM AUTHOR]

Abstract: An assessment of the relationship between displacement rates of objects located in areas of active soil creep and rainfall intensities was performed using a permanent-scatterer technique of synthetic aperture radar interferometry. The study focussed on two areas in central Slovenia during the period between April 1992 and December 2000. Based on field assessments, six permanent scatterers for one area and 11 scatterers for the other were selected for analysis from >4300 available permanent scatterers. Displacement rates related to creeping processes were compared with the different durations and intensities of rain in order to assess the threshold values that initiate the creeping process and to assess the relationship between the speed of the movement and the precipitation events. Although the permanent scatterer displacement data contain much noise, our results indicate that soil creep is induced by 20mm of rain in 1day or 50mm of rain in 3days, causing an average elevation decrease of 0.5 and 1mm, respectively. The elevation decreases due to soil creep were observed as instantaneous events, since no increased correlations were observed when a time lag between precipitation and displacement was taken into account. Models developed in this research indicated very similar rates of tectonic uplift for the two research areas in the event of no rain, and these rates were found to be faster than the regional tectonic uplift. This suggests that areas with high rates of tectonic uplift and areas of active soil creep may be related. [Copyright &y& Elsevier]

Ground surface deformations can be related to tectonic motions, landsliding, flooding, erosion, groundwater pumping, karst processes, etc. Ground movement data can be obtained from stationary observations using standard geodetic methods, GPS as well as using geostationary satellites. The combination of the methods and additional geological information can improve the understanding of the processes and clarify the causes of the ground surface movements. In Lithuania, the ground surface deformations are usually related to landsliding, karst, suffusion, technogenic processes, which can trigger deformations of foundations, destruction of buildings, and other harmful accidents. Lithuania is planning to build a new Nuclear Power Plant (NPP), therefore the assessment of the stability of the ground (and structures upon it) across potential new NPP construction sites and their vicinity is a question of vital importance. IAEA SSG-9 safety guidelines recommend remote sensing imagery to be employed to better understand ongoing rates and the type of tectonic activity, therefore the rate of ground surface movements is the vital information for planning and designing a new NPP. The Persistent Scatterer Interferometry (PSI) data has been used to provide historical motion measurements across the new planned Visaginas NPP area. The aim of this paper is to present the PSI dataset interpretation results and clarify the causes of the ground surface vertical movements in the studied Visaginas area. [ABSTRACT FROM AUTHOR]

The development of Differential Synthetic Aperture Radar Interferometry (D-InSAR), in terms of its evolution from classic to advanced forms, such as Least-Squares approach, Permanent Scatterer Interferometry, Small Baseline Subset, and Coherent Pixel Technique, is reviewed, describing concisely the main principles of each method and highlighting the difference and relationship between them. Applications of InSAR technology in China were then introduced, together with the obstacles to overcome and feasible strategies, such as integrating MERIS/MODIS data to compensate for the atmospheric effect and GPS, and multi-platform SAR data to make InSAR technique practical and operational under various conditions. The latest developments were then analyzed along with high-quality SAR data, available thanks to the newly launched high-tech satellites, TerraSAR-X, and Cosmo Sky-med, and conclusions were drawn about the main limitations of the technique. [ABSTRACT FROM AUTHOR]

The Permanent Scatterers Interferometric SAR technique (PSInSAR) is a method that accurately estimates the near vertical terrain deformation rates, of the order of ∼1 mm year-1, overcoming the physical and technical restrictions of classic InSAR. In this paper the method is strengthened by creating a robust processing chain, incorporating PSInSAR analysis together with algorithmic adaptations for Permanent Scatterer Candidates (PSCs) and Permanent Scatterers (PSs) selection. The processing chain, called PerSePHONE, was applied and validated in the geophysically active area of the Gulf of Corinth. The analysis indicated a clear subsidence trend in the north-eastern part of the gulf, with the maximum deformation of ∼2.5 mm year-1 occurring in the region north of the Gulf of Alkyonides. The validity of the results was assessed against geophysical/geological and geodetic studies conducted in the area, which include continuous seismic profiling data and GPS height measurements. All these observations converge to the same deformation pattern as the one derived by the PSInSAR technique. [ABSTRACT FROM AUTHOR]

When using differential SAP, interferometry (DInSAR) to monitor the surface deformation over a long time scale, it is often strongly affected by the spatial and temporal decorrelations and atmospheric dishomogeneities. The recently developed Permanent Scatterers (PS) technique proposed by Fertti et al. can overcome these difficulties by interpreting time-series of interferometric phase only at coherent point scatterers. In this study, we apply this PS technique using 25 ERS-1/2 scenes from 1992 to 2000 to monitor the subsidence in Suzhou. By using the linear deformation model, the deformation map in Suzhou urban area over the eight years is obtained. And the calculated results are in good agreement with the measurements of leveling. [ABSTRACT FROM AUTHOR]