Search

Distributed Scatterers Interferometry (DS-InSAR) has been widely applied to increase the number of measurement points (MP) in complex mountainous areas with dense vegetation and complicated topography. However, DS-InSAR method adopts batch processing mode. When new observation data acquired, the entire archived data is reprocessed, completely ignoring the existing results, and not suitable for high-performance processing of operational observation data. The current research focuses on the automation of SAR data acquisition and processing optimization, but the core time series analysis method remains unchanged. In this paper, based on the traditional Sequential Estimator proposed by Ansari in 2017, a Recursive Sequential Estimator with Flexible Batches (RSEFB) is improved to divide the large dataset flexibly without requirements on the number of images in each subset. This method updates and processes the newly acquired SAR data in near real-time, and obtains long-time sequence results without reprocessing the entire data archived, helpful to the early warning of landslide disaster in the future. 132 Sentinel-1 SAR images and 44 TerraSAR-X SAR images were utilized to inverse the line of sight (LOS) surface deformation of Xishancun landslide and Huangnibazi landslide in Li County, Sichuan Province, China. RSEFB method is applied to retrieve time-series displacements from Sentinel-1 and TerraSAR-X datasets, respectively. The comparison with the traditional Sequential Estimator and validation through Global Position System (GPS) monitoring data proved the effectiveness and reliability of the RSEFB method. The research shows that Xishancun landslide is in a state of slow and uneven deformation, and the non-sliding part of Huangnibazi landslide has obvious deformation signal, so continuous monitoring is needed to prevent and mitigate possible catastrophic slope failure events. [ABSTRACT FROM AUTHOR]

Southern California, USA, has been suffering severe surface deformation due to its active crustal movement under the north–south compression of the Pacific Plate and North American Plate. Meanwhile, affected by groundwater extraction and recharge, oil exploitation, surface subsidence, uplift, and seasonal deformation occur commonly in this region. In this paper, multi-path SAR datasets were collected to investigate and monitor surface deformation in Southern California. The unified simultaneous least squares (USLS) approach is applied to remove the deformation discontinuity between adjacent SAR image paths. Multiple deformation patterns of structural faults, groundwater withdrawal, and oil exploitation are observed with the interferometric synthetic aperture radar (InSAR) technique. The InSAR-derived results were validated with GPS monitoring data. The correlations between land deformation and groundwater withdrawal, faults, and precipitation were intensively analyzed, finding out and mastering the magnitude and characteristics of ground deformation in Southern California. [ABSTRACT FROM AUTHOR]

SAR Interferometry (InSAR) is a powerful technique for mapping land surface deformation, but single one-dimensional (1D) InSAR line-of-sight (LOS) measurement limits its application in three-dimensional (3D) displacement retrieval. Traditional methods were developed for measuring large-scale deformation. In this paper, to retrieve the slow 3D deformation process in the Jiaju landslide, a surface-parallel flow model is applied, according to the existing geological data gained from this landslide. Nine ENVISAT ASAR images and 19 ALOS PALSAR images were collected to reconstruct the 3D deformation field. An iterative method for correcting the characteristic value (IMCCV) with maximum likelihood estimation (M-estimation) adaptively generates an accurate stochastic model. The 3D deformation measurements show that the northern part of the Jiaju landslide clearly had horizontal deformation with the largest deformation velocity exceeding 15 cm year−1, while the southern part was relatively stable. Similarly, large vertical deformation appeared in the northern part (−2 cm year−1) and little deformation occurred in the southern part (−0.5 cm year−1). Compared with GPS measurements, the standard deviation is 1.4 cm year−1 and 0.7 cm year−1 in horizontal and vertical directions, respectively. Therefore, the Jiaju landslide exhibited movements in the horizontal direction accompanied by slight settlement in the vertical direction. [ABSTRACT FROM AUTHOR]