Quantifying the kinematic evolution patterns of mountain glaciers near Yarlung Tsanpo River performs a major role in evaluating the glacial instability and the secondary disasters. For the Sedongpu Basin near the Yarlung Tsanpo River Valley, the dramatic geomorphic landscape variations triggered by the ice-rock avalanche events were visually identified as the dominant texture deficiencies in time-series optical images. To improve the image correlation quality broken by these image texture deficiencies, the Landsat-8/Sentinel-2 optical images were divided into different groups, then a stepwise combination strategy was innovatively proposed to derive the glacier time-series displacement velocities in different temporal stages. The standard deviations (STD) of the optical measurements in the stable area maintained around 0.04 m/yr for the normalized displacement velocity and maintained from 0.6 to 1.7 m for the cumulative displacement time series. The obvious variations in glacier displacement velocity were identified before each collapse event. Subsequently, the offset-tracking procedures were performed on 7 Sentinel-1A Synthetic Aperture Radar (SAR) images to acquire the range and azimuth displacement velocities. To better reveal the dynamic mechanism of the glacier activity, the three-dimensional (3D) glacial displacement velocity was also derived by using optical and SAR results. The precipitation, temperature, and seismic activities were assumed as the main triggering factors of controlling the glacial dynamic mechanism and final collapse events. Additionally, the dynamic mechanism of the active glaciers in Sedongpu Basin conformed to a power law, which was limited by the changes of the internal stress friction force on the sliding base surface. The aim of this study is to shed a light on interpreting the precursory displacement patterns and their implicit failure mechanism of these ice-rock avalanche events with the conventional freely optical and SAR observations.

As a world-class problem that has confused the field of geoscience for a long time, the formation mechanism of the peculiar feather-shaped dunes in Kumtag Desert hasn't been clarified due to the deficiency of a comprehensive investigation on the dune dynamic characteristics. Because of the quickly changeable dune morphology and sands' low dielectric constants, the traditional single technique generally was only used to identify or quantify dune mobility in one or two dimensions, cannot retrieve the complete information of dune dynamic characteristics. To overcome these deficiencies, a comprehensive study of confusing the optical image cross-correlation, SAR offset-tracking, Small Baseline Subsets (SBAS-) InSAR and InSAR coherence was performed here to identify and quantify the movements of feather-shaped dunes from a muti-dimensional (EW, NS, slant-range, azimuth, coherence) perspective. These results showed that the feather-shaped dunes demonstrate a movement tendency from the northeastern to the southwestern orientation (204.32° ± 52.15°) with the displacement magnitude of 3.34 ± 2.26 m/yr, in consistent with the predominant wind condition. Specifically, the spatial heterogeneity was found that these dunes move along a relatively small slope gradient (0°∼6°) and a northwestern-southeastern facing slope aspect (300°∼350°, 120°∼180°). Besides, the large displacement velocities are mainly concentrated in the pinna rachis rather than the rami of the feather-shaped dunes. This study sheds a light on the comprehensive investigation on the large-scale dynamic characteristics of peculiar feather-shaped dunes by combining the medium-resolution optical and SAR satellite observations.

The optical image correlation is a highly effective technique for retrieving large-gradient ground displacements. However, its reliance on solar illumination in passive optical imaging introduces widespread topographic shadowing artifact (TSA) into displacement measurements. To address this limitation, this study investigates the spatiotemporal heterogeneity of TSA. We reveal that TSA's temporal evolution follows a sinusoidal function in the north-south (NS) direction and an irregular periodic function in the east-west (EW) direction. Furthermore, TSA predominantly contaminates NS displacement components rather than EW displacement components. Spatially, TSA primarily affects shady hillsides with slope aspects of 0° ∼ 90° and 240° ∼ 360°, and slope gradients of 17° ∼ 67°. Subsequently, we innovatively develop a physics-constrained model to characterize TSA's spatiotemporal heterogeneity and mitigate its interference in displacement measurements. Applying this model to correct TSA observation time series in a stable region reduced averages by 94.38% (EW) and 98.22% (NS), from the initial ranges of -0.18 ∼ 0.13 m (EW) / -0.40 ∼ 0.48 m (NS), with standard deviations decreased by 47.18% (EW) and 62.83% (NS), from initial ranges of 0 ∼ 1.89 m (EW) / 0 ∼ 2.74 m (NS). Leveraging this physics-constrained model, a novel Model Correction (MC) method is subsequently proposed for mitigating TSA in co-seismic displacements. Validation demonstrates the enhanced measurement consistency of MC method in two seismic cases with RMSE of 0.52 m and 0.42 m for NS co-seismic displacements, improved by 26.76% and 54.84%, respectively. This study provides fundamental insights into TSA's spatiotemporal evolution patterns and advances the precision of ground displacement measurement using optical image correlation technique