Constructing high-precision subsidence basins is of paramount importance for mining subsidence monitoring. Traditional unmanned aerial vehicle (UAV) photogrammetry techniques typically construct subsidence basins by directly differencing digital elevation models (DEMs) from different monitoring periods. However, this method often neglects the influence of horizontal displacement on the accuracy of the subsidence basin. Taking a mining area in Ordos, Inner Mongolia, as an example, this study employed the normalized cross-correlation (NCC) matching algorithm to extract horizontal displacement information between two epochs of a digital orthophoto map (DOM) and subsequently corrected the horizontal position of the second-epoch DEM. This ensured that the planar positions of ground feature points remained consistent in the DEM before and after subsidence. Based on this, the vertical displacement in the subsidence area (the subsidence basin) was obtained via DEM differencing, and the parameters of the post-correction subsidence basin were inverted using the probability integral method (PIM). The experimental results indicate that (1) the horizontal displacement was influenced by the gully topography, causing the displacement within the working face to be segmented on both sides of the gully; (2) the influence of the terrain on the subsidence basin was significantly reduced after correction; (3) the post-correction surface subsidence curve was smoother than the pre-correction curve, with abrupt error effects markedly diminished; (4) the accuracy of the post-correction subsidence basin increased by 43.12% compared with the total station data; and (5) comparing the measured horizontal displacement curve with that derived using the probability integral method revealed that the horizontal displacement on the side of an old goaf adjacent to the newly excavated working face shifted toward the advancing direction of the new working face as mining progressed. This study provides a novel approach and insights for using low-cost UAVs to construct high-precision subsidence basins.

Edgecumbe, a dormant volcano located on Kruzof Island in the southeastern part of Alaska, USA, west of the Sitka Strait, has exhibited increased volcanic activity since 2018. To assess the historical and current intensity of this activity and explore its relationship with seismic events in the surrounding region, this study utilized data from the ERS-1/2, ALOS-1, and Sentinel-1 satellites. The Permanent Scatterer Interferometric Synthetic Aperture Radar (PS-InSAR) and Small Baseline Subset InSAR (SBAS-InSAR) techniques were employed to obtain surface deformation data spanning nearly 30 years. Based on the acquired deformation field, the point-source Mogi model was applied to invert the position and temporal volume changes in the volcanic source. Then, by integrating seismic activity data from the surrounding area, the correlation between volcanic activity and earthquake occurrences was analyzed. The results indicate the following: (1) the coherence of interferograms is influenced by seasonal variations, with snow accumulation during the winter months negatively impacting interferometric coherence. (2) Between 1992 and 2000, the surface of the volcano remained relatively stable. From 2007 to 2010, the frequency of seismic events increased, leading to significant surface deformation, with the maximum Line-of-Sight (LOS) deformation rate during this period reaching −26 mm/yr. Between 2015 and 2023, the volcano entered a phase of accelerated uplift, with surface deformation rates increasing to 68 mm/yr after August 2018. (3) The inversion results for the period from 2015 to 2023 show that the volcanic source, located at a depth of 5.4 km, experienced expansion in its magma chamber, with a volumetric increase of 57.8 × 10⁶ m³. These inversion results are consistent with surface deformation fields obtained from both ascending and descending orbits, with cumulative LOS displacement reaching approximately 210 mm and 250 mm in the ascending and descending tracks, respectively. (4) Long-term volcanic surface deformation, changes in magma source volume, and seismic activity suggest that the earthquakes occurring after 2018 have facilitated the expansion of the volcanic magma source and intensified surface deformation. The uplift rate around the volcano has significantly increased.

With its high spatiotemporal resolution and wide-area coverage, InSAR technology has become an essential tool for monitoring mining-induced surface subsidence. However, the large-gradient deformation caused by the traditional caving method has hindered this technology’s widespread application in subsidence monitoring. With the increasing adoption of backfill mining techniques, both the magnitude and the gradient of surface deformation have been significantly reduced, creating new opportunities for applying InSAR to subsidence monitoring in mining areas. Nevertheless, current research on InSAR under backfill mining conditions remains relatively limited, particularly with respect to the applicability of time-series InSAR techniques in such settings. In this study, the Wu’an mining area, characterized by the traditional caving method, and the Fengfeng mining area, which employs overburden isolated grouting backfill mining, were selected as representative cases. By integrating Small Baseline Subset InSAR (SBAS-InSAR) time-series deformation results with ground-based leveling measurements, we comparatively analyzed the interferometric coherence characteristics and deformation monitoring performance associated with the two mining methods. We then evaluated the monitoring applicability and engineering feasibility of InSAR under overburden isolated grouting backfill mining conditions. The results indicate that, under similar surface land cover conditions, the gradient of surface deformation exerts a strong influence on interferometric coherence. Comparison with leveling measurements shows that the RMSE in the Fengfeng mining area under overburden isolated grouting backfill mining is at least 68.2% lower than that in the Wu’an mining area under caving mining. Moreover, overburden isolated grouting backfill mining can effectively mitigate mining-induced surface deformation, limiting the maximum subsidence in the Fengfeng mining area to less than 300 mm and to less than 200 mm in village areas. Using Sentinel-1 data and a conventional SBAS-InSAR processing workflow, InSAR demonstrates higher reliability and applicability for surface subsidence monitoring in mining areas under overburden isolated grouting backfilling conditions than in those under caving mining conditions. This study aims to provide a useful reference for mining subsidence monitoring based on Sentinel-1 C-band data and a conventional SBAS-InSAR processing workflow.

On 1 January 2024, a magnitude 7.5 earthquake struck Japan's Noto Peninsula. Thoroughly elucidating the seismic mechanism and tectonic activity characteristics of this event holds significant importance for assessing regional seismic hazard. Existing studies predominantly rely on ALOS-2 PALSAR-2 imagery and geodetic data, overlooking the unique role of optical remote sensing data in reconstructing horizontal displacement fields and the potential of Sentinel-1 intensity information for extracting azimuthal deformation. Consequently, this study comprehensively utilises multi-source remote sensing data from ALOS-2 PALSAR-2 and Sentinel-1/2. Employing Differential Interferometric Synthetic Aperture Radar (D-InSAR), Synthetic Aperture Radar Pixel Offset Tracking (POT), and Optical Image Correlation (OIC) techniques to obtain a high-precision co-seismic deformation field. This enabled the inversion of fault slip distributions, revealing earthquake rupture characteristics and stress effects. This study successfully obtained the complete three-dimensional co-seismic deformation field of the earthquake, revealing significant deformation characteristics both along the fault strike and in the normal direction. The slip distribution inversion results clarified the geometric parameters and motion characteristics of the primary rupture fault, demonstrating spatially concentrated slip distribution. Furthermore, analysis based on co-seismic Coulomb stress changes indicated a significant spatial correlation between co-seismic stress perturbations and aftershock distribution. This suggests that static stress triggering plays a dominant role in aftershock activity, while also identifying stress-loading zones with potentially high seismic hazard for the future. The application of multi-source remote sensing technology effectively compensates for the monitoring shortcomings of single techniques in regions with large deformation gradients. It significantly enhances the informational completeness and spatial continuity of the co-seismic deformation field, providing a reliable method for obtaining high-precision, multi-dimensional surface displacement data. The subsequent inversion of slip distribution and Coulomb stress analysis, based on multi-source deformation data, not only provided a detailed characterisation of the Noto earthquake's fault geometry and rupture behaviour but also further elucidated the triggering mechanisms and spatial control exerted by co-seismic stress perturbations on the aftershock sequence. These findings have deepened our understanding of the seismic rupture dynamics in this region and offer crucial insights for assessing post-seismic hazard risks and identifying potential precursory phenomena.