Earthquake triggered landslides often pose a great threat to human life and property. Emerging research has been devoted to documenting coseismic landslides failed during or shortly after earthquakes, however, the long-term seismic effect that causes unstable landslides only to accelerate, moderately or acutely, without immediate failures is largely neglected. Here we show the activation and recovery of these earthquake accelerated landslides (EALs) in Central Italy, based on satellite radar observations. Unlike previous studies based on single or discrete landslides, we established a large inventory of 819 EALs and statistically quantified their spatial clustering features against a set of conditioning factors, thus finding that EALs did not rely on strong seismic shaking or hanging wall effects to occur and larger landslides were more likely to accelerate after earthquakes than smaller ones. We also discovered their accelerating-to-recovering sliding dynamics, and how they differed from the collapsed 759 coseismic landslides. These findings contribute to a more comprehensive understanding of the earthquake-triggering landslide mechanism and are of great significance for long-term landslide risk assessment in seismically active areas.

Interferometric Synthetic Aperture Radar (InSAR) enables detailed investigation of surface landslide movements, but it cannot provide information about subsurface structures. In this work, InSAR measurements were integrated with seismic noise in situ measurements to analyse both the surface and subsurface characteristics of a complex slow-moving landslide exhibiting multiple failure surfaces. The landslide body involves a town of around 6000 inhabitants, Villa de la Independencia (Bolivia), where extensive damages to buildings have been observed. To investigate the spatial-temporal characteristics of the landslide motion, Sentinel-1 displacement time series from October 2014 to December 2019 were produced. A new geometric inversion method is proposed to determine the best-fit sliding direction and inclination of the landslide. Our results indicate that the landslide is featured by a compound movement where three different blocks slide. This is further evidenced by seismic noise measurements which identified that the different dynamic characteristics of the three sub-blocks were possibly due to the different properties of shallow and deep slip surfaces. Determination of the slip surface depths allows for estimating the overall landslide volume (9.18 · 10⁷ m³). Furthermore, Sentinel-1 time series show that the landslide movements manifest substantial accelerations in early 2018 and 2019, coinciding with increased precipitations in the late rainy season which are identified as the most likely triggers of the observed accelerations. This study showcases the potential of integrating InSAR and seismic noise techniques to understand the landslide mechanism from ground to subsurface.

Emergency response after earthquakes, especially rapid access to building damage information, is of great significance to ensure timely rescue and reduce casualties. However, manual field surveys of building damages are inefficient and dangerous, and optical satellite data are more susceptible to cloud interference after earthquakes. Synthetic Aperture Radar (SAR) is now widely used in disaster response efforts due to its full-time and all-weather capability. According to the change in coherence between SAR images before and after earthquakes, it is possible to identify damaged buildings that cause coherence loss. However, the accuracy of traditional coherence-based damage detection methods is relatively low due to biases in coherence estimation and inconsistency in spatio-temporal baselines. In this study, we propose a new method to produce a post-earthquake Building Damage Proxy Map (BDPM) based on multi-temporal Sentinel-1 coherence, which incorporates homogeneous SAR pixel coherence estimation and histogram matching techniques. The former is used to reduce estimation biases and the latter to reduce the effect of baseline inconsistencies in adjacent coherence maps. We successfully applied this method to the 2022 Mw 6.2 Afghanistan earthquake, the 2023 strong earthquake sequence in Turkey, and the 2023 M s 6.2 Jishishan, China earthquake. We also verified its accuracy (over 80%) by comparing the BDPM with results from the United Nations Institute for Training and Research (UNITAR) and analyzed various factors affecting the distribution of damaged buildings. These analyses confirm the effectiveness of our method for generating BDPM using free medium-resolution Sentinel-1 data, which will greatly assist in earthquake emergency response.

Rapid population growth combined with recent drought events and decades of political instability have left the residents of Kabul facing water scarcity, significantly relying on groundwater. Groundwater overexploitation might have induced various magnitudes of ground subsidence, however, to date, no comprehensive study of ground subsidence in Kabul has been conducted. In this study, we investigated the spatio-temporal evolution of ground deformation phenomena and its main governing processes in Kabul from 2014 to 2019 using C-Band Sentinel-1 derived Interferometric Synthetic Aperture Radar (InSAR) time-series from both ascending and descending orbits to extract the two-dimensional (2D) surface displacement field. Four subsidence bowls were distinguished with highly variable spatial extents and deformation magnitudes over four separate aquifer basins, with the maximum value of −5.3 cm/year observed in the Upper Kabul aquifer basin. A wavelet analysis suggests that there is a strong correlation between the groundwater level variations and subsidence. Investigation of hydrogeological data further reveals that the observed subsidence could be attributed to the presence of highly compressible clayey soils. This detailed space-borne regional survey provides new insights into the main governing mechanism of land subsidence in Kabul and may direct better mitigation plans of potential hazards.

Underground mining activities often lead to large local surface displacements. In this case, the interferometric fringes are dense, the deformation gradient between adjacent pixels tends to exceed π, and traditional phase unwrapping (PU) methods that satisfy the phase continuity assumption have difficulty correctly retrieving the deformation. Deep learning-based PU methods can overcome the phase continuity assumption to a certain extent. However, deep learning-based PU methods also have shortcomings, such as weak generalization, difficulty in transfer, and lack of interpretability. To address these issues, this paper presents a new PU method for large gradient deformation of mining areas that couples knowledge and a deep learning network (KLC-Net). This method integrates the knowledge of the mining area subsidence mechanism and the InSAR phase prior knowledge into the learning network and constructs a knowledge-learning coupling framework of input sample constraints, objective function constraints and network structure constraints. The simulation experiments show that when the noise level is less than π, the KLC-Net algorithm is suitable for interferograms with different imaging geometries. The actual engineering experimental results show that even under severe temporal decorrelation conditions, the KLC-Net algorithm can still effectively retrieve surface deformations up to 1.6 m with an average RMSE of 23.5 mm. These experimental results show that the KLC-Net algorithm can effectively improves the ability and accuracy of PU under large gradient deformations in coal mining areas, and also improves the generalization performance and interpretability of deep learning-based PU methods.