| dc.description.abstract | The increasing frequency of geological hazards, worsened by climate change, poses a major national concern for Vietnam. The country stands out as a hotspot for widespread occurrences of two dominant geohazards: land subsidence and landslides. These hazards often remain unnoticed until they trigger pronounced impacts on infrastructure and result in casualties. While ground observation proves ineffective in monitoring these hazards, integrating satellite-based data offers a potentially more efficient solution. The primary concerns with utilizing satellite data are its practical application and accuracy levels. The objective of this thesis is to demonstrate practical use cases of satellite data in the detection and management of anthropogenic geohazards. With appropriate processing, satellite measurement can achieve high accuracy for practical applications worldwide. Furthermore, combining ground observations with satellite analysis offers a more comprehensive study than relying solely on either method. This thesis presents two cases demonstrating the utilization of satellite data to study geohazards in Vietnam. Chapter 2 examines the long-term subsidence in Hanoi city using Interferometric Synthetic Aperture Radar (InSAR) technology. We process multi-SAR satellites imagery to provide a continuous observation of ground displacement between 2007 and 2018. The time series of displacement reveals the significant subsidence in suburban strongly correlated with the depletion of groundwater since 1990. Over two decades, the rapid loss of groundwater storage, combined with the gradual compaction of hydrogeological layers, has resulted in delayed subsidence. To improve the subsidence prediction, we apply a one-dimensional diffusion model to determine properties of these layers, thereby enhancing the accuracy our predictions. Furthermore, we explore factors contributing to sinking cities in Southeast Asia to address the issue. In Chapter 3, we focus on assessing potential geohazards at an open-pit mining site. Initially, we employ photogrammetric stereo techniques to generate multi-temporal Digital Elevation Models from optical satellite images, unveiling two decades of elevation changes with the emergence of manmade slopes at the Nui Beo mining site in Quang Ninh province. Subsequently, we discover that significant landscape alterations at the mining site have led to subsidence in nearby residential areas, as detected through InSAR between 2015 and 2021. In the open-pit, the mixing of water-related signals and displacement trends in InSAR time series poses a challenge for identifying slope stability. To address this, we decompose the signal to retrieve corrected displacement time series. We apply the inverse velocity method on corrected displacement to assess slope instability and estimate the timing of potential failure. Ultimately, we identify hotspots that should be monitored for risk management and warning purposes. | en_US |