Synthetic Aperture Radar (SAR) has revolutionized the geospatial assessment of surface subsidence, offering precise, temporally dense, and spatially continuous measurements regardless of weather or illumination conditions. This paper presents a comprehensive analysis of SAR-based techniques employed in the detection and quantification of surface subsidence, including Differential Interferometric SAR (D-InSAR), Persistent Scatterer Interferometry (PSI), Small Baseline Subset (SBAS), and Coherent Pixel Technique (CPT). The theoretical frameworks, operational requirements, spatial-temporal resolutions, and inherent limitations of each method are examined. A comparative evaluation is provided to illustrate the strengths and trade-offs of these techniques across varying geological contexts, urban environments, and subsidence-inducing mechanisms such as mining, groundwater extraction, and tectonic activity. The review underscores the growing relevance of SAR interferometry in deformation monitoring and risk mitigation and identifies emerging trends in data fusion, machine learning integration, and satellite mission advancements.