Defining the influence area of uplift and subsidence from underground gas storage in anticline structural traps: Insights from InSAR cross-correlation

We investigate the relationship between Underground Gas Storage (UGS) operations and ground deformation of three UGS fields in the Po Plain basin, Italy, hosted in Pliocene clastic deposits within anticline structural traps. Sentinel-1 InSAR data from 2015 to 2021 were analyzed to quantify seasonal uplift and subsidence patterns associated with the cyclic injection and withdrawal of gas. The methodology evaluates correlations between UGS activity and the seasonal amplitude of vertical displacement using cross-correlation parameters R and K, which measure the shape (R) and scale (K) similarity between vertical displacement time series and gas volume fluctuations. Results show that, with the UGS injection/withdrawal plan implemented until 2021, seasonal displacement peaks occur within gas field boundaries and diminish outward. Along the major axis of the anticline traps, UGS-related vertical displacements cease before reaching the field boundary, while transversally, they extend up to approximately 0.5 km beyond. Frequency distributions of seasonal amplitude, R and K values were used to define threshold values for R and K, enabling a quantitative identification of the effective UGS influence area, with GNSS data providing additional constraints. Our findings highlight the influence of structural trap geometry and bounding faults in shaping surface subsidence and uplift patterns. These findings underscore the need for advanced monitoring technologies and a comprehensive understanding of subsurface geology to an effective management of UGS operations. As global demand for gas storage increases, integrating geomechanical modeling with ground deformation monitoring will enhance risk assessment, ensure operational safety, and optimize gas storage strategies. The proposed methodology provides valuable insights for monitoring induced ground deformation, offering a framework for sustainable and effective UGS management.