Cluster analysis applications for ground deformation monitoring due to fluid production/injection in underground geological formations, based on InSAR measurements

Underground storage of natural gas (UGS) represents a key tool worldwide used for giving real-time responses to energy demands, in areas lacking near gas reservoirs or with limited gas supply, becoming strategic against high future prices and temporary shortages (Verga, 2018). UGS involves the cyclical injection and withdrawn of gas into subsurface formations in response to the seasonal energy needs (storage during spring-summer months and production during autumn-winter months). Storage activities are expected to increase for meeting the SDGs (Fibbi et al., 2022) storing also H2 and CO2 as potential energy sources and potential solutions to fulfil the net-zero targets. The InSAR satellite measurements have been successfully applied for monitoring the anthropogenic induced ground deformations (GD). The effects of UGS activity are characterized by a seasonal cyclical vertical oscillation behaviour (uplift during injection periods and subsidence during withdrawn). (Codegone et al., 2016). Whereas a more continuous behaviour in time for extended time-frame (i.e. trend) is typical of other anthropic-originated GD, like hydrocarbon production or aquifer withdrawn. However, interpreting large InSAR datasets can be difficult due to the volume of data generated, rising the need for a reliable, consistent, versatile and easy-to-deploy investigation approach. This works addresses both challenges studying two cases, one UGS site near Minerbio city, and one coastal zone near to Ravenna, both in the Po Plain area, part of the Emilia-Romagna region in northern Italy.