MONITORING AND ASSESSING SURFACE DEFORMATION IN THE ALFREDO MAINIERI PROTTI GEOTHERMAL FIELD, GUANACASTE, COSTA RICA 2021-2022

The Alfredo Mainieri Protti Geothermal Field, located near Miravalles Volcano in Costa Rica's Guanacaste Volcanic Cordillera, has been operational since 1994, providing electricity to nearly 224,000 homes. This study utilizes synthetic aperture radar interferometry (InSAR) to monitor ground displacement in this region, a task historically challenging due to dense vegetation and a dynamic atmosphere. Using Sentinel-1A satellite data from March 2021 to March 2022, we produced dozens of interferograms and applied StAMPS Small Baselines (SB) methods to assess temporal ground displacement associated with geothermal activity. The analysis revealed significant ground displacement around the geothermal plant. The phase range in the line of sight (LOS) showed an average displacement of ~7 cm in areas corresponding to the plant's production Units 1, 2, and 5, some of them exhibiting the substantial negative displacement (~11 cm). In contrast, some units displayed uplift (~7 cm), suggesting a decrease in production or fluid recovery. Additionally, the plant’s injection wells showed ground displacement of -3 cm with periodic increases, likely due to subsurface fluid injection.The time series analysis indicated cycles of uplift and subsidence, with total displacement values of ~3 cm over the year, linked to the extraction and injection processes at the plant. These findings underscore the impact of geothermal activities on ground surface deformation and highlight the importance of InSAR for continuous monitoring of geothermal fields and their interaction with magma bodies. The study demonstrates InSAR's capability to manage anthropogenic ground displacement non-invasively, providing crucial data for risk and hazard management in tropical environments.