The application of remote-sensing techniques to monitor CO2-storage sites for surface leakage : method development and testing at Latera (Italy) where naturally produced CO2 is leaking to the atmosphere

Two airborne remote-sensing flights were conducted above a geothermal field in central Italy (the Latera caldera) where deep, naturally produced CO2 is migrating to surface along faults and leaking to the atmosphere at spatially restricted gas vents. The goal of these surveys was to understand if it is possible to locate CO2 leaking from a CO2 geological storage site through the application of indirect remote-sensing methods that primarily measure plant stress and subsequent ground-based verification using near-surface gas geochemistry techniques. The overall success rate obtained by integrating six different datasets was 39%, although some individual techniques, such as one NDVI survey, achieved a 47% success rate. While the work did discover some vents that were previously unknown, it also failed to locate five vents that are known to exist and, perhaps, other unknown vents. Future work will focus on understanding the various causes of false positives, automation of preliminary data interpretation, and the direct hyperspectral measurement of atmospheric CO2 produced by these natural seeps.