High-resolution ERT imaging of CO2 degassing along active faults on the south-west flank of the Matese Mts. (Southern Apennines)

The emission of gas along active faults represents the shallow manifestation of a gases migration path from a deep natural source, and it indicates that the fault zones are characterized by high permeability, acting as drains in the crust . When these gases reach the surface, they are usually discharged into the atmosphere from small areas known as gas vents. Understanding gas migration along faults is a key scientific problem in many geoscience researches, such as geothermal exploration and geohazard assessment. The growing attention to this issue is related to the potential impact of the natural CO2 release on human health and ecosystems, groundwater quality, soil mineralogy and CO2 concentrations in the atmosphere. In this framework, for the purposes of the gas hazard assessment, the geophysical prospecting methods are successfully and increasingly applied for the identification of active faults and for the detection and monitoring of CO2 degassing along them. In particular, over the last decade, geoelectrical surveys performed by electrical resistivity tomography (ERT) technique have proven to be among the most appropriate prospecting methods to detect spatial distributions of carbon dioxide, whose emission in non-volcanic areas is essentially controlled by fractures, faults and fault damage zones. Indeed, the ERT technique is able to identify the areas of influence of the gas vent as either conductive and resistive anomalies, depending on the geological environment and the physical, chemical and biological conditions of the investigated risk areas. In this work, we present the results of a high-resolution electrical resistivity tomography survey aimed to identify the active fault zones that control the release of significant CO2 flows in the Ailano area (Matese Mts., Southern Italy).