Anomalous soil CO2 degassing in relation to faults and eruptive fissures on Mount Etna (Sicily, Italy)

The relationships between soil gas emissions and both tectonic and volcano-tectonic structures on Mt. Etna have been studied. The investigation consisted of soil CO2 flux measurements along traverses orthogonal to the main faults and eruptive fissures of the volcano. Anomalous levels of soil degassing were found mainly in coincidence with faults, whereas only 49% of the eruptive fissures were found to produce elevated CO2 soil fluxes. This result suggests that only zones of strain are able to channel deep gases to the surface. According to this hypothesis, several previously unknown structures are suggested. Based on our geochemical data, new structural maps of different areas of Etna are proposed. The soil CO2 fluxes observed in this study are higher than those measured in a 1987 study, and they are consistent with the higher level of volcanic unrest during the current study.