Soil CO2 degassing in the Azores archipelago

The Azores archipelago is located at the triple junction among the Eurasian, American and African plates and is formed by nine volcanic islands. Present-day activity is characterized not only by seismicity and ground deformation episodes, but secondary manifestations of volcanism are also observed as fumarolic fields, thermal and cold CO2-rich springs as well as soil diffuse degassing areas. The main gases diffusely released through the surface of volcanic edifices in these last areas are CO2 and 222Rn. Permanent monitoring of the main CO2 degassing areas has been carried out in the Azores since 2001 using stations that perform measurements by the accumulation chamber method. Diurnal and seasonal variations have been identified in the long-CO2 time series and the gas flux variations are partially explained by meteorological influences (e.g. rainfall, barometric pressure, wind speed).