Quiescent volcanoes can release through diffuse soil degassing amounts of CO2 higher than the gas discharged by active fumarolic systems and some times comparable to the gas emitted by plumes of erupting volcanoes. However the diffuse degassing rate can not be directly compared to volcanic activity because of the strong influence that air and soil environmental variables have on soil fluxes. Rain, barometric pressure, soil and air temperature and humidity, wind speed and wind direction can affect soil gas concentration, and consequently the diffuse soil degassing. In order to investigate the possibility of using soil CO2 flux (jCO2) as a geochemical tracer of volcanic activity, the Osservatorio Vesuviano has recently installed four soil CO2 automatic stations (SCAS), two at Vesuvio and two at Campi Flegrei (Solfatara crater). At Vesuvio SCAS are located one at the bottom of the crater close to fumarolic vents and the other one on the western crater rim.. At Campi Flegrei the two SCAS are located inside Solfatara crater were large amount of deeply derived fluids are released through both fumarolic activity and soil diffuse degassing. SCAS automatically acquire: jCO2, soil and air temperature, soil and air humidity, barometric pressure, wind speed. The results of 2 years of continuous monitoring suggest that jCO2 is differently affected by environmental parameters in each of the monitoring sites. In order to use profitably the information contained in the data recorded, we have quantified the relation among the external factors and the flux outcomes, and then we have removed the contribution of the external factors from the raw data. The filtered data, which are related to the “deep” sign, suggest that during 1998-2000 no important variations on jCO2 occurred at the monitoring sites. In order to obtain information on the whole degassing process, periodical jCO2 and soil temperature surveys have been performed covering representative sector of Vesuvio and Solfatara. The results of these periodic measurements show variations which could be related to changes in the deep systems.
CONTINUOUS AND DISCONTINUOUS MONITORING OF CO2 SOIL DIFFUSE DEGASSING IN VOLCANIC SITES: THE CASE OF SOLFATARA (CAMPI FLEGREI) AND VESUVIO VOLCANOES
MORETTI, Roberto;
2001
Abstract
Quiescent volcanoes can release through diffuse soil degassing amounts of CO2 higher than the gas discharged by active fumarolic systems and some times comparable to the gas emitted by plumes of erupting volcanoes. However the diffuse degassing rate can not be directly compared to volcanic activity because of the strong influence that air and soil environmental variables have on soil fluxes. Rain, barometric pressure, soil and air temperature and humidity, wind speed and wind direction can affect soil gas concentration, and consequently the diffuse soil degassing. In order to investigate the possibility of using soil CO2 flux (jCO2) as a geochemical tracer of volcanic activity, the Osservatorio Vesuviano has recently installed four soil CO2 automatic stations (SCAS), two at Vesuvio and two at Campi Flegrei (Solfatara crater). At Vesuvio SCAS are located one at the bottom of the crater close to fumarolic vents and the other one on the western crater rim.. At Campi Flegrei the two SCAS are located inside Solfatara crater were large amount of deeply derived fluids are released through both fumarolic activity and soil diffuse degassing. SCAS automatically acquire: jCO2, soil and air temperature, soil and air humidity, barometric pressure, wind speed. The results of 2 years of continuous monitoring suggest that jCO2 is differently affected by environmental parameters in each of the monitoring sites. In order to use profitably the information contained in the data recorded, we have quantified the relation among the external factors and the flux outcomes, and then we have removed the contribution of the external factors from the raw data. The filtered data, which are related to the “deep” sign, suggest that during 1998-2000 no important variations on jCO2 occurred at the monitoring sites. In order to obtain information on the whole degassing process, periodical jCO2 and soil temperature surveys have been performed covering representative sector of Vesuvio and Solfatara. The results of these periodic measurements show variations which could be related to changes in the deep systems.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
