Most quiescent volcanoes dissipate important amounts of energy through the direct expulsion of volcanic-hydrothermal fluids. At Solfatara the soil diffuse degassing of deeply derived CO2 affects an area of about 0.5 Km2. The anomalous area (named DDS, Diffuse Degassing Structure) releases about 1500 td-1 of CO2 which corresponds a thermal energy of about 10exp13 Jd-1. At Campi Flegrei the energy involved in such a process is predominant with respect to conduction, and to the energy released by seismic activity and ground deformation. Carbon dioxide soil flux was measured in continuous during five years (1998-2003) inside the crater of Solfatara, at FLXOV1 site, by using the time 0, depth 0 accumulation chamber method. The automatic station acquires, at selectable time intervals, CO2 soil flux and some parameters that influence the CO2 flux, i.e. barometric pressure, air and soil temperature, air and soil humidity, wind speed, rain. The statistical analysis on CO2 soil flux data showed that (1) the highest frequency fluctuations are due to variation of environmental parameters (particularly soil humidity and air temperature) and (2) the long-term trend of the filtered data is correlated with the ground deformation. The correlation between the long-term trend and ground deformation increases back-shifting the CO2 flux signal of 3 months. This delay is due to the inertia of the gas diffusion in the subsoil. In addition, we present here new data on conductive thermal flow and temperature gradient of the soil which was monitored at FLXOV1 site by an automatic instrument since October 2001.
CONTINUOUS MONITORING OF CO2 SOIL DIFFUSE DEGASSING AND HEAT FLUX AT SOLFATARA CRATER (PHLEGRAEAN FIELDS, ITALY)
MORETTI, Roberto;
2003
Abstract
Most quiescent volcanoes dissipate important amounts of energy through the direct expulsion of volcanic-hydrothermal fluids. At Solfatara the soil diffuse degassing of deeply derived CO2 affects an area of about 0.5 Km2. The anomalous area (named DDS, Diffuse Degassing Structure) releases about 1500 td-1 of CO2 which corresponds a thermal energy of about 10exp13 Jd-1. At Campi Flegrei the energy involved in such a process is predominant with respect to conduction, and to the energy released by seismic activity and ground deformation. Carbon dioxide soil flux was measured in continuous during five years (1998-2003) inside the crater of Solfatara, at FLXOV1 site, by using the time 0, depth 0 accumulation chamber method. The automatic station acquires, at selectable time intervals, CO2 soil flux and some parameters that influence the CO2 flux, i.e. barometric pressure, air and soil temperature, air and soil humidity, wind speed, rain. The statistical analysis on CO2 soil flux data showed that (1) the highest frequency fluctuations are due to variation of environmental parameters (particularly soil humidity and air temperature) and (2) the long-term trend of the filtered data is correlated with the ground deformation. The correlation between the long-term trend and ground deformation increases back-shifting the CO2 flux signal of 3 months. This delay is due to the inertia of the gas diffusion in the subsoil. In addition, we present here new data on conductive thermal flow and temperature gradient of the soil which was monitored at FLXOV1 site by an automatic instrument since October 2001.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
