Continuous Monitoring of Co2 Soil Diffuse Degassing In Volcanic Sites: Influence of Environmental and Volcanic Parameters. The Case of Solfatara and Ves Uvius Volcanoes (naples, Italy)
Abstract
Carbon dioxide soil flux was measured in continuous during four years (1998-2001) inside Solfatara crater (temporal series FLXOV1 and FLXOV3) and Vesuvio crater (temporal series FLXOV4) by using the accumulation chamber method. In order to use the acquired data for surveillance purposes it is crucial to distinguish the external factors and to remove their contributions from the raw data. Therefore the CO2 soil flux measurements are coupled with measurements of parameters that potentially can influence the CO2 outcomes, i.e. barometric pressure, air and soil temperature, air and soil humidity, wind speed, rain. The multiple regression analysis (Draper and Smith, 1981) permits to model the effects of external factors on the CO2 soil flux data. The Best Subset Search (Garside, 1971) procedure was employed in order to choose the minimal number of parameters to insert in the model. Filtering the raw data shows that (1) the high frequency fluctuations are due to variation of environmental parameters and (2) the influencing parameters are different according to the site of measurement (soil humidity and air temperature in the case of Solfatara crater, barometric pressure in the case of Vesuvio). In the case of the FLXOV1 record of Solfatara (2 years comprising 8290 CO2 soil flux measurements) it was possible to derive a relation, which permits to eliminate automatically the external noise from the flux data. By applying Integrated Auto Regressive Moving Average process (Box and Jenkins, 1976), and Change Point procedure (Mulargia and Tinti, 1985) a significant change in the long-time trend has been found at the end of March 2000. Concurrently an inversion in the deformation of the soil, from subsidence to uplift, was registered. This deformation event was accompanied by a seismic crisis in August 2000.
- Publication:
-
EGS General Assembly Conference Abstracts
- Pub Date:
- 2002
- Bibcode:
- 2002EGSGA..27.2904G