Carbon dioxide diffuse degassing in the geothermal area of the Copahue ? Caviahue Volcanic Complex

CARDELLINI C; AGUSTO M; NOGUÉS V; LAMBERTI M C; AGUSTO M; FORINO P; LAMBERTI M C; CHIODINI G; SZENTIVÁNYI J; CASELLI A

Puerto Varas

Congreso; Cities on Volcanoes 9; 2016

IAVCEI

The Copahue ? Caviahue Volcanic Complex (CCVC) islocated on the Argentinean ? Chilean border hosting an important magmatic ?hydrothermal system. During 2012 a new eruptive cycle start and it is stillongoing. Several techniques have been used to study the evolution of thiscycle, however, simultaneously we have been working on a project of estimationof the geothermal energy available in this area. The development of a projectof utilization of a renewable energy could constitute a great benefit for theregion around this volcanic complex. In order to contribute to this eventualproject, a carbon dioxide soil diffuse degassing survey has been performed overan area of about 1 km2. 1819 measurements were collected over three campaignscarried out in the summers of 2014, 2015 and 2016. The data were elaboratedusing the Graphical Statistical Approach and the Sequential GaussianSimulations method (GSA and SGS respectively). By means of the GSA, fourlog-normal populations were defined at CCVC geothermal field. Out of the entiredataset, 9% of the measured fluxes belong to a population with a CO2 flux meanvalue of 1421 gm-2day-1, and it is interpreted to represent a population fed byan endogenous, hydrothermal source. The other populations are interpreted asbackground populations related to soil respiration processes. The SGS methodwas applied in order to map the diffuse degassing structures present in theCCVC and to obtain estimates of the total CO2 release. Carbon dioxide anomalieswere registered at three out of the four geothermal sites located in theArgentinean side of the CCVC. The total amount of CO2 released by the wholearea of the geothermal field is 208.5 td-1. Preliminary results by using CO2 asa tracer of the original vapor phase indicate a natural thermal release of upto 100 MW.