HR: 0830h
AN: V21C-0542    [PDF]
TI: Dinamic of Diffuse CO2 Degassing at the NW Volcanic Rift-Zone of Tenerfe, Canary Island
AU: * Mart\'{i}n, M
AF: Faculty of Chemistry, Univ. of La Laguna, Tenerife, Canary Island, La Laguna, 38206 Spain
AU: D\'{i}az, F
AF: Faculty of Chemistry, Univ. of La Laguna, Tenerife, Canary Island, La Laguna, 38206 Spain
AU: Galindo, I
AF: Environmental Research Division, ITER, Tenerife, Canary Islands, Granadilla, 38611 Spain
AU: Salazar, P
EM: psalazar@iter.rcanaria.es
AF: Environmental Research Division, ITER, Tenerife, Canary Islands, Granadilla, 38611 Spain
AU: Salazar, J
AF: Environmental Research Division, ITER, Tenerife, Canary Islands, Granadilla, 38611 Spain
AU: Hern\'{a}ndez, P
AF: Environmental Research Division, ITER, Tenerife, Canary Islands, Granadilla, 38611 Spain
AU: P\'{e}rez, N
AF: Environmental Research Division, ITER, Tenerife, Canary Islands, Granadilla, 38611 Spain
AB: Tenerife is one of the most active volcanic island of the Canarian archipelago with six historical eruptions. The most recent volcanic activity took place along the NW rift-zone in 1909, Chinyero volcano. Fumarolic activity is absent along the NW rift-zone; therefore, diffuse $CO_{2}$ degassing studies constitute a major geochemical program for the volcanic surveillance of the area. The first survey was carried out in 2000, and 446 observation sites were well distributed along the study area of (72 $Km^{2}$). The most recent survey of diffuse $CO_{2}$ degassing and surface pressure gradient measurements was carried out from July 17 to August 6, 2003 with 441 observation sites covering the same area. Soil $CO_{2}$ efflux measurements were performed by means of a portable NDIR sensor according to the accumulation chamber method, while pressure gradient measurements were performed by means of a Setra 239 Model pressure transducer. Statistical-graphical analysis of the soil $CO_{2}$ efflux data showed two overlapping populations. The background geometric mean was 1.7 g$m^{-2}$$d^{-1}$ and represents 97.5% of the total data. The highest observed $CO_{2}$ efflux value for this 2003 survey was 13 g$m^{-2}$$d^{-1}$, and it is very similar to the observed highest value for the 2000 survey, 15 g$m^{-2}$$d^{-1}$. These peak measurements are 7-9 times background values. Most of the study area showed background values of diffuse $CO_{2}$ emission rate for both surveys. Peak $CO_{2}$ efflux values are spatially correlated to volcanic alignments with a WNW-ESE trend suggesting a clear structural control on the mechanism of diffuse degassing. Surface pressure gradient distribution did not show a clear relationship with $CO_{2}$ efflux distribution. For the 2000 and 2003 survey, the estimated total output for de diffusee CO2 emissioon were 79 and 146 td-1, respectively.
UR: http://www.iter.es
DE: 8400 VOLCANOLOGY
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2003 Fall Meeting