HR: 0830h
AN: V21C-0541    [PDF]
TI: Monitoring Diffuse Carbon Dioxide Degassing and Surface Pressure Gradient at Cerro Negro Volcano, Nicaragua
AU: * Meli\'{a}n, G
EM: gladys@iter.rcanaria.es
AF: Environmental Research Division, ITER, Tenerife, Canary Islands, Granadilla, 38611 Spain
AU: Marrero, R
AF: Environmental Research Division, ITER, Tenerife, Canary Islands, Granadilla, 38611 Spain
AU: Galindo, I
AF: Environmental Research Division, ITER, Tenerife, Canary Islands, Granadilla, 38611 Spain
AU: Salazar, J L
AF: Environmental Research Division, ITER, Tenerife, Canary Islands, Granadilla, 38611 Spain
AU: Hern\'{a}ndez, P A
AF: Environmental Research Division, ITER, Tenerife, Canary Islands, Granadilla, 38611 Spain
AU: P\'{e}rez, N M
AF: Environmental Research Division, ITER, Tenerife, Canary Islands, Granadilla, 38611 Spain
AU: Strauch, W
AF: Instituto $Nicarag\"{u}ense$ de Estudios Territoriales, INETER,, P.O. Box,, Managua, 2110 Nicaragua
AB: Diffuse $CO_{2}$ emission studies are becoming a useful geochemical tool for volcano monitoring. Significant temporal variations of diffuse $CO_{2}$ degassing rate seem to be directy related to changes of activity volcanic. Since 1999 a research collaboration program between INETER and ITER has been established for monitoring diffuse $CO_{2}$ emission from Cerro Negro, the most active volcano from the western hemisphere.\\ Surface pressure gradient and diffuse $CO_{2}$ degassing surveys were carried out on March 2002 and 2003 at Cerro Negro. An additional survey of $CO_{2}$ efflux was performed on December 1999. Sampling site distributions were similar for the 1999, 2002 and 2003 surveys covering an area of 0.6 $km^{2}$. Pressure gradient measurements were performed by means of a Setra 239 pressure transducer, and soil $CO_{2}$ efflux measurements were performed by means of a portable NDIR sensor according to the accumulation chamber method. Surface pressure gradient values ranged from -11.7 to 232.8 Pa$m^{-1}$ and -24.2 to 102.0 Pa$m^{-1}$ for 2002 and 2003 surveys, respectively. Soil $CO_{2}$ efflux ranged from 0.5 to 35,000 g$m^{-2}$$d^{-1}$ for 1999, 0.3 to 26,500 g$m^{-2}$$d^{-1}$ for 2002, and 0.3 to 3,002 g$m^{-2}$$d^{-1}$ for 2003 surveys. The total diffuse $CO_{2}$ output for the 2003 survey was estimated about 34 t$d^{-1}$, which is one and two orders of magnitude lower than the estimated for the 1999 survey, 2,800 t$d^{-1}$, (Salazar et al., 2001) and the 2002 survey, 280 t$d^{-1}$, (Galindo et al., 2002). These surveys took place 3 (1999), 17 (2002) and 29 (2003) months after the most recent eruption of Cerro Negro, August 1999. The observed decreasing trend on the diffuse $CO_{2}$ emission is temporarily correlated with a reducing tendency on the surface pressure gradient suggesting a lower advective component for the diffuse degassing mechanism on the surface environment at Cerro Negro. These results show a clear relationship between diffuse $CO_{2}$ emission and the eruptive cycle of Cerro Negro; therefore, the potential of this geochemical tool for its volcanic surveillance.
UR: http://www.iter.es
DE: 8400 VOLCANOLOGY
DE: 8499 General or miscellaneous
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2003 Fall Meeting