Dynamics of diffuse CO2 emission from El Hierro volcanic system, Canary Islands
http://adsabs.harvard.edu/abs/2009AGUFM.V21D2023B
Abstract
El Hierro Island (278 km2) is one of the youngest and the southwesternmost of the Canary Islands and rises 4000 m above the sea floor. The main characteristics of El Hierro consist on a truncated trihedron shape and three convergent ridges of volcanic cones. Since fumarolic activity is absent at the surface environment of El Hierro, the study of the evolution of diffuse CO2 emissions becomes an ideal geochemical tool for monitoring its volcanic activity. Since 1998, diffuse CO2 emission has been investigated at El Hierro volcanic system. Since then, a total of 9 diffuse CO2 emission surveys have been performed in the summer periods of 1998, 2001, 2003, 2004, 2005, 2006, 2007, 2008 and 2009, with approximately 600 observation sites. Diffuse CO2 emission measurements were performed by means of a portable NDIR sensor according to the accumulation chamber method. Soil CO2 efflux contour maps were constructed using a Sequential Gaussian Simulation (SGS) as interpolation method. Soil CO2 efflux for all the studies ranged from negligible values to 57.4 g m-2 d-1. Most of the study area showed CO2 efflux background values about 1.3 g m-2 d-1. Relatively high CO2 efflux values (>10 g m-2 d-1), if we consider the mean of the background, were measured along the main volcanic-structural features of study area. The total diffuse CO2 output released to atmosphere was estimated for each survey considering the positive volume generated by interpolation, showing a range between 358 and 1.434 t d-1. Our results reveal significant variations from 1998 to 2009 and indicate that CO2 emissions at El Hierro fluctuate greatly. Temporal variations in the total CO2 output do not seem to be masked by external variations, showing a temporal correlation with the peaks of seismic activity occurred in 2004 and previously to the soil gas survey. The observed changes in the diffuse CO2 emission between 1998 and 2009 suggest a close relationship between strain/stress changes in the subsurface of El Hierro volcanic system and the dynamics of CO2 emission. Performing frequent soil CO2 efflux surveys appear to be an effective surveillance tool for El Hierro volcanic system.
Perhaps FREEPERS and loved ones on the East Coast—particularly in low lying areas . . . would do well to stay alert to realities currently in the Canary Islands???
THANKS TONS for the links, whenifhow:
http://adsabs.harvard.edu/abs/2009AGUFM.V21D2023B
Let me see if I can add some paragraphing to the Abstract:
Abstract
El Hierro Island (278 km2) is one of the youngest and the southwesternmost of the Canary Islands and rises 4000 m above the sea floor. The main characteristics of El Hierro consist on a truncated trihedron shape and three convergent ridges of volcanic cones.
.
Since fumarolic activity is absent at the surface environment of El Hierro, the study of the evolution of diffuse CO2 emissions becomes an ideal geochemical tool for monitoring its volcanic activity.
.
Since 1998, diffuse CO2 emission has been investigated at El Hierro volcanic system. Since then, a total of 9 diffuse CO2 emission surveys have been performed in the summer periods of 1998, 2001, 2003, 2004, 2005, 2006, 2007, 2008 and 2009, with approximately 600 observation sites.
.
Diffuse CO2 emission measurements were performed by means of a portable NDIR sensor according to the accumulation chamber method. Soil CO2 efflux contour maps were constructed using a Sequential Gaussian Simulation (SGS) as interpolation method.
.
Soil CO2 efflux for all the studies ranged from negligible values to 57.4 g m-2 d-1. Most of the study area showed CO2 efflux background values about 1.3 g m-2 d-1. Relatively high CO2 efflux values (>10 g m-2 d-1), if we consider the mean of the background, were measured along the main volcanic-structural features of study area.
.
The total diffuse CO2 output released to atmosphere was estimated for each survey considering the positive volume generated by interpolation, showing a range between 358 and 1.434 t d-1. Our results reveal significant variations from 1998 to 2009 and indicate that CO2 emissions at El Hierro fluctuate greatly.
.
Temporal variations in the total CO2 output do not seem to be masked by external variations, showing a temporal correlation with the peaks of seismic activity occurred in 2004 and previously to the soil gas survey.
.
The observed changes in the diffuse CO2 emission between 1998 and 2009 suggest a close relationship between strain/stress changes in the subsurface of El Hierro volcanic system and the dynamics of CO2 emission.
.
Performing frequent soil CO2 efflux surveys appear to be an effective surveillance tool for El Hierro volcanic system.
This is not a good thing. No fumaroles means there are most likely no 'safety valves' for the magma chamber.......