Volcanic gases
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Total CO2 output of Puracé volcano (Colombia) was estimated on the basis of fluids discharged by fumaroles, soil gases, and dissolved carbon species in the aquifer. The soil CO2 emission was computed from a field survey of 512 points of... more
Total CO2 output of Puracé volcano (Colombia) was estimated on the basis of fluids discharged by fumaroles, soil gases, and dissolved carbon species in the aquifer. The soil CO2 emission was computed from a field survey of 512 points of CO2 soil flux measurements at the main degassing areas of Puracé volcano. The CO2 flux from Puracé's plume was estimated using an indirect method, that used the SO2 plume flux and CO2 /SO2 ratio of the main high temperature fumarole. The total output of CO2 was estimated at ≅ 1500 t/ day. The main contribution of CO2 comes from the plume (summit degassing) and from soil degassing that emit 673 and 812 t/day, respectively. The contributions of summit and soil degassing areas are comparable, indicating an intermediate degassing style partitioned between closed and open conduit systems. The estimated water vapor discharge (as derived from the chemical composition of the fumaroles, the H2O/CO2 ratio, and the SO2 plume flux) allowed calculation of the total thermal energy (fumarolic, soil degassing, and aqui-fer) released from the Puracé volcanic system. This was 360 MW.
This work presents the results of an extensive geochemical survey aimed at measuring soil CO 2 effluxes and soil temperatures over a large portion of Mt. Etna's summit area, coupled with an updated structural survey of the same area. The... more
This work presents the results of an extensive geochemical survey aimed at measuring soil CO 2 effluxes and soil temperatures over a large portion of Mt. Etna's summit area, coupled with an updated structural survey of the same area. The main goals of this study were i) to find concealed or hidden volcano-tectonic structures in the studied area by detecting anomalous soil gas emissions, ii) to investigate the origin of the emitted gas and the mechanism of gas and heat transport to the surface, iii) to produce a structural model based both on the surface geology and on the soil gas data and, lastly, iv) to contribute to the assessment of hazard from slope failure and crater collapses at Mt. Etna. The results revealed many concealed structural lines that followed the major directions of structural weakness in the summit area of Mt. Etna, mostly due to a combined action of gravitational spreading of the volcano and magma intrusions. Both recent and old volcano-tectonic lines were found to act as pathways for the leakage of magmatic gases to the surface. An important role in driving magmatic gases to the surface is also played by fracturing and faulting due to caldera-forming collapses and smaller crater collapses. Correlation between soil CO 2 emissions and soil temperature allowed discriminating areas of active shallow hy-drothermal circulation along deep fractures (characterized by high values of both parameters, but mostly soil temperature) from those affected by undeveloped fractures that did not reach the surface (characterized by high CO 2 emissions at low temperature). The former corresponded to weak zones of the volcano edifice that were frequently site of past eruptions, indicating that those areas keep a high potential for future opening of eruptive fissures. The latter were likely related to sites where new eruptive fissures may open in the near future due to backward propagation of extensional tectonic stress.
JVGR, 2002. A monitoring system is described which is installed at the Galeras volcano, Colombia. Several parameters like CO2, Rn in the fumarolic gas as well as vapour temperature and pressure are measured every 6 seconds. Variations... more
JVGR, 2002. A monitoring system is described which is installed at the Galeras volcano, Colombia. Several parameters like CO2, Rn in the fumarolic gas as well as vapour temperature and pressure are measured every 6 seconds. Variations in these parameters are observed at a short period of increased seismic activity. At this stage, however, it is uncertain if these variations are linked with the seismic processes. From monitored data we conclude that air can enter the fumarolic gas system which may be influenced by wind direction and strength.
- by Faber, E. and +1
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- Physical Volcanology, Telemetry, Physicochemical, Volcanic gases
The first measurements of volcanic gases in Colombia were obtained during a geothermal feasibility study managed by the Latin American Energy Organization (OLADE), which was executed in the eighties of the twentieth century on several... more
The first measurements of volcanic gases in Colombia were obtained during a geothermal feasibility study managed by the Latin American
Energy Organization (OLADE), which was executed in the eighties of the twentieth century on several volcanoes of Colombia and Ecuador
with the international collaboration of the French BRGM and Geotermica Italiana.
The program for permanent gas monitoring at active volcanoes in Colombia, defining as active those volcanoes which have showed evidences of heat and mass transfer from the Earth’s interior
to the surface, especially in the form of fumaroles and/or thermal springs, initiated just after the worldwide known “Armero’s Tragedy” in 1985.
As a result of the eruption of Nevado del Ruiz, 23000 people, who were living in Armero, Chinchina and Villamaria municipalities, very close to six rivers originated in the flanks of Nevado del Ruiz volcano, lost their lives.
Volcanoes of Colombia with greatest fumarolic manifestations during the last forty years include: Nevado del Ruiz, Nevado del Tolima, Nevado
del Huila, Puracé, Galeras and Cumbal. Some solfatara manifestations can be found at Cerro Machín, Sotara and Azufral volcanoes. Azufral
volcano hosts a green lake inside its crater, and some volcanoes such as Nevado de Santa Isabel and Paramillo de Santa Rosa host lagoons, which sometimes showed thermal and bubbly gas manifestations, also evidenced by the death of births in their banks.
Methodologies which have been used for gas measurements at Colombian active volcanoes for about the last four decades, can be summarized as:
① Frequent on-site sampling with preservation procedures for transport and analyses in a laboratory;
② Permanent networks of soil Radon sensors;
③ Permanent gas telemetered systems in the period 1996-2004;
④ Campaign and permanent networks of gas remote sensors.
Energy Organization (OLADE), which was executed in the eighties of the twentieth century on several volcanoes of Colombia and Ecuador
with the international collaboration of the French BRGM and Geotermica Italiana.
The program for permanent gas monitoring at active volcanoes in Colombia, defining as active those volcanoes which have showed evidences of heat and mass transfer from the Earth’s interior
to the surface, especially in the form of fumaroles and/or thermal springs, initiated just after the worldwide known “Armero’s Tragedy” in 1985.
As a result of the eruption of Nevado del Ruiz, 23000 people, who were living in Armero, Chinchina and Villamaria municipalities, very close to six rivers originated in the flanks of Nevado del Ruiz volcano, lost their lives.
Volcanoes of Colombia with greatest fumarolic manifestations during the last forty years include: Nevado del Ruiz, Nevado del Tolima, Nevado
del Huila, Puracé, Galeras and Cumbal. Some solfatara manifestations can be found at Cerro Machín, Sotara and Azufral volcanoes. Azufral
volcano hosts a green lake inside its crater, and some volcanoes such as Nevado de Santa Isabel and Paramillo de Santa Rosa host lagoons, which sometimes showed thermal and bubbly gas manifestations, also evidenced by the death of births in their banks.
Methodologies which have been used for gas measurements at Colombian active volcanoes for about the last four decades, can be summarized as:
① Frequent on-site sampling with preservation procedures for transport and analyses in a laboratory;
② Permanent networks of soil Radon sensors;
③ Permanent gas telemetered systems in the period 1996-2004;
④ Campaign and permanent networks of gas remote sensors.
Remote sensing data and methods are increasingly being embedded into assessments of volcanic processes and risk. This happens thanks to their capability to provide a spectrum of observation and measurement opportunities to accurately... more
Remote sensing data and methods are increasingly being embedded into assessments of volcanic processes and risk. This happens thanks to their capability to provide a spectrum of observation and measurement opportunities to accurately sense the dynamics, magnitude, frequency, and impacts of volcanic activity in the ultraviolet (UV), visible (VIS), infrared (IR), and microwave domains. Launched in mid-2018, the Special Issue "Remote Sensing of Volcanic Processes and Risk" of Remote Sensing gathers 19 research papers on the use of satellite, aerial, and ground-based remote sensing to detect thermal features and anomalies, investigate lava and pyroclastic flows, predict the flow path of lahars, measure gas emissions and plumes, and estimate ground deformation. The strong multidisciplinary character of the approaches employed for volcano monitoring and the combination of a variety of sensor types, platforms, and methods that come out from the papers testify the current scientific and technology trends toward multi-data and multi-sensor monitoring solutions. The research advances presented in the published papers are achieved thanks to a wealth of data including but not limited to the following: thermal IR from satellite missions (e.g., MODIS, VIIRS, AVHRR, Landsat-8, Sentinel-2, ASTER, TET-1) and ground-based stations (e.g., FLIR cameras); digital elevation/surface models from airborne sensors (e.g., Light Detection And Ranging (LiDAR), or 3D laser scans) and satellite imagery (e.g., tri-stereo Pléiades, SPOT-6/7, PlanetScope); airborne hyperspectral surveys; geophysics (e.g., ground-penetrating radar, electromagnetic induction, magnetic survey); ground-based acoustic infrasound; ground-based scanning UV spectrometers; and ground-based and satellite Synthetic Aperture Radar (SAR) imaging (e.g., TerraSAR-X, Sentinel-1, Radarsat-2). Data processing approaches and methods include change detection, offset tracking, Interferometric SAR (InSAR), photogrammetry, hotspots and anomalies detection, neural networks, numerical modeling, inversion modeling, wavelet transforms, and image segmentation. Some authors also share codes for automated data analysis and demonstrate methods for post-processing standard products that are made available for end users, and which are expected to stimulate the research community to exploit them in other volcanological application contexts. The geographic breath is global, with case studies in Chile, and Iceland. The added value of the published research lies on the demonstration of the benefits that these remote sensing technologies have brought to knowledge of volcanoes that pose risk to local communities; back-analysis and critical revision of recent volcanic eruptions and unrest periods; and improvement of modeling and prediction methods. Therefore, this Special Issue provides not only a collection of forefront research in remote sensing applied to volcanology, but also a selection of case studies proving the societal impact that this scientific discipline can potentially generate on volcanic hazard and risk management.
Imaging cameras operating at ultraviolet (UV) and infrared (IR) wavelengths can measure sulfur dioxide (SO2) gas path concentrations or slant column densities. These measurements are useful in a variety of applications including the... more
Imaging cameras operating at ultraviolet (UV) and infrared (IR) wavelengths can measure sulfur dioxide (SO2) gas path concentrations or slant column densities. These measurements are useful in a variety of applications including the monitoring of emissions from volcanoes and also emissions from stacks at industrial plants and on ships. The usefulness of these data is increased if the emission rates (or fluxes) of the gases can also be estimated. Here we present an optical flow algorithm that allows rapid and accurate estimates of emission rates using both UV and IR camera imagery sampling at around 1 Hz or higher. Examples are provided from measurements made at Turrialba volcano, Costa Rica and also at a ship in Hong Kong harbour. Other aspects of the properties of the fluid flow are also introduced, notably the divergence and the vorticity of the two-dimensional wind field. We demonstrate how the divergence can be used in a new method to calculate the emission rate and show how rotational effects observed in volcanic plumes and the resulting entrainment of ambient air affects plume rise and can be observed using vorticity. This is an important aspect for understanding the emplacement of gases and particles into the atmosphere that are subsequently transported by atmospheric winds, sometimes causing pollution episodes at long distances from the source.
Volcanic gas dispersal can be a serious threat to people living near active volcanoes since it can have short- and long-term effects on human health, and severely damage crops and agricultural land. In recent decades, reliable... more
Volcanic gas dispersal can be a serious threat to people living near active volcanoes since it can have short- and long-term effects on human health, and severely damage crops and agricultural land. In recent decades, reliable computational models have significantly advanced, and now they may represent a valuable tool to make quan- titative and testable predictions, supporting gas dispersal forecasting and hazard assessments for public safety. Before applying a specific modelling tool into hazard quantification, its calibration and its sensitivity to initial and boundary conditions should be carefully tested against available data, in order to produce unbiased hazard quantifications. In this study, we provided a number of prototypical tests aimed to validate the modelling of gas dispersal from a hazard perspective. The tests were carried out at La Soufrière de Guadeloupe volcano, one of the most active gas emitters in the Lesser Antilles.
La Soufrière de Guadeloupe has shown quasi-permanent degassing of a low-temperature hydrothermal nature since its last magmatic eruption in 1530 CE, when the current dome was emplaced. We focused on the distribu- tion of CO2 and H2S discharged from the three main present-day fumarolic sources at the summit, using the mea- surements of continuous gas concentrations collected in the period March–April 2017. We developed a new probabilistic implementation of the Eulerian code DISGAS-2.0 for passive gas dispersion coupled with the mass-consistent Diagnostic Wind Model, using local wind measurements and atmospheric stability information from a local meteorological station and ERA5 reanalysis data. We found that model outputs were not significantly affected by the type of wind data but rather upon the relative positions of fumaroles and measurement stations. Our results reproduced the statistical variability in daily averages of observed data over the investigated period within acceptable ranges, indicating the potential usefulness of DISGAS-2.0 as a tool for reproducing the observed fumarolic degassing and for quantifying gas hazard at La Soufrière. The adopted testing procedure allows for an aware application of simulation tools for quantifying the hazard, and thus we think that this kind of testing should actually be the first logical step to be taken when applying a simulator to assess (gas) hazard in any other volcanic contexts.
La Soufrière de Guadeloupe has shown quasi-permanent degassing of a low-temperature hydrothermal nature since its last magmatic eruption in 1530 CE, when the current dome was emplaced. We focused on the distribu- tion of CO2 and H2S discharged from the three main present-day fumarolic sources at the summit, using the mea- surements of continuous gas concentrations collected in the period March–April 2017. We developed a new probabilistic implementation of the Eulerian code DISGAS-2.0 for passive gas dispersion coupled with the mass-consistent Diagnostic Wind Model, using local wind measurements and atmospheric stability information from a local meteorological station and ERA5 reanalysis data. We found that model outputs were not significantly affected by the type of wind data but rather upon the relative positions of fumaroles and measurement stations. Our results reproduced the statistical variability in daily averages of observed data over the investigated period within acceptable ranges, indicating the potential usefulness of DISGAS-2.0 as a tool for reproducing the observed fumarolic degassing and for quantifying gas hazard at La Soufrière. The adopted testing procedure allows for an aware application of simulation tools for quantifying the hazard, and thus we think that this kind of testing should actually be the first logical step to be taken when applying a simulator to assess (gas) hazard in any other volcanic contexts.
A gas monitoring system has been installed on the volcano Galeras in Colombia as part of a multi-parameter station. Gases are extracted from the fumarolic vapour through a short pipe. After the water has been condensed the gas passes over... more
A gas monitoring system has been installed on the volcano Galeras in Colombia as part of a multi-parameter station. Gases are extracted from the fumarolic vapour through a short pipe. After the water has been condensed the gas passes over sensors for carbon dioxide, sulphur dioxide and radon. Other parameters measured are temperature of the fumarolic vapour, fumarolic pressure, temperature of the ambient air and the ambient atmospheric pressure. The signals of the sensors are digitised in the electronics. The digital data are transmitted every 6 seconds by a telemetry system to the observatory down in the city of Pasto via a repeater station at the rim of the Galeras. The system at the volcano is powered by batteries connected to solar panels. Data are stored in the observatory, they are plotted and compared with all the other information of the multi-parameter station. Although the various compounds of the gas system are well preserved for the very aggressive environment close to the fumarole some problems still remain: Sulphur often plugs the pipe to the sensors and requires maintenance more often than desired. As the volcano is most of the time in clouds the installed solar power system (about 400 Watts maximum power) does not enable to run the system at the fumarole (consumption about 15 Watts) continuously during all nights. Despite these still existing problems some results have been obtained encouraging us to continue the operation of the system, to further develop the technical quality and to increase the number of fumaroles included into a growing monitoring network.
In March 2000 seismic activity in the crater increased accompanied by a small eruption. Several hours before the eruption occurred the usually high CO2-concentration of the fumarolic gas was no longer constant as before but started to oscillate. It continued to oscillate until the seismic events started. Then the CO2-concentration as well as the radon counts decreased and the pressure of the fumarolic vapour increased. Some hours later the seismic activity ceased and the CO2 and radon readings increased again.
From other observations it is suggested that meteorological parameters like wind direction and wind speed at the volcano do influence the pressure and flow regime in the conduits of the fumarole. The observations made so far are important to improve the understanding of processes within the volcano. However, more events have to be waited for during the coming years before processes in the volcano can be modelled.
In March 2000 seismic activity in the crater increased accompanied by a small eruption. Several hours before the eruption occurred the usually high CO2-concentration of the fumarolic gas was no longer constant as before but started to oscillate. It continued to oscillate until the seismic events started. Then the CO2-concentration as well as the radon counts decreased and the pressure of the fumarolic vapour increased. Some hours later the seismic activity ceased and the CO2 and radon readings increased again.
From other observations it is suggested that meteorological parameters like wind direction and wind speed at the volcano do influence the pressure and flow regime in the conduits of the fumarole. The observations made so far are important to improve the understanding of processes within the volcano. However, more events have to be waited for during the coming years before processes in the volcano can be modelled.