17 research outputs found
Volcanic plume height monitoring using calibrated web cameras at the Icelandic Meteorological Office: system overview and first application during the 2021 Fagradalsfjall eruption
This research was funded by the International Civil Aviation Organization (ICAO) under the Joint Finance Agreement with the Icelandic Meteorological Office, for working paper JS.212.WP.2054The Icelandic Meteorological Office maintains a national network of webcams designed and built in house for environmental monitoring. During the 2021 Fagradalsfjall eruption these cameras, along with a temporary near-field network of commercial cameras installed by the Department of Civil Protection and Emergency Management, were used to estimate the height of the SO2 plume and lava fountain. Here we present the webcam designs, the techniques used to calibrate them, and the messaging system and web interface that allow near real time measurements to be made from the images. With this system we were able to make estimates of heights with an accuracy on the order of tens to a few hundreds of meters with a lag typically of five to ten minutes at up to ten minute intervals when weather conditions were favorable. The plume heights were then used to constrain the performance of the SO2 dispersion model used for air quality forecasts while fountain heights were used to delineate danger zones where visitors at the eruption site were in danger of being hit by ballistic clasts.Icelandic Meteorological OfficeInternational Civil Aviation Organizatio
Insights into volcanic hazards and plume chemistry from multi-parameter observations: the eruptions of FimmvörĂ°uhĂĄls and Eyjafjallajökull (2010) and Holuhraun (2014â2015)
The eruptions of Eyjafjallajökull volcano in 2010 (including its initial effusive phase at FimmvörĂ°uhĂĄls and its later explosive phase from the central volcano) and BĂĄrĂ°arbunga volcano in 2014â2015 (at Holuhraun) were widely reported. Here, we report on complementary, interdisciplinary observations made of the eruptive gases and lavas that shed light on the processes and atmospheric impacts of the eruptions, and afford an intercomparison of contrasting eruptive styles and hazards. We find that (i) consistent with other authors, there are substantial differences in the gas composition between the eruptions; namely that the deeper stored Eyjafjallajökull magmas led to greater enrichment in Cl relative to S; (ii) lava field SO2 degassing was measured to be 5â20% of the total emissions during Holuhraun, and the lava emissions were enriched in Cl at both fissure eruptionsâparticularly FimmvörĂ°uhĂĄls; and (iii) BrO is produced in Icelandic plumes in spite of the low UV levels
Isotopically (ÎŽ13C and ÎŽ18O) heavy volcanic plumes from Central Andean volcanoes: a field study
Stable isotopes of carbon and oxygen in volcanic
gases are key tracers of volatile transfer between Earthâs interior
and atmosphere. Although important, these data are available
for few volcanoes because they have traditionally been difficult
to obtain and are usually measured on gas samples collected
from fumaroles. We present new field measurements of bulk
plume composition and stable isotopes (ÎŽ13CCO2 and ÎŽ18OH2O+
CO2) carried out at three northern Chilean volcanoes using
MultiGAS and isotope ratio infrared spectroscopy. Carbon
and oxygen in magmatic gas plumes of Lastarria and Isluga
volcanoes have ÎŽ13C in CO2 of +0.76â° to +0.77â° (VPDB),
similar to slab carbonate; and ÎŽ18O in the H2O + CO2 system
ranging from +12.2â° to +20.7â° (VSMOW), suggesting significant
contributions from altered slab pore water and carbonate.
The hydrothermal plume at Tacora has lower ÎŽ13CCO2 of
â3.2â° and ÎŽ18OH2O+CO2 of +7.0â°, reflecting various scrubbing,
kinetic fractionation, and contamination processes. We
show the isotopic characterization of volcanic gases in the field
to be a practical complement to traditional sampling methods,
with the potential to remove sampling bias that is a risk when
only a few samples from accessible fumaroles are used to characterize
a given volcanoâs volatile output. Our results indicate
that there is a previously unrecognized, relatively heavy isotopic
signature to bulk volcanic gas plumes in the Central Andes,
which can be attributed to a strong influence from components
of the subducting slab, but may also reflect some local crustal
contamination. The techniques we describe open new avenues
for quantifying the roles that subduction zones and arc volcanoes
play in the global carbon cycle.Published653V. ProprietĂ dei magmi e dei prodotti vulcaniciJCR Journa
Unrest at the Nevados de ChillĂĄn volcanic complex: a failed or yet to unfold magmatic eruption?
Resuming erupting activity at volcanoes that have been long quiescent poses a significant challenge to hazard assessment, as it require assessment of whether the change in activity is an isolated event or the beginning of a new eruptive sequence. Such inception is often poorly characterised as quiescent volcanoes tend to be poorly equipped and not extensively monitored, especially with respect to gas geochemistry. Here, we report gas composition and flux measurements from a newly opened vent at the very onset of eruptive activity at the Nevados de ChillĂĄn volcanic complex (Chile) in January-February 2016. The molar proportions of H2O, CO2, SO2, H2S and H2 gases are found to be 98.4, 0.97, 0.11, 0.01 and 0.5 mol% respectively. The mean SO2 flux recorded in early February 2016 during periods of eruptive discharge amounts to 0.4-0.6 kg s-1. Our results indicate that the new vent opening was propelled by magmatic gases, triggering repeated eruptions. Ash particles ejected by the first blast of 8 January are dominated by lithic fragments of dacitic composition. By contrast the ash ejected in a subsequent eruption contains both lithic fragments of dense dacite, and a fresher, sparsely vesicular material of basaltic andesite composition. By October 2017 the ejected ash is back to being dominated by the dense dacitic lithic material. Together with the seismic and deformation record, these observations point to the explosive activity resulting from a small intrusion of basaltic to andesitic magma at shallow level. The fate of this magma, whether stalling or eventually triggering a magmatic eruption, remains to be seen, but current observations suggest the former is most likely
First recorded eruption of Nabro volcano, Eritrea, 2011
We present a synthesis of diverse observations of the first recorded eruption of Nabro volcano, Eritrea, which began on 12 June 2011. While no monitoring of the volcano was in effect at the time, it has been possible to reconstruct the nature and evolution of the eruption through analysis of re- gional seismological and infrasound data and satellite remote sensing data, supplemented by petrological analysis of erupted products and brief field surveys. The event is notable for the comparative rarity of recorded historical eruptions in the region and of caldera systems in general, for the prodi- gious quantity of SO2 emitted into the atmosphere and the significant human impacts that ensued notwithstanding the low population density of the Afar region. It is also relevant in understanding the broader magmatic and tectonic signifi- cance of the volcanic massif of which Nabro forms a part and which strikes obliquely to the principal rifting directions in the Red Sea and northern Afar. The whole-rock compositions of
Editorial responsibility: G. Giordano
the erupted lavas and tephra range from trachybasaltic to trachybasaltic andesite, and crystal-hosted melt inclusions contain up to 3,000 ppm of sulphur by weight. The eruption was preceded by significant seismicity, detected by regional networks of sensors and accompanied by sustained tremor. Substantial infrasound was recorded at distances of hundreds to thousands of kilometres from the vent, beginning at the onset of the eruption and continuing for weeks. Analysis of ground deformation suggests the eruption was fed by a shal- low, NWâSE-trending dike, which is consistent with field and satellite observations of vent distributions. Despite lack of prior planning and preparedness for volcanic events in the country, rapid coordination of the emergency response miti- gated the human costs of the eruption
Use of motion estimation algorithms for improved flux measurements using SO 2 cameras
International audienceSO2 cameras are rapidly gaining popularity as a tool for monitoring SO2 emissions from volcanoes. Several different SO2 camera systems have been developed with varying patterns of image acquisition in space, time and wavelength. Despite this diversity, there are two steps common to the workflows of most of these systems; aligning images of different wavelengths to calculate apparent absorbance and estimating plume transport speeds, both of which can be achieved using motion estimation algorithms. Here we present two such algorithms, a Dual Tree Complex Wavelet Transform-based algorithm and the FarnebÀck Optical Flow algorithm. We assess their accuracy using a synthetic dataset created using the numeric cloud-resolving model ATHAM, and then apply them to real world data from Villarrica volcano. Both algorithms are found to perform well and the ATHAM simulations offer useful datasets for benchmarking and validating future algorithms
Multi-parametric field experiment links explosive activity and persistent degassing at Stromboli
Co-auteur Ă©trangerInternational audienceVisually unattainable magmatic processes in volcanic conduits, such as degassing, are closely linked to eruptive styles at the surface, but their roles are not completely identified and understood. To gain insights, a multi-parametric experiment at Stromboli volcano (Aeolian Islands, Italy) was installed in July 2016 focusing on the normal explosive activity and persistent degassing. During this experiment, gas-dominated (type 0) and particle-loaded (type 1) explosions, already defined by other studies, were clearly identified. A FLIR thermal camera, an UV SOâ camera and a scanning DOAS were deployed to record pyroclast and SO2 masses emitted during individual explosions, as well as persistent SOâ fluxes, respectively. An ASHER instrument was also deployed in order to collect ash fallouts and to measure the grain size distribution of the samples. SO2 measurements confirm that persistent degassing was far greater than that emitted during the explosions. Further, we found that the data could be characterized by two periods. In the first period (25-27 July), activity was mainly characterized by type 0 explosions, characterized by high velocity jets. Pyroclast mass fluxes were relatively low (280 kg/event on average), while persistent SO2 fluxes were high (274 t/d on average). In the second period (29-30 July), activity was mainly characterized by type 1 explosions, characterized by low velocity jets. Pyroclast mass fluxes were almost ten times higher (2400 kg/event on average), while persistent gas fluxes were significantly lower (82 t/d on average). Ash characterization also indicates that type 0 explosions fragments were characterized by a larger proportion of non-juvenile material compared to type 1 explosions fragments. This week-long field experiment suggests that, at least within short time periods, Stromboli's type 1 explosions can be associated with low levels of degassing and the mass of particles accompanying such explosive events depends on the volume of a degassed magma cap sitting at the head of the magma column. This could make the classic particle-loaded explosions of Stromboli an aside from the true eruptive state of the volcano. Instead, gas-dominated explosions can be associated with hig
Multi-parametric field experiment links explosive activity and persistent degassing at Stromboli
Co-auteur Ă©trangerInternational audienceVisually unattainable magmatic processes in volcanic conduits, such as degassing, are closely linked to eruptive styles at the surface, but their roles are not completely identified and understood. To gain insights, a multi-parametric experiment at Stromboli volcano (Aeolian Islands, Italy) was installed in July 2016 focusing on the normal explosive activity and persistent degassing. During this experiment, gas-dominated (type 0) and particle-loaded (type 1) explosions, already defined by other studies, were clearly identified. A FLIR thermal camera, an UV SOâ camera and a scanning DOAS were deployed to record pyroclast and SO2 masses emitted during individual explosions, as well as persistent SOâ fluxes, respectively. An ASHER instrument was also deployed in order to collect ash fallouts and to measure the grain size distribution of the samples. SO2 measurements confirm that persistent degassing was far greater than that emitted during the explosions. Further, we found that the data could be characterized by two periods. In the first period (25-27 July), activity was mainly characterized by type 0 explosions, characterized by high velocity jets. Pyroclast mass fluxes were relatively low (280 kg/event on average), while persistent SO2 fluxes were high (274 t/d on average). In the second period (29-30 July), activity was mainly characterized by type 1 explosions, characterized by low velocity jets. Pyroclast mass fluxes were almost ten times higher (2400 kg/event on average), while persistent gas fluxes were significantly lower (82 t/d on average). Ash characterization also indicates that type 0 explosions fragments were characterized by a larger proportion of non-juvenile material compared to type 1 explosions fragments. This week-long field experiment suggests that, at least within short time periods, Stromboli's type 1 explosions can be associated with low levels of degassing and the mass of particles accompanying such explosive events depends on the volume of a degassed magma cap sitting at the head of the magma column. This could make the classic particle-loaded explosions of Stromboli an aside from the true eruptive state of the volcano. Instead, gas-dominated explosions can be associated with hig
Monitoring and forecasting hazards from a slow growing lava dome using aerial imagery, tri-stereo Pleiades-1A/B imagery and PDC numerical simulation
International audienceIn December of 2017, a lava dome emerged at the Nevados de Chillan volcanic complex in the southern Andean volcanic zone, Chile, at the base of a summit crater excavated by explosions during two preceding years of unrest. This posed a number of potential hazards to the surrounding touristic region, so the eruption was carefully monitored. Structure from Motion techniques were used to generate DEMs from satellite and aerial images, from which several useful measurements could be made. Dome growth was characterised at an unprecedented resolution, allowing for the calculation of discharge rates and effusion rates in near real time. A simple model fit to the distance between the dome and crater rim predicted relatively accurately the arrival of the dome toe at the crater rim and the onset of dome collapse outside the crater. Simulations of the path and extent that potential pyroclastic density currents (PDC) generated by dome collapse would follow showed that PDC were not directly threatening populated areas. Over its life cycle as of August 2019, the dome growth was punctuated by frequent explosions, averaging around 30 per day, one of which generated a minor 600 m long PDC on 13 to 15 of July 2018. There appears to be a positive correlation between explosion frequency and lava dome growth rate suggesting that both explosive and effusive processes can coexist, operating at different timescales but responding to the same driving force. A positive correlation is apparent between dome growth rate and seismic activity such as the frequency of tremor and long-period earthquakes suggesting that these might be used as proxies to estimate effusion rate. Initial lava dome effusion rates of 1730 ± 110 m3/day in January 2018 declined to 100 ± 150 m3/day in June 2019. These growth rates are extremely slow when compared to other lava domes, about 300 to 600 times slower than the lava domes at Mt Unzen (1992) and Mt. St. Helens (1980)
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Near-surface magma flow instability drives cyclic lava fountaining at Fagradalsfjall, Iceland
Acknowledgements: We thank the Icelandic Ministry of Environment, Energy and Climate (Umhverfis-, orku- og loftslagsrĂĄĂ°uneytiĂ°; URN) for funding the volcano monitoring efforts at Fagradalsfjall, and Prof. Evgenia Ilyinskaya (University of Leeds) for acquiring the FTIR spectrometer used in this study. We thank Sveinbjörn SteinĂŸĂłrsson for providing help with the eruption monitoring efforts at the University of Iceland and the Department of Civil Protection (Almannavarnir) for providing help and access to the eruption site. S.W.S. thanks Prof. Eva Eibl (University of Potsdam) for stimulating discussions and insight into the physical mechanisms driving intermittent lava fountaining at Fagradalsfjall.AbstractLava fountains are a common manifestation of basaltic volcanism. While magma degassing plays a clear key role in their generation, the controls on their duration and intermittency are only partially understood, not least due to the challenges of measuring the most abundant gases, H2O and CO2. The 2021 Fagradalsfjall eruption in Iceland included a six-week episode of uncommonly periodic lava fountaining, featuringâ~â100â400âm high fountains lasting a few minutes followed by repose intervals of comparable duration. Exceptional conditions on 5 May 2021 permitted close-range (~300âm), highly time-resolved (everyâ~â2âs) spectroscopic measurement of emitted gases during 16 fountain-repose cycles. The observed proportions of major and minor gas molecular species (including H2O, CO2, SO2, HCl, HF and CO) reveal a stage of CO2 degassing in the upper crust during magma ascent, followed by further gas-liquid separation at very shallow depths (~100âm). We explain the pulsatory lava fountaining as the result of pressure cycles within a shallow magma-filled cavity. The degassing at Fagradalsfjall and our explanatory model throw light on the wide spectrum of terrestrial lava fountaining and the subsurface cavities associated with basaltic vents.</jats:p