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Chigna, Gustavo
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Chigna, Gustavo
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- PublicationOpen AccessSynoptic analysis of a decade of daily measurements of SO2 emission in the troposphere from volcanoes of the global ground-based Network for Observation of Volcanic and Atmospheric Change(2021)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;; ; ; ; ; ; ; ; ; ; ; ; ; ; ;; ; ; ; ; ; ; ; ; ; ;; ; ; ;; Volcanic plumes are common and far-reaching manifestations of volcanic activity during and be-tween eruptions. Observations of the rate of emission and composition of volcanic plumes are essential to rec-ognize and, in some cases, predict the state of volcanic activity. Measurements of the size and location of theplumes are important to assess the impact of the emission from sporadic or localized events to persistent orwidespread processes of climatic and environmental importance. These observations provide information onvolatile budgets on Earth, chemical evolution of magmas, and atmospheric circulation and dynamics. Space-based observations during the last decades have given us a global view of Earth’s volcanic emission, particularlyof sulfur dioxide (SO2). Although none of the satellite missions were intended to be used for measurementof volcanic gas emission, specially adapted algorithms have produced time-averaged global emission budgets.These have confirmed that tropospheric plumes, produced from persistent degassing of weak sources, dominatethe total emission of volcanic SO2. Although space-based observations have provided this global insight intosome aspects of Earth’s volcanism, it still has important limitations. The magnitude and short-term variabilityof lower-atmosphere emissions, historically less accessible from space, remain largely uncertain. Operationalmonitoring of volcanic plumes, at scales relevant for adequate surveillance, has been facilitated through the useof ground-based scanning differential optical absorption spectrometer (ScanDOAS) instruments since the be-ginning of this century, largely due to the coordinated effort of the Network for Observation of Volcanic andAtmospheric Change (NOVAC). In this study, we present a compilation of results of homogenized post-analysisof measurements of SO2flux and plume parameters obtained during the period March 2005 to January 2017of 32 volcanoes in NOVAC. This inventory opens a window into the short-term emission patterns of a diverseset of volcanoes in terms of magma composition, geographical location, magnitude of emission, and style oferuptive activity. We find that passive volcanic degassing is by no means a stationary process in time and thatlarge sub-daily variability is observed in the flux of volcanic gases, which has implications for emission budgetsproduced using short-term, sporadic observations. The use of a standard evaluation method allows for intercom-parison between different volcanoes and between ground- and space-based measurements of the same volcanoes.The emission of several weakly degassing volcanoes, undetected by satellites, is presented for the first time. Wealso compare our results with those reported in the literature, providing ranges of variability in emission notaccessible in the past. The open-access data repository introduced in this article will enable further exploitationof this unique dataset, with a focus on volcanological research, risk assessment, satellite-sensor validation, andimproved quantification of the prevalent tropospheric component of global volcanic emission.405 49 - PublicationOpen AccessThe Magmatic Gas Signature of Pacaya Volcano, With Implications for the Volcanic CO2 Flux From Guatemala(2018)
; ; ; ; ; ; ; ; ; ; ;; ; ; ; ; ;Pacaya volcano in Guatemala is one of the most active volcanoes of the Central American Volcanic Arc (CAVA). However, its magmatic gas signature and volatile output have received little attention to date. Here, we present novel volcanic gas information from in-situ (Multi-GAS) and remote (UV camera) plume observations in January 2016. We find in-plume H2O/SO2 and CO2/SO2 ratios of 2-20 and 0.6-10.5, and an end-member magmatic gas signature of 80.5 mol. % H2O, 10.4 mol. % CO2, and 9.0 mol. % SO2. The SO2 flux is evaluated at 8856550 tons/d. This, combined with co-acquired volcanic plume composition, leads to H2O and CO2 fluxes of 2,23061,390 and 7006440, and a total volatile flux of 3,800 tons/d. We use these results in tandem with previous SO2 flux budgets for Fuego and Santiaguito to estimate the total volcanic CO2 flux from Guatemala at 1,1606600 tons/day. This calculation is based upon CO2/total S (St) ratios for Fuego (1.560.75) and Santiaguito (1.460.75) inferred from a gas (CO2/St ratio) versus traceelement (Ba/La ratio) CAVA relationship. The H2O-poor and low CO2/St ratio ( 1.0-1.5) signature of Pacaya gas suggests dominant mantle-wedge derivation of the emitted volatiles. This is consistent with 3He/4He ratios in olivine hosted fluid inclusions (FIs), which range between 8.4 and 9.0 Ra (being Ra the atmospheric 3He/4He ratio) at the upper limit of MORB range (861 Ra). These values are the highest ever measured in CAVA and among the highest ever recorded in arc volcanoes worldwide, indicating negligible 4He contributions from the crust/slab.237 79 - PublicationOpen AccessIncrement in the volcanic unrest and number of eruptions after the 2012 large earthquakes sequence in Central America(2021-11-17)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;; ; ; ; ; ; ; ;Understanding the relationship cause/effect between tectonic earthquakes and volcanic eruptions is a striking topic in Earth Sciences. Volcanoes erupt with variable reaction times as a consequence of the impact of seismic waves (i.e. dynamic stress) and changes in the stress field (i.e. static stress). In 2012, three large (Mw ≥ 7.3) subduction earthquakes struck Central America within a period of 10 weeks; subsequently, some volcanoes in the region erupted a few days after, while others took months or even years to erupt. Here, we show that these three earthquakes contributed to the increase in the number of volcanic eruptions during the 7 years that followed these seismic events. We found that only those volcanoes that were already in a critical state of unrest eventually erupted, which indicates that the earthquakes only prompted the eruptions. Therefore, we recommend the permanent monitoring of active volcanoes to reveal which are more susceptible to culminate into eruption in the aftermath of the next large-magnitude earthquake hits a region.165 8 - PublicationOpen AccessThermal Remote Sensing for Global Volcano Monitoring: Experiences From the MIROVA System(2020-01-27)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;Volcanic activity is always accompanied by the transfer of heat from the Earth’s crust to the atmosphere. This heat can be measured from space and its measurement is a very useful tool for detecting volcanic activity on a global scale. MIROVA (Middle Infrared Observation of Volcanic Activity) is an automatic volcano hot spot detection system, based on the analysis of MODIS data (Moderate Resolution Imaging Spectroradiometer). The system is able to detect, locate and quantify thermal anomalies in near real-time, by providing, on a dedicated website (www.mirovaweb.it), infrared images and thermal flux time-series on over 200 volcanoes worldwide. Thanks to its simple interface and intuitive representation of the data, MIROVA is currently used by several volcano observatories for daily monitoring activities and reporting. In this paper, we present the architecture of the system and we provide a state of the art on satellite thermal data usage for operational volcano monitoring and research. In particular, we describe the contribution that the thermal data have provided in order to detect volcanic unrest, to forecast eruptions and to depict trends and patterns during eruptive crisis. The current limits and requirements to improve the quality of the data, their distribution and interpretation are also discussed, in the light of the experience gained in recent years within the volcanological community. The results presented clearly demonstrate how the open access of satellite thermal data and the sharing of derived products allow a better understanding of ongoing volcanic phenomena, and therefore constitute an essential requirement for the assessment of volcanic hazards.93 19