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Aiuppa A.,University of Palermo | Aiuppa A.,Italian National Institute of Geophysics and Volcanology | Robidoux P.,University of Palermo | Tamburello G.,University of Palermo | And 7 more authors.
Earth and Planetary Science Letters | Year: 2014

Obtaining accurate estimates of the CO2 output from arc volcanism requires a precise understanding of the potential along-arc variations in volcanic gas chemistry, and ultimately of the magmatic gas signature of each individual arc segment. In an attempt to more fully constrain the magmatic gas signature of the Central America Volcanic Arc (CAVA), we present here the results of a volcanic gas survey performed during March and April 2013 at five degassing volcanoes within the Costa Rica-Nicaragua volcanic segment (CNVS). Observations of the volcanic gas plume made with a multicomponent gas analyzer system (Multi-GAS) have allowed characterization of the CO2/SO2-ratio signature of the plumes at Poás (0.30±0.06, mean ± SD), Rincón de la Vieja (27.0±15.3), and Turrialba (2.2±0.8) in Costa Rica, and at Telica (3.0±0.9) and San Cristóbal (4.2±1.3) in Nicaragua (all ratios on molar basis). By scaling these plume compositions to simultaneously measured SO2 fluxes, we estimate that the CO2 outputs at CNVS volcanoes range from low (25.5±11.0 tons/day at Poás) to moderate (918 to 1270 tons/day at Turrialba). These results add a new information to the still fragmentary volcanic CO2 output data set, and allow estimating the total CO2 output from the CNVS at 2835±1364 tons/day. Our novel results, with previously available information about gas emissions in Central America, are suggestive of distinct volcanic gas CO2/ST (= SO2 + H2S)-ratio signature for magmatic volatiles in Nicaragua (~3) relative to Costa Rica (~0.5-1.0). We also provide additional evidence for the earlier theory relating the CO2-richer signature of Nicaragua volcanism to increased contributions from slab-derived fluids, relative to more-MORB-like volcanism in Costa Rica. The sizeable along-arc variations in magmatic gas chemistry that the present study has suggested indicate that additional gas observations are urgently needed to more-precisely confine the volcanic CO2 from the CAVA, and from global arc volcanism. © 2014 Elsevier B.V. Source

Conde V.,Chalmers University of Technology | Bredemeyer S.,Leibniz Institute of Marine Science | Saballos J.A.,Instituto Nicaraguense Of Estudios Territoriales Ineter | Galle B.,Chalmers University of Technology | Hansteen T.H.,Leibniz Institute of Marine Science
International Journal of Earth Sciences | Year: 2015

San Cristóbal volcano is the highest and one of the most active volcanoes in Nicaragua. Its persistently high activity during the past decade is characterized by strong degassing and almost annual VEI 1–2 explosions, which present a threat to the local communities. Following an eruption on 8 September 2012, the intervals between eruptions decreased significantly, which we interpret as the start of a new eruptive phase. We present here the results of semi-continuous SO2 flux measurements covering a period of 18 months, obtained by two scanning UV-DOAS instruments installed as a part of the network for observation of volcanic and atmospheric change project, and the results of real-time seismic amplitude measurements (RSAM) data. Our data comprise a series of small to moderately explosive events in December 2012, June 2013 and February 2014, which were accompanied by increased gas emissions and seismicity. In order to approach an early warning strategy, we present a statistical method for the joint analysis of gas flux and seismic data, by using continuous wavelet transform and cross-wavelet transform (XWT) methods. This analysis shows that the XWT coefficients of SO2 flux and RSAM are in good agreement with the occurrence of eruptive events and thus may be used to indicate magma ascent into the volcano edifice. Such multi-parameter surveillance efforts can be useful for the interpretation and surveillance of possible eruptive events and could thus be used by local institutions for the prediction of upcoming volcanic unrest. © 2015 Springer-Verlag Berlin Heidelberg Source

Perez N.M.,Instituto Tecnologico Y Of Energias Renovables Iter | Hernandez P.A.,Instituto Tecnologico Y Of Energias Renovables Iter | Padilla G.,Instituto Tecnologico Y Of Energias Renovables Iter | Nolasco D.,Instituto Tecnologico Y Of Energias Renovables Iter | And 12 more authors.
Geology | Year: 2011

The global CO2 discharge from subaerial volcanism has been estimated at ~300 Mt yr-1. However, estimates of CO2 emissions from volcanic lakes have not been considered. In order to improve this information, extensive research on CO2 emissions of volcanic lakes worldwide has been performed. The observed normalized average CO2 emission rates increase from alkaline (5.5 t km-2 d-1), to neutral (201.2 t km-2 d-1), to acid (614.2 t km-2 d-1) in volcanic lakes. Taking into account (1) normalized CO2 emission rates, (2) the number of volcanic lakes in the world (~769), and (3) the fraction and average areas of the investigated alkaline, neutral, and acid volcanic lakes, the estimated global CO2 emission from volcanic lakes is 117 ± 19 Mt yr-1, with 94 ± 17 Mt yr-1 as deep-seated CO2. This study highlights the importance of a revision of the actual global CO2 discharge from subaerial volcanism. © 2011 Geological Society of America. Source

Scaini C.,Barcelona Supercomputing Center | Folch A.,Barcelona Supercomputing Center | Navarro M.,Instituto Nicaraguense Of Estudios Territoriales Ineter
Journal of Volcanology and Geothermal Research | Year: 2012

Concepción volcano in Ometepe Island, Nicaragua, is a highly active volcano with a rich historical record of explosive eruptions. Tephra fallout from Concepción jeopardizes the surrounding populations, whereas volcanic ash clouds threat aerial navigation at a regional level. The assessment of these hazards is important for territorial planning and adoption of mitigation measures. Here we compute probabilistic hazard maps for Concepción volcano considering three different eruptive scenarios based on past reference events. Previous geological analysis is used to quantify the eruption parameters of the reference events. We account for uncertainties in the definition of the scenarios trough probability density functions. A representative meteorological dataset is created for each scenario by running the WRF-ARW mesoscale meteorological model over a typical meteorological year, defined in terms of wind speed and direction at a given atmospheric height. Tephra transport and deposition under different eruption and wind conditions is modelled using the FALL3D dispersion model. For each scenario, simulations are combined to build probabilistic hazard maps for critical values of tephra load and for threshold values of airborne ash concentration at relevant flight levels. Results are useful to identify the expected impacts for each eruption type and aim at improving the assessment and management of risk in the region. © 2012 Elsevier B.V. Source

Longpre M.-A.,Queens College, City University of New York | Longpre M.-A.,McGill University | Stix J.,McGill University | Costa F.,Nanyang Technological University | And 2 more authors.
Journal of Petrology | Year: 2014

Cosigüina volcano, in northwestern Nicaragua, erupted violently on 20-24 January 1835, producing pumice, scoria, ash fall deposits, and pyroclastic flows with a bulk tephra volume of ~6 km3. New geochemical data are presented for bulk-rocks, matrix glasses, melt inclusions and minerals from the 1835 deposits and a pre-1835 basaltic andesite tephra, with the aim of shedding light on the magmatic processes and associated timescales that led to the eruption. Our results reveal that the 1835 eruption was fed by a compositionally and thermally zoned magma reservoir situated ~4 km (PH2O ~100MPa) beneath the volcano. Small volumes of crystal-poor dacite (510 wt % phenocrysts, 63·8-64·8 wt % SiO2, ~950°C) and silicic andesite (<10 wt % phenocrysts, 62·2 wt % SiO2, 960-1010°C) were erupted first, followed by relatively crystal-rich andesite (15-30 wt % phenocrysts, 57·4-58·8 wt % SiO2, 960-1010°C), which accounts for ~90% of the erupted magma. The pre-1835 basaltic andesite (~20 wt % phenocrysts, 52·4wt % SiO2, 1110-1170°C) represents a mafic end-member for Cosigüina. The major and trace element compositions of the bulk-rocks, melt inclusions and matrix glasses suggest that (1) the pre-1835 basaltic andesite is a plausible parent for the 1835 magmas, (2) the 1835 andesite bulk-rocks do not represent true melts, but instead mixtures of silicic andesite liquid and a component of accumulated crystals dominated by plagioclase, and (3) the silicic andesite and dacite formed from the andesite magma through liquid extraction followed by fractional crystallization. Observed bimodal to trimodal crystal populations are consistent with a multi-stage, polybaric differentiation process, with calcic plagioclase (An75-90, An90-95) and magnesian clinopyroxene (Mg#=67-75), plus olivine and magnetite, forming from mafic andesite, basaltic andesite and basalt in the lower crust. The calcic plagioclase exhibits sieve textures, which may be the result of H2O-undersaturated decompression during magma ascent to the upper crust; An50-65 plagioclase lacking a sieve texture, orthopyroxene (Mg#=61 and 63-72), clinopyroxene (Mg#=67), magnetite and apatite crystallized from andesite to dacite liquids in the shallow magma reservoir. An75-90 plagioclase comprising entire phenocrysts or cores with An50-65 rims in the 1835 magmas is cognate from earlier stages of differentiation and shows evidence of extensive diffusion of Mg when compared with similar An75-95 crystals hosted in the pre-1835 basaltic andesite. Using plagioclase-melt Mg partitioning and modelling of the Mg diffusion process, we constrain the residence time of these crystals in the silicic liquids to more than 100 years and less than 2000 years, with detailed analysis of three crystals yielding ~400 years. We propose that magma reservoir zonation occurred on timescales of 102-103 years at Cosigüina.The occurrence of H2O-rich fluid inclusions in all 1835 samples and volatile element systematics in melt inclusions imply that the magmas were saturated with a vapour phase (H2O, S, ± CO2) during much of their evolution in the upper crust. Accumulation of free gas at the top of the magma reservoir may have led to overpressurization of the system, triggering the eruption. Catastrophic release of this exsolved vapour and syn-eruptive devolatilization of the melt injected several teragrams of S into the atmosphere. Our data, coupled with independent evidence from ice cores and tree rings, indicate that the Cosigüina eruption had a sizeable atmospheric impact comparable with or larger than that of the 1991 Pinatubo eruption. Stratigraphic evidence shows that Cosigüina has produced >15 compositionally zoned explosive eruptions in the past, suggesting that similar future eruptions are likely.The products of the 1835 eruption of Cosigüina share many features with compositionally zoned eruptive sequences elsewhere, such as the climactic eruption of Mount Mazama, the AD 79 'Pompei' eruption of Vesuvius and the 1912 eruption of Novarupta-Katmai. © The Author 2014. Published by Oxford University Press. All rights reserved. Source

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