Mount Etna as a terrestrial laboratory to investigate recent volcanic activity on Venus by future missions:A comparison with Idunn Mons, Venus

The recently selected missions to Venus have opened a new era for the exploration of this planet. These missions will provide information about the chemistry of the atmosphere, the geomorphology, local-to-regional surface composition, and the rheology of the interior. One key scientific question to be addressed by these future missions is whether Venus remains volcanically active, and if so, how its volcanism is currently evolving. Hence, it is fundamental to analyze appropriate terrestrial analog sites for the study of possibly active volcanism on Venus. To this regard, we propose Mount Etna - one of the most active and monitored volcanoes on Earth - as a suitable terrestrial laboratory for remote and in-situ investigations to be performed by future missions to Venus. Being characterized by both effusive and explosive volcanic products, Mount Etna offers the opportunity to analyze multiple eruptive styles, both monitoring active volcanism and identifying the possible occurrence of pyroclastic activity on Venus. We directly compare Mount Etna with Idunn Mons, one of the most promising potentially active volcanoes of Venus. Despite the two structures show a different topography, they also show some interesting points of comparison, and in particular: a) comparable morpho-structural setting, since both volcanoes interact with a rift zone, and b) morphologically similar volcanic fields around both Mount Etna and Idunn Mons. Given its ease of access, we also propose Mount Etna as an analog site for laboratory spectroscopic studies to identify the signatures of unaltered volcanic deposits on Venus

Flank instability at Mount Etna: testing the sensitivity of forward models to the internal structure

The deformation recorded at Mount Etna during the last 15 years clearly shows that there is an interplay between activity of magmatic sources and instability of the SE sector. In particular, the anomalous sliding of the SE flank can be triggered by summit or flank eruptions (e.g., 2002), but it is also observed during quiescent loading phases (e.g., 1993-1997). This deformation is usually modeled by sub-horizontal dislocation surfaces (embedded in an elastic half space) whose parameters are determined fitting the observed surface deformation. The purpose of this paper is to investigate whether models forced by a simple isotropic expansion source but taking into account the internal structure of Mount Etna are capable to focus a significant amount of horizontal deformation in the eastern flank. We perform computations based on the finite element method along a 2D cross section. The deformation models include both topography and a synthetic reconstruction of the internal layering constrained by geology, seismic tomography and experimental measurements of Etnean rocks. We study the sensitivity of the predicted surface displacement to variations of internal layers rheology and/or mechanical parameters. Our first results suggest that significant contributions to increase the deformation in the SE sector are due to plastic rheology of the clay layers and to asymmetrical distribution of elastic parameters related to the high velocity body underneath Mount Etna imaged by seismic tomography

The use of infrasound in volcano monitoring : contribution for future application in the Azores Islands

Dissertação de Mestrado, Vulcanologia e Riscos Geológicos, 22 de fevereiro de 2019, Universidade dos Açores.Infrassons resultam de perturbações na pressão atmosférica associadas quer a fontes naturais quer antropogénicas. Entre as causas naturais estão eventos extremos que ocorrem na atmosfera, tais como tempestades, avalanches, sismos e erupções vulcânicas. As principais origens das fontes antropogénicas são explosões relacionadas com a atividade mineira, produção química e testes nucleares. Devido á sua baixa frequência (<20 Hz), podem percorrer longas distâncias através de correntes atmosféricas e serem registados a vários milhares de quilómetros de distância da fonte. Erupções vulcânicas são processos através dos quais os sistemas vulcânicos restauram o equilíbrio perturbado pela ascensão de magma de um reservatório na profundidade da crosta. Quando um vulcão entra em erupção, liberta energia sob a forma de ondas de pressão para a atmosfera, geralmente de baixa frequência, abaixo da faixa audível para o ouvido humano. O uso de infrassons proporciona uma valiosa ferramenta de trabalho para monitorização da atividade vulcânica, tanto a nível local como a nível global. Existe uma variedade de estilos eruptivos, e cada um produz inequívocos sinais de infrassons, normalmente relacionados com explosões, tremor, desenvolvimento da coluna eruptiva e desgaseificação. A utilização de infrassons aumenta a eficácia na monitorização da perigosidade vulcânica, uma vez que o campo de pressão dos infrassons pode estar diretamente relacionado com a taxa de fluxo de gás libertado. Recentemente, o estudo de vulcões ativos através de infrassons, tem permitido, com sucesso, avanços na mitigação do risco vulcânico e na compreensão dos processos de origem vulcânica. No vulcão Etna, em Itália, a monitorização com recurso a um array de microbarómetros permitiu sugerir uma transição de fluxo de gás lento a impulsivo na génese de fontes de lava, com as duas fases a serem associadas a diferentes assinaturas dos sinais infrassónicos. O Instituto de Investigação em Vulcanologia e Avaliação de Riscos - IVAR, opera uma estação de infrassons localizada na ilha da Graciosa, IS42, que integra o Sistema Internacional de Monitorização (IMS) que operacionaliza o regime de verificação do Tratado de Proibição Total de Ensaios Nucleares (CTBT). Integra também o consórcio do projeto ARISE da União Europeia, com o objetivo de desenvolver trabalhos de colaboração sobre a utilização de infrassons na observação de eventos extremos. Inserido no tema, o trabalho apresentado no âmbito desta tese tem como objetivos, (1) a verificação da capacidade da estação I42PT de detetar, localizar e caraterizar ondas infrassónicas originadas por atividade vulcânica a longas distâncias, mostrando como exemplos a erupção do vulcão Grímsvötn, na Islândia, de 21 a 30 de maio de 2011, e episódios eruptivos paroxísticos de maio a agosto de 2011 e atividade eruptiva entre 16 a 22 de maio de 2016 do vulcão Mt. Etna em Itália; e (2) a verificação da capacidade da estação I42PT de detetar localizar e caraterizar ondas infrassónicas originadas por outros eventos extremos na área do Atlântico Norte.ABSTRACT: Infrasound is an atmospheric pressure perturbation associated both to natural or man-made sources. Among the natural causes are the atmospheric extreme events like severe weather, avalanches, earthquakes and volcanic eruptions. The major sources of anthropogenic sources are explosions related with mining, chemical production and nuclear tests. Due its low frequency (<20 Hz) they can travel long distance in atmospheric waveguides and be recorded several thousand kilometres from the source. Eruptions are processes in which volcanoes restore the equilibrium perturbed by rising magma in a chamber deep in the crust. When a volcano erupts, it releases energy in the form of pressure waves into the atmosphere, generally with low frequency, below the audible range of human hearing. The use of infrasound provides a valuable working tool for monitoring volcanic activity, both in the near- and far-field. There are a variety of eruptive styles, and each one produces unique and different infrasound signals, most commonly related to explosions, tremor, eruptive column and degassing. Infrasound also enhances the efficacy of the volcanic hazard monitoring once the infrasonic pressure field may be directly associated with the flux rate of gas released. Recently, infrasound studies from active volcanoes have permitted successful advances in volcanic hazards mitigation and in the understanding of volcanic source. On Etna volcano, infrasound array monitoring allowed to suggest a gas flow regime transition from slug to churn flow, driving lava fountains, with the two phases being reflected by different infrasonic signature. The Instituto de Investigação em Vulcanologia e Avaliação de Riscos - IVAR operates an infrasound station (IS42) located in Graciosa island, which integrates the International Monitoring System (IMS) that operationalise the verification regime of the Comprehensive Test-Ban Treaty (CTBT). It also integrates the European Union ARISE project consortium, with the objective to develop collaborative research on infrasound regarding extreme events. The work presented within the scope of this thesis has as objectives: - (1) the verification of the capacity of the I42PT station to detect, locate and characterize infrasound waves originated from volcanic activity and propagated over long distances, showing as examples the eruption of the Grímsvötn volcano, Iceland, from 21st to 30th May 2011, and Mt. Etna volcano (Italy) paroxysmal eruptive episodes from May-August 2011 and eruptive activity between 16th to 22nd May2016. -(2) to check the ability of the I42PT station to detect and characterize infrasonic waves originating from other extreme events in the North-Atlantic area

Impulsive supply of volatile-rich magmas in the shallow plumbing system of Mt. Etna volcano

Magma dynamics at Mt. Etna volcano are frequently recognized as the result of complex crystallization regimes that, at shallow crustal levels, unexpectedly change from H2O -undersaturated to H2O-saturated conditions, due to the impulsive and irregular arrival of volatile-rich magmas from mantle depths. On this basis, we have performed hydrous crystallization experiments for a quantitative understanding of the role of H2O in the differentiation of deep-seated trachybasaltic magmas at the key pressure of the Moho transition zone. For H2O = 2.1–3.2 wt %, the original trachybasaltic composition shifts towards phonotephritic magmas never erupted during the entire volcanic activity of Mt. Etna. Conversely, for H2O = 3.8–8.2 wt %, the obtained trachybasalts and basaltic trachyandesites reproduce most of the pre-historic and historic eruptions. The comparison with previous low pressure experimental data and natural compositions from Mt. Etna provides explanation for (1) the abundant release of H2O throughout the plumbing system of the volcano during impulsive ascent of deep-seated magmas; (2) the upward acceleration of magmas feeding gas-dominated, sustained explosive eruptions; (3) the physicochemical changes of gas-fluxed magmas ponding at shallow crustal levels; and (4) the huge gas emissions measured at the summit craters and flank vents which result in a persistent volcanic gas plume

Silicon Tetrafluoride on Io

Silicon tetrafluoride (SiF4) is observed in terrestrial volcanic gases and is predicted to be the major F - bearing species in low temperature volcanic gases on Io (Schaefer and Fegley, 2005b). SiF4 gas is also a potential indicator of silica-rich crust on Io. We used F/S ratios in terrestrial and extraterrestrial basalts, and gas/lava enrichment factors for F and S measured at terrestrial volcanoes to calculate equilibrium SiF4/SO2 ratios in volcanic gases on Io. We conclude that SiF4 can be produced at levels comparable to the observed NaCl/SO2 gas ratio. We also considered potential loss processes for SiF4 in volcanic plumes and in Io's atmosphere including ion-molecule reactions, electron chemistry, photochemistry, reactions with the major atmospheric constituents, and condensation. Photochemical destruction (tchem ~ 266 days) and/or condensation as Na2SiF6 (s) appear to be the major sinks for SiF4. We recommend searching for SiF4 with infrared spectroscopy using its 9.7 micron band as done on Earth.Comment: 16 pages, 2 figures, 1 table; Icarus, in pres

Lava channel formation during the 2001 eruption on Mount Etna: evidence for mechanical erosion

We report the direct observation of a peculiar lava channel that was formed near the base of a parasitic cone during the 2001 eruption on Mount Etna. Erosive processes by flowing lava are commonly attributed to thermal erosion. However, field evidence strongly suggests that models of thermal erosion cannot explain the formation of this channel. Here, we put forward the idea that the essential erosion mechanism was abrasive wear. By applying a simple model from tribology we demonstrate that the available data agree favorably with our hypothesis. Consequently, we propose that erosional processes resembling the wear phenomena in glacial erosion are possible in a volcanic environment.Comment: accepted for publication in Physical Review Letter

Etna International Training School of Geochemistry. Science meets Practice

Also this year, the \u201cEtna International Training School of Geochemistry. Science meets practice\u201d took place at Mt. Etna, now in its fourth edition. The school was hosted in the historical Volcanological Observatory \u201cPizzi Deneri\u201d, one of the most important sites of the INGV - Osservatorio Etneo for geochemical and geophysical monitoring. Mount Etna, located in eastern Sicily, is the largest active volcano in Europe and one of the most intensely degassing volcanoes of the world [Allard et al., 1991; Gerlach, 1991]. Mt Etna emits about 1.6 % of global H2O fluxes from arc volcanism [Aiuppa et al., 2008] and 10 % of global average volcanic emission of CO2 and SO2 [D\u2019Alessandro et al., 1997; Caltabiano et al., 2004; Aiuppa et al., 2008; Carn et al., 2017]. Furthermore, Gauthier and Le Cloarec, [1998] underscored that Mt. Etna is an important source of volcanic particles, having a mass flux of particle passively released from the volcano during non-eruptive period estimated between 7 to 23 tons/day [Martin et al., 2008; Calabrese et al., 2011]. In general, Etna is considered to be still under evolution and rather \u2018friendly\u2019, which, along with the above, makes it a favorable natural laboratory to study volcanic geochemistry. The Observatory Pizzi Deneri was sponsored by Haroun Tazieff, and it was built in 1978 by the CNR - International Institute of Volcanology under the direction of Prof. Letterio Villari. It is located at the base of the North-East crater (2,850 m a.s.l.), near the Valle del Leone and it was built on the rim of the Ellittico caldera. A picturesque building, consisting of two characteristics domes in front of the breath-taking panorama of the summit craters. Even though it is quite spartan as an accommodation facility, the dormitories, kitchen, seminar room and laboratory are well equipped. In other words, the Pizzi Deneri observatory is a unique place close to the top of the most active volcano of Europe. The observatory lies in a strategic location making it one of the most important sites for monitoring, research and dissemination of the scientific culture. After six field multidisciplinary campaigns (2010-2015) organized by a group of researchers of several institutions (INGV of Palermo, Catania, Naples, Bologna; Universities of Palermo, Florence, Mainz, Heidelberg), the idea of sharing and passing on the experience to the new generation of students has materialized, and the \u201cEtna International Training School of Geochemistry. Science meets practice\u201d was born in 2016. The four editions of the school were partially funded by INGV of Palermo and Catania, European Geoscience Union (EGU), Societ\ue0 Geochimica Italiana (SoGeI) and Associazione Naturalistica Geode. The conceptual idea of the school is to share scientific knowledge and experiences in the geochemical community, using local resources with a low-cost organization in order to allow as many students as possible access to the school. The \u201cEtna International Training School of Geochemistry. Science meets practice\u201d is addressed to senior graduate students, postdoctoral researchers, fellows, and newly appointed assistant professors, aiming to bring together the next generation of researchers active in studies concerning the geochemistry and the budget of volcanic gases. Introduce the participants with innovative direct sampling and remote sensing techniques. Furthermore, it gives young scientists an opportunity to experiment and evaluate new protocols and techniques to be used on volcanic fluid emissions covering a broad variety of methods. The teaching approach includes theoretical sessions (lectures), practical demonstrations and field applications, conducted by international recognized geochemists. We thank all the teachers who helped to make the school possible, among these: Tobias Fischer (University of New Mexico Albuquerque), Jens Fiebig (Institut f\ufcr Geowissenschaften Goethe-Universit\ue4t Frankfurt am Main), Andri Stefansson (University of Iceland, Institute of Earth Sciences), Mike Burton (University of Manchester), Nicole Bobrowski (Universit\ue4t Heidelberg Institute of Environmental Physics and Max Planck Institute for Chemistry), Alessandro Aiuppa (Universit\ue0 di Palermo), Franco Tassi (Universit\ue0 di Firenze), Walter D\u2019Alessandro (INGV of Palermo), Fatima Viveiros (University of the Azores). Direct sampling of high-to-low temperature fumaroles, plume measurement techniques (using CO2/SO2 sensors such as Multi-GAS instruments, MAX-DOAS instruments and UV SO2 cameras, alkaline traps and particle filters), measurement of diffuse soil gas fluxes of endogenous gases (CO2, Hg0, CH4 and light hydrocarbons), sampling of mud volcanoes, groundwaters and bubbling gases. Sampling sites include the active summit craters, eruptive fractures and peripheral areas. The students have shown an active participation both to the lessons and the fieldworks. Most of them describe the school as formative and useful experience for their future researches. Their enthusiasm is the real engine of this school