1,723,904 research outputs found
VOLCANIC CO2 FLUX MEASUREMENTS BY TUNABLE DIODE LASER ABSORPTION SPECTROSCOPY
Full text linkIntroduction
In the last decades, the use of near-infrared room-temperature diode lasers for gas sensing has grown significantly. The use of these devices, for instance in combination with optical fibers, is particularly convenient for volcanic monitoring applications [1,2]. Here, we report on the first results of the application of an open-path infrared tunable laser-based at Campi Flegrei (Southern Italy). Such Diode-laser-based measurements were performed, during two field campaigns (october 2012, and january 2013), in the attempt to obtain novel information on the current degassing unrest of Solfatara and Pisciarelli fumarolic fields.
Results and Discussion
At each site, we used an ad-hoc designed measurement geometry, using a TDLS (a Gas Finder unit) and several differently positioned retroreflectors (mirrors), to scan the fumaroles’ plume from different angles and distances. From post-processing of the data (acquired at 1 hz), we derived tomographic maps of CO2 concentrations in the plume and, by integration and combination with plume transport speed (from video cameras), we inferred the CO2 flux directly. The so-calculated fluxes, the first ever obtained at Campi Flegrei, average of 500 tons/day, and support a significant contribution of fumaroles to the total CO2 budget. The cumulative (fumarole [this study] +soil [3]) CO2 output from Campi Flegrei is finally evaluated at 1600 tons/day.
[1] Gianfrani L. et al. (2000). Appl. Phys. B-Rapid Common. 70, 467-470. [2] Richter D. et al (2002), Optics and Lasers in Engineering, Volume 37, Issues 2–3, Pages 171-186. [3] Chiodini G. et al. (2010), Journal of Geophysical Research, Volume 115, B03205, doi:10.1029/2008JB006258
CO2/CH4 ratio in fumaroles a powerful tool to detect magma degassing episodes at quiescent volcanoes
No full textLong time series of fumarolic compositions at Campi Flegrei (Italy),
Mammoth Mountain (California), Panarea (Italy) and Nisyros (Greece) show rapid
increases, up to orders of magnitude, of the CO2/CH4 ratio systematically with the
occurrence of volcanic unrest periods. These easily detected anomalies originate with
the arrival of CH4-poor magmatic fluids in the shallower levels of the volcanoes. The
data suggest that volcanoes are characterized by magmatic activity at depth also in
periods of apparent quiescence. The activity is constituted by the pulsing release of large
amount of fluids which either cause unrest periods (seismicity and ground deformation)
or possibly could precede volcanic eruption. This type of volcanic activity can be
monitored trough the classical geophysical techniques together with the systematic
sampling and analysis of fumaroles.In press4.5. Degassamento naturaleJCR Journalreserve
A New Web-Based Catalog of Earth Degassing Sites in Italy
No full textItaly is a region characterized by intense and widespread processes of Earth degassing. High-temperature gases are released by crater plumes and fumaroles in volcanic environments throughout Italy. Also prevalent are numerous low-temperature gas emissions rich in carbon dioxide (CO2). These low-temperature emissions are located in a large area, mainly in the western sector of central and southern Ital
Long-term TIR imagery processing for spatiotemporal monitoring of surface thermal features in volcanic environment: A case study in the Campi Flegrei (Southern Italy)
No full textDifferent procedures were used to analyze a comprehensive time series of nighttime thermal
infrared images acquired from October 2006 to June 2013 by a permanent station at Pisciarelli (Campi
Flegrei, Italy). The methodologies were aimed at the detection and quantification of possible spatiotemporal
changes in the ground-surface thermal features of an area affected by diffuse degassing. Long-term infrared
time series images were processed without taking into account atmospheric conditions and emissivity
estimations. The data obtained were compared with the trends of independent geophysical and geochemical
parameters, which suggested that long-term temporal variations of the surface maximum temperatures were
governed by the dynamics of the deeper hydrothermal system. Analogously, the dynamics of the shallow
hydrothermal system are likely to control the short-period thermal oscillations that overlie the long-term
thermal signals. The map of the yearly rates of temperature change shows temperature increases clustered
in the thermal anomalous area of the infrared images, without evidence of modifications to the extension of
the anomaly or of growth of new areas with significant thermal emission. This suggests that in the present state,
the heat transfer is mainly due to hot gas emission through preexisting fractures and vents. Our data indicate
that the comprehensive picture of the spatiotemporal evolution of the thermal features of the hydrothermal
sites obtained by long-term infrared monitoring can provide useful information toward refining physical
and conceptual models, as well as improving surveillance of active volcanoes.The TIR monitoring system was partially funded by the 2000–2006 National Operating
Programme and by the Italian Civil Protection Department in the framework of the 2004–2006 agreement with the Istituto Nazionale di Geofisica e Vulcanologia.Published812–8262V. Dinamiche di unrest e scenari pre-eruttivi5V. Sorveglianza vulcanica ed emergenzeJCR Journalrestricte
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Inquinamento indotto dai gas delle eruzioni vulcaniche
No full textSono brevemente descritti i processi che portano alla separazione dei gas da magma ed il ruolo dei gas magmatici nelle eruzioni vulcaniche.Vengono quindi riportati esempi della composizione di gas vulcanici e degli effetti negativi legati all'immissione in atmosfera di grandi quantità di gas vulcanici durante le eruzioni.Infine viene descritto il processo legato all'emissione di gas endogeni in una vasta zona dell'Italia centrale e meridionale.Published857-8651.2. TTC - Sorveglianza geochimica delle aree vulcaniche attivereserve
Inquinamento indotto dai gas delle eruzioni vulcaniche
No full textSono brevemente descritti i processi che portano alla separazione dei gas da magma ed il ruolo dei gas magmatici nelle eruzioni vulcaniche.Vengono quindi riportati esempi della composizione di gas vulcanici e degli effetti negativi legati all'immissione in atmosfera di grandi quantità di gas vulcanici durante le eruzioni.Infine viene descritto il processo legato all'emissione di gas endogeni in una vasta zona dell'Italia centrale e meridionale.Published857-8651.2. TTC - Sorveglianza geochimica delle aree vulcaniche attivereserve
Magma degassing episodes and volcanic unrest periods in quiescent volcanoes
No full textLong time series of fumarolic chemical and isotopic compositions, at Solfatara (Campi Flegrei) and Vulcano highlight the occurrence of mixing processes among magmatic and hydrothermal fluids. At Solfatara temperatures of about 360°C of the hydrothermal system are inferred by methane chemical-isotopic geoindicators and by the H2/Ar geothermometer. These high temperatures are representative of a deep zone where magmatic gases flash hydrothermalliquid forming a gas pIume where the kinetically fast reactive species (H2 and CO) re-equilibrate at temperatures of 200240°C. The stable isotope compositions of the two dominant species, i.e, H20 and C02, shows that sampled effluents are mixture between magmatic fluids and the vapor generated at about 360°C by the vaporization of hydrothermalliquids of meteotic origino Similar mixing processes between magmatic fluids and a hydrothermal component of marine origin have been recognized at Vulcano high temperature fumaroleso In both the system a typical 'andesitic' water type composition and high C02 contents characterizes the magmatic component. Our hypothesis is that pulsing injections of these C02-rich magmatic fluids at the bottom of the hydrothermal systems trigger the bradyseismic crises, periodically affecting Campi Flegrei, and the periodical volcanic unrest periods of Vulcano. At Campi Flegrei a strong increase of the fraction of the magmatic component, marked in fact the bradyseismic crisis of 1982-84 and four minor episodes occurred in 1989, 1994 and 2000 and 2006. Increases of the magmatic component in the fumaroles of Vulcano were recorded in 1979-1981, 1985, 1988, 1996, 2004 and 2005 concurrently with anomalous seismic activity localized in the erater area. Physical-numerical simulations of the injection of hot, C02 rich fluids at the base of a hydrothermal system, asses the physical feasibility the processo Ground deformations, gravitational anomalies and seismic crisis can be well explained by the complex fluid dynamic processes caused by magma degassing episodes. Data on the fumaroles of other volcanoes, for example Vesuvio, Panarea, Nisyros (Greece), Mammoth (California), suggest that magma degassing episodes frequently occur in dormant volcanoes causing volcanic unrest processes not necessarily linked to magma movement but rather to pulsating degassing processes from deep pressurized, possibly stationary, magma bodies.INGV; AIV; Comune di Nicolosi(POrta dell'Etna)UnpublishedNicolosi(Catania)1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive2.4. TTC - Laboratori di geochimica dei fluidi4.5. Studi sul degassamento naturale e sui gas petroliferiope
Earth's degassing
No full textIt is presented an overview of the studies which has been developed for the quantification and the mapping of Earth degassing processes...Istituto Nazionale di Geofisica e Vulcanologia;Consiglio Nazionale delle Ricerche;Università degli Studi di Firenze;International Association for Mathematical GeosciencesPublishedAbbadia S.Salvatore,Siena,Italy2.4. TTC - Laboratori di geochimica dei fluidi4.5. Studi sul degassamento naturale e sui gas petroliferiope
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