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Laboratory for Earthquake Chemistry, Faculty of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113, Japan
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- PublicationOpen AccessContribution of CO2 and H2S emitted to the atmosphere by plume and diffuse degassing from volcanoes: the Etna volcano case study(2015-02-28)
; ; ; ; ; ; ; ; ; ; ; ;Hernández, P. A.; Instituto Volcanológico de Canarias, INVOLCAN, 38400 Puerto de la Cruz, Tenerife, Canary Islands, Spain ;Melián, G.; Instituto Volcanológico de Canarias, INVOLCAN, 38400 Puerto de la Cruz, Tenerife, Canary Islands, Spain ;Giammanco, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Sortino, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia ;Barrancos, J.; Instituto Volcanológico de Canarias, INVOLCAN, 38400 Puerto de la Cruz, Tenerife, Canary Islands, Spain ;Pérez, N. M.; Instituto Volcanológico de Canarias, INVOLCAN, 38400 Puerto de la Cruz, Tenerife, Canary Islands, Spain ;Padrón, E.; Instituto Volcanológico de Canarias, INVOLCAN, 38400 Puerto de la Cruz, Tenerife, Canary Islands, Spain ;López, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Donovan, A.; Department of Geography, University of Cambridge, Downing Place, Cambridge CB2 3EN, England ;Mori, T.; Geochemical Research Center, Graduate School of Science, The University of Tokyo, Hongo, Bunkyo-Ku 113-0033, Tokyo, Japan ;Notsu, K.; Center for Integrated Research and Education of Natural Hazards (CIREN), Shizuoka University, 422-8529, Japan; ; ; ; ; ; ; ; ; ; Active subaerial volcanoes often discharge large amounts of CO2 and H2S to the atmosphere, not only during eruptions but also during periods of quiescence. These gases are discharged through focused (plumes, fumaroles, etc.) and diffuse emissions. Several studies have been carried out to estimate the global contribution of CO2 and H2S emitted to the atmosphere by subaerial volcanism, but additional volcanic degassing studies will help to improve the current estimates of bothCO2 andH2S discharges. In October 2008, a wide-scale survey was carried out at Mt. Etna volcano, one the world’s most actively degassing volcanoes on Earth, for the assessment of the total budget of volcanic/hydrothermal discharges of CO2 and H2S, both from plume and diffuse emissions. Surface CO2 and H2S effluxes were measured by means of the accumulation chamber method at 4075 sites, covering an area of about 972.5 km2. Concurrently, plume SO2 emission at Mt. Etna was remotely measured by a car-borne Differential Optical Absorption Spectrometry (DOAS) instrument. Crater emissions of H2O, CO2 and H2S were estimated by multiplying the plume SO2 emission times the H2O/SO2, CO2/SO2 and H2S/SO2 gas plume mass ratios measured in situ using a portable multisensor. The total output of diffuse CO2 emission from Mt. Etna was estimated to be 20,000 ± 400 t day-1 with 4520 t day-1 of deep-seated CO2. Diffuse H2S output was estimated to be 400 ± 20 kg day-1, covering an area of 9.1 km2 around the summit craters of the volcano. Diffuse H2S emission on the volcano flanks was either negligible or null, probably due to scrubbing of this gas before reaching the surface. During this study, the average crater SO2 emission rate was *2100 t day-1. Based on measured SO2 emission rates, the estimated H2O, CO2 and H2S emission rates from Etna’s crater degassing were 220,000 ± 100,000, 35,000 ± 16,000 and 510 ± 240 t day-1, respectively. These high values are explained in terms of intense volcanic activity at the time of this survey. The diffuse/plume CO2 emission mass ratio at Mt. Etna was *0.57, that is typical of erupting volcanoes (mass ratio\1). The average CO2/SO2 molar ratio measured in the plume was 11.5, which is typical of magmatic degassing at great depth beneath the volcano, and the CO2/H2S mass ratio in total diffuse gas emissions was much higher (*11,000) than in plume gas emissions (*68). These results will provide important implications for estimates of volcanic total carbon and sulfur budget from subaerial volcanoes.380 97 - PublicationOpen AccessRemote detection of fumarolic gas chemistry at Vulcano, Italy, using an FT-IR spectral radiometer(1995-06)
; ; ; ; ; ; ;Mori, T.; Laboratory for Earthquake Chemistry, Faculty of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113, Japan ;Notsu, K.; Laboratory for Earthquake Chemistry, Faculty of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113, Japan ;Yasunori, T.; Laboratory for Earthquake Chemistry, Faculty of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113, Japan ;Wakita, H.; Laboratory for Earthquake Chemistry, Faculty of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113, Japan ;Nuccio, P. M.; Univ. Palermo ;Italiano, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia; ; ; ; ; An infrared absorption spectroscopy remote sensing technique was used to determine the S02/HCl ratio in fumarolic plumes at Vulcano, Italy. The measurements were made from the southern crater rim of Fossa Grande Crater, about 400 m from the fumarolic area in the crater. Infrared absorption spectra of HCl and SO, were observed for four fumaroles a few tens of metres apart using the hot fumarolic surface as an infrared light source. The measured S02/HCl ratios in the FA, F47, FW and lower parti of the F21 fumaroles were 4.5-5.4, 3.5, 9.5-11.2 and 5.8 respectively. The S02/HCl ratio of the FA fumarole was higher than that of the gas collected directly in the fumarolic vent (S02/HCl ratio = 2.9), and was closer to the S~,,,,,,/HCl ratio (= 4.6) of the collected gas. Our results show that the SO,/HCl ratios of two fumaroles only a few tens of metres apart exhibits differences of about twofold. This suggests that this remote monitoring technique is capable of detecting spatial distribution in the S02/HCl ratios of volcanic plumes. Because temporal variations in S/Cl ratios can provide precursory signals for volcanic eruptions [l-31, this remote sensing technique can used efficiently for evaluation of volcanic activity.156 229 - PublicationOpen AccessHELIUM ISOTOPES AND TECTONICS IN SOUTHERN ITALY(1989-06)
; ; ; ; ;Sano, Y.; Laboratory for Earthquake Chemistry, Faculty of Science, University of Tokyo, Japan ;Wakita, H.; Laboratory for Earthquake Chemistry, Faculty of Science, University of Tokyo, Japan ;Nuccio, P. M.; Univ. Palermo ;Italiano, F.; Instituto di Geochimica dei Fluidi; ; ; Geodynamic evolution of southern Italy can be understood within the framework of the Mediterranean- Alpine System. Subduction of a plate along the Sicily- Calabrian forearc under the Tyrrhenian Sea has been suggested by many geophysicists, although it is not yet confirmed and remains somewhat controversial. Helium isotope ratios provide useful information on the geotectonic structure of the region. We report here the 3He/4He ratios of terrestrial gas samples from southern Italy. The observed 3He/4He ratios are relatively high in the Eolian volcanic arc region and low in the other areas. Dichotomous explanations are presented. Firstly volcanic arc-forearc hypothesis suggests the subduction along the Sicily-Calabrian forearc. Secondly horizontal transport hypothesis is described based on the relationship between the ratios and radial distance from the recent spreading basin in Southern Tyrrhenian Sea.216 391