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Wakita, H.
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Wakita, H.
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- 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