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Univ. Roma3, Italy
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- PublicationRestrictedThermal enhancement of radon emission from geological materials. Implications for laboratory experiments on rocksunder increasing deformation(2011)
; ; ; ; ; ; ;Tuccimei, P.; Univ. Roma3, Italy ;Castelluccio, M.; Univ. Roma3, Italy ;Moretti, S.; Univ. Roma3, Italy ;Mollo, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Vinciguerra, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Scarlato, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; ; ; ; ; ; ; ; ;Veress, B.; // ;Szigethy, J.; //; Radon gas is the subject of a great deal of research because its concentration builds up into indoor air and the long-term radon exposure is considered the second cause of lung cancer, after smoking. In addition to that, the release of radon from soil is under investigation in active volcanic and seismic areas because radon anomalies are believed to occur before earthquakes and volcanic eruptions. Several papers report results of laboratory experiments on the effects of activity concentration of 222Rn and 220Rn precursors, humidity content and grain size of geological materials over the radon emission. However no correspondent studies have targeted the effect of the temperature on radon release. The present contribution focuses on the influence of temperature, varying from 20 to 60 °C, on 222Rn and 220Rn emission from two volcanic rocks, a tuff and a lava flow. The experimental apparatus consists of a small accumulation chamber coupled to solid-state alpha spectroscopy; it also allows to keep constant the experimental temperatures applied to the rock sample. The effect of ambient temperature on detection efficiency is also investigated. Results show a significant enhancement of radon emissions from rocks with increasing temperature. The results of these experiments suggest that thermal enhancement of radon emission can be used to investigate more precisely the correlation between physical mechanisms determining damage in stressed rocks and radon release, taking advantage of the improved radon emission. Experimental test with a better resolution are the key to interpret radon anomalies preceding earthquakes or volcanic eruption.217 37 - PublicationRestrictedUnderstanding Slow Deformation Before Dynamic Failure(2010)
; ; ; ; ; ; ; ; ; ;Ventura, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Vinciguerra, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Moretti, S.; Univ. of Florence, Italy ;Meredith, P. G.; UCL, UK ;Heap, M .J.; UCL,UK ;Baud, P.; Univ. of Strasb., France ;Shapiro, S. A.; Freie Univ., Berlin, Germany ;Dinske, C.; Freie Univ., Berlin, Germany ;Kummerow, J.; Freie Univ., Berlin, Germany; ; ; ; ; ;; ; ; ; ;Beer, T.; Csiro, AustraliaSlow deformation and fracturing have been shown to be leading mechanisms towards failure, marking earthquake ruptures, flank eruption onsets and landslide episodes. The common link among these processes is that populations of microcracks interact, grow and coalesce into major fractures. We present (a) two examples of multidisciplinary field monitoring of characteristic “large scale” signs of impending deformation from different tectonic setting, i.e. the Ruinon landslide (Italy) and Stromboli volcano (Italy) (b) the kinematic features of slow stress perturbations induced by fluid overpressures and relative modelling; (c) experimental rock deformation laboratory experiments and theoretical modelling investigating slow deformation mechanisms, such stress corrosion crack growth. We propose an interdisciplinary unitary and integrated approach aimed to: (1) transfer of knowledge between specific fields, which up to now aimed at solve a particular problem; (2) quantify critical damage thresholds triggering instability onset; (3) set up early warning models for forecasting the time of rupture with application to volcanology, seismology and landslide risk prevention.438 87