Showing papers by "Giovanni Chiodini published in 2009"

Role of non-mantle CO2 in the dynamics of volcano degassing: The Mount Vesuvius example

Abstract: Mount Vesuvius, Italy, quiescent since A.D. 1944, is a dangerous volcano currently characterized by elevated CO2 emissions of debated origin. We show that such emissions are most likely the surface manifestation of the deep intrusion of alkalic-basaltic magma into the sedimentary carbonate basement, accompanied by sidewall assimilation and CO2 volatilization. During the last eruptive period (1631–1944), the carbonate-sourced CO2 made up 4.7–5.3 wt% of the vented magma. On a yearly basis, the resulting CO2 production rate is comparable to CO2 emissions currently measured in the volcanic area. The chemical and isotopic composition of the fumaroles supports the predominance of this crust-derived CO2 in volatile emissions at Mount Vesuvius.

CO2/CH4 ratio in fumaroles a powerful tool to detect magma degassing episodes at quiescent volcanoes

Abstract: [1] Long 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.

Numerical model of gas dispersion emitted from volcanic sources

Abstract: An Eulerian model for passive gas dispersion based on the K-theory for turbulent diffusion, coupled with a mass consistent wind model is presented. The procedure can be used to forecast gas concentration over large and com- plex terrains. The input to the model includes the topography, wind measurements from meteorological stations, atmospheric stability information and gas flow rate from the ground sources. Here, this model is applied to study the distribution of the CO2 discharged from the hot sources of the Solfatara Volcano, Naples, Italy, where the in- put data were measured during a 15 day campaign in June 2001 carried out to test an Eddy Covariance (EC) sta- tion by Osservatorio Vesuviano-INGV, Naples.

Carbon-14 as a marker of seismic activity

Abstract: Seismic events in volcanic systems can be accompanied by the release of gas from the Earth's crust: of particular interest here is fossil CO2, which contains no trace of carbon-14, and therefore dilutes the carbon-14 present in the surrounding atmosphere. When landscape conformation hampers mixing confining the low carbon-14 atmosphere, it can be wondered whether a trace of the release may be found in the wood of the trees breathing it. The present article describes a limited experimental campaign aimed at testing this idea, which was conducted on trees from the Pozzuoli caldera. The results presented can in no way be conclusive; however, they seem to yield support to the possibility of finding such markers of seismic activity.

Carbon dixide emission in Italy: Shallow crustal sources or subduction related fluid recycling?

Abstract: Carbon dixide emission in Italy: Shallow crustal sources or subduction related fluid recycling? G. CHIODINI, R. AVINO , S. CALIRO, C. CARDELLINI, A. COSTA AND F. FRONDINI Istituto Nazionale di Geofisica e Vulcanologia, sezione di Napoli, OV, via Diocleziano 328, 80124 Napoli, Italy (chiod@ov.ingv.it) Università di Perugia, Dipartimento di Scienze della Terra, piazza Università, 06123 Perugia, Italy (geochem@unipg.it)