HR: 0830h
AN: V21C-0536    [PDF]
TI: Temporal variations of fumarole and soil gases at Mt. Etna volcano (Italy) from 2000 to 2003.
AU: * Giammanco, S
EM: giamm@pa.ingv.it
AF: Istituto Nazionale di Geofisica e Vulcanologia - Sezione di Palermo, Via Ugo La Malfa 153, Palermo, I-90146 Italy
AU: Pecoraino, G
EM: pecorain@pa.ingv.it
AF: Istituto Nazionale di Geofisica e Vulcanologia - Sezione di Palermo, Via Ugo La Malfa 153, Palermo, I-90146 Italy
AB: Gas samples were collected during the period 2000 - 2003 from six sites on Mt. Etna volcano. The main gas species emitted at all sites is CO$_{2}$, but huge emission of organic CH$_{4}$ occur at some places. The origin of CO$_{2}$ is largely magmatic, compatible with a source marked by $\delta^{13}$C values in the range -2 to -1 $\permil$. Concurrent He emissions were characterised by He isotope values in the range 1.02 to 7.61 Ra, the highest values being measured where air contamination was lowest, and suggest a variable contribution of a magmatic component. During the studied period significant variations of CO$_{2}$ efflux, CO$_{2}$, He, CO, CH$_{4}$ concentrations and C and He isotopes were observed more or less at all sites. The variations in the chemical and isotopic parameters measured are coherent with magma accumulation at depth and its progressive migration towards the surface. The arrival of each batch of magma at depth ($>$ 10 km) produces anomalies (mainly CO$_{2}$ efflux and CO concentration increases) that are best observed at the most peripheral sites. Migration of magma towards the surface (depth $<$ 10 km) produces anomalies that are observed at sites closer to the summit craters. Short-term anomalies were recognised in anomalous increases of fumaroles temperature, which occurred some weeks to some days before Etna's eruptions and were due to greater input of high-enthalpy fluids (mainly water vapour) through the major fracture systems that cut the summit of Etna. The latest data indicate a new episode of magma replenishment at depth which has then produced magma migration and accumulation at shallower depth. The intensity of the observed anomalies would suggest a likely evolution towards a new eruption in the short period.
DE: 1040 Isotopic composition/chemistry
DE: 1099 General or miscellaneous
DE: 8419 Eruption monitoring (7280)
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2003 Fall Meeting