Monitoring gases at volcanic fumaroles

E. Faber1, S. Inguaggiato2, G. G. Valencia3, D. Seidl4
1Federal Institute for Geosciences and Natural Resources, Stilleweg 3, 30655 Hannover, Germany.
Tel. : +49-511-643-2882,
E-mail: eckhard.faber@bgr.de
2Consiglio Nazionale delle Ricerche Instituto Geochimica dei Fluidi, Via Torino, 90133 Palermo, Italy
3Observatorio Vulcanologico y Sismologico, Carrera 31 No. 18-07, Pasto, Colombia
4Federal Institute for Geosciences and Natural Resources, Mozartstraße 57, 91052 Erlangen, Germany

Emission of gases from fumaroles is thought to reflect magmatic activity at volcanic sites. A system has been designed to monitor composition of emitted gases in minute to sub-minute intervals. Test measurements have been made at the volcanoes La Fossa (Italy) and Galeras (Colombia) and are used to improve the technical equipment. For analysis, a mass spectrometer, gas chromatographs, radon units and sensor based units are available and are tested and optimised. Also pipes and pumps are available to connect the analytical equipment to remote fumaroles over a distance of more than 1000 m. Depending on the local situation like power supply, accessibility of fumaroles, weather conditions, altitude etc. the instruments are selected. Depending on this selection, components like CO2, N2, O2, Ar, SO2, H2S, Rn, H2, can be monitored. However, as volcanoes and fumaroles are the most hostile environments one can imagine for laboratory equipment, we faced quite a lot of problems like stability and continuity of the instruments and measurements and durability of the material inserted into fumaroles used for the connection to the instruments. Details will be presented.