Temporal variations of ~3He/~4He ratios of dissolved helium in groundwaters of Mt Etna, Southern Italy

摘要

He isotopes were measured in groundwaters of Mt Etna in order to provide further insights on the relationship between volcanic activity and the geochemistry of dissolved gases. The intense seismicity and the strombolian activity that characterized Mt Etna since the end of 1994 was accompanied by a variation in the fluid regime, leading to the input of magmatic He and CO_2. He and CO_2 contents and ~3He/~4He isotopic ratios showed interesting variations in some of the selected sampling sites, during the last months of 1994 and in the middle of both 1995 and 1996, in concordance with the renewal of summit crater activity and the intensity of both volcanic tremor and earthquakes.