Sulphur dioxide discharge from Mount Etna

Abstract

REMOTE sensing of SO₂ emitted by Mount Etna in its normal state of permanent activity, indicates much higher flow-rates than those previously measured by the same method (correlation spectrometry) on other volcanoes. A set of measurements in June 1975 provided a mean SO₂ flow-rate of 3,740 t d⁻¹ for this volcano. This is a striking result both for volcanology and for environmental sciences. The knowledge of the mass discharge of chemical species from an active volcano and of its variations, both in time and space, is of great interest for the understanding of eruptive mechanisms and the establishment of geochemical balances. The SO₂ content of a volcanic plume can be measured from a distance by an optical correlation technique; this method was perfected a few years ago and has since been widely used for the remote sensing of air pollution in industrial areas¹. During June 1975, we used the correlation spectrometer Barringer Cospec II to measure the SO₂ emitted by the active vents in the summit of Mount Etna (Central Crater, Bocca Nuova, North-East Crater and 1964 Crater), 3,200 m above sea level.