Monitoring active volcanoes using a handheld thermal camera

Abstract

Thermal imaging has recently been introduced in volcanology to analyse a number of different volcanic processes. This system allows us to detect magma movements within the summit conduits of active volcanoes, and then to reveal volcanic activity within the craters even through the thick curtain of gases usually released by volcanoes such as Mt Etna and Stromboli. Thermal mapping is essential during effusive eruptions, since it distinguishes lava flows of different age and concealed lava tubes’ path, improving hazard evaluation. Recently, thermal imaging has also been applied to reveal failure planes and instability on the flanks of active volcanoes. Excellent results have been obtained in terms of volcanic prediction during the two recent eruptions of Mt Etna and Stromboli, both occurred in 2002-2003. On Etna, thermal images monthly recorded on the summit of the volcano revealed the opening of fissure systems several months in advance. After the onset of the flank eruption, daily thermal mapping allowed us to monitor a complex lava flow field spreading within a forest, below a thick plume of ash and gas. At Stromboli, helicopter-borne thermal surveys allowed us to recognise the opening of fractures along the Sciara del Fuoco, one hour before the large failure that caused severe destruction on the island on 30 December 2002. This was the first time ever that volcanic flank collapse has been monitored with a thermal camera. In addition, we could follow the exceptional explosive event of the 5th April 2003 at Stromboli from helicopter with a thermal camera recording images immediately before, during and after the huge explosion. We believe that a more extended use of thermal cameras in volcano monitoring, both on the ground and from fixed positions, will significantly improve our understanding of volcanic phenomena and hazard evaluations during volcanic crisis.