HR: 11:05h
AN: V42A-04    [Abstracts]
TI: Volcanic Processes, and Possible Precursors of Eruptions at Etna and Stromboli Volcanoes Revealed by Thermal Surveys
AU: * Calvari, S
EM: calvari@ct.ingv.it
AF: Istituto Nazionale di Geofisica e Vulcanologia - Sezione di Catania, Piazza Roma 2, Catania, 95123, Italy
AB: Thermal imaging has recently been introduced in volcanology to analyze a number of different volcanic processes. This system allows us to detect magma movements within the summit conduits of volcanoes, and then to reveal volcanic activity within the craters even through the thick curtain of gases usually released by active 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 eruptions of Mt Etna and Stromboli 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. At Stromboli, helicopter-borne thermal surveys allowed us to recognize the opening of fractures one hour before the large failure that caused severe destruction on the island on 30 December 2002. The INGV - Sezione di Catania started in 2001 to monitor active volcanoes using a hand-held thermal camera. This instrument was used in field and from helicopter to detect any thermal anomaly recorded on the surface of active volcanoes, and has since been applied to a number of eruptions and eruptive processes. After the two major eruptions at Etna and Stromboli, fixed thermal cameras have been installed on Stromboli, Etna and Vulcano, allowing us to keep under control the eruptive activity, flank stability and ash emission. On Etna, we have monitored the 2002-03, 2004-05, July 2006 and August-December 2006 eruptions. On Stromboli, thermal surveys from helicopter allowed us to follow the propagation of ephemeral vents and thus the path of hidden lava tubes, as well as the stages of inflation and deflation of the upper lava flow field. Thermal cameras have also been used to calculate the effusion rate, the most important parameter to estimate maximum lava flow length, and also to detect ash plumes on Etna in good weather conditions. However, the three most recent eruptions on Etna, occurred on 2004-05, July 2006 and August-December 2006, did not show evident thermal anomalies on the summit craters before the opening of eruptive fissures. Thus, the role of thermal anomalies and their meaning should be compared to and discussed with other geophysical data in order to understand when and if these data can be used to forecast eruptions.
UR: http:www.ct.ingv.it
DE: 8419 Volcano monitoring (7280)
DE: 8425 Effusive volcanism
SC: Volcanology, Geochemistry, and Petrology [V]
MN: 2007 Joint Assembly