HR: 1330h
AN: V22A-0573    [PDF]
TI: Large scale ground deformation of Etna observed by GPS between 1994 and 1999
AU: Briole, P
EM: briole@ipgp.jussieu.fr
AF: IPGP, Laboratoire de sismologie, case 89 4, Place Jussieu, PARIS cedex 05, 75252 France
AU: * Houli\'e, N
EM: houlie@ipgp.jussieu.fr
AF: IPGP, Laboratoire de sismologie, case 89 4, Place Jussieu, PARIS cedex 05, 75252 France
AU: Bonforte, A
EM: bonforte@ct.ingv.it
AF: INGV, Piazza Roma, 2, Catania, 000 Italy
AU: Puglisi, G
EM: plugisi-g@ct.ingv.it
AF: INGV, Piazza Roma, 2, Catania, 000 Italy
AB: Using the GAMIT software, we processed 33 GPS campaigns carried out at Etna from 1994 to 1999. The temporal evolution at twenty-two points observed three times or more is analyzed. Our solution confirms, improves and extends the one previously published by Bonforte and Puglisi (2003), estimated for the period 1994-1996 processing their data with the Trimble GPSurvey 2.3 software. The times series at almost all points show no temporal change of the deformation pattern during the five years period. This suggests that at large scale the volcano evolved in a steady manner during this interval, although this was not the case for the eruptive activity registered at the summit, which varied from calm to episodically explosive during the same period. The deformation field is interpreted as the sum of a global inflation of the volcano and an eastward motion of its eastern flank. This measured eastward motion reaches 40 mm/yr along the Ionian coast, on the eastern and south-eastern flanks of the volcano, and is still 9 mm/yr on the southernmost border, in Catania. Previously published InSAR data covering the same time interval quantitatively agree with our GPS results. Moreover they allow to accurately assess the location of the active structures that decouple the mobile flank from the stable part of the volcano. To the South those are mainly the Nicolosi - Tremestieri fault and the Gravina fault and to the North the Pernicana fault. The GPS results show that the relative motion has the same direction of those three structures, highlighting that they are affected by pure shear strain, without almost any component of compression or extension. Our GPS solutions are not accurate enough to estimate vertical velocities, which in any case do not show evident trends, as horizontal components do, and are very little in magnitude.
DE: 8109 Continental tectonics--extensional (0905)
DE: 8158 Plate motions--present and recent (3040)
DE: 8400 VOLCANOLOGY
DE: 8414 Eruption mechanisms
DE: 8419 Eruption monitoring (7280)
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2003 Fall Meeting