Publication Date:
2017-04-03
Description:
Mount Etna has developed at the intersection of two regional tectonic lineaments, the NNW–SSE trending Hybleo–Maltese
escarpment, which separates the thick inland continental crust of the African platform from the Ionian Mesozoic oceanic crust, and
the NE–SW Messina–Fiumefreddo fault that marks a rift zone between south Calabria and north-eastern Sicily, extending as far as
the Mt. Etna area. All tectonic features affect, with outstanding surface features, the eastern side of the volcano.
The eastern flank of the volcano is affected by a long-term motion toward ESE. In 1997, in order to increase the detail of the
ground deformation pattern on the lower eastern flank of Mt. Etna, a new GPS network, the “Ionica” network, was installed on this
sector of the volcano. This GPS network consists of 24 stations and covers the lower eastern flank of the volcano from the town of
Catania to Taormina and from the coastline up to an altitude of about 1300 m. All the new stations consist in self-centring
benchmarks; this kind of benchmark allows all station set-up errors to be avoided. Before the merging of the Ionica network to the
frame of the global GPS network of Mt. Etna (in June 2001), three surveys were carried out on this network: in September 1997,
August 1998 and January 2001.
From the ground deformation pattern, it is possible to distinguish two different sectors, showing different characteristics of
deformation. The southern part of the network shows a more uniform distribution of the vertical motion with a mean SE-ward
horizontal component while the northern one shows an heterogeneous vertical motion with a ESE-ward horizontal component.
Furthermore, a higher velocity is detected between 1997 and 1998, due to the additional stress induced by a shallow intrusion on
the NW flank of the volcano.
The model resulting from data inversions defines a wide sliding plane beneath the entire eastern flank of the volcano with a low
dip angle. The expected velocity vectors fit well the observed ones, even if the measured velocities are still quite higher than
expected, at lowermost stations. The vertical inclination of the velocity vectors measured during the 1998–2001 period, gradually
decreases from West to East suggesting a sort of rotational movement of the south-eastern flank, interrupted by some anomalous
vectors on the lower part, that show higher vertical velocities. These anomalies, being located on a wedge defined by the
intersection of the main NNW–SSE and NE–SW fault systems and near the Timpe faults, are probably due to the activity of the
vertical faults cutting the lower eastern flank of Mt. Etna. Stations lying on the hanging wall and on the footwall of the Timpe fault
system are affected by similar horizontal displacements, meaning that these structures are moving eastwards together with the
sliding flank; this evidence suggests that the Timpe faults are probably second order structures, with respect to the detachment
surface. These results depict a structural framework of the eastern flank of Mt. Etna in which the low angle dislocation can be considered
as a first order approximation of an actual listric plane and the current active part of the Timpe fault system is confined above the
detachment surface.
Description:
Published
Description:
357-369
Description:
reserved
Keywords:
ground deformation
;
flank dynamics
;
volcano–tectonics
;
Etna volcano
;
04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations
;
04. Solid Earth::04.03. Geodesy::04.03.07. Satellite geodesy
;
04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
Format:
813929 bytes
Format:
application/pdf
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