The eastern slope of Mt. Etna is characterised by shallow seismicity originating from normal-oblique faulting, Timpe fault system, related to WNW-ESE regional extension. Several interpretations of the unstable eastern flank indicate a simple gravity-controlled mechanism enhanced by magmatic intrusions. Conversely some Authors indicate one or more causative factors or interaction between them (regional stress, gravity and dike-induced rifting) to produce the slow sliding of eastern flank of the volcano. Two geodetic subnetworks were established in 2010 and in 2014, along the southeastern edge of the unstable eastern flank of Mt. Etna volcano. These networks have been surveyed since late 2014 with GNSS techniques. According to some Authors, the time–space boundaries of the lateral sliding, which is probably much younger and shallower than is generally stated and differentially involves distinct blocks, remains to be constrained more accurately. The resulting horizontal velocity field (De Guidi et al., 2018) allowed us to observe a westward decay of the rate and a different azimuthal pattern of motion between the western and the eastern network. In this study we distinguish near southern boundary (Tremestieri-San Gregorio-Acitrezza fault zone) of unstable eastern slope, four distinct blocks, characterised by different strike and modules of velocity, separated by active fault segments characterised by different kinematics. We suggest that shallower sliding of eastern Etna slope could be explained invoking the criteria models of shear deformation at different depth and temperature. The amount of stress field related to terrain mechanical parameters affected by shear fault segments, has been estimated in order to provide useful indications.

Criteria models of shear deformation along the southern margin of unstable eastern flank of Mt. Etna.

De Guidi G.;Carnemolla F
;
Brighenti F.
2019

Abstract

The eastern slope of Mt. Etna is characterised by shallow seismicity originating from normal-oblique faulting, Timpe fault system, related to WNW-ESE regional extension. Several interpretations of the unstable eastern flank indicate a simple gravity-controlled mechanism enhanced by magmatic intrusions. Conversely some Authors indicate one or more causative factors or interaction between them (regional stress, gravity and dike-induced rifting) to produce the slow sliding of eastern flank of the volcano. Two geodetic subnetworks were established in 2010 and in 2014, along the southeastern edge of the unstable eastern flank of Mt. Etna volcano. These networks have been surveyed since late 2014 with GNSS techniques. According to some Authors, the time–space boundaries of the lateral sliding, which is probably much younger and shallower than is generally stated and differentially involves distinct blocks, remains to be constrained more accurately. The resulting horizontal velocity field (De Guidi et al., 2018) allowed us to observe a westward decay of the rate and a different azimuthal pattern of motion between the western and the eastern network. In this study we distinguish near southern boundary (Tremestieri-San Gregorio-Acitrezza fault zone) of unstable eastern slope, four distinct blocks, characterised by different strike and modules of velocity, separated by active fault segments characterised by different kinematics. We suggest that shallower sliding of eastern Etna slope could be explained invoking the criteria models of shear deformation at different depth and temperature. The amount of stress field related to terrain mechanical parameters affected by shear fault segments, has been estimated in order to provide useful indications.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/20.500.11769/367139
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