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  • Elsevier Science Limited  (1)
  • Rendiconti Online della Società Geologica Italiana  (1)
  • 2015-2019  (2)
  • 1
    Publication Date: 2015-02-25
    Description: We studied the ongoing tectonics of the region extending between the Aeolian Arc and the Ionian Sea offshore, including the southern Calabria and the north-eastern Sicily, through an in-depth analysis of seismological data. For this area, recent studies have shown a very complex tectonic framework, fragmented into crustal blocks separated by seismically active belts and characterized by neighbouring collisional, subduction and active volcanic (Etna and Aeolian Arc) domains. Contraction affects mainly the western sector with an E-W oriented compressive belt extending from the Aeolian archipelago to the Ustica Island. Conversely, the eastern sector (i.e. NE Sicily and western Calabria) is dominated by Late Quaternary extensional deformation. The definition of the seismogenic sources in this area is a difficult task and a matter of intense debate, mainly because morphological expressions of the faults are not evident, since the terrains traverse make it more difficult to keep track of faulting activity, and because there are difficulties in recognizing geological formations and tectonic structures at the great depth reaching the Tyrrhenian and Ionian Seas. In our study, a selected dataset consisting of more than 4000 small-to moderate-magnitude earthquakes (1.0≤ML≤4.8), collected in two decades by a local seismic network, were used to perform a simultaneous inversion of both 3D velocity structure and earthquake locations, in order to trace the characteristics of the faulting systems. The obtained velocity images and the foci distribution depict relevant structural features at depth. In particular, velocity anomalies and hypocentres highlight some WNW-ESE to NW-SE lineaments between the Aeolian Islands and the Ionian Sea. In addition, the fault plane solutions for the best recorded earthquakes were determined and used to resolve the current local stress fields and to characterize the faulting regime of the main seismogenic sources. The results were combined to achieve a coherent geodynamic scheme and to better characterize the active tectonics of the region.
    Description: Published
    Description: http://www.geoscienze2014.it/
    Description: 1T. Geodinamica e interno della Terra
    Description: open
    Keywords: Tomography ; Faulting Regime ; Crustal Stress ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Conference paper
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  • 2
    Publication Date: 2017-04-04
    Description: A close relationship between earthquake swarms, volcanic eruptions, and ground deformation at Mt. Etna was well documented shortly before the beginning of the July–August 2001 eruption. Past experiences at this volcano suggest how magma/dike intrusion in the shallow crust or in the upper part of the volcanic pile normally occurs after several years/months of internal recharging. Since seismic investigations provide a means to study the scale and origin of stress perturbations at active volcanoes, allowing to better investigating the preparation phase of an eruption, in this paper, we performed a close examination of the seismic activity recorded at Mt. Etna in the months preceding the 2001 eruption and in particular between November 2000 and July 2001. After integrating data recorded by the two networks operating during that time and run by the Istituto Internazionale di Vulcanologia and SISTEMA POSEIDON, we relocated 522 earthquakes by using the tomoDD code in a 3D velocity model, and then we computed their fault plane solutions. The application of different selection criteria enabled obtaining a good-quality revised data set consisting of 111 fault plane solutions. The high-precision locations identified well-defined seismic clusters, in different periods, suggesting a link with the magma migration from a depth of 8–13 km b.s.l. towards shallower zones. Moreover, the computed maximum compressive stress axis, as inferred from earthquake focal mechanisms, indicated a roughlyW-E-oriented σ1. This findings reflect an overpressure of the mid to shallow crust due to the progressive magma uprising in central portion of the volcano and also highlighted a rotation of the local stress field with respect to the regional one N-S trending. In addition, P-axis distribution pointed out the presence of a center of pressure located to the south of the Central Craters. These results provide particularly compelling evidence for a direct causal link between pressurization of the midlevel volcanic plumbing system by ascending magma and precursory local stress field reorientations, demonstrating that seismological analysis can be used to detect subtle local stress changes that herald eruptive activity.
    Description: Published
    Description: 11-23
    Description: 1T. Geodinamica e interno della Terra
    Description: JCR Journal
    Description: restricted
    Keywords: Volcanic unrest ; Mt. Etna ; earthquakes ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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