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- PublicationRestrictedVolcanic unrest leading to the July-August 2001 lateral eruption at Mt. Etna: seismological constraints(2015)
; ; ; ; ; ;Sicali, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Barberi, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Cocina, O.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Musumeci, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Patanè, D.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; ; ; ; 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.565 47 - PublicationOpen AccessMultidisciplinary geophysical study of the NE sector of the unstable flank of Etna volcano(2015-04-12)
; ; ;Siniscalchi, A.; ; ;Romano, G.; ;Tripaldi, S. ;Bonforte, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Cocina, O.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia ;Siniscalchi, A.; Università degli Studi di Bari, Dipartimento di scienze della Terra e Geoambientali ;Barberi, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Guglielmino, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Romano, G.; Università degli Studi di Bari, Dipartimento di scienze della Terra e Geoambientali ;Sicali, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Tripaldi, S.; Università degli Studi di Bari, Dipartimento di scienze della Terra e Geoambientali; ; ;Università degli Studi di Bari, Dipartimento di scienze della Terra e Geoambientali; ; ;Università degli Studi di Bari, Dipartimento di scienze della Terra e Geoambientali; Università degli Studi di Bari, Dipartimento di scienze della Terra e GeoambientaliOn volcanic areas, usually characterized by complex structural environments, a lot of independent geophysical studies are usually performed. The non-uniqueness of the geophysical inverse models, the different level of reso- lution and sensitivity of the results spurred us to integrate independent geophysical datasets and results collected on Mt. Etna volcano, in order to obtain more accurate and reliable model interpretation. Mt. Etna volcano is located along the eastern coast of Sicily and it is characterized by a complex structural set- ting. In this region, the general N-S compressive regime related to the Africa – Europe collision interacts with the WNW-ESE extensional regime associated to the Malta Escarpment dynamics, observable along the eastern coast of Sicily. At Mt Etna, a great number of studies concerns the existence of instability phenomena; a general eastward mo- tion of the eastern flank of the volcano has been measured with always increasing detail and its relationship with the eruptive and magmatic activity is being investigated. The unstable flank appears bounded to the north by the E–W-trending Provenzana - Pernicana Fault System and to the SW by the NS Ragalna Fault system. Eastwards, this area is divided by several NW–SE trending faults. Recent studies consider this area as divided into several blocks characterized by different shape and kinematics. Ground deformation studies (GPS and InSAR) define the NE portion of the unstable flank as the most mobile one. In the frame of the MEDiterranean Supersites Volcanoes (MED-SUV) project, ground deformation data (GPS and INSAR), 3D seismicity, seismic tomography and two resistivity model profiles, have been analyzed together, in order to put some constraints on the deep structure of the NE sector of the unstable flank. Seismic data come from the permanent network run by the Istituto Nazionale di Geofisica e Vulcanologia (INGV) - Sezione di Catania, Osservatorio Etneo. Ground deformation data comes from InSAR Permanent Scatterers analyses of different spaceborn sensors. The resistivity models come from a MT survey carried out on the eastern flank of the volcano and consisting of thirty broad-band soundings along N-S and NW-SE oriented profiles. We found that the NE sector of the sliding volume, modeled by ground deformation data inversions and character- ized by the highest displacement velocity, is characterized low resistivity values and it is bounded by two seismic clusters. The northern one is clearly related to the Pernicana fault and it’s not deeper than 3 km b.s.l. while the second one is located southwards, beneath the northern wall of the Valle del Bove, not related to any evident struc- ture at the surface. An evident layer with very reduced seismicity lies at 3 km of depth and well corresponds to the simplified analytic models of a sliding planar surface resulting from GPS data inversions.233 123 - PublicationOpen AccessSeismic and volcanic activity during 2014 in the region involved by TOMO-ETNA seismic active experiment(2016)
; ; ; ; ; ; ; ; ; ; ; ; ; ;Barberi, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Giampiccolo, E.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Musumeci, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Scarfì, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Bruno, V.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Cocina, O.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Diaz-Moreno, A.; Universidad de Granada, Granada, Spain ;Sicali, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Tusa, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Tuvè, T.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Zuccarello, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Ibanez, J. M.; Universidad de Granada, Granada, Spain ;Patanè, D.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; ; ; ; ; ; ; ; ; ; ; ; This paper presents an overview of the seismic and volcanic activity occurred during 2014 in the region involved by the TOMO-ETNA seismic active experiment (Mt. Etna, Aeolian Islands and Peloritani-Messina Strait areas). To better characterize the seismicity over the year, threedimensional hypocenter locations and focal mechanism solutions of a dataset of 678 selected small-to-moderate magnitude earthquakes (0.5≤ML≤4.3) were analyzed. In the framework of the TOMO-ETNA experiment, a temporary seismic network was installed on-land from June to November 2014, both to acquire seismic signals produced by shots and to record the local seismicity. Data collected by the temporary network were used to integrate those deriving from the permanent seismic network operated by the Istituto Nazionale di Geofisica e Vulcanologia (INGV)- Osservatorio Etneo, thus obtaining a numerically more robust dataset. In agreement with previous analysis and studies, the distribution of the hypocentral locations is well representative of the seismicity that typically characterizes this area. The selected well-constrained 42 fault plane solutions evidence two domains characterized by different motions and style of deformation. In particular, an extensional domain in the northeastern Sicily and a strike-slip regime in the northernmost part of the studied region have been observed.1381 205 - PublicationOpen AccessGeophysical multidisciplinary investigation of the structure of the unstable sector of Mt. Etna volcano(2014-07-07)
; ; ;Siniscalchi, Agata; ; ;Romano, Gerardo; ;Tripaldi, Simona ;Bonforte, Alessandro; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Cocina, Ornella; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Siniscalchi, Agata; Università di Bari ;Barberi, Graziella; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Guglielmino, Francesco; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Romano, Gerardo; Università di Bari ;Sicali, Simona; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Tripaldi, Simona; Università di Bari; ; ;Università di Bari; ; ;Università di Bari; Università di BariMount Etna is characterized by a complex regional tectonics with a N-S compression related to the Africa - Europe convergence that interacts with a WNW-ESE extension associated to the Malta Escarpment. A general eastward motion is present in the eastern flank. Although the existence of these phenomena is overt, the geometry of the sliding sector is still debated. The non-uniqueness of the geophysical inverse models and the different limitations in resolution and sensitivity of each technique spurred us to undertake a joint interpretation of the independent datasets in order to better constrain the results. Seismic data come from the network run by the Istituto Nazionale di Geofisica e Vulcanologia (INGV) - Osservatorio Etneo, Sezione di Catania. The relocated seismicity defines two main seismogenic volumes in the NE sector of the volcano: the first cluster is related to the known Pernicana Fault system, while the second one is located southwards, beneath the northern wall of the Valle del Bove. The resistivity models come from a MT survey carried out on the eastern flank of the volcano and consisting of thirty broad-band soundings along N-S and NW-SE oriented profiles. The resistivity modeling of MT profiles reveal three major layers in a resistive-conductive-resistive sequence. A low resistivity volume is clearly identified on the NE flank of the volcano, between The Pernicana fault and the northern wall of the Valle del Bove. Ground deformation studies (GPS and InSAR) revealed the segmentation of the unstable flank and define the NE sector as the most mobile one; this sector is perfectly bounded by the two seismic clusters and corresponds to the low resistivity volume. The sliding surface modeled by ground deformation data inversions well matches in depth with a resistivity transition and with two seismogenic layers.272 95 - PublicationRestrictedCharacterization of seismicity at Mt. Etna volcano (Italy) by inter-event time distribution(2014)
; ; ; ; ;Sicali, S. ;Barbano, M. S. ;D'Amico, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Azzaro, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ; ;; The space time inter-event time (IET) distributions of earthquakes occurring from 1988 to 2011 at Mt. Etna are analysed in order to identify the periodicity or stationary behaviour of seismicity, and to correlate it with the volcano-tectonic features of the region. The comparison between IET distributions at Etna with those obtained both for Sicily and Italy, shows that IETs at a larger scale are well-modelled by a gamma distribution, whereas at Etna local scale they are characterised by a bimodal curve, in which the two peaks are related to: (i) the contribution of local seismic swarms with very short inter-event times, and (ii) the background regional stationary seismicity. IET analysis is an important tool to investigate the behaviour of seismicity at different crustal levels in the Etna region, distinguishing sectors that are influenced by volcano dynamics or regional tectonics. Indeed, the spatial variation of IET distributions, obtained by analysing different Etna crustal sectors, shows that seismicity shallower than 5 km is almost entirely characterised by short inter-event times and is mainly confined to the summit area. For earthquakes deeper than 5 km occurring in the eastern flank of the volcano, as well as in eastern Sicily, IET distributions are characterised by independent events which suggest that both areas are influenced by the same extensional regional regime. By contrast, IET distributions obtained for the western flank and northwestern Sicily are marked by two peaks, indicating that the compressional stress is acting in both areas.396 43 - PublicationOpen AccessGeophysical multidisciplinary investigation of the structure of an unstable flank: the NE sector of Mt. Etna.(2014-09-09)
; ; ; ; ; ; ; ; ;Bonforte, Alessandro; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Cocina, Ornella; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Siniscalchi, Agata; Università degli Studi di Bari ;Barberi, Graziella; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Guglielmino, Francesco; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Romano, Gerardo; Università degli Studi di Bari ;Sicali, Simona; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Tripaldi, Simona; Università degli Studi di Bari; ; ; ; ; ; ; Mount Etna is characterized by a complex regional tectonics with a N-S compression related to the Africa – Europe convergence that interacts with a WNW-ESE extension associated to the Malta Escarpment. A general eastward motion is present in the eastern flank. Although the existence of these phenomena is overt, the geometry of the sliding sector is still debated. The non-uniqueness of the geophysical inverse models and the different limitations in resolution and sensitivity of each technique spurred us to undertake, in the frame of the MEDiterranean Supersites Volcanoes (MED-SUV) project, a joint interpretation of independent data in order to better constrain the results. Seismic data come from the network run by the Istituto Nazionale di Geofisica e Vulcanologia (INGV) – Osservatorio Etneo, Sezione di Catania. The relocated seismicity defines two main seismogenic volumes in the NE sector of the volcano: the first cluster is related to the known Pernicana Fault system, while the second one is located southwards, beneath the northern wall of the Valle del Bove. The resistivity models come from a MT survey carried out on the eastern flank of the volcano and consisting of thirty broad-band soundings along N-S and NW-SE oriented profiles. The resistivity modeling of MT profiles reveal three major layers in a resistive-conductive-resistive sequence. A low resistivity volume is clearly identified on the NE flank of the volcano, between The Pernicana fault and the northern wall of the Valle del Bove. Ground deformation studies (GPS and InSAR) revealed the segmentation of the unstable flank and define the NE sector as the most mobile one; this sector is perfectly bounded by the two seismic clusters and corresponds to the low resistivity volume. The sliding surface modeled by ground deformation data inversions well matches in depth with a resistivity transition and with two seismogenic layers.252 84