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De Luca, L.
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De Luca, L.
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- PublicationOpen AccessAn analysis of the first-arrival times picked on the DSS and wide-angle seismic section recorded in Italy since 1968(2004)
; ; ; ; ; ;De Luca, L.; Istituto per la Dinamica dei Processi Ambientali - CNR, Milano, Italy ;De Franco, R.; Istituto per la Dinamica dei Processi Ambientali - CNR, Milano, Italy ;Biella, G.; Istituto per la Dinamica dei Processi Ambientali - CNR, Milano, Italy ;Corsi, A.; Istituto per la Dinamica dei Processi Ambientali - CNR, Milano, Italy ;Tondi, R.; Istituto per la Dinamica dei Processi Ambientali - CNR, Milano, Italy; ; ; ; We performed an analysis of refraction data recorded in Italy since 1968 in the frame of the numerous deep seismic sounding and wide-angle reflection/refraction projects. The aims of this study are to construct a parametric database including the recording geometric information relative to each profile, the phase pickings and the results of some kinematic analyses performed on the data, and to define a reference 1D velocity model for the Italian territory from all the available refraction data. As concerns the first goal, for each seismic section we picked the P-wave first-arrival-times, evaluated the uncertainties of the arrival-times pickings and determined from each travel time-offset curve the 1D velocity model. The study was performed on 419 seismic sections. Picking was carried out manually by an algorithm which includes the computation of three picking functions and the picking- error estimation. For each of the travel time-offset curves a 1D velocity model has been calculated. Actually, the 1D velocity-depth functions were estimated in three different ways which assume: a constant velocitygradient model, a varying velocity-gradient model and a layered model. As regards the second objective of this work, a mean 1D velocity model for the Italian crust was defined and compared with those used for earthquake hypocentre locations and seismic tomographic studies by different institutions operating in the Italian area, to assess the significance of the model obtained. This model can be used in future works as input for a next joint tomographic inversion of active and passive seismic data.461 632 - PublicationOpen AccessSouthern-Tyrrhenian seismicity in space-time-magnitude domain(2006-11-23T14:15:54Z)
; ; ; ; ; ;Adelfio, G.; Dipartimento di Chimica e Fisica della Terra (CFTA), Università di Palermo, Itatly ;Chiodi, M.; Dipartimento di Chimica e Fisica della Terra (CFTA), Università di Palermo, Itatly ;De Luca, L.; Dipartimento di Chimica e Fisica della Terra (CFTA), Università di Palermo, Itatly ;Luzio, D.; Dipartimento di Chimica e Fisica della Terra (CFTA), Università di Palermo, Itatly ;Vitale, M.; Dipartimento di Chimica e Fisica della Terra (CFTA), Università di Palermo, Itatly; ;; ; An analysis is conducted on a catalogue containing more than 2000 seismic events occurred in the southern Tyrrhenian Sea between 1988 and October 2002, as an attempt to characterise the main seismogenetic processes active in the area in space, time and magnitude domain by means of the parameters of phenomenological laws. We chose to adopt simple phenomenological models, since the low number of data did not allow to use more complex laws. The two main seismogenetic volumes present in the area were considered for the purpose of this work. The first includes a nearly homogeneous distribution of hypocentres in a NW steeply dipping layer as far as about 400 km depth. This is probably the seismological expression of the Ionian lithospheric slab subducting beneath the Calabrian Arc. The second contains hypocentres concentrated about a sub-horizontal plane lying at an average depth of about 10 km. It is characterised by a background seismicity spread all over the area and by clusters of events that generally show a direction of maximum elongation. The parameters of the models describing seismogenetically homogeneous subsets of the earthquake catalogue in the three analysis domains, along with their confidence intervals, are estimated and analysed to establish whether they can be regarded as representative of a particular subset.226 854 - PublicationOpen AccessThe Palermo (Sicily) seismic cluster of September 2002, in the seismotectonic framework of the Tyrrhenian Sea-Sicily border area(2004)
; ; ; ; ; ; ; ; ; ; ;Giunta, G.; Dipartimento di Geologia e Geodesia, Università degli Studi di Palermo, Italy ;Luzio, D.; Dipartimento di Chimica e Fisica della Terra (CFTA), Università degli Studi di Palermo, Italy ;Tondi, E.; Dipartimento di Scienze della Terra, Università degli Studi di Camerino, Italy ;De Luca, L.; Dipartimento di Chimica e Fisica della Terra (CFTA), Università degli Studi di Palermo, Italy ;Giorgianni, A.; Dipartimento di Geologia e Geodesia, Università degli Studi di Palermo, Italy ;D'Anna, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Renda, P.; Dipartimento di Geologia e Geodesia, Università degli Studi di Palermo, Italy ;Cello, G.; Dipartimento di Scienze della Terra, Università degli Studi di Camerino, Italy ;Nigro, F.; Dipartimento di Geologia e Geodesia, Università degli Studi di Palermo, Italy ;Vitale, M.; Dipartimento di Chimica e Fisica della Terra (CFTA), Università degli Studi di Palermo, Italy; ; ; ; ; ; ; ; ; The northern coast of Sicily and its offshore area represent a hinge zone between a sector of the Tyrrhenian Basin, characterized by the strongest crustal thinning, and the sector of the Sicilian belt which has emerged. This hinge zone is part of a wider W-E trending right-lateral shear zone, which has been affecting the Maghrebian Chain units since the Pliocene. Seismological and structural data have been used to evaluate the seismotectonic behavior of the area investigated here. Seismological analysis was performed on a data set of about 2100 seismic events which occurred between January 1988 and October 2002 in the Southern Tyrrhenian Sea. This paper focuses in particular on a set of data relating to the period from 6th September 2002, including both the main shock and about 540 aftershocks of the Palermo seismic sequence. The distribution of the hypocenters revealed the presence of two main seismogenic zones. The events of the easternmost zone may be related to the Ionian lithospheric slab diving beneath the Calabrian Arc. The seismicity associated with the westernmost zone is closely clustered around a sub-horizontal regression plane contained within the thinned Southern Tyrrhenian crust, hence suggesting that this seismogenic zone is strictly connected to the deformation field active within the hinge zone. On the basis of both structural and seismological data, the brittle deformation pattern is characterized by high-angle faults, mainly represented by transcurrent synthetic right-lateral and antithetic left-lateral systems, producing both restraining/uplifting and releasing/subsiding zones which accommodate strains developing in response to the current stress field (characterized by a maximum axis trending NW-SE) which has been active in the area since the Pliocene. The cluster of the seismic sequence which started with the 6th September 2002's main shock is located within the hinge zone. The distribution of the hypocenters relative to this sequence emphasizes the presence of a high-angle NE-SW-oriented deformation belt within which several shear surfaces are considered to be found sub-parallel to that established for the main shock. The kinematics of all these structures is consistent with a compressive right-lateral focal mechanism.310 2002 - PublicationOpen AccessFractal dimension confidence interval estimation of epicentral distributions(1999-10)
; ; ; ; ;De Luca, L.; Dipartimento di Chimica e Fisica della Terra (CFTA), Università di Palermo, Italy ;Lasocki, S.; Institute of Geophysics, University of Mining and Metallurgy, Krakow, Poland ;Luzio, D.; Dipartimento di Chimica e Fisica della Terra (CFTA), Università di Palermo, Italy ;Vitale, M.; Dipartimento di Chimica e Fisica della Terra (CFTA), Università di Palermo, Italy; ; ; Estimates of the fractal dimension of hypocentral distributions require evaluating the range of independent variables in which fractal parameters exhibit a power law. Systematic and accidental errors are produced mainly by the subjective selection of this range, the insufficiency of data sets as well as by hypocenter mislocations. Therefore it is very important to determine the confidence intervals which are associated with fractal dimension estimates. The effects of various sources of errors are studied using different geometric clusters of epicenters, which have been synthetically generated using a multicluster algorithm with different hierarchical levels, so as to reproduce some characteristics of the patterns typical of real epicenter distributions. Subsequently, groups of differently sized subsets of synthetic epicenters were obtained by randomly sampling each distribution. Confidence intervals of fractal dimensions were thus calculated using all the estimates obtained for the various subsets. This procedure was also tested on real seismic data, consisting of epicentral distributions in three Sicilian areas and five clusters of mining-induced seismic events (Wujek coal mine, Poland). In that analysis both correlation dimensions and their confidence intervals were taken into account.159 376