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Dipartimento di Scienza dei Materiali, via per Arnesano, 73100 Lecce, Italy
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- PublicationRestrictedSource ambiguity from an estimation of the scaling exponent of potential field power spectra(2000)
; ; ; ;Quarta, T.; Dipartimento di Scienza dei Materiali, via per Arnesano, 73100 Lecce, Italy ;Fedi, M.; Dipartimento di Geofisica e Vulcanologia, L.go S. Marcellino 10, 80138 Napoli, Italy ;De Santis, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; ; An analysis of the field scaling power spectrum yields useful information about the source distribution, but it is uncertain whether deterministic, random, fractal or mixed approaches have to be used for the interpretation. To this end, the scaling properties of potential field spectra are analysed for a number of different source models of geological interest. Besides the models of Naidu (purely random sources) and Spector and Grant (gross block statistical ensembles) we consider other types of density and magnetization distributions with spectral exponents in the fractal range, such as a single homogeneous body with a random white source distribution. Spectral slopes in the fractal range are obtained. We also study the effects of important natural sources, such as salt domes and sedimentary basins, representing them with simple Gaussians or combinations of Gaussian signals. The same spectral slopes as for gravity signals generated by 3-D fractal source distributions are found for them. Hence the power law decay of the field is not a characteristic only of fractal source models. If a 3-D fractal source distribution is assumed a priori, a way of verifying the goodness of the model is to examine the whitened field at source level. The probability that the whitened field derives from a random white population is estimated for synthetic and real anomalies by applying the usual statistical tests.179 19 - PublicationOpen AccessApplication of 3D visualization techniques in the analysis of GPR data for archaeology(2002)
; ; ; ; ; ;Nuzzo, L.; Osservatorio di Fisica e Chimica della Terra e dell Ambiente, Dipartimento di Scienza dei Materiali, Università di Lecce, Italy ;Leucci, G.; Osservatorio di Fisica e Chimica della Terra e dell Ambiente, Dipartimento di Scienza dei Materiali, Università di Lecce, Italy ;Negri, S.; Osservatorio di Fisica e Chimica della Terra e dell Ambiente, Dipartimento di Scienza dei Materiali, Università di Lecce, Italy ;Carrozzo, M. T.; Osservatorio di Fisica e Chimica della Terra e dell Ambiente, Dipartimento di Scienza dei Materiali, Università di Lecce, Italy ;Quarta, T.; Osservatorio di Fisica e Chimica della Terra e dell Ambiente, Dipartimento di Scienza dei Materiali, Università di Lecce, Italy; ; ; ; In this work, some results of a GPR survey carried out in a 10000 m2 large archaeological site, located in Lecce (Italy) near to a necropolis dating from the Messapian to the Roman imperial age, are reported. After a preliminary survey, performed on the entire area along parallel 1 m spaced profiles using a 200 MHz and a 500 MHz antenna in single-fold continuous mode, some smaller areas were selected, where the survey was repeated decreasing the profile spacing down to 0.50 m for the lower frequency antenna and to 0.25 m for the higher one. For two selected zones (D and B) the processed data were visualized in 3D space not only by the standard time slice technique, but also by two recently proposed approaches, namely by iso-amplitude surfaces of the complex trace amplitude and by 3D projection of energy and envelope stacks. The immediacy in revealing the spatial positioning of highly reflecting bodies, such as the anomaly interpreted as an old refilled cistern in zone D, makes 3D visualization techniques very attractive in archaeological applications of GPR. Their sensitivity to the signal/noise ratio is, on the other hand, highlighted by the quite poor performance in zone B, where the only reliable result provided by all the techniques was the soil/bedrock reflection, whereas none of them could effectively enhance the visibility of weak dipping reflections noted on 2D sections and probably related to fractures or bedding planes in the calcarenitic basement. The performance of the various techniques in these two different situations allowed insights into their main advantages and drawbacks to be gained.1022 879 - PublicationOpen AccessA revisitation of the triangular prism surface area method for estimating the fractal dimension of fractal surfaces(1997-08)
; ; ; ;De Santis, A.; Istituto Nazionale di Geofisica, Roma, Italy ;Fedi, M.; Dipartimento di Geofisica e Vulcanologia, Università "Federico II", Napoli, Italy ;Quarta, T.; Dipartimento di Scienza dei Materiali, Università di Lecce, ltaly; ; Fractal dimension is widely used to give a measure of variability and roughness of curves, signals, objects, sta- tistical distributions, and so on, We found that an often used method, the so-called triangular prism surface- area method, for estimating the tractal dimension of fractal surfaces possesses some intrinsic mistake., in appli- cation. This note describes the misintel"pretation and suggests the proper application, that we calI Revised Tri- angular Prism Method (RTPM). To show its feasibility we apply RTPM to some synthetic Euclidean and frac- tal surfaces of known dimension.285 564 - PublicationOpen AccessGravity modelling of the lower crust in Sardinia (Italy)(1997-10)
; ; ; ; ; ; ; ;Carrozzo, M. T.; Dipartimento di Scienza dei Materiali, Università di Lecce, Italy ;Balia, R.; Istituto di Giacimenti Minerari, Geofisica e Scienze Geologiche, Università di Cagliari, Italy ;Loddo, M.; Dipartimento di Geologia e Geofisica, Università di Bari, Italy ;Luzio, D.; Istituto di Geofisica Mineraria, Università di Palermo, Italy ;Margiotta, C.; Dipartimento di Scienza dei Materiali, Università di Lecce, Italy ;Quarta, T.; Dipartimento di Scienza dei Materiali, Università di Lecce, Italy ;Trudu, R.; Istituto di Giacimenti Minerari, Geofisica e Scienze Geologiche, Università di Cagliari, Italy; ; ; ; ; ; In this paper an example is given of an application of statistical techniques to the Bouguer anomalies analysis in order to design a simple crustal model using few a priori assumptions. All gravity measurements carried out in Sardinia have been collected and processed. The Bouguer anomalies have been calculated according to local density estimates. Spectral analysis of the Bouguer anomalies has been carried out along selected profiles in order to estimate the mean depth of the Moho discontinuity and that of an infracrustal discontinuity. The use of this technique inferred the presence of a discontinuity at a mean depth of ~ 28 km, interpreted as Moho and the likely presence of an infracrustal discontinuity at a mean depth of ~18 km, interpreted as the upper-lower crust transition. In order to roughly reconstruct the shape of these interfaces, 2D inversion techniques were applied to the large wavelength components of the Bouguer anomalies, relative to profiles oriented along the E-W direction, extracted from low-pass filtered Bouguer anomaly maps. The density model obtained is compatible with some velocity models achieved from the interpretation of the seismic refraction profiles carried out within the European Geotraverse project.162 229