http://hdl.handle.net/2122/209 Ricerca nel canale cerca http://www.earth-prints.org/simple-search http://hdl.handle.net/2122/5638 Titolo: Possible causes of arc development in the Apennines, central Italy<br/><br/>Autori: Billi, A.; Dipartimento di Scienze Geologiche, Università “Roma Tre,” Largo S.L. Murialdo, 00146 Rome, Italy; Tiberti, M. M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia<br/><br/>Abstract: In central Italy, the geometry, kinematics,and tectonic evolution of the late NeogeneUmbrian Arc, which is one of the mainthrusts of the northern Apennines, havelong been studied. Documented evidencefor orogenic curvature includes vertical axisrotations along both limbs of the arcand a positive orocline test along the entirearc. The cause of the curvature is, however,still unexplained. In this work, we focusour attention on the southern portion ofthe Umbrian Arc, the so-called Olevano-Antrodoco thrust. We analyze, in particular,gravity and seismic-reflection data and consider available paleomagnetic, stratigraphic,structural, and topographic evidence fromthe central Apennines to infer spatial extent,attitude, and surface effects of a midcrustalanticlinorium imaged in the CROP-11 deepseismic profile. The anticlinorium has horizontaldimensions of ~50 by 30 km, andit is located right beneath the Olevano-Antrodoco thrust. Stratigraphic, structural,and topographic evidence suggests that theanticlinorium produced a surface uplift duringits growth in early Pliocene times. Wepropose an evolutionary model in which,during late Neogene time, the Olevano-Antrodoco thrust developed in an out-of sequencefashion and underwent ~16° ofclockwise rotation when the thrust ran intoand was then raised and folded by the growinganticlinorium (late Messinian–early Pliocenetime). This new model suggests a causallink between midcrustal folding and surficialorogenic curvature that is consistent withseveral available data sets from the northernand central Apennines; more evidence is,however, needed to fully test our hypothesis.Additionally, due to the occurrence of midcrustalbasement-involved thrusts in otherorogens, this model may be a viable mechanismfor arc formation elsewhere. http://hdl.handle.net/2122/5018 Titolo: Rapid 3-D forward model of potential fields with application to the Palinuro Seamount magnetic anomaly (southern Tyrrhenian Sea, Italy)<br/><br/>Autori: Caratori Tontini, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Cocchi, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Carmisciano, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia<br/><br/>Abstract: We show a set of forward model equations in the Fourier domain for calculating the3-D gravity and magnetic anomalies of a given 3-D distribution of density ormagnetization. One property of the potential field equations is that they are given byconvolution products, providing a very simple analytic expression in the Fourier domain.Under this assumption, the domain of the density or magnetization parameters isconnected by a biunivoc relationship with the data space, and potential field anomalies canbe seen as filtered versions of the corresponding density or magnetization distributions.A very fine spatial discretization can be obtained by using a large number of pointswithin a unique 3-D grid, where both the source distributions and field data are defined.The main advantage of this formulation is that it dramatically reduces execution times,providing a very fast forward model tool useful for modeling anomalies at differentaltitudes. We use this method to evaluate an average magnetization of 8 A/m for thePalinuro Seamount in the Tyrrhenian Sea (southern Italy), thus performing a jointinterpretation of morphological and newly acquired magnetic data. http://hdl.handle.net/2122/4979 Titolo: Tidal gravity observations at Mt. Etna and Stromboli: results concerning the modeled and observed tidal factors<br/><br/>Autori: Panepinto, S.; Università degli Studi di Palermo, Italy; Greco, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Luzio, D.; Università degli Studi di Palermo, Ital; Ducarme, B.; Royal Observatory of Belgium, Brussels, Belgium<br/><br/>Abstract: Continuous gravity observations performed in the last few years, both at Mt. Etna and Stromboli, have promptedthe need to improve the tidal analysis in order to acquire the best corrected data for the detection of volcanorelated signals. On Mt. Etna, the sites are very close to each other and the expected tidal factor differences arenegligible. It is thus useful to unify the tidal analysis results of the different data sets in a unique tidal model.This tidal model, which can be independently confirmed by a modeling of the tidal parameters based on the elasticresponse of the Earth to tidal forces and the computation of the ocean tides effects on gravity, is very usefulfor the precise tidal gravity prediction required by absolute or relative discrete gravity measurements. Thechange in time of the gravimeters’ sensitivity is also an important issue to be checked since it affects not onlythe results of tidal analysis but also the accuracy of the observed gravity changes. Conversely, if a good tidalmodel is available, the sensitivity variations can be accurately reconstructed so as to retune observed tidalrecords with the synthetic tide, since the tidal parameters are assumed to be constant at a given location. http://hdl.handle.net/2122/4731 Titolo: RAPPORTO SULLE INDAGINI DI SISMICA A RIFLESSIONE, GRAVIMETRICHE, MAGNETOMETRICHE, MORFOBATIMETRICHE E CAMPIONAMENTO FONDO MARE NELL’ ARCO CALABRO (MAR IONIO) CAMPAGNA CALAMARE08<br/><br/>Autori: Polonia, A.; CNR - ISMAR; Bortoluzzi, G.; CNR - ISMAR; Gasperini, L.; CNR - ISMAR; Ligi, M.; CNR - ISMAR; Carrara, G.; CNR - ISMAR; Cuffaro, M.; CNR - ISMAR; D'Oriano, F.; CNR - ISMAR; Riminucci, F.; CNR - ISMAR; Zittellini, N.; CNR - ISMAR; Torelli, L.; Università di Parma; Capozzi, R.; Università di Bologna; Oppo, D.; Università di Bologna; Viola, I.; Università di Bologna; Minelli, L.; Università di Roma-3; Gallais, F.; Université di Brest; Carmisciano, C.; INGV; Gambetta, M.; INGV; Locritani, M.; INGV; Muccini, F.; INGV; Carone, S.; Istituto Idrografico della Marina; Laterra, A.; Istituto Idrografico della Marina<br/><br/>Abstract: The study of the Calabrian Arc in the Ionian Sea is key to understanding of thegeological processes in the Mediterranean Sea. We present the technical details and results ofcruise CALAMARE08 with N/O Urania during spring 2008. We acquired a large set of geologicaland geophysical data, among them Multichannels Seismic and SBP, magnetometry, gravimetry,swath bathymetry and coring of sea bottom. http://hdl.handle.net/2122/4723 Titolo: Possible causes of arc development in the Apennines, central Italy<br/><br/>Autori: Billi, A.; Dipartimento di Scienze Geologiche, Università “Roma Tre”, Rome, Italy; Tiberti, M. M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia<br/><br/>Abstract: In central Italy, geometry, kinematics, and tectonic evolution of the late Neogene Umbrian Arc, which is one of the main thrusts of the northern Apennines, have long been studied. Documented evidence for orogenic curvature includes vertical-axis rotations along both limbs of the arc and a positive orocline test along the entire arc. The curvature’s cause is, however, still unexplained. In this work, we focused our attention on the southern portion of the Umbrian Arc, the so-called Olevano-Antrodoco thrust. We analyze, in particular, gravity and seismic reflection data and consider available paleomagnetic, stratigraphic, structural, and topographic evidence from the central Apennines to infer spatial extent, attitude, and surface effects of a mid-crustal anticlinorium imaged in the CROP-11 deep seismic profile. The anticlinorium has horizontal dimensions of about 50 by 30 km and is located right beneath the Olevano-Antrodoco thrust. Stratigraphic, structural, and topographic evidence suggests that the anticlinorium produced a surface uplift during its growth in early Pliocene times. We propose an evolutionary model in which, during late Neogene time, the Olevano-Antrodoco thrust developed in an out-of-sequence fashion and underwent about 16° of clockwise rotation when the thrust ran into and was then raised and folded by the growinganticlinorium (late Messinian-early Pliocene time). This new model suggests a causal link between mid-crustal folding and surficial orogenic curvature that is consistent with several available data sets from the northern-central Apennines; more evidence is, however, needed to fully test hypothesis. Additionally, due to the occurrence of mid-crustal basement-involved thrusts in other orogens, this model may be a viable mechanism for arc formation elsewhere. http://hdl.handle.net/2122/4456 Titolo: Looking inside the Panarea Island (Aeolian Archipelago, Italy) by gravity and magnetic data<br/><br/>Autori: Cocchi, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Caratori Tontini, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Carmisciano, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Stefanelli, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Anzidei, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia; Esposito, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia; Del Negro, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Greco, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Napoli, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia<br/><br/>Abstract: In this paper we show and discuss the results of gravity and magnetic surveys of Panarea Island and its archipelago. The most recent volcanic manifestation occurred in November 2002 with a shallow submarine gas eruption between the islets of Dattilo, Panarelli, Lisca Bianca, Bottaro and Lisca Nera.Currently, the activity of Panarea is monitored through a multidisciplinary study under the umbrella of the Italian Department of Civil Protection with the goal of defining the hazard of this area. With this aim, in May 2006 the first gravity and magnetic surveys of Panarea Island and its archipelago were performed. The offshore magnetic data were obtained using a marine magnetometer, a Geometrics G880, from the Istituto Idrografico dell Marina (IIM). Onshore and offshore magnetic data were integrated into an unique dataset for complete magnetic coverage of the study area. By using two micro-gravimeters (LaCoste & Romberg), gravity data were collected along tracks every 250 meters. The gravity dataset was processed using the standard method. A Bouguer reduction was applied to the free-air gravity dataset using a detailed digital elevation model of the island and the neighbouring sea after evaluation of the optimal Bouguer density to reduce the topographic effect.The result is a Bouguer anomaly map that shows lateral variations in density distribution and the relationships between the shallow volcanic/crustal features and tectonic lineaments. This evidence is also highlighted by the magnetic pattern, which suggests the importance of the youngest volcanic deposits with respect to the magnetic features of the island. http://hdl.handle.net/2122/4448 Titolo: Rapid 3D forward model of potential fields with application to the Palinuro Seamount magnetic anomaly (Southern Tyrrhenian Sea, Italy)<br/><br/>Autori: Caratori Tontini, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Cocchi, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Carmisciano, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia<br/><br/>Abstract: We show a set of forward model equations in the Fourier domain for calculatingthe 3D gravity and magnetic anomalies of a given 3D distribution of densityor magnetization. One property of the potential-field equations is that they are givenby convolution products, providing a very simple analytic expression in the Fourier domain.Under this assumption, the domain of the density or magnetization parametersis connected by a biunivoc relationship with the data space, and potential-field anomaliescan be seen as filtered versions of the corresponding density or magnetization distributions.A very fine spatial discretization can be obtained by using a large numberof points within a unique 3D grid, where both the source distributions and field dataare defined. The main advantage of this formulation is that it dramatically reduces executiontimes, providing a very fast forward model tool useful for modeling anomaliesat different altitudes. We use this method to evaluate an average magnetization of 8 A/mfor the Palinuro Seamount in the Tyrrhenian Sea (Southern Italy), thus performing ajoint interpretation of morphological and newly acquired magnetic data. http://hdl.handle.net/2122/4347 Titolo: Sea gravity data in the Gulf of Naples. A contribution to delineating the structural pattern of the Phlegraean Volcanic District<br/><br/>Autori: Berrino, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Corrado, G.; Dipartimento di Scienze della Terra, Università “Federico II”, Napoli, Italy; Riccardi, U.; Dipartimento di Scienze della Terra, Università “Federico II”, Napoli, Italy<br/><br/>Abstract: Bathymetric and gravity surveys were carried out from 1988 to 1994, in the Gulf of Naples (Southern Italy) tooffshore extend the already existing Bouguer anomaly map. In order to improve the knowledge of thestructural setting beneath the active Neapolitan volcanoes (Vesuvio, Campi Flegrei and Ischia), 862 stationswere surveyed within the isobath of 400 m; at the same time, and about 2000 on-land gravity values werealso collected. A new Bouguer anomaly map spanning the whole volcanic region was drawn from the finaldata set. Gravity anomalies were referred to the new absolute gravity station in Naples and computedaccording to 1980 Geodetic Reference System. Finally, a density value of 2200 kg/m3 was used in thecomputation of the Bouguer and terrain effects. We carried out the inversion of the gravity anomaliesadopting a 2.5-D modelling along selected profiles crossing the investigated area. The interpretative modelswere constrained to data obtained from deep wells and other geophysical investigations.In a previous paper, we investigated in detail the area around the Vesuvio. Here we focus on the PhlegraeanVolcanic District (PVD), formed by Campi Flegrei, and the islands of Procida and Ischia. Our interpretationpermits to outline two separate caldera-like structures in Campi Flegrei and their rims, mainly in the offshoresector. Moreover, it highlights a sharp separation between the island of Ischia and the rest of the PVD whileshowing Procida as well integrated, at least from the structural point of view. Ischia appears to be a blockdelimited all around and stepped by a series of volcano–tectonic structures. Both the qualitative descriptionand the quantitative interpretation of the Bouguer anomaly in the PVD area, together with the comparisonwith the gravity features of the rest of the Neapolitan area, would suggest that the uprising basementbeneath the island of Ischia, inducing most of the gravity signal, could be the carbonate ones. The certaintyand the discrimination between a carbonate or lava basement beneath Campi Flegrei is not yet deducible. Inaddition, for this area, the presence of a magma chamber from the Bouguer anomaly, taking into account theinformation provided by further geophysical and geochemical researches, was checked. The add-on bodyimproves the model as a whole and doesn't impact on the presence of a residual magma chamber.Finally, the quantitative interpretation also permitted to define the shape and the depth of the 2600 kg/m3basement (carbonate in places) and of the overlapping denser polygenic layer on which the inferred mainstructures was drawn. http://hdl.handle.net/2122/4341 Titolo: 3D Gravity Inversion by Growing Bodies and Shaping Layers at Mt. Vesuvius (Southern Italy)<br/><br/>Autori: Berrino, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Camacho, A. G.; Instituto de Astronomı´a y Geodesia (CSIC-UCM),Spain<br/><br/>Abstract: To improve our knowledge of the structural pattern of Mt. Vesuvius and its magmatic system,which represents one of the three volcanoes located in the Neapolitan area (together with Campi Flegrei andIschia; southern Italy), we analyze here the Bouguer gravity map that is already available through itsinterpretation by means of 2.5-dimensional modelling. We have carried out a three-dimensional interpretationusing a new and original algorithm, known as ‘Layers’, that has been especially processed for this purpose.Layers works in an automatic and non-subjective way, and allows the definition of the structural settings interms of several layers, each representing a specific geological formation. The same data are also interpreted interms of isolated and shallow anomalous density bodies using a well tested algorithm known as ‘Growth’. Wefocus our inversions on the Mt. Vesuvius volcano, while globally analyzing the entire Neapolitan area, in orderto investigate the deep structures, and in particular the deep extended ‘sill’ that has been revealed by seismictomography.The final models generally confirm the global setting of the area as outlined by previous investigations,mainly for the shape and depth of the carbonate basement below Mt. Vesuvius. The presence of lateral densitycontrasts inside the volcano edifice is also shown, which was only hypothesized in the 2.5-dimensionalinversion. Moreover, the models allow us to note a high density body that rises from the top of the carbonatebasement and further elongates above sea level. This probably represents an uprising of the same basement,which is just below the volcano and which coincides with the VP and VP/VS anomalies detected under the crater.The three-dimensional results also reveal that the two inversion methods provide very similar models, where thehigh density isolated body in the Growth model can be associated with the rising high density anomaly in theLayers model. Taking into account the density of these modelled bodies, we would also suggest that theyrepresent solidified magma bodies, as suggested by other studies. Finally, we did not clearly detect any deepanomalous body that can be associated with the sill that was suggested by seismic tomography. http://hdl.handle.net/2122/3504 Titolo: A new approach for residual gravity anomaly profile interpretations: Forced Neural Network (FNN)<br/><br/>Autori: Osman, O.; Istanbul Commerce University, Eminonu, Istanbul, Turkey; Muhittin Albora, A.; Istanbul University, Engineering Faculty, Geophysical Department, Avcilar, Istanbul, Turkey; Ucan, O. N.; Istanbul University, Engineering Faculty, Electrical & Electronics Dept, Avcilar, Istanbul, Turkey<br/><br/>Abstract: This paper presents a new approach for interpretation of residual gravity anomaly profiles, assuming horizontalcylinders as source. The new method, called Forced Neural Network (FNN), is introduced to determine the undergroundstructure parameters which cause the anomalies. New technologies are improved to detect the bordersof geological bodies in a reliable way. In a first phase one neuron is used to model the system and a back propagationalgorithm is applied to find the density difference. In a second phase, density differences are quantifiedand a mean square error is computed. This process is iterated until the mean square error is small enough. Afterobtaining reliable results in the case of synthetic data, to simulate real data, the real case of the Gulf of Mexicogravity anomaly map, which has the form of anticline structure, is examined. Gravity anomaly values from across section of this real case, result to be very close to those obtained with the proposed method.