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The Earth Expansion Evidence – A Challenge for Geology, Geophysics and Astronomy

Fri, 30 Nov 2012 23:00:00 GMT

Title: The Earth Expansion Evidence – A Challenge for Geology, Geophysics and Astronomy Authors: Scalera, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Boschi, E.; University of Bologna; Cwojdzinski, S.; Polish Geological Survey Editors: Scalera, Giancarlo; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Boschi, Enzo; University of Bologna; Cwojdzinski, Stefan; Polish Geological Survey

Mantle viscosity inference: a comparison between Simulated Annealing and Neighbourhood Algorithm inversion methods

Wed, 31 Dec 2003 23:00:00 GMT

Title: Mantle viscosity inference: a comparison between Simulated Annealing and Neighbourhood Algorithm inversion methods Authors: Piana Agostinetti, N.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia; Spada, G.; Università di Urbino; Cianetti, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia Abstract: Two direct search methods, simulated annealing and neighbourhood algorithm, are applied to the inversion of the viscosity profile of the mantle using relative sea level time-histories for the Hudson Bay region. In problems characterized by a low-dimensional model space (Nd = 2 in this study), the two inversion methods show comparable performances. When a larger number of dimensions is involved (specifically Nd = 6), we directly show that simulated annealing is less effective than neighbourhood algorithm in overcoming the obstacles that are found in the model space when our specific data set is employed. This study confirms that modifications of the conventional Monte Carlo inversion method, such as simulated annealing and neighbourhood algorithm, are viable tools to determine the viscosity profile of the mantle, which, until recently, has been mainly tackled by means of linearized techniques.

Core-mantle boundary topography: seismology

Sun, 31 Dec 2006 23:00:00 GMT

Title: Core-mantle boundary topography: seismology Authors: Morelli, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia Editors: Gubbins, David; University of Leeds; Herrero-Bervera, Emilio; University of Hawaii at Manoa Abstract: n/a

Initial burst of oceanic crust accretion in the Red Sea due to edge driven mantle convection

Mon, 03 Oct 2011 22:00:00 GMT

Title: Initial burst of oceanic crust accretion in the Red Sea due to edge driven mantle convection Authors: Ligi, M.; Istituto di Scienze Marine, Consiglio Nazionale delle Ricerche, Bologna; Bonatti, E.; Istituto di Scienze Marine, Consiglio Nazionale delle Ricerche, Bologna e Lamont Doherty Earth Observatory, Columbia University; Caratori Tontini, F.; GNS Science, Ocean Exploaration Section, New Zealand; Cipriani, A.; Lamont Doherty Earth Observatory, Columbia University; Cocchi, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Schettino, A.; Dipartimento di Scienze della Terra, Università di Camerino; Bortoluzzi, G.; Istituto di Scienze Marine, Consiglio Nazionale delle Ricerche, Bologna; Ferrante, V.; Istituto di Scienze Marine, Consiglio Nazionale delle Ricerche, Bologna; Khalil, S.; Department of Geological and Biological Sciences, Suez Canal University, Egypt; Mitchell, N.; School of Earth, Atmosphere and Environmental Sciences, University of Manchester; Rasul, N.; Saudi Geological Survey, Saudi Arabia Abstract: The 500 m.y. cycle whereby continents assemble in a single supercontinent and then fragment and disperse again involves the rupturing of a continent and the birth of a new ocean, with the formation of passive plate margins. This process is well displayed today in the Red Sea, where Arabia is separating from Africa. We carried out geophysical surveys and bottom rock sampling in the two Red Sea northernmost axial segments of initial oceanic crust accretion, Thetis and Nereus. Areal variations of crustal thickness, magnetic intensity, and degree of melting of the subaxial upwelling mantle reveal an initial burst of active oceanic crust generation and rapid seafloor spreading below each cell, occurring as soon as the lid of continental lithosphere breaks. This initial pulse may be caused by edge-driven subrift mantle convection, triggered by a strong horizontal thermal gradient between the cold continental lithosphere and the hot ascending asthenosphere. The thermal gradient weakens as the oceanic rift widens; therefore the initial active pulse fades into steady, more passive crustal accretion, with slower spreading and along axis rift propagation.

Seismic attenuation and mantle wedge temperature in the northern Apennine subtuction zone (Italy) from teleseismic body wave spectra.

Mon, 13 Sep 2010 22:00:00 GMT

Title: Seismic attenuation and mantle wedge temperature in the northern Apennine subtuction zone (Italy) from teleseismic body wave spectra. Authors: Piccinini, D.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Di Bona, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia; Lucente, F. P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia; Levin, V.; Rutgers University; Park, J.; Yale University Abstract: We analyze P and S wave spectra from moderate‐ to deep‐focus teleseisms recorded at the Retreating‐Trench, Extension, and Accretion Tectonics (RETREAT) temporary broadband seismic network to assess the variations of the Earth mantle attenuation in the northern Apennines region (Italy). For each earthquake, we compute the ratio between the spectrum at each station and the average spectrum, in order to estimate t* residuals (Δt*) from the spectral ratio decay. The number and distribution of the teleseisms useable for the P wave t* calculation allow for a gross azimuthal analysis; although the (Δt*) values at single station display, in most cases, azimuthal‐dependent fluctuations, their overall distribution shows a partition of the study region into two main areas, whose gross features remain almost unchanged over the whole azimuthal range. This partition is confirmed by the S wave t* mean values, computed for each station over the set of useable events. We distinguish a relatively high attenuation area on the western, Tyrrhenian side and a relatively low attenuation area on the eastern, Adriatic side. By correlating our Δt* estimates and the velocity structure derived from the existing tomographic models, we compute the ranges of possible P and S wave Q values in the mantle wedge above the Apennines slab (on the Tyrrhenian side) and in the asthenosphere below the Adriatic region. Furthermore, the determined attenuation properties are used to draw some inferences on the thermal state of the uppermost mantle and on the physical properties of the tectonic elements, which constitute the subduction system in the region. Description: An edited version of this paper was published by AGU. Copyright (2010) American Geophysical Union.

Dike propagation within active central volcanic edifices: constraints from Somma-Vesuvius, Etna and analogue models

Thu, 12 Feb 2009 23:00:00 GMT

Title: Dike propagation within active central volcanic edifices: constraints from Somma-Vesuvius, Etna and analogue models Authors: Acocella, V.; Dip. Scienze Geologiche Roma Tre, L. S.L. Murialdo, 1, Roma, Italy; Neri, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Sulpizio, R.; CIRISIVU, c/o Dip. Geomineralogico, via Orabona 4, 70125 Bari, Italy Abstract: Dikes within stratovolcanoes are commonly expected to have radial patterns. However, other patterns may also be found, due to regional stresses, magmatic reservoirs and topographic variations. Here, we investigate dike patterns within volcanic edifices by studying dike and fissure complexes at Somma-Vesuvius and Etna (Italy) using analogue models. At the surface, the dikes and fissures show a radial configuration. At depths of tens to several hundreds of metres, in areas exposed by erosion, tangential and oblique dikes are also present. Analogue models indicate that dikes approaching the flanks of cones, regardless of their initial orientation, reorient to become radial (parallel to the maximum gravitational stress). This re-orientation is a significant process in shallow magma migration and may also control the emplacement of dikefed fissures reaching the lower slopes of the volcano.

Sea-floor spreading initiation: constraints from geophysical data of the Thetis Deep, northern Red Sea

Sun, 14 Dec 2008 23:00:00 GMT

Title: Sea-floor spreading initiation: constraints from geophysical data of the Thetis Deep, northern Red Sea Authors: Ligi, M.; CNR-ISMAR Bologna; Bonatti, E.; CNR-ISMAR Bologna; Bortoluzzi, G.; CNR-ISMAR Bologna; Brunelli, D.; Università di Modena, Dipartimento di Scienze della Terra; Caratori Tontini, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Cipriani, A.; Doherty Earth Observatory, Columbia University,; Cocchi, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Cuffaro, M.; CNR-ISMAR Bologna; Ferrante, V.; CNR-ISMAR Bologna Abstract: A major step in the "Wilson Cycle" is the splitting of a continent and the birth of a new ocean, with the consequent formation of passive plate margins. The transition from a continental to an oceanic rift can be observed today nowhere better than in the Red Sea/Gulf of Aden system. We have carried out during several years a number of expeditions in the axial portion of the Northern Red Sea, in the region where the northernmost nuclei of axial emplacement of oceanic crust can be observed. High resolution multibeam, magnetics, gravity and multichannel seismic reflection surveys from the Thetis Deep revealed rates and modes of initial pulses of sea floor spreading, velocity of S to N axial propagation of the oceanic rift, evolution of initial MORB-type crust and nature of the mantle thermal anomaly that caused the transition from a continental to an oceanic rift. The Thetis deep is made of three en echelon fault-bounded axial basins that are joined together with axial volcanic ridges and a large number of scattered small central volcanoes. The southern basin shows a strong linear magnetic anomaly corresponding to the axial neo-volcanic zone. Two negative symmetric anomalies identified as Matuyama are present in the southernmost part of this basin, suggesting that the emplacement of oceanic crust at this site started roughly 2.5 Ma, with an average half spreading rate of 6 mm/yr. The central sub-basin is also characterized by a strongly magnetic linear neo- volcanic zone that, however, is flanked only by a small, "vanishing" symmetrical negative anomaly suggesting emplacement of oceanic crust not earlier than about 1 Ma. The northern sub-basin does not show a clearly defined linear neo-volcanic zone although it displays a strong central magnetization suggesting initial emplacement of oceanic crust < 0.7 Ma. This pattern implies a south to north time progression of the initial emplacement of oceanic crust within the Thetis system, with a propagation rate of about 20 mm/yr. Gravity data inversions constrained by seismic data reveal that the oceanic crust extends from the axial neo-volcanic ridges toward the master faults of the axial depression with crustal thickness ranging from 4 to 6 km. The increasing thickness of basaltic crust toward the edges of the basin together with higher degree of melting, inferred by the geochemistry of the basaltic glasses, and higher central magnetization of the northernmost and youngest basin suggest a pulse of faster spreading rate at the onset of sea-floor spreading.

SKS splitting in Southern Italy: anisotropy variations in a fragmented subduction zone.

Mon, 31 Dec 2007 23:00:00 GMT

Title: SKS splitting in Southern Italy: anisotropy variations in a fragmented subduction zone. Authors: Baccheschi, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia; Margheriti, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia; Steckler, M. S.; Lamont-Doherty Observatory, Palisades, NY (USA) Abstract: In this paper we present a collection of good quality shear wave splitting measurements in Southern Italy. In addition to a large amount of previous splitting measurements, we present new data from 15 teleseisms recorded from 2003 to 2006 at the 40 stations of the CAT/SCAN temporary network. These new measurements provide additional constraints on the anisotropic behaviour of the study region and better define the fast directions in the southern part of the Apulian Platform. For our analysis we have selected wellrecorded SKS phases and we have used the method of Silver and Chan to obtain the splitting parameters: the azimuth of the fast polarized shear wave (φ) and delay time (δt). Shear wave splitting results reveal the presence of a strong seismic anisotropy in the subduction system below the region. Three different geological and geodynamic regions are characterized by different anisotropic parameters. The Calabrian Arc domain has fast directions oriented NNE–SSW and the Southern Apennines domain has fast directions oriented NNW–SSE. This rotation of fast axes, following the arcuate shape of the slab, is marked by a lack of resolved measurements which occurs at the transition zone between those two domains. The third domain is identified in the Apulian Platform: here fast directions are oriented almost N–S in the northern part and NNE–SSW to ENE–WSW in the southern one. The large number of splitting parameters evaluated for events coming from different back-azimuth allows us to hypothesize the presence of a depth-dependent anisotropic structure which should be more complicated than a simple 2 layer model below the Southern Apennines and the Calabrian Arc domains and to constrain at 50 km depth the upper limit of the anisotropic layer, at least at the edge of Southern Apennines and Apulian Platform. We interpret the variability in fast directions as related to the fragmented subduction system in the mantle of this region. The trench-parallel φ observed in Calabrian Arc and in Southern Apennines has its main source in the asthenospheric flow below the slab likely due to the pressure induced by the retrograde motion of the slab itself. The pattern of φ in the Apulian Platform does not appear to be the direct result of the rollback motion of the slab, whose influence is limited to about 100 km from the slab. The anisotropy in the Apulian Platform may be related to an asthenospheric flow deflected by the complicated structure of the Adriatic microplate or may also be explained as frozen-in lithospheric anisotropy.

Are we going towards a global planetary magnetic change?

Wed, 10 Sep 2008 22:00:00 GMT

Title: Are we going towards a global planetary magnetic change? Authors: De Santis, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Qamili, E.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia Editors: De Santis, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Baker, R.; Israel Institute of Technology, Israel; Klug, B.; Univ. of Natural Res. & Applied Life Sciences, Austria; Vanicek, P.; University of New Brunswick, Canada; D'El-Rey Silva, L. J. H.; Universidade de Brasilia, Brazil; Foyo, A.; University of Cantabria, Spain; Ercanoglu, M.; Hacettepe University, Turkey; Dordevic, D.; University of Belgrade, Serbia Abstract: The dipolar part of the geomagnetic field has been decaying rapidly during the last few hundreds of years. In addition to this classical argument, from Information theory applied to geomagnetism, there are some evidences that the recent Earth magnetic field is showing characteristics typical of a reversal in progress. If this is true, many scientific and environmental questions will arise. For instance, it will be of particular interest to monitor the time-space dynamics the South Atlantic Anomaly, where the magnetic field is strongly reduced (a sort of "planetary magnetic hole"). Here we find one of the most favourite places where Low Earth Orbiting (LEO) satellites are lost or present some damages, due to the vicinity of "clouds" of electric particles (Van Allen belts) to the Earth's surface. The decay of the field will also decrease the screening effect to the solar wind and cosmic charges, so enhancing the cosmic radiation illuminating our planet: possible negative consequences are expected in terms of increase of skin cancers. Also important will be the study of the possible evolution of the core dynamics that will be generating this specific condition of the geomagnetic field.

Environment and Geoscience

Wed, 10 Sep 2008 22:00:00 GMT

Title: Environment and Geoscience Authors: De Santis, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Baker, R.; Israel Institute of Technology, Israel; Klug, B.; Univ. of Natural Res. & Applied Life Sciences, Austria; Vanicek, P.; University of New Brunswick, Canada; D'El-Rey Silva, L. J. H.; Universidade de Brasilia, Brazil; Foyo, A.; University of Cantabria, Spain; Ercanoglu, M.; Hacettepe University, Turkey; Dordevic, D.; University of Belgrade, Serbia Editors: De Santis, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Baker, R.; Israel Institute of Technology, Israel; Klug, B.; Univ. of Natural Res. & Applied Life Sciences, Austria; Vanicek, P.; University of New Brunswick, Canada; D'El-Rey Silva, L. J. H.; Universidade de Brasilia, Brazil; Foyo, A.; University of Cantabria, Spain; Ercanoglu, M.; Hacettepe University, Turkey; Dordevic, D.; University of Belgrade, Serbia Abstract: This book contains the proceedings of the 1st WSEAS International Conference on Environmental and Geological Science and Engineering (EG'08) which was held in Malta, September 11-13, 2008. This conference aims to disseminate the latest research and applications in Renewable Energy, Mineral Resources, Natural Hazards and Risks, Environmental Impact Assessment, Urban and Regional Planning Issues, Remote Sensing and GIS, and other relevant topics and applications. The friendliness and openness of the WSEAS conferences, adds to their ability to grow by constantly attracting young researchers. The WSEAS Conferences attract a large number of well-established and leading researchers in various areas of Science and Engineering as you can see from http://www.wseas.org/reports. Your feedback encourages the society to go ahead as you can see in http://www.worldses.org/feedback.htm The contents of this Book are also published in the CD-ROM Proceedings of the Conference. Both will be sent to the WSEAS collaborating indices after the conference: www.worldses.org/indexes In addition, papers of this book are permanently available to all the scientific community via the WSEAS E-Library. Expanded and enhanced versions of papers published in this conference proceedings are also going to be considered for possible publication in one of the WSEAS journals that participate in the major International Scientific Indices (Elsevier, Scopus, EI, ACM, Compendex, INSPEC, CSA .... see: www.worldses.org/indexes) these papers must be of high-quality (break-through work) and a new round of a very strict review will follow. (No additional fee will be required for the publication of the extended version in a journal). WSEAS has also collaboration with several other international publishers and all these excellent papers of this volume could be further improved, could be extended and could be enhanced for possible additional evaluation in one of the editions of these international publishers. Finally, we cordially thank all the people of WSEAS for their efforts to maintain the high scientific level of conferences, proceedings and journals.