Subduction polarity reversal at the junction between the Western Alps and the Northern Apennines, Italy     

Gianluca Vignaroli  Claudio Faccenna  Laurent Jolivet  Claudia Piromallo  Federico Rossetti 《Tectonophysics》2008,450(1-4):34-50

The controversial relationship between the orogenic segments of the Western Alps and the Northern Apennines is here explored integrating recently published 3D tomographic models of subduction with new and re-interpreted geological observations from the eclogitic domain of the Voltri Massif (Ligurian Alps, Italy), where the two belts joint each other. The Voltri Massif is here described as an extensional domain accommodating the opposing outward migration of the Alpine and Apennine thrust fronts, since about 30–35 Ma. Using tomographic images of the upper mantle and paleotectonic reconstructions, we propose that this extensional setting represents the surface manifestation of an along strike change in polarity of the subducted oceanic slab whose polarity changed laterally in space and in time. Our tectonic model suggests that the westward shift of the Alpine thrust front from the Oligocene onward was the consequence of the toroidal asthenospheric flow induced by the retreat of the Apenninic slab.  相似文献   

Early Cretaceous migmatitic mafic granulites from the Sabzevar range (NE Iran): implications for the closure of the Mesozoic peri-Tethyan oceans in central Iran   总被引：2，自引：0，他引：2  

Federico Rossetti  Mohsen Nasrabady  Gianluca Vignaroli  Thomas Theye  Axel Gerdes  Mohammad Hossein Razavi  Hosein Moin Vaziri 《地学学报》2010,22(1):26-34

The ophiolitic mélange of the Sabzevar Range (northern Iran) is a remnant of the Mesozoic oceanic basins on the northern margin of the Neotethys that were consumed during the Arabia–Eurasia convergence history. Occurrence of km-scale, dismembered mafic HP granulitic slices is reported in this study. Granulites record an episode of amphibole-dehydratation melting and felsic (tonalite/throndhjemite) melt segregation at c. 1.1 GPa and 800 °C. In situ U(-Th)–Pb geochronology of zircon and titanite grains hosted in melt segregations points to an Early Cretaceous (Albian) age for the metamorphic climax. Results of this study (i) impose reconsideration of the current palaeotectonic models of the Neothetyan convergent margin during the Early Cretaceous and (ii) argue that punctuated events of subduction of short-lived back-arc oceanic basins accompanied the long-lasting history of the Neotethyan subduction in the region.  相似文献   

The 1995 FAO Code of Conduct for Responsible Fisheries: Adopting,implementing or scoring results?     

Gilles Hosch  Gianluca Ferraro  Pierre Failler 《Marine Policy》2011

The paper presents the results of a major assessment of Code adoption and implementation in nine fishing countries in Asia (China, Thailand, Vietnam), Africa (Senegal, Guinea Bissau and Guinea) and in the Caribbean (Jamaica, Dominican Republic and Trinidad & Tobago), which are part of the international research project ECOST. The main findings are that the Code as an international policy instrument remains relevant and adaptable to the current international fisheries context, and that its guiding principles and provisions have been endorsed and adopted in almost unanimous fashion by the countries covered, and integrated into fisheries policy letters and legal frameworks. However, results also suggest that tackling the truly difficult issues in fisheries, such as combating illegal, unreported and unregulated (IUU) fishing or adjusting fishing overcapacity has been a lot less successful. The design and implementation of necessary measures often remains very weak in domains with important economic and political dimensions. The causes for this are attributed to a mix of administrative inertia, lack of political will and stamina, and short-sighted economic considerations.  相似文献   

Modeling the 2004 Sumatra tsunami at Seychelles Islands: site-effect analysis and comparison with observations     

Roberto Tonini  Alberto Armigliato  Gianluca Pagnoni  Stefano Tinti 《Natural Hazards》2014,70(2):1507-1525

The M _w = 9.1 mega-thrust Sumatra–Andaman earthquake that occurred on December 26, 2004, was followed by a devastating tsunami that killed hundreds of thousands of people and caused catastrophic effects on human settlements and environments along many coasts of the Indian Ocean, where even countries very far from the source were affected. One of these cases is represented by the Republic of Seychelles, where the tsunami reached the region about 7 h after the earthquake and produced relevant damages, despite the country was more than 4,500 km far from the seismic source. In the present work, we present and discuss a study of the 2004 Sumatra tsunami by means of numerical simulations with the attention focused on the effects observed at the Seychelles Archipelago, a region never previously investigated with this approach. The case is interesting since these islands lay on a very shallow oceanic platform with steep slopes so as the ocean depth changes from thousands to few tens of meters over short distances, with significant effects on the tsunami propagation features: the waves are strongly refracted by the oceanic platform and the tsunami signal is modified by the introduction of additional frequencies. The study is used also to validate the UBO-TSUFD numerical code on a real tsunami event in the far field, and the results are compared with the available observations, i.e., the sea level time series recorded at the Pointe La Rue station, Mahé Island, and run-up measurements and inundation lines surveyed few weeks after the tsunami at Praslin Island, where the tsunami hit during low tide. Synthetic results are found in good agreement with observations, even though some of the observations remain not fully solved. Moreover, simulations have been run in high-tide condition since the 2004 Sumatra tsunami hitting at high tide can be taken as the worst-case scenario for the Seychelles islands and used for tsunami hazard and risk assessments.  相似文献   

Optical properties of Laue lenses for hard X-rays (>60 keV)     

Alessandro Pisa  Filippo Frontera  Gianluca Loffredo  Damiano Pellicciotta  Natalia Auricchio 《Experimental Astronomy》2005,20(1-3):219-228

We report on preliminary results obtained with a Monte Carlo (MC) code developed to study the optical properties of Laue lenses for astro-physical observations. The MC code is written in the Python programming language and uses open source libraries. Among the physical quantities which can be investigated with the MC code, we paid our attention mainly to the estimation of the effective area, field of view (FOV) and point spread function (PSF) of the lens for observation of sources on-axis and off-axis.  相似文献   

Theoretical analysis and tuning criteria of the Kalman filter-based tracking loop   总被引：1，自引：0，他引：1  

Xinhua Tang  Gianluca Falco  Emanuela Falletti  Letizia Lo Presti 《GPS Solutions》2015,19(3):489-503

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The EChO payload instrument – an overview     

Paul Eccleston  Bruce Swinyard  Marcel Tessenyi  Giovanna Tinetti  Ingo Waldmann  Marc Ferlet  Ranah Irshad  Tanya Lim  Kevin Middleton  Tom Bradshaw  Martin Crook  Tom Hunt  Berend Winter  Ian Bryson  Naidu Bezawada  William Taylor  Neil Bowles  Enzo Pascale  Gianluca Morgante  Emanuele Pace  Alberto Adriani  Jean-Michel Reess  Marc Ollivier  Roland Ottensamer  Mirek Rataj  Gonzalo Ramos Zapata  Jan-Rutger Schrader  Avri Selig  Kate Isaak  Martin Linder  Ludovic Puig 《Experimental Astronomy》2015,40(2-3):427-447

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Use of seismic early warning information to calibrate variable dampers for structural control of a highway bridge: evaluation of the system robustness     

Giuseppe Maddaloni  Nicola Caterino  Gianluca Nestovito  Antonio Occhiuzzi 《Bulletin of Earthquake Engineering》2013,11(6):2407-2428

The seismic events occurred in recent years highlighted the extreme vulnerability of large part of the existing constructed facilities and the need to adopt innovative solutions to improve their seismic performance. With this purpose, the possible exploitation of a seismic early warning system (SEWS) in the framework of semi-active structural control using magnetorheological (MR) dampers is herein investigated. The main idea consists in the use of these time-varying properties devices to control an hosting structure by changing their behaviour according to an anticipate estimate, provided by the SEWS, of the peak ground acceleration (PGA) of the incoming earthquake. In this way, the dampers are able to adapt their mechanical characteristics to the specific earthquake obtaining the optimal seismic response. The present paper describes the application of this protection technique to a case-study problem, a highway bridge located in Southern California. The seismic response of the benchmark bridge is investigated by nonlinear time-history analyses by adopting 16 real earthquake ground excitations. These accelerograms cover a wide variety of magnitudes, distances to fault and soil types. Possible errors on estimation of PGA provided by SEWS and their effects on the proposed control system are also considered. The results obtained confirm that unavoidable errors in the PGA estimates provided by the SEWS do not propagate to the seismic response. Conversely, the proposed strategy turns out to damp these errors, resulting in a robust seismic behaviour of the protected structure.  相似文献   

Benford’s Law in Time Series Analysis of Seismic Clusters     

Gianluca Sottili  Danilo M. Palladino  Biagio Giaccio  Paolo Messina 《Mathematical Geosciences》2012,44(5):619-634

Benford’s analysis is applied to the recurrence times of approximately 17,000 seismic events in different geological contexts of Italy over the last 6 years, including the Mt. Etna volcanic area and the seismic series associated with the destructive M _w 6.3, 2009 L’Aquila earthquake. A close conformity to Benford’s law and a power-law probability distribution for the recurrence times of consecutive events is found, as typical of random multiplicative processes. The application of Benford’s law to the recurrence event times in seismic series of specific seismogenic regions represents a novel approach, which enlarges the occurrence and relevance of Benford-like asymmetries, with implications on the physics of natural systems approaching a power law behaviour. Moreover, we propose that the shift from a close conformity of Benford’s law to Brownian dynamics, observed for time separations among non-consecutive events in the study seismic series, may be ruled by a periodical noise factor, such as the effects of Earth tides on seismicity tuning.  相似文献   

The CaGeO3–Ca3Fe2Ge3O12 garnet join: an experimental study     

Gianluca Iezzi  Tiziana Boffa-Ballaran  Catherine McCammon  Falko Langenhorst 《Physics and Chemistry of Minerals》2005,32(3):197-207

Germanate garnets are often used as isostructural analogues of silicate garnets to provide insight into the crystal chemistry and symmetry of the less accessible natural garnet solid solutions. We synthesised two series of germanate garnets at 3 GPa along the join^VIIICa₃^VI(CaGe)^IVGe₃O₁₂–^VIIICa₃^VIFe₂^IVGe₃O₁₂ at 900 °C and 1,100 °C. Samples with compositions close to the CaGeO₃ end-member consist of tetragonal garnet with a small amount of triclinic CaGe₂O₅. Samples with nominal compositions between X_Fe=0.4 and 1.0 consist of a mixture of tetragonal and cubic garnets; whereas, single-phase cubic garnets were obtained for compositions with X_Fe>1.2 (X_Fe gives the iron content expressed in atoms per formula unit, and varies between 0 and 2 along the join). Run products which were primarily single-phase garnet were investigated using Mössbauer spectroscopy. Spectra from samples synthesised at 1,100°C consist of one well-resolved doublet that can be assigned to Fe³⁺ in the octahedral site of the garnet structure. A second doublet, present primarily in samples synthesised at 900°C, can be assigned to Fe²⁺ at the octahedral sites of the garnet structure. The relative abundance of Fe²⁺ decreases with increasing iron content. Transmission electron microscopy analyses confirm this tendency and show that the garnets are essentially defect-free. The unit-cell parameters of tetragonal ^VIIICa₃^VI(CaGe)^IVGe₃O₃ garnet decrease with increasing synthesis temperature, and the deviation from cubic symmetry becomes smaller. Cubic garnets show a linear decrease of unit-cell parameter with increasing iron content. The results are discussed in the context of iron incorporation into ^VIIIMg₃^VI(MgSi)^IVSi₃O₃ majorite.  相似文献