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   

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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Slope dynamics of Lake Albano (Rome,Italy): insights from high resolution bathymetry     

Francesca Bozzano  Paolo Mazzanti  Marco Anzidei  Carlo Esposito  Mario Floris  Gianluca Bianchi Fasani  Alessandra Esposito 《地球表面变化过程与地形》2009,34(11):1469-1486

New detailed data about the morphology of the submerged slopes of Lake Albano (Rome, Italy) have been collected by a sonar multibeam survey financed by the Italian Department of Civil Protection. These data allow for investigation of the subaqueous slope dynamics of the lake, which partially fills a volcanic depression, and the elucidation of the relationships between subaqueous and subaerial slope processes. Subaerial, submerged and combined subaerial/submerged landslide‐related morphologies were detected around the inner slopes of the lake. In the submerged slopes, several gravity‐induced landforms were recognized: landslide scar areas, landslide accumulations, erosional chutes and channels, block fields, isolated blocks, scarps and slope breaks. An attempt to evaluate the state of activity of the submerged slopes was carried out by taking into consideration the relative freshness of some selected landforms. Interpretation of bathymetric data, as well as direct surveys of the subaerial slopes, was used to assess the morphometric features and interpret the type of movement of the landslides. We propose a comprehensive classification based on the landslide's size and type of movement. We recognized rock fall/topples, debris flows, rock slides and slump, complex rock slides/channelled flows and debris slide and slump. The volume of the main landslides ranged between 10¹ and 10³ m³, while a few rock and debris slides have volumes ranging between 10³ and 10⁵ m³. Two large palaeo‐landslides with volumes on the order of 10⁶ m³ were identified in the southern and northern part of the lake, respectively. Velocities of the recognized landslides range from rapid to extremely rapid. Two main landslide hazard scenarios have been depicted from the results of the integrated analysis of both subaerial and submerged gravity‐induced landforms. The most hazardous scenario involves extremely rapid large volume events (>10⁶ m³) that could, if they interacted with water, induce catastrophic tsunamis. Copyright © 2009 John Wiley & Sons, Ltd.  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 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   

Morphological,sedimentological and tectonic features of diamante-m. Carpinoso Marine terrace flight (tyrrhenian coast of northern Calabria,Italy)     

Luigi Carobene  Gianluca Ferrini 《地球表面变化过程与地形》1993,18(3):225-239

Marine terrace flights resulting from the interaction of Quaternary glacio-eustatic fluctuations and tectonic uplift are a typical feature of the Tyrrhenian coast of Calabria in Southern Italy; in particular a térrace flight with four orders of terraces is evident in the Diamante area. The lowest terrace levels (fourth order: Diamante-Cirella terrace) are typified by a calcarenitic deposit with Cladocora caespitosa which give a Th/U age > 300,000 years. The third order terrace has a sedimentary cover formed of a basal discontinuous level of well rounded pebbles which underlies a deeply weathered coarse-grained sand horizon. The deposit ends with a paleosol locally cut by erosional scours filled by yellowish tuff deposits. The formation of this terrace dates from the Middle Pleistocene. The second order terrace presents a sedimentary cover composed of two generations of soils and is attributed to Middle Pleistocene age. The first order terrace (M. Carpinoso terrace) presents a wave-cut platform covered by a clastic deposit of marine and continental origin; this deposit consists of superimposed depositional events separated by unconformities, bounded by two diachronous surfaces. The formation of the wave-cut platform could be related to several sea-level stands during a long-lasting slow subsidence phase of the coastal area during the Lower Pleistocene. The uplift following terrace formation displaced the first order terrace most markedly; tectonic lineations controlled the hydrographic pattern and erosion of the surfaces.  相似文献   

On the growth of nitric and sulfuric acid aerosol particles under stratospheric conditions     

Patrick Hamill  R. P. Turco  O. B. Toon 《Journal of Atmospheric Chemistry》1988,7(3):287-315

We present a theory for the formation of frozen aerosol particles in the Antarctic stratosphere, the coldest region of the Earth's stratosphere. The theory is applied specifically to the formation of polar stratospheric clouds. We suggest that the condensed ices are composed primarily of nitric acid and water with small admixtures of other compounds such as H₂SO₄ and HCl in solid solution. Our assumed particle formation mechanism is in agreement with the magnitude and seasonal behavior of the optical extinctions observed in the winter polar stratosphere. Physical chemistry and thermodynamic considerations suggest that at temperatures between about 200 and 185 K, stratospheric particulates are composed primarily of frozen nitric acid solutions with a composition near that of the trihydrate. Available data suggest the particles are amorphous solid solutions and not in the crystalline hydrate form. At lower temperatures (i.e., below the forst point of pure water) cirrus-like ice clouds can form.  相似文献   

Photodissociation rates in the atmosphere below 100km     

R. P. Turco 《Surveys in Geophysics》1975,2(2):153-192

In this survey we consider the atmospheric photodissociation rates of the molecules, O₂, O₃, NO, NO₂, N₂O, N₂O₅, HNO₃, HO₂, H₂O, H₂O₂, CO₂, CH₄, CH₂O, SO₂, and H₂S. Data for the absorption cross sections and quantum yields of these molecules are assembled here along with other information pertinent to the determination of photodissociation rates. The most recent techniques for computing atmospheric photodissociation rates are discussed. Photodissociation rates for all of the molecules are given at several solar zenith angles for altitudes up to 100 kilometres. A knowledge of the photodissociation rates of atmospheric molecules is essential to the resolution of many important atmospheric problems. Pollution of the stratosphere by high-flying aircraft, and of the troposphere by other anthropogenic activities, can only be described in terms of complex photochemical-dynamical models in which photolytic processes have a dominant role. A great deal of scientific effort is presently being spent in determining the mechanisms which control ozone, nitric oxide, and excited molecular oxygen concentrations in the mesosphere. Photolytic processes are already known to be important to all of these species. The photodissociation rates presented here can be applied directly to atmospheric problems such as these, or the methodology and data contained in this work can be used to compute photorates as needed.  相似文献   

Nouvelles synthéses hydrothermales du zircon: substitutions isomorphiques; relation morphologie-milieu de croissance     

Raoul Caruba  Alain Baumer  Guy Turco 《Geochimica et cosmochimica acta》1975,39(1):11-26

Zircon has been synthesized from a large number of mineral salts and also from one organic compound of zirconium. Its crystallization requires an acid reactive environment.The obtained crystals have been studied morphologically and the crystallographic forms obtained are linked to the presence of specific ions.The study of substitutions in the zircon network shows that hydro-zircon αZr(SiO₄)_1?x(OH)_4x will form only when fluorine is present. Other varieties of the α and β phases ZrSiO₄ have been obtained, substituting Hf, U, for Zr, and Ge for Si and an immiscible α phase ThSiO₄.Germanium enters the zircon network only at low temperature. Uranium and Hf, but not Th, can substitute for Zr in zircon.  相似文献