Using GB-SAR technique to monitor slow moving landslide   总被引：3，自引：0，他引：3  

Linhsia Noferini  Massimiliano Pieraccini  Daniele Mecatti  Giovanni Macaluso  Carlo Atzeni  Matteo Mantovani  Gianluca Marcato  Alessandro Pasuto  Sandro Silvano  Fabrizio Tagliavini 《Engineering Geology》2007,95(3-4):88-98

A Ground-Based SAR (GB-SAR) interferometer was employed to measure the surface displacements of a landslide occurring in the Carnian Alps, north-eastern Italy, which has affected a national road and seriously damaged a road tunnel still under construction. Moreover, since the landslide is located on the left bank of the Tagliamento River Valley, it is feared that this mass movement might dam the river, creating a basin that would increase natural hazard for the valley inhabitants. The data collected from December 2002 to July 2005 by a conventional monitoring system, consisting of a GPS network and boreholes equipped with inclinometric tubes, showed that the landslide was moving at a quasi-constant rate of about 3 cm per year. Due to the slow deformation rate of the landslide, a recently developed GB-SAR technique based on the analysis of a restricted ensemble of coherent points was used. Two surveys, each lasting two days, were planned in December 2004 and July 2005, in order to map and measure the surface displacements that occurred over time. The results from the radar were compared with the ones derived from the GPS monitoring network. An agreement was achieved among the data collected, showing the capability of the GB-SAR technique to measure displacements even within a time span of several months between the surveys.  相似文献   

Continuous in situ measurements of volcanic gases with a diode-laser-based spectrometer: CO<Subscript>2</Subscript> and H<Subscript>2</Subscript>O concentration and soil degassing at Vulcano (Aeolian islands: Italy)     

Maurizio De Rosa  Gianluca Gagliardi  Alessandra Rocco  Renato Somma  Paolo De Natale  Giuseppe De Natale 《Geochemical transactions》2007,8(1):5

We report on a continuous-measurement campaign carried out in Vulcano (Aeolian islands, Sicily), devoted to the simultaneous monitoring of CO₂ and H₂O concentrations. The measurements were performed with an absorption spectrometer based on a semiconductor laser source emitting around a 2-μm wavelength. The emitted radiation was selectively absorbed by two molecular ro-vibrational transitions specific of the investigated species. Data for CO₂ and H₂O concentrations, and CO₂ soil diffusive flux using an accumulation chamber configuration, were collected at several interesting sampling points on the island (Porto Levante beach- PLB, Fossa Grande Crater – FOG- and Valley of Palizzi, PAL). CO₂/H₂O values, measured on the ground, are very similar (around 0.019 (± 0.006)) and comparable to the previous discrete detected values of 0.213 (Fumarole F5-La Fossa crater rim) and 0.012 (Fumarole VFS – Baia Levante beach) obtaid during the 1977–1993 heating phase of the crater fumaroles.  相似文献   

Impact of climate change on staple food crop production in Nigeria     

Valentina Mereu  Gianluca Carboni  Andrea Gallo  Raffaello Cervigni  Donatella Spano 《Climatic change》2015,132(2):321-336

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Nummulitids,lepidocyclinids and Sr-isotope data from the Oligocene of Kutch (western India) with chronostratigraphic and paleobiogeographic evaluations     

György Less  Gianluca Frijia  Ercan Özcan  Pratul K. Saraswati  Mariano Parente  Pramod Kumar 《Geodinamica Acta》2018,30(1):183-211

Due to its intermediate geographical position between the Mediterranean and W Pacific, the Oligocene shallow-marine sequence of Kutch (India) is of key importance in paleobiogeographical interpretations. Larger benthic foraminifera (LBF) are a fundamental link for the correlation between the Mediterranean shallow benthic zones (SBZ) and the W Pacific ‘letter stages’. LBF were re-evaluated by morphometric studies of the internal test from five stratigraphic sections of the Maniyara Fort Formation. Based on their significant affinity to coeval fauna in the Mediterranean, they were assigned to W Tethyan SBZ zones, supported by Sr-isotope stratigraphy. In the Basal Member, traditionally considered as early Rupelian, we identified Nummulites bormidiensis, N. kecskemetii and Heterostegina assilinoides assigning it to the early Chattian SBZ 22B Zone. The Coral Limestone Member, previously considered as late Rupelian, is also assigned to this zone, for the presence of N. bormidiensis, Eulepidina formosoides-dilatata and Nephrolepidina morgani-praemarginata. Its early Chattian age (26.5–29 Ma) is further supported by Sr-isotope data. Miogypsinoides complanatus and Spiroclypeus margaritatus in the Bermoti Member (the top of the formation) document the late Chattian SBZ 23 Zone and the Sr-isotope data (22.5–24 Ma) place it close to the Oligocene–Miocene boundary.  相似文献   

Clastic sedimentation in the Late Oligocene Southalpine Foredeep: from tectonically controlled melting to tectonically driven erosion     

Andrea Di Capua  Giovanni Vezzoli  Alessandro Cavallo  Gianluca Groppelli 《Geological Journal》2016,51(3):338-353

The Villa Olmo Conglomerate (lower member of the Como Conglomerate Formation, Gonfolite Lombarda Group, Southern Alps, Italy) represents the first coarse clastic inputs into the Oligocene Southalpine Foredeep. A number of techniques including sedimentary lithofacies analyses, clast counts on turbidite conglomerate bodies, sandstone petrography through Gazzi–Dickinson point‐count method and XRF analyses, and optical and minero‐chemical analyses on single clasts have been performed, in order to better define the sediment source area and geodynamic conditions which promoted sedimentation in the Southalpine Foredeep at the end of the Oligocene. The Villa Olmo Conglomerate interdigitates with the upper part of the Chiasso Formation, and gradually passes upward into the overlying Como Conglomerate Formation. Provenance analyses (conglomerate clast counts and sandstone petrography) reveal a strong metamorphic provenance signal, likely sourced from eroded Southalpine basement. An increase in igneous plutonic clasts reflects sediment supply from the Southern Steep Belt and a decrease of volcano‐sedimentary Mesozoic cover sequences. Optical and minero‐chemical analyses on volcanic detritus detect the presence of sub‐intrusive to effusive, andesite to rhyolite products, ascribable to the Varese‐Lugano Permian volcanoclastic suite, as well as Oligocene andesite products. Plutonic clasts document the presence of tonalites, granites, and brittle deformed granodiorites (with two micas), being likely sourced from the tonalite tail of the Bergell Pluton and the plutonic units of the Bellinzona‐Dascio Zone. The identification of this provenance suite implies palaeo‐drainage from the region between Varese (Southern Alps) and the Bellinzona‐Dascio Zone (Central Alps). The Villa Olmo Conglomerate is the first depositional record of the onset of tectonically driven erosion in the Alpine belt. We infer that the previous low sediment budget regime (Eocene–Middle Oligocene) was a consequence of a tectonically controlled melting phase, during which tectonic events promoted magmatic production in the middle crust of the Central Alps at rates higher than those of crustal deformation, so inhibiting sediment production. We conclude that changes in the deep structures of the Alpine Orogenic chain have controlled the main geodynamic processes during Oligocene–Neogene times, and have controlled sediment composition and supply into the Southalpine Foredeep. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

MgAl2O4 spinels from Allende and NWA 763 carbonaceous chondrites: Structural refinement,cooling history,and trace element contents     

Davide Lenaz  Vanni Lughi  Diego Perugini  Maurizio Petrelli  Gianluca Turco  Birger Schmitz 《Meteoritics & planetary science》2019,54(12):3089-3100

MgAl₂O₄ spinels from Allende and NWA 763 carbonaceous chondrites were studied by X‐ray single crystal diffraction, SEM, electron microprobe, LA‐ICP‐MS, and Raman spectroscopy. Those from Allende are almost pure, but, in one case, we found a strong FeO_tot zonation. Spinels from NWA 763 show Mg‐Fe²⁺ substitutions. Almost pure MgAl₂O₄ spinels from both meteorites underwent slow cooling and reached their intracrystalline closure temperature (T_c) in the range 460–520 °C. The NWA 763 spinel with higher FeO content shows a T_c of about 720 °C. X‐ray single crystal diffraction and Raman spectroscopy suggest a slow cooling and an ordered structure with trivalent cations in M site and divalent in T site. Among the trace elements, Ti and Co are enriched with respect to the terrestrial analogs, while Mn, Ni, and Sn show intermediate values between different terrestrial occurrences. Vanadium cannot be used as a tracer of extraterrestrial origin as for Cr‐spinels, because its content is similar in extraterrestrial and terrestrial spinels. In the zoned crystal from Allende, Co show a strong zonation similar to that of FeO.  相似文献   

Quaternary faults and seismicity in the Umbro-Marchean Apennines (Central Italy): evidence from the 1997 Colfiorito earthquake     

F. Calamita  M. Coltorti  D. Piccinini  P. P. Pierantoni  A. Pizzi  M. Ripepe  V. Scisciani  E. Turco 《Journal of Geodynamics》2000,29(3-5)

Analyses of structural and geomorphological data combined with remote sensing interpretation confirm previous knowledge on the existence of an extensional Quaternary tectonic regime in the Colfiorito area (Umbro-Marchean Central Apennines). This is characterized by a maximum principal axis of finite strain oriented approx. NE–SW, which is the result of a progressive deformation process due to pure and radial extension. Surface geological data, the crustal tectonic setting (reconstructed using a CROP 03 seismic reflection profile), and seismological data relative to the autumn 1997 Colfiorito earthquake sequence constrain the following seismotectonic model. We interpret the seismogenic SW-dipping low-angle normal fault pictured by seismic data as an inverted thrust ramp located in the basement at depth between 5 and 10 km. The surface projection of this seismogenic structure defines a crustal box within which high-angle normal faults are responsible for the deformation of the uppermost crust. The regional patterns of pre-existing basement thrusts therefore control the seismotectonic zoning of the area that cannot be directly related to the high-angle normal fault systems which cut through different crustal boxes; the latter system records, in fact, re-shear along pre-existing normal faults. Moreover, Quaternary slip-rates relative to high-angle normal faults in the Central Apennines are closely related to seismic hazard within each crustal box.  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