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| Registros recuperados: 64 | |
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| Sultan, Nabil; Cochonat, Pierre; Foucher, Jean-paul; Mienert, J. |
| We present a theoretical study of the thermodynamic chemical equilibrium of gas hydrate in soil by taking into account the influence of temperature, pressure, pore water chemistry, and the mean pore size distribution. The model uses a new formulation based on the enthalpy form of the law of conservation of energy. The developed model shows that due to a temperature and pressure increase, hydrates may dissociate at the top of the hydrate occurrence zone to ensure a chemical equilibrium with the surrounding bulk water. This original result confirms what has been already shown through experiments. The second part of the paper presents an application of the model through a back-analysis of the giant Storegga Slide on the Norwegian margin. Two of the most... |
| Tipo: Text |
Palavras-chave: Storegga; Slope failure; GLE; Finite difference; Methane hydrate. |
| Ano: 2004 |
URL: http://archimer.ifremer.fr/doc/2004/publication-699.pdf |
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| Sultan, Nabil; Bohrmann, G.; Ruffine, Livio; Pape, T.; Riboulot, Vincent; Colliat, J. -l.; De Prunele, Alexis; Dennielou, Bernard; Garziglia, Sebastien; Himmler, Tobias; Marsset, Tania; Peters, C. A.; Rabiu, A.; Wei, J.. |
| In previous works, it has been suggested that dissolution of gas hydrate can be responsible for pockmark formation and evolution in deep water Nigeria. It was shown that those pockmarks which are at different stages of maturation are characterized by a common internal architecture associated to gas hydrate dynamics. New results obtained by drilling into gas hydrate-bearing sediments with the MeBo seafloor drill rig in concert with geotechnical in situ measurements and pore water analyses indicate that pockmark formation and evolution in the study area are mainly controlled by rapid hydrate growth opposed to slow hydrate dissolution. On one hand, positive temperature anomalies, free gas trapped in shallow microfractures near the seafloor and coexistence of... |
| Tipo: Text |
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| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00188/29913/28373.pdf |
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| Dennielou, Bernard; Jallet, Laurent; Sultan, Nabil; Jouet, Gwenael; Giresse, Pierre; Voisset, Michel; Berne, Serge. |
| Emplacement of post-glacial turbidites is commonly controlled by rapid changes in sea level or by seismicity. On the continental rise of the Gulf of Lions (Western Mediterranean), an aseismic area, we identified turbiditic beds deposited during the rising stage and highstand of sea level. Swath bathymetry, sediment cores, in situ Cone Penetrating Tests (CPTU), heavy mineral associations and radiocarbon dating determined the source, composition, distribution and age of the turbiditic beds. Turbidites are composed of homogeneous to positively graded silts to medium sand with quartz (up to 90%), shell debris and shelfal benthic faunas. Their distribution on the sea floor is very patchy and controlled by abundant inherited erosional bedforms. Their source is... |
| Tipo: Text |
Palavras-chave: Holocene; Late Pleistocene; Sea level; Turbidites; Sand; Outer shelf; Canyons. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/2009/publication-6316.pdf |
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| Sultan, Nabil; Plaza-faverola, Andreia; Vadakkepuliyambatta, Sunil; Buenz, Stefan; Knies, Jochen. |
| Sub-sea Arctic methane and gas hydrate reservoirs are expected to be severely impacted by ocean temperature increase and sea-level rise. Our understanding of the gas emission phenomenon in the Arctic is however partial, especially in deep environments where the access is difficult and hydro-acoustic surveys are sporadic. Here, we report on the first continuous pore-pressure and temperature measurements over 4 days in shallow sediments along the west-Svalbard margin. Our data from sites where gas emissions have not been previously identified in hydro-acoustic profiles show that tides significantly affect the intensity and periodicity of gas emissions. These observations imply that the quantification of present-day gas emissions in the Arctic may be... |
| Tipo: Text |
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| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00654/76564/77690.pdf |
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| Sultan, Nabil. |
| In the IODP 372A proposal, working hypotheses used with respect to actively deforming gas hydrate‐bearing landslides were based on an initial calculation considering gas hydrate to occur in fresh water. This initial inaccuracy leads to predict the base of methane hydrate stability zone (MHSZ) to be at around 162 meters below the seafloor (mbsf) at site U1517 while it is expected to be between 85 and 128 mbsf. It is most interesting that important negative chloride anomalies were measured well below the theoretical MHSZ without direct evidence of the presence of gas hydrate. These anomalies are usually a strong indication of gas hydrate occurrence. This initial inaccurate hypothesis provides the opportunity to evaluate the effectiveness of the indirect... |
| Tipo: Text |
Palavras-chave: Hikurangi; Hydrate; IODP; Salinity. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00628/74043/73389.pdf |
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| Sultan, Nabil; Cochonat, Pierre; Canals, M; Cattaneo, Antonio; Dennielou, Bernard; Haflidason, H; Laberg, J; Long, D; Mienert, J; Trincardi, F; Urgeles, R; Vorren, T; Wilson, C. |
| The Costa target areas exhibit the variability of slope instabilities needed to improve our understanding of sediment physical and mechanical properties in areas prone to sliding. That is why in this project, we have analysed the different slope failures events from different parts of the Costa target areas, which reflect diverse triggering mechanisms. The aim of the first part of this study was to identify the geotechnical response of the sediment to different external mechanisms (earthquake, rapid sedimentation and gas hydrate melting). We have focused on the relation between external mechanisms and the consequence change in the in-situ stress state and the physical, mechanical, and elastic properties of the sediment. In the second part of the paper, the... |
| Tipo: Text |
Palavras-chave: Slope instability; Sensitivity; Sedimentation; Hydrate; Earthquake. |
| Ano: 2004 |
URL: http://archimer.ifremer.fr/doc/2004/publication-700.pdf |
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| Sultan, Nabil; Gaudin, Mathieu; Berne, Serge; Canals, Miquel; Urgeles, Roger; Lafuerza, Sara. |
| To improve understanding of evolution of submarine canyons, a three-dimensional slope-stability model is applied to Bourcart Canyon in the western Gulf of Lions in the Mediterranean Sea. The model builds on previous work by Chen and others, and it uses the upper bound theorem of plasticity to calculate the factor of safety of a kinematically admissible failing mass. Examples of three-dimensional failure surfaces documented in the literature were used to test the model formulation. Model application to Bourcart Canyon employed the results of a detailed stratigraphic analyses based on data acquired by swath bathymetry, sub-bottom profiling, high-resolution seismic reflection surveys, and piston coring. The sediment layers were also characterized using... |
| Tipo: Text |
Palavras-chave: Cascadia accretionary complex; Upper bound theorem; Stability analysis; Continental slope; Limit equilibrium; Western gulf; Offshore; Margin; Initiation; Sediment. |
| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2007/publication-2410.pdf |
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| Blouin, Arthur; Sultan, Nabil; Callot, Jean-paul; Imbert, Patrice. |
| Gassy sediments are common in marine environments and are characterized by a specific mechanical behavior significantly different from that of water-saturated sediments. It is shown that gas causes damage and initiates fractures in sediments. To define the controlling parameters dominating the damage process during gas exsolution and its consequences in terms of hydro-mechanical behavior, we developed a specific consolidation apparatus to test sediments collected from the active Absheron Mud Volcano. Indeed, mud volcano formation is initiated by gas exsolution and subsequent mud generation at depth from stratified sediments. Gas was generated in the samples by circulating carbonated water through the fine-grained sediments, then decreasing the total... |
| Tipo: Text |
Palavras-chave: Consolidation testing; Gas exsolution; Gassy sediments; Sediment damage; Mud volcano. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00588/70043/67974.pdf |
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| Sultan, Nabil; Savoye, Bruno; Jouet, Gwenael; Leynaud, Didier; Cochonat, Pierre; Henry, P.; Stegmann, Sylvia; Kopf, Achim. |
| The Var prodelta progrades across a straight, narrow shelf (less than 2 km wide) with a very steep continental slope reaching locally more than 30 degrees. Historically, the Var delta front is sadly famous for the 1979 catastrophic submarine landslide that resulted in several casualties and infrastructural damage. Geotechnical and geophysical investigations carried out in late 2007 to the east of the 1979 landslide scar provide evidence for the possible occurrence of a new important sedimentary collapse and submarine landslide. Geophysical data acquired in the area show the presence of several seafloor morphological steps rooted to shallow subsurface seismic reflections. Moreover, in situ piezocone measurements demonstrate the presence of several shear... |
| Tipo: Text |
Palavras-chave: CPTu; Gassy soil; Piezocone; Shear zone; Submarine landslides. |
| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00004/11481/8096.pdf |
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| Urgeles, Roger; Cattaneo, Antonio; Puig, Pere; Liquete, Camino; De Mol, Ben; Amblas, David; Sultan, Nabil; Trincardi, Fabio. |
| Most Mediterranean prodeltas show undulated sediment features on the foresets of their Holocene wedges. These features have been described all along the Mediterranean for the last 30 years and interpreted as either soft sediment deformation and incipient landsliding, and more recently, as sediment transport structures. We perform a review and detailed analysis of these undulated sediment features using ultrahigh-resolution seismic and bathymetric data as well as geotechnical information and hydrodynamic time series and hydrographic transects. In this study we show that the characteristics of the sediment undulations (configuration of the reflections down section and between adjacent undulations and overall morphologic characteristics) are incompatible with... |
| Tipo: Text |
Palavras-chave: Undulated sediments; Prodeltas; Slope failure; Sediment waves; Hyperpycnal flows; Internal waves. |
| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00043/15388/12841.pdf |
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| Bourillet, Jean-francois; Damy, Gilbert; Dussud, Loic; Sultan, Nabil; Woerther, Patrice; Migeon, Sebastien. |
| Various observations pointed out that cores performed with gravity piston corer show signifi cant distortions mainly located at the top of the core. A series of 15 cores were performed at the same location on a submarine sand wave (Var canyon, France). Six different settings of the corer – three freefall heights and three slacks of the piston cable – were tested, including duplicates. Two accelerometers recorded simultaneously the movements of the core tube and the movements of the triggering arm. Then the z displacements were obtained by a double integration versus time of the measured acceleration. The analyses of results allowed the authors to estimate the amplitude and the duration of the elastic recoil of the aramid cable, andto distinguish four steps... |
| Tipo: Text |
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| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/00071/18198/15766.pdf |
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| Blouin, Arthur; Imbert, Patrice; Sultan, Nabil; Callot, Jean-paul. |
| The morphology of mud volcanoes (MV) has been extensively studied over the last few decades. Although recent research has begun to focus on deep processes and structures, little is known about mud generation mechanisms. This study aims to investigate the feeder system and formation of an active kilometer‐scale MV by relying on a 3‐D seismic survey and an in‐situ dataset on the Absheron anticline (South Caspian Basin). Seismic data show a depleted area in the Anhydritic Surakhany Formation (ASF), whose mineralogical composition fits with surface mud. Well data show that the ASF is a succession of evaporitic beds and low temperature shales near its fracture pressure. Biostratigraphic analysis confirms a Pliocene origin for the mud, suggesting that the ASF... |
| Tipo: Text |
Palavras-chave: Mud volcano; Pore pressure; Methane; Modeling; Seismic. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00481/59304/62057.pdf |
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| Lafuerza, S.; Frigola, J.; Canals, M.; Jouet, Gwenael; Bassetti, Maria-angela; Sultan, Nabil; Berne, Serge. |
| We show the results provided by piezocone tests in determining the stratigraphic profile and the soil classification of two drilling sites in the outer shelf and the upper slope of the Gulf of Lion, PRGL2 and PRGL1, respectively. Correlations with grain-size data indicate that sleeve friction can be used for profiling fine-grained sediments (site PRGL1), whereas cone tip resistance is the most adequate for sequences made of alternations of coarse- and fine-grained intervals (site PRGL2). Normalized cone resistance and friction ratio proved to be also appropriate for soil stratigraphy as it depicts trends in the coarse fraction of the tested soil. Silts and clays present in similar proportions at site PRGL1 responded to piezocone testing as pure clays... |
| Tipo: Text |
Palavras-chave: Gulf of Lion; Soil classification; Stratigraphy; Piezocone. |
| Ano: 2008 |
URL: http://archimer.ifremer.fr/doc/2008/publication-6121.pdf |
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| Dan, Gabriela; Sultan, Nabil; Cattaneo, Antonio; Deverchere, J; Yelles, K. |
| On 21st May 2003, a damaging earthquake of Mw: 6.9 struck the region of Boumerdès 40 km east of Algiers in northern Algeria. The seismic shocks had devastating effects in the offshore area between the cities of Algiers and Dellys, where numerous cable breaks were observed. The submarine area encompassing the 2003 Boumerdès epicenter (central Algerian margin) was recently investigated using geophysical and sampling tools. It has been observed that small-size slides and mass-transport deposits occur across this area. Thus, a detailed analysis was performed on 25 submarine slides identified in water depth from 500 m to 2700 m, by measuring different morphological parameters (i.e. surface, head-scarp height, slope in the source area and in adjacent... |
| Tipo: Text |
Palavras-chave: Triggering mechanism; Morphology; Mass transport deposit; Algeria. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/2009/acte-6453.pdf |
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| Sultan, Nabil; Garziglia, Sebastien. |
| In this work and in order to consider theoretically the effect of gas hydrates on the mechanical properties of their host sediments, hydrate fraction was introduced as a state variable in the framework of a Critical State model. For the proposed model, the process of de-structuration and softening of natural clay was considered as a proxy for the gas-hydrate-bearing-sediments behaviour. The developed constitutive model seemed to reproduce the main key behaviours of gas-hydrate-bearing sands observed by Masui and co-authors: i) the elastic properties (Young Modulus, shear modulus) and the strength of the sediment-hydrate medium increase with the hydrate fraction ii) the mechanical softening of the gas-hydrate bearing sediment is amplified with the hydrate... |
| Tipo: Text |
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| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00035/14626/11904.pdf |
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| Sultan, Nabil; Cattaneo, Antonio; Sibuet, Jean-claude; Schneider, Jean-luc. |
| The swath bathymetric data acquired during the "Sumatra Aftershocks" cruise from the Sunda trench in the Indian Ocean to the north of the Sumatra Island imaged several scars and deposits. In situ pore pressure measurements using the Ifremer piezometer and coring demonstrate that high excess pore pressure and sediment deformation was generated by a recent event in the scar of the slope failure zone identified by J.T. Henstock and co-authors. This excess pore pressure is localized in the upper sedimentary layers and is not related to an interplate subduction process. Numerical simulations of the hydrological system that take into account the hydro-mechanical properties of the upper sediment layer show that the excess pore pressure and sediment deformations... |
| Tipo: Text |
Palavras-chave: Tsunami; Sumatra; Slope failure; Pore pressure; Earthquake. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/2009/publication-6740.pdf |
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| Dan, Gabriela; Sultan, Nabil; Savoye, Bruno; Deverchere, Jacques; Yelles, Karim. |
| The Algerian margin is a seismically active region, where during the last century, several large magnitude earthquakes took place. This study combines geotechnical and sedimentological data with numerical modelling to quantitatively assess the present-day slope stability of the Algerian margin. Geotechnical laboratory tests, such as cyclic triaxial tests, oedometric tests and vane shear tests were carried out on sediment cores collected on the study area. The liquefaction potential of a sediment column located about 30 km from the BoumerdSs earthquake epicentre of 21st May 2003 was evaluated theoretically for an earthquake of M (w) = 6.8. We show that thin sand and silt beds such as those described on recovered sediment cores are the main cause of sediment... |
| Tipo: Text |
Palavras-chave: Earthquakes; Potential of liquefaction; Slope stability; Algerian margin. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/2009/publication-6448.pdf |
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| Registros recuperados: 64 | |
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