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Registros recuperados: 6
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Character of seismic motion at a location of a gas hydrate-bearing mud volcano on the SW Barents Sea margin ArchiMer
Franek, Peter; Mienert, Jurgen; Buenz, Stefan; Geli, Louis.
The Håkon Mosby mud volcano (HMMV) at 1270 m water depth on the SW Barents Sea slope has been intensively studied since its discovery in 1989. A variety of sensors monitored morphological, hydrological, geochemical, and biological parameters in the HMMV area. An ocean bottom seismometer deployment allowed us to register seismic motion for 2 years, from October 2008 to October 2010. The analysis of seismic records documents two types of seismic signals. The first type are harmonic tremors with frequency peaks around 4–5 and 8–10 Hz that occur in swarms. Their origin could be from fluid flow circulation or resonant vibrations of gas bubbles or from delayed movement of fluid-rich sediments in the conduit or in a deeper pseudo-mud chamber of the HMMV. Because...
Tipo: Text
Ano: 2014 URL: http://archimer.ifremer.fr/doc/00204/31491/29901.pdf
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Estimation of gas hydrate concentration from multi-component seismic data at sites on the continental margins of NW Svalbard and the Storegga region of Norway ArchiMer
Westbrook, G; Chand, S; Rossi, G; Long, C; Bunz, S; Camerlenghi, A; Carcione, J; Dean, S; Foucher, Jean-paul; Flueh, E; Gei, D; Haacke, R; Madrussani, G; Mienert, Jurgen; Minshull, T; Nouze, Herve; Peacock, S; Reston, T; Vanneste, M; Zillmer, M.
High-resolution seismic experiments, employing arrays of closely spaced, four-component ocean-bottom seismic recorders, were conducted at a site off western Svalbard and a site on the northern margin of the Storegga slide, off Norway to investigate how well seismic data can be used to determine the concentration of methane hydrate beneath the seabed. Data from P-waves and from S-waves generated by P-S conversion on reflection were inverted for P- and S-wave velocity (V-p and V-s), using 3D travel-time tomography, 2D ray-tracing inversion and 1D waveform inversion. At the NW Svalbard site, positive V-p anomalies above a sea-bottom-simulating reflector (BSR) indicate the presence of gas hydrate. A zone containing free gas up to 150-m thick, lying immediately...
Tipo: Text Palavras-chave: Continental margin; Hydrate concentration; Seismic velocity; S wave; P wave.
Ano: 2008 URL: http://archimer.ifremer.fr/doc/2008/publication-6122.pdf
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High-resolution 3D-seismic data indicate focussed fluid migration pathways above polygonal fault systems of the mid-Norwegian margin ArchiMer
Hustoft, S; Mienert, Jurgen; Bunz, S; Nouze, Herve.
Seismic attribute analysis and interpretation of high-resolution 3D- and 2D-seismic data reveal focussed fluid flow processes through the gas hydrate stability zone (GHSZ) at the northern flank of the giant Storegga Slide. Diffusive fluid migration predominantly starts from a widespread polygonal fault system in fine-grained sediments of the Miocene Kai Formation. The overlying 600-700 m thick Plio-Pleistocene Naust Formation shows spatially related soft-sediment deformation and overlying fluid conduits. A low relief antiform structure connects to an overlying 250 m high, 300 m wide and 3 km elongated columnar zone, where seismic signatures suggest self-enhanced permeability, i.e. natural hydraulic fracturing. "Push-down" effects create an elongated...
Tipo: Text Palavras-chave: Acoustic pipes and pockmarks; Feeding of methane to hydrate deposits; Hydraulic fracturing; Polygonal faulting; Norwegian margin.
Ano: 2007 URL: http://archimer.ifremer.fr/doc/2007/publication-4077.pdf
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Societal need for improved understanding of climate change, anthropogenic impacts, and geo-hazard warning drive development of ocean observatories in European Seas ArchiMer
Ruhl, Henry A.; Andre, Michel; Beranzoli, Laura; Cagatay, M. Namik; Colaco, Ana; Cannat, Mathilde; Danobeitia, Juanjo J.; Favali, Paolo; Geli, Louis; Gillooly, Michael; Greinert, Jens; Hall, Per O. J.; Huber, Robert; Karstensen, Johannes; Lampitt, Richard S.; Larkin, Kate E.; Lykousis, Vasilios; Mienert, Jurgen; Miguel Miranda, J.; Person, Roland; Priede, Imants G.; Puillat, Ingrid; Thomsen, Laurenz; Waldmann, Christoph.
Society's needs for a network of in situ ocean observing systems cross many areas of earth and marine science. Here we review the science themes that benefit from data supplied from ocean observatories. Understanding from existing studies is fragmented to the extent that it lacks the coherent long-term monitoring needed to address questions at the scales essential to understand climate change and improve geo-hazard early warning. Data sets from the deep sea are particularly rare with long-term data available from only a few locations worldwide. These science areas have impacts on societal health and well-being and our awareness of ocean function in a shifting climate. Substantial efforts are underway to realise a network of open-ocean observatories around...
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Ano: 2011 URL: http://archimer.ifremer.fr/doc/00044/15557/15923.pdf
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Structure and Drivers of Cold Seep Ecosystems ArchiMer
Foucher, Jean-paul; Westbrook, Graham K.; Boetius, Antje; Ceramicola, Silvia; Dupre, Stephanie; Mascle, Jean; Mienert, Jurgen; Pfannkuche, Olaf; Pierre, Catherine; Praeg, Daniel.
Submarine hydrocarbon seeps are geologically driven "hotspots" of increased biological activity on the seabed. As part of the HERMES project, several sites of natural hydrocarbon seepage in the European seas were investigated in detail, including mud volcanoes and pockmarks, in study areas extending from the Nordic margin, to the Gulf of Cadiz, to the Mediterranean and Black seas. High-resolution seabed maps and the main properties of key seep sites are presented here. Individual seeps show ecosystem zonation related to the strength of the methane flux and distinct biogeochemical processes in surface sediments. A feature common to many seeps is the formation of authigenic carbonate constructions. These constructions exhibit various morphologies ranging...
Tipo: Text Palavras-chave: Mosby mud volcano; Deep sea fan; Eastern mediterranean sea; Black sea; Anaerobic oxidation; Hydrocarbon seeps; Carbonate crusts; Sidescan sonar; Hydrate ridge; Gas chimneys.
Ano: 2009 URL: http://archimer.ifremer.fr/doc/2009/publication-6387.pdf
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The role of sedimentation rate and permeability in the slope stability of the formerly glaciated Norwegian continental margin: the Storegga slide model ArchiMer
Leynaud, Didier; Sultan, Nabil; Mienert, Jurgen.
Despite the gently dipping slopes (ca 1 degrees), large-scale submarine slope failures have occurred on the mid-Norwegian continental margin (Storegga, Sklinnadjupet, Traenadjupet), suggesting the presence of special conditions predisposing to failure in this formerly glaciated margin. With a volume estimated between 2,400 and 3,200 km(3) and an affected area of approximately 95,000 km(2), the Storegga slide represents one of the largest and best-studied submarine slides of Holocene age known worldwide. Finite element modeling of slope failure indicates that a large (6.5 < Ms < 7.0) seismic triggering mechanism would not be sufficient to cause failure at more than 110 m below the seabed as observed for the slip planes at Storegga (northern sidewall)....
Tipo: Text Palavras-chave: Submarine slide; Slope stability; Sediment overpressure; Rapid sedimentation.
Ano: 2007 URL: http://archimer.ifremer.fr/doc/2007/publication-3521.pdf
Registros recuperados: 6
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