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Registros recuperados: 4
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Fine-scale gas distribution in marine sediments assessed from deep-towed seismic data ArchiMer
Ker, Stephan; Le Gonidec, Y.; Marsset, Bruno; Westbrook, Graham; Gibert, D.; Minshull, T. A..
In the context of seismic imaging of gas/gas-hydrate systems, the fine-scale structure of subseabed gas-related reflections is assessed by taking advantage of the source signature of the deep-towed high-resolution SYSIF seismic device. We demonstrate the value of an original wavelet-based method and associated multiscale seismic attributes, applied to seismic data recently acquired on the western margin of the Arctic archipelago of Svalbard. From analysis in the wavelet domain, we recognize two types of gas-related reflections associated with submetre-scale distribution of gas. We identify a thin gas-charged layer associated with an apparent normal polarity reflection, and we detect gas patches associated with a reverse-polarity bright spot with...
Tipo: Text Palavras-chave: Wavelet transform; Gas and hydrate systems; Wave propagation; Acoustic properties; Arctic region.
Ano: 2014 URL: http://archimer.ifremer.fr/doc/00175/28602/27019.pdf
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Microevents produced by gas migration and expulsion at the seabed: a study based on sea bottom recordings from the Sea of Marmara ArchiMer
Tary, Jean-baptiste; Geli, Louis; Guennou, Claude; Henry, Pierre; Sultan, Nabil; Cagatay, N.; Vidal, V..
Different types of 4-component ocean bottom seismometers (OBS) were deployed for variable durations ranging from 1 week to about 4 months in 2007, over soft sediments covering the seafloor of the Tekirdag Basin (western part of the Sea of Marmara, Turkey). Non-seismic microevents were recorded by the geophones, but generally not by the hydrophones, except when the hydrophone is located less than a few tens of centimetres above the seafloor. The microevents are characterized by short durations of less than 0.8 s, by frequencies ranging between 4 and 30 Hz, and by highly variable amplitudes. In addition, no correlation between OBSs was observed, except for two OBSs, located 10 m apart. Interestingly, a swarm of similar to 400 very similar microevents (based...
Tipo: Text Palavras-chave: Time series analysis; Gas and hydrate systems; Body waves; Interface waves; Seismic attenuation; Wave propagation.
Ano: 2012 URL: http://archimer.ifremer.fr/doc/00089/20012/17825.pdf
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Resistivity image beneath an area of active methane seeps in the west Svalbard continental slope ArchiMer
Goswami, Bedanta K.; Weitemeyer, Karen A.; Minshull, Timothy A.; Sinha, Martin C.; Westbrook, Graham; Marin-moreno, Hector.
The Arctic continental margin contains large amounts of methane in the form of methane hydrates. The west Svalbard continental slope is an area where active methane seeps have been reported near the landward limit of the hydrate stability zone. The presence of bottom simulating reflectors (BSR) on seismic reflection data in water depths greater than 600 m suggests the presence of free gas beneath gas hydrates in the area. Resistivity obtained from marine controlled source electromagnetic (CSEM) data provides a useful complement to seismic methods for detecting shallow hydrate and gas as they are more resistive than surrounding water saturated sediments. We acquired two CSEM lines in the west Svalbard continental slope, extending from the edge of the...
Tipo: Text Palavras-chave: Electrical properties; Marine electromagnetics; Gas and hydrate systems; Arctic region.
Ano: 2016 URL: https://archimer.ifremer.fr/doc/00350/46081/45740.pdf
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Spatial and temporal dynamics of gas-related processes in the Sea of Marmara monitored with ocean bottom seismometers ArchiMer
Tsang-hin-sun, Eve; Batsi, Evangelia; Klingelhoefer, Frauke; Géli, Louis.
In the Sea of Marmara, areas of gas seepage or cold seeps are tightly related to the faults system and understanding the spatial and temporal dynamics in gas-related processes is crucial for geohazard mitigation. Although acoustic surveys proved to be efficient in detecting and locating cold seeps, temporal variability or trends in the gas-related processes are still poorly understood. Two arrays of 10 ocean bottom seismometers were deployed in the western part of the Sea of Marmara in 2011 and 2014, respectively. In addition to the local seismic events, the instruments recorded a large number of short duration events and long-lasting tremors. Short duration events are impulsive signals with duration < 1 s, amplitude well above the noise level and a...
Tipo: Text Palavras-chave: Gas and hydrate systems; Spatial analysis; Time-series analysis; Earthquake source observations; Seismicity and tectonics.
Ano: 2019 URL: https://archimer.ifremer.fr/doc/00473/58426/61003.pdf
Registros recuperados: 4
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