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Registros recuperados: 4
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3-D sediment-basement tomography of the Northern Marmara trough by a dense OBS network at the nodes of a grid of controlled source profiles along the North Anatolian fault ArchiMer
Bayrakci, Gaye; Laigle, Mireille; Becel, A.; Hirn, A.; Taymaz, T.; Yolsal-cevikbilen, S..
A 3-D tomographic inversion of first arrival times of shot profiles recorded by a dense 2-D OBS network provides an unprecedented constraint on the P-wave velocities heterogeneity of the upper-crustal part of the North Marmara Trough (NMT), over a region of 180 km long by 50 km wide. One of the specific aims of this controlled source tomography is to provide a 3-D initial model for the local earthquake tomography (LET). Hence, in an original way, the controlled source inversion has been performed by using a code dedicated to LET. After several tests to check the results trade-off with the inversion parameters, we build up a 3-D a priori velocity model, in which the sea-bottom topography, the acoustic and the crystalline basements and the Moho interfaces...
Tipo: Text Palavras-chave: Body waves; Seismic tomography; Continental tectonics: strike-slip and transform; Crustal structure..
Ano: 2013 URL: http://archimer.ifremer.fr/doc/00185/29601/28033.pdf
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Along-arc segmentation and interaction of subducting ridges with the Lesser Antilles Subduction forearc crust revealed by MCS imaging ArchiMer
Laigle, Mireille; Becel, Anne; De Voogd, Beatrice; Sachpazi, Maria; Bayrakci, Gaye; Lebrun, Jean-frederic; Evain, Mikael; "Thales Was Right" Seismic Reflection working group.
We present the results from a new grid of deep penetration multichannel seismic (MCS) profiles over the 280-km-long north-central segment of the Lesser Antilles subduction zone. The 14 dip-lines and 7 strike-lines image the topographical variations of (i) the subduction interplate décollement, (ii) the top of the arcward subducting Atlantic oceanic crust (TOC) under the huge accretionary wedge up to 7 km thick, and (iii) the trenchward dipping basement of the deeply buried forearc backstop of the Caribbean upper plate. The four northernmost long dip-lines of this new MCS grid reveal several-kilometres-high topographic variations of the TOC beneath the accretionary wedge offshore Guadeloupe and Antigua islands. They are located in the prolongation of those...
Tipo: Text Palavras-chave: Lesser Antilles Subduction Zone; Reflection seismics; Deep outer forearc crust; Backstop; Seismogenic megathrust fault.
Ano: 2013 URL: http://archimer.ifremer.fr/doc/00139/25003/23109.pdf
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Dehydration of subducting slow-spread oceanic lithosphere in the Lesser Antilles ArchiMer
Paulatto, Michele; Laigle, Mireille; Galve, Audrey; Charvis, Philippe; Sapin, Martine; Bayrakci, Gaye; Evain, Mikael; Kopp, Heidrun.
Subducting slabs carry water into the mantle and are a major gateway in the global geochemical water cycle. Fluid transport and release can be constrained with seismological data. Here we use joint active-source/local-earthquake seismic tomography to derive unprecedented constraints on multi-stage fluid release from subducting slow-spread oceanic lithosphere. We image the low P-wave velocity crustal layer on the slab top and show that it disappears beneath 60–100 km depth, marking the depth of dehydration metamorphism and eclogitization. Clustering of seismicity at 120–160 km depth suggests that the slab’s mantle dehydrates beneath the volcanic arc, and may be the main source of fluids triggering arc magma generation. Lateral variations in seismic...
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Ano: 2017 URL: https://archimer.ifremer.fr/doc/00392/50321/51004.pdf
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Earth's free oscillations recorded by free-fall OBS ocean-bottom seismometers at the Lesser Antilles subduction zone ArchiMer
Becel, A.; Laigle, Mireille; Diaz, J.; Montagner, J. -p.; Hirn, A..
Three unburied ocean bottom seismometers (OBS) equipped with Trillium 240 s broad-band seismometers recorded spheroidal free oscillations of the Earth out to periods over 1000 s period, for the M = 8.1, April 1, 2007 Solomon Islands earthquake. In contrast to broadband observatories of the global network that operate in quiet continental locations, these instruments were dropped on the several-km thick layer of sediments of the forearc and accretionary wedge of the Lesser Antilles subduction zone. Furthermore, a high ambient noise level due to the ocean surface infragravity waves is expected to cover the frequency band of Earth's normal modes band when recorded at these sites. In spite of these hostile environmental conditions, the frequency of clearly...
Tipo: Text Palavras-chave: Lesser Antilles; Broadband seismology; Free oscillations; Ocean bottom seismometers.
Ano: 2011 URL: http://archimer.ifremer.fr/doc/00185/29606/27971.pdf
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