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| 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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| 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... |
| Tipo: Text |
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| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00392/50321/51004.pdf |
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| 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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| Gay, Aurelien; Padron Mora, Crelia; Meyer, Solene; Beaufort, Daniel; Oliot, Emilien; Lallemand, Serge E; Marcaillou, Boris; Philippon, Mélody; Cornée, Jean-jacques; Audemard, Franck A; Lebrun, Jean-frédéric; Klingelhoefer, Frauke; Mercier De Lepinay, Bernard; Munch, Philippe; Garrocq, Clément; Boucart, Milton; Laigle, Mireille; Schenini, Laure; The Garanti Cruise Team,. |
| Based on an extensive seismic and multibeam dataset, 1-5 km wide giant polygons were identified at the bottom of the Grenada basin, covering a total area of ~55000 km². They represent the top part of an active underlying polygonal fault system due to the volumetric contraction of clay- and smectite-rich sediments during burial. To date, this is the widest area of outcropping polygonal faults ever found on Earth. The seabed polygons are bounded by rectilinear ~1000-1500 m wide and ~10-60 m deep furrows, depending on the location in the basin. They are relatively regular in the north Grenada Basin, whereas they are getting longer and more elongated in the south Grenada Basin. The polygonal faults consist in a set of discrete normal faults affecting... |
| Tipo: Text |
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| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00688/79963/82891.pdf |
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