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101. Which parameterization is suitable for acoustic vertical transverse isotropic full waveform inversion ? : Part 1. Sensitivity and trade-off analysis

Author: Gholami, Y., Brossier, R., Prieux, V., Operto, S., Ribodetti, A., Virieux, J., Géoazur (GEOAZUR 6526), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Institut des Sciences de la Terre (ISTerre), Centre National de la Recherche Scientifique (CNRS)-PRES Université de Grenoble-Université Joseph Fourier - Grenoble 1 (UJF)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry]), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), and Université Joseph Fourier - Grenoble 1 (UJF)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-PRES Université de Grenoble-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)
Subjects: 010504 meteorology & atmospheric sciences, Wave propagation, Computation, Acoustics, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, 010502 geochemistry & geophysics, 01 natural sciences, Geochemistry and Petrology, ALGORITHME, CALIBRAGE, Wavenumber, Anisotropy, 0105 earth and related environmental sciences, Physics, PROSPECTION MAGNETIQUE, METHODE D'ANALYSE, PROPAGATION D'ONDE, Isotropy, SISMOGRAMME, MODELISATION, ONDE SISMIQUE, PROSPECTION ACOUSTIQUE, Transverse plane, Geophysics, Frequency domain, Acoustic approximation
Abstract: International audience; In most geologic environments, accounting for anisotropy is necessary to perform acoustic full waveform inversion (FWI) of wide-azimuth and wide-aperture seismic data because of the potential dependence of wave speeds on the direction of the wave propagation. In the framework of multiparameter FWI, the subsurface parameterization controls the influence of the different parameter classes on the modeled seismic data as a function of the scattering angle and hence the resolution with which the parameters can be reconstructed and the potential trade-off between different parameters. We have evaluated a numerical procedure based on computation of the scattering patterns of the different parameters to assess the sensitivity of the seismic data to different parameterizations of vertical transverse isotropic media in the acoustic approximation. Among the different categories we have tested, a monoparametric FWI was found for imaging one wave speed with a broad wavenumber content, keeping the Thomsen parameters fixed, which have a small influence on the data relative to the wave speed. This raises the question of the initial information required in the background models of the Thomsen parameters to perform reliable monoparameter FWI. Alternatively, simultaneously inverting the horizontal and vertical wave speeds introduces limited trade-off effects because these wave speeds have significant influence on the data for distinct ranges of scattering angles, while the influence of the Thomsen parameter δ remains weak. With such parameterization, the short-to-intermediate wavelengths of the vertical velocity are updated from the short-to-intermediate scattering angles, while the long-to-intermediate wavelengths of the horizontal velocity are updated from the wide-to-intermediate scattering angles. We concluded that the choice of the subsurface parameterization can be driven by the acquisition geometry, which controls the scattering-angle coverage and hence the resolving power of FWI, and by the accuracy of the available initial FWI models. Read More: http://library.seg.org/doi/abs/10.1190/geo2012-0204.1
Published: 2013

102. 2D Multi-parameter VTI Acoustic Full Waveform Inversion of Wide-aperture OBC Data from the Valhall Field

Author: Jean Virieux, Alessandra Ribodetti, Stéphane Operto, Y. Gholami, J. H. Kommedal, Romain Brossier, and O. I. Barkved
Subjects: Regional geology, Attenuation, Engineering geology, Normal moveout, Gemology, Economic geology, Igneous petrology, Seismology, Geology, Environmental geology
Abstract: We apply 2D VTI acoustic FWI to wide-aperture OBC data from the Valhall field. Initial models for FWI are determined by VTI reflection traveltime tomography. Mono-parameter and multi-parameter VTI FWI are applied to the hydroacoustic component for reconstruction of seismic wavespeeds and Thomsen parameters, while density and attenuation are kept at their initial values during FWI. Two types of inversions are considered: in the first one, we invert only for one velocity and we keep fixed two Thomsen parameters. In the second one, we invert for two velocities, while the extra Thomsen pa- rameter is kept fixed during FWI. As long as the two Thomsen parameters describe the long wavelength content of the subsurface, the first type of inversion succeeds in reconstructing the wavespeed with a high resolution. The second type of inversion succeeds in reconstructing the two wavespeeds, vertical or normal moveout and horizontal velocities, but with a lower resolution for the horizontal velocities. Reverse time migrations and common image gathers, which are computed in the initial and final FWI models, show that FWI models do not allow us to improve the deep part of the migrated images, where the footprint of anisotropy is shown.
Published: 2012

103. Making Seismic Data as CSEM Data through the Bäcklund Transform

Author: S. Operto, J. Virieux, A. Ribodetti, S. Garambois, and Romain Brossier
Subjects: Bäcklund transform, Partial differential equation, Discrete sine transform, Wave propagation, Laplace transform applied to differential equations, Mathematical analysis, Petrology, Seismogram, Continuous wavelet transform, Fractional Fourier transform, Geology, Physics::Geophysics
Abstract: Backlund transform is applied to a seismogram in order to construct a new signal where the time is transformed in a pseudo‐time the square of its dimension is expressed in seconds. The Backlund transform links partial differential equations related to wave propagation to partial differential equations related to diffusion. Potential applications have been performed previously from magnetotelluric data to pseudo‐seismic signals by using the inverse of the Backlund transform. This transform could be applied to the seismic signal through real computations. Therefore, we propose to transform seismic data into pseudo‐CSEM signals for possible applications of these diffusive signals as the initial stage of the full waveform inversion of seismic data.
Published: 2012

104. Seismic waves : research and analysis

Author: Víctor M. Cruz-Atienza, Alessandra Ribodetti, Diego Mercerat, Romain Brossier, Jean Virieux, V. Etienne, Stéphane Garambois, Stéphane Operto, Olivier Coutant, Emmanuel Chaljub, Josué Tago, V. Prieux, Institut des Sciences de la Terre (ISTerre), Université Joseph Fourier - Grenoble 1 (UJF)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-PRES Université de Grenoble-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Géoazur (GEOAZUR 6526), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Instituto de Geofisica [Mexico], Universidad Nacional Autónoma de México = National Autonomous University of Mexico (UNAM), Géoazur, Publications, Kanao, M. (ed.), Centre National de la Recherche Scientifique (CNRS)-PRES Université de Grenoble-Université Joseph Fourier - Grenoble 1 (UJF)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry]), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (... - 2019) (UNS), Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), and Universidad Nacional Autónoma de México (UNAM)
Subjects: MODELE MATHEMATIQUE, METHODE D'ANALYSE, PROPAGATION D'ONDE, 010504 meteorology & atmospheric sciences, Scale (ratio), Synthetic seismogram, Geophysical imaging, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Geophysics, Inverse problem, 010502 geochemistry & geophysics, 01 natural sciences, Seismic wave, ONDE SISMIQUE, Seismic tomography, ETUDE COMPARATIVE, [SDU.STU] Sciences of the Universe [physics]/Earth Sciences, Seismic refraction, Vertical seismic profile, Seismology, Geology, 0105 earth and related environmental sciences
Abstract: International audience; The Earth is an heterogeneous complex media from the mineral composition scale (10−6m) to the global scale ( 106m). The reconstruction of its structure is a quite challenging problem because sampling methodologies are mainly indirect as potential methods (Günther et al., 2006; Rücker et al., 2006), diffusive methods (Cognon, 1971; Druskin & Knizhnerman, 1988; Goldman & Stover, 1983; Hohmann, 1988; Kuo & Cho, 1980; Oristaglio & Hohmann, 1984) or propagation methods (Alterman & Karal, 1968; Bolt & Smith, 1976; Dablain, 1986; Kelly et al., 1976; Levander, 1988; Marfurt, 1984; Virieux, 1986). Seismic waves belong to the last category. We shall concentrate in this chapter on the forward problem which will be at the heart of any inverse problem for imaging the Earth. The forward problem is dedicated to the estimation of seismic wavefields when one knows the medium properties while the inverse problem is devoted to the estimation of medium properties from recorded seismic wavefields.
Published: 2012

105. The South Ecuador subduction channel: evidence for a dynamic mega-shear zone from 2D fine-scale seismic reflection imaging, implications for material transfer

Author: Collot, Jean-Yves, Ribodetti, Alessandra, Sage, Françoise, Agudelo, W., Géoazur (GEOAZUR 6526), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), ECOPETROL, Ecopétr, Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (1965 - 2019) (UNS), and COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)
Subjects: [SDU.STU]Sciences of the Universe [physics]/Earth Sciences
Abstract: International audience; Tectonic processes that control the transition from poorly consolidated sediment entering the subduction channel (SC) to the seismogenic zone are documented using seismic imaging. We applied pre-stack depth migration and a post-processing sequence to a seismic reflection line acquired across the Ecuador convergent margin to obtain a 2D-quantitative image of the first ∼24 km of the SC. Structural interpretation shows that the SC consists of a 630-1150-m-thick, low-velocity, continuous sheet of sediment that dips ∼6° landward and undergoes shear deformation. The long sheet is bounded at top and bottom by décollement thrusts, and developed over time Riedel shears and basal thrust faulting and folding downdip, pointing to a dynamic mega-shear zone. Modeling the strong uppermost and basal SC reflectors reveals that they are associated with 40-80-m-thick, 50-350 m/s, low-velocity perturbations layers inferred to be fluid rich and mechanically weak. A fine-scale velocity model shows two anomalously low-Vp areas in the long sheet, advocating patches of over-pressured fluids. Evidence for Vp variations along the upper-plate foundation suggests either underplated bodies or a fluid-damage zone. A simple temporal reconstruction indicates that underthrusting the long sheet initiated >450 kyr ago and interrupted ∼54 ± 13 kyr ago, when frontal accretion resumed. During this transient evolution, the SC boundaries revealed highly unstable as most of the SC was underplated while down going plate material may have been sheared off and incorporated to the SC.
Published: 2011

106. A multi-scale strategy for handling broadband seismic

Author: Virieux, J., Operto, S., Asnaashari, A., Brossier, R., Castellanos, C., Etienne, V., Gholami, Y., Hu, G., Pageot, D., Prieux, V., Ribodetti, A., Roques, A., Institut des Sciences de la Terre (ISTerre), Centre National de la Recherche Scientifique (CNRS)-PRES Université de Grenoble-Université Joseph Fourier - Grenoble 1 (UJF)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry]), Géoazur (GEOAZUR 6526), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), SEISCOPE, Université Joseph Fourier - Grenoble 1 (UJF)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-PRES Université de Grenoble-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (1965 - 2019) (UNS), and COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)
Subjects: [SDU.STU]Sciences of the Universe [physics]/Earth Sciences
Abstract: International audience; Full waveform inversion is a promising imaging technology for high-resolution images of the subsurface, but suffers from intrinsic non-linearities that require adequate strategies for overcoming them. One crucial issue is related to the starting model from which one has to start when considering local optimization strategies. Depending on the complexity of the data often related to the frequency content of the waves, the initial model selection may range from a crude smooth model for low frequencies to already quite accurate models for high frequencies. We shall investigate relations between the data complexity either when recorded or after time transformation, the model discretisation as well as the optimization strategy in order to better quantify acquisition design and related data interpretation one should consider. ©2011 Society of Exploration Geophysicists
Published: 2011

107. Hierarchical strategy for full waveform inversion in the frequency domain

Author: Stéphane Operto, B. Dupuy, D. Pageot, Alessandra Ribodetti, J. Virieux, G. Hu, Y. Gholami, V. Prieux, Romain Brossier, A. Roques, V. Etienne, and C. Castellanos
Subjects: Engineering, business.industry, Frequency domain, Outlier, Geophone, Inversion (meteorology), White noise, Minification, Solver, Acoustic approximation, business, Algorithm
Abstract: Full waveform inversion (FWI) of seismic traces recorded at the free surface allows the reconstruction of the physical parameters structure on the underlying medium. Our two main objectives are the reconstruction of multiple classes of parameters on one side and the formulation of both the acoustic and elastic FWI for 3D geometries. A quasi-Newtonian method with a preconditioned L-BFGS algorithm provides scaled gradients of the misfit function for each class of parameter. For onshore applications where body waves and surface waves are jointly inverted, P- and S-wave velocities (VP and VS) must be reconstructed simultaneously using a hierarchical inversion algorithm with two nested levels of data preconditioning. The first one concerns the frequency sampling from low to high frequencies during the inversion procedure. The second one performs a data preconditioning by an exponential decay after the first arrival time. Simultaneous inversion of multiple frequencies rather than successive inversions of single frequencies significantly increases the S/N ratio of the models. For offshore applications where VS can have a minor footprint in the data, a hierarchical approach which first reconstructs VP in the acoustic approximation from the hydrophone component followed by the joint reconstruction of VP and VS from the geophone components can be the approach of choice. Among all the possible minimization criteria, we found that the L1 norm provides the most robust and easy-to-tune criterion as expected for this norm. In particular, successfull reconstruction of VP and VS on a realistic synthetic offshore case study is possible when white noise with outliers has been added to the data. The feasibility of 3D FWI is highly dependent on the efficiency of the seismic modelling. Frequencydomain modelling based on direct solver allows one to tackle small-scale problems involving few millions of unknowns at low frequencies. If the seismic modelling engine embeds expensive sourcedependent tasks, source encoding can be used to mitigate the computational burden of multiple-source modelling. However, the source encoding is very sensitive to noise in the framework of efficient frequency-domain FWI where a limited number of frequencies is inverted sequentially. Time-domain modelling for the estimation of harmonic components of the solution is an alternative of choice even for 3D frequency-domain FWI because it allows one to extract an arbitrary number of frequencies at a minimum extra cost, a procedure useful when multiple frequencies are inverted together.
Published: 2011

108. An Overview of Numerical Methods Suitable for Geophysical Imaging

Author: R. Brossier H. Calandra, V. Etienne, R-E Plessix, Stéphane Operto, Alessandra Ribodetti, and Jean Virieux
Subjects: Partial differential equation, Discontinuous Galerkin method, Electromagnetism, Geophysical imaging, Earth science, Numerical analysis, Inversion (meteorology), Weak formulation, Spectral method, Geology, Computational science
Abstract: Modelling methods are nowadays at the heart of any geophysical interpretation approach. These are heavily relied upon by imaging techniques in elastodynamics and electromagnetism, where they are crucial for the extraction of subsurface characteristics from ever larger and denser datasets. While highfrequency or one-way approximations are very powerful and efficient, they reach their limits when complex geological settings and solutions of full equations are required for high resolution imaging. A review of three important formulations will be carried out during this presentation: the spectral method, which is very efficient and accurate but generally restricted to simple earth structures, and often layered earth structures; the pseudo-spectral, finite-difference and finite-volume methods based on strong formulation of the partial differential equations, which are easy to implement and currently represent a good compromise between accuracy, efficiency and flexibility; and the continuous or discontinuous Galerkin finite-element methods that are based on the weak formulation, which lead to more accurate earth representations and therefore to more accurate solutions, although with higher computational costs and more complex use. The choice between these different approaches is still difficult and depends on the applications. Guidelines are given here through discussion of the requirements for imaging/ inversion.
Published: 2011

109. On the Footprint of Attenuation on Full-waveform Inversion of Land Data - A Case Study from the Polish Basin

Author: Stéphane Operto, Alessandra Ribodetti, and Michal Malinowski
Subjects: Regional geology, Hydrogeology, Attenuation, Engineering geology, Gemology, Economic geology, Acoustic approximation, Geomorphology, Geology, Seismology, Environmental geology
Abstract: Here we assess the potential of the visco-acoustic frequency domain full-waveform inversion (FWI) to reconstruct P-wave velocity and P-wave attenuation factor (Qp) from onshore seismic data. We show that both the velocity and the attenuation factor can be reliably reconstructed with a comparable resolution and without trade-off for sufficiently attenuating media and sufficiently-accurate velocity starting model by non-linear inversion. We applied both the acoustic and visco-acoustic FWI to real wide-aperture onshore seismic data with a strong footprint of attenuation that were recorded in the Polish Basin. We show how a heuristic normalisation of the data with offset allows us to remove the effect of the attenuation from the data and reconstruct a reliable velocity model in the acoustic approximation. Alternatively, visco-acoustic FWI allows us to reconstruct jointly both a reliable velocity model and a Q model from the true-amplitude data. We find the recovered velocity and Q models consistent with the expected lithology and stratigraphy in the study area. We link high-attenuation zones with the increased clay content and the presence of the mineralized fluids.
Published: 2011

110. Seismic stratigraphy and deformational styles of the offshore Cyrenaica (Libya) and bordering Mediterranean Ridge

Author: L. Mbida, Yem, Camera, L., Mascle, J., Ribodetti, A., Géoazur (GEOAZUR 6526), Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Nice Sophia Antipolis (... - 2019) (UNS), Université Côte d'Azur (UCA)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Applied Geology Laboratory UYI, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, and COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Europe, divergent [Continental margins], Image processing, convergent [Continental margins], Africa, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences
Abstract: International audience; Off northwest Libya the Cyrenaica foreland basin domain and its Pan-African continental crust, which constitute the African promontory, are overthrusted by the Mediterranean Ridge Complex. The thrust belt contact and its seismic stratigraphy have been analysed using pre-stack depth-migrated multichannel seismic (MCS) lines recorded during the MEDISIS survey (2002). The geometry and sedimentary distribution analysis through the wedge-top depocentres allow reconstruction of schematic cross-sections of the tectono-sedimentary wedge that includes two major thrust sequences separated by an apparently poorly deformed transition zone. Based on time-space variation of several piggyback basins, we propose that these thrust sequences relate to distinct phases of shortening. (1) A first event, which probably occurred just prior to the Messinian crisis in latest Miocene (Tortonian times?) and (2) A second event, that has finally led to the present-day overthrusting of the Mediterranean Ridge over the Libyan continental slope.
Published: 2011

111. A multi‐scale strategy for handling broadband seismic data

Author: J. Virieux, S. Operto, A. Asnaashari, R. Brossier, C. Castellanos, V. Etienne, Y. Gholami, G. Hu, D. Pageot, V. Prieux, A. Ribodetti, and A. Roques
Published: 2011

112. Joint ray plus Born least-squares migration and simulated annealing optimization for target-oriented quantitative seismic imaging

Author: Ribodetti, Alessandra, Operto, S., Agudelo, W., Collot, Jean-Yves, and Virieux, J.
Abstract: A seismic processing workflow based on iterative ray + Born migration/inversion and target-oriented postprocessing of the migrated image is developed for fine-scale quantitative characterization of reflectors. The first step of the workflow involves linear iterations of the ray + Born migration/inversion. The output of the first step is a true-amplitude migrated image parameterized by velocity perturbations. In a second step, postprocessing of the migrated image is performed through a random search with a very-fast simulated annealing (VFSA) algorithm. The forward problem of the global optimization is a simple convolutional model that linearly relates a vertical profile of the band-limited migrated image after depth-to-time conversion to a 1D velocity model composed of a stack of homogeneous layers of arbitrary velocity and thickness. The aim of the postprocessing is to eliminate the limited bandwidth effects of the source from the migrated image for resolution improvement and enhanced geological interpretation of selected targets. The global optimization approach allows for uncertainty analysis required by the intrinsic nonuniqueness of the velocity model output by the postprocessing. The relevance of the convolutional model when applied to the output of the ray + Born migrated inversion is first illustrated with a one-layer model. The accuracy and the robustness of the workflow to image geologically complicated models are then illustrated with an application to the synthetic Marmousi model. Some practical issues (e. g., the source wavelet estimate and the scaling of the migrated image required by the VFSA optimization) are discussed with an application to a 2D real seismic multichannel reflection data set collected in the Gulf of Guayaquil (Ecuador). The postprocessing is applied to derive the fine-scale velocity structure of a decollement zone on top of the subduction channel. The postprocessing allows for mapping structural variations along different segments of the decollement, which can be associated with changes in fluid content and porosity.
Published: 2011

113. Acoustic VTI full waveform inversion: Sensitivity analysis and realistic synthetic examples

Author: Stéphane Operto, Romain Brossier, Alessandra Ribodetti, Jean Virieux, and Y. Gholami
Subjects: Azimuth, Horizontal and vertical, Transverse isotropy, Geophysical imaging, Normal moveout, Acoustics, Inversion (meteorology), Anisotropy, Image resolution, Geology
Abstract: Full waveform inversion (FWI) is a seismic imaging method suitable for wide aperture / azimuth acquisitions thanks to its ability to account for waves propagating over a broad range of incidence angles. Wide aperture / azimuth acquisitions makes, however, the imaging quite sensitive to anisotropy because of the intrinsic difference between vertical and horizontal velocities in vertical transversely isotropic (VTI) media. In this study, we present a numerical procedure to define the best parametrization for acoustic VTI FWI. High-resolution velocity model for either the vertical, the horizontal or the normal move out (NMO) velocity can be developed by monoparameter FWI, when the considered wave speed is combined with the Thomsen’s parameters δ and e in the parametrization, and when available smooth background models of δ and e are kept fixed during FWI. An alternative is to jointly reconstruct two wavespeeds (for example, the vertical and the horizontal velocities) using a model parametrization that combines these two wavespeeds and δ . However, the spatial resolution of the two resulting velocity models is more limited that of the velocity model obtained with the first mentioned parametrization.
Published: 2011

114. Two‐dimensional acoustic anisotropic (VTI) full waveform inversion: The Valhall case study

Author: Y. Gholami, Jean Virieux, Romain Brossier, Stéphane Operto, Alessandra Ribodetti, and V. Prieux
Subjects: Geophysical imaging, Transverse isotropy, Isotropy, Geometry, Inversion (meteorology), Wave speed, Anisotropy, Parametrization, Geology, Full waveform
Abstract: Anisotropy can have a significant footprint in seismic imaging from surface wide-aperture data, because of the difference between vertical and horizontal velocities in vertical transversely isotropic (VTI) media. A key issue in anisotropic full waveform inversion (FWI) is to define a suitable parametrization of the subsurface model, and the number of parameter classes that can be reliably reconstructed for the chosen parametrization. We address this issue with an application of frequency-domain acoustic isotropic/anisotropic FWI to real surface wide-aperture data recorded by an ocean bottom cable in the Valhall field. Isotropic FWI results show that the horizontal velocity is mainly reconstructed in the upper structure, dominantly constrained by diving waves and supercritical reflections. This can lead to depth stretching and/or overestimated velocity perturbations in the deep velocity structure, mainly controlled by short-aperture reflections. Monoparameter anisotropic FWI shows a reliable reconstruction of either the vertical, the horizontal or the NMO velocity, when the model is parametrized by one wave speed and the Thomsen’s parameters δ and e . For such mono-parameter FWI, the smooth δ and e background models are kept constant during FWI iterations. Alternatively, the vertical and the horizontal velocities can be jointly reconstructed by multiparameter FWI, when the subsurface model is parametrized by the two wave speeds and δ , this latter is kept fixed during FWI iterations.
Published: 2011

115. High-resolution seismic attenuation imaging from wide-aperture onshore data by visco-acoustic frequency-domain full-waveform inversion

Author: Malinowski, M., Operto, S., Ribodetti, A., Institute of Geophysics [Warsaw], Polska Akademia Nauk = Polish Academy of Sciences (PAN), Géoazur (GEOAZUR 6526), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Polska Akademia Nauk (PAN), Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Nice Sophia Antipolis (... - 2019) (UNS), Université Côte d'Azur (UCA)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (1965 - 2019) (UNS), and COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)
Subjects: MODELE MATHEMATIQUE, METHODE D'ANALYSE, PROPAGATION D'ONDE, [SDU]Sciences of the Universe [physics], [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, SISMOLOGIE, TOMOGRAPHIE, SISMOGRAMME, BASSIN SEDIMENTAIRE, ONDE SISMIQUE
Abstract: International audience; Here we assess the potential of the visco-acoustic frequency domain full-waveform inversion (FWI) to reconstruct P-wave velocity (VP) and P-wave attenuation factor (Q) from surface onshore seismic data. First, we perform a sensitivity analysis of the FWI based upon a grid search analysis of the misfit function and several synthetic FWI examples using velocity and Q models of increasing complexity. Subsequently, we applied both the acoustic and visco-acoustic FWI to real surface wide-aperture onshore seismic data from the Polish Basin, where a strong attenuation of the seismic data is observed. The sensitivity analysis of the visco-acoustic FWI suggests that the FWI can jointly reconstruct the velocity and the attenuation factor if the signature of the attenuation is sufficiently strong in the data. A synthetic example corresponding to a homogeneous background model with an inclusion shows a reliable reconstruction of VP and Q in the inclusion, when Q is as small as 90 and 50 in the background model and in the inclusion, respectively. A first application of acoustic FWI to real data shows that a heuristic normalization of the data with offset allows us to compensate for the effect of the attenuation in the data and reconstruct a reliable velocity model. Alternatively, we show that visco-acoustic FWI allows us to reconstruct jointly both a reliable velocity model and a Q model from the true-amplitude data. We propose a pragmatical approach based upon seismic modelling and source wavelet estimation to infer the best starting homogeneous Q model for visco-acoustic FWI. We find the source wavelet estimation quite sensitive to the quality of the velocity and attenuation models used for the estimation. For example, source-to-source wavelets are significantly more consistent when computed in the final FWI model than in the initial one. A good kinematic and amplitude match between the early-arriving phases of the real and time-domain synthetic seismograms computed in the final FWI model provides an additional evidence of the reliability of the final FWI model. We find the recovered velocity and attenuation models consistent with the expected lithology and stratigraphy in the study area. We link high-attenuation zones with the increased clay content and the presence of the mineralized fluids.
Published: 2011

116. Joint ray + Born least-squares migration and simulated annealing optimization for target-oriented quantitative seismic imaging

Author: Jean-Yves Collot, Stéphane Operto, William Agudelo, Alessandra Ribodetti, Jean Virieux, Géoazur (GEOAZUR 6526), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (... - 2019) (UNS), Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), ECOPETROL, Instituto Colombiano del Petroleo, Risques, Laboratoire de Géophysique Interne et Tectonophysique (LGIT), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Laboratoire Central des Ponts et Chaussées (LCPC)-Institut des Sciences de la Terre (ISTerre), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut national des sciences de l'Univers (INSU - CNRS)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS)-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut national des sciences de l'Univers (INSU - CNRS)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS)-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR), Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Nice Sophia Antipolis (... - 2019) (UNS), Université Côte d'Azur (UCA)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Risques (Risques), Laboratoire Central des Ponts et Chaussées (LCPC)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Laboratoire Central des Ponts et Chaussées (LCPC)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Laboratoire Central des Ponts et Chaussées (LCPC)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), and Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Laboratoire Central des Ponts et Chaussées (LCPC)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 010504 meteorology & atmospheric sciences, Iterative method, Geophysical imaging, Geometry, Inverse problem, 010502 geochemistry & geophysics, 01 natural sciences, Seismic wave, Random search, Geophysics, Wavelet, Geochemistry and Petrology, Simulated annealing, [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology, Algorithm, Global optimization, Geology, 0105 earth and related environmental sciences
Abstract: A seismic processing workflow based on iterative [Formula: see text] migration/inversion and target-oriented postprocessing of the migrated image is developed for fine-scale quantitative characterization of reflectors. The first step of the workflow involves linear iterations of the [Formula: see text] migration/inversion. The output of the first step is a true-amplitude migrated image parameterized by velocity perturbations. In a second step, postprocessing of the migrated image is performed through a random search with a very-fast simulated annealing (VFSA) algorithm. The forward problem of the global optimization is a simple convolutional model that linearly relates a vertical profile of the band-limited migrated image after depth-to-time conversion to a 1D velocity model composed of a stack of homogeneous layers of arbitrary velocity and thickness. The aim of the postprocessing is to eliminate the limited bandwidth effects of the source from the migrated image for resolution improvement and enhanced geological interpretation of selected targets. The global optimization approach allows for uncertainty analysis required by the intrinsic nonuniqueness of the velocity model output by the postprocessing. The relevance of the convolutional model when applied to the output of the [Formula: see text] migrated inversion is first illustrated with a one-layer model. The accuracy and the robustness of the workflow to image geologically complicated models are then illustrated with an application to the synthetic Marmousi model. Some practical issues (e.g., the source wavelet estimate and the scaling of the migrated image required by the VFSA optimization) are discussed with an application to a 2D real seismic multichannel reflection data set collected in the Gulf of Guayaquil (Ecuador). The postprocessing is applied to derive the fine-scale velocity structure of a décollement zone on top of the subduction channel. The postprocessing allows for mapping structural variations along different segments of the décollement, which can be associated with changes in fluid content and porosity.
Published: 2011

117. Application of 2D acoustic frequency-domain full-waveform inversion to OBC wide-aperture data from the Valhall field

Author: Alessandra Ribodetti, D. Pageot, A. Roques, Jean Virieux, Amir Asnaashari, Romain Brossier, Y. Gholami, Stéphane Operto, V. Prieux, Clara Castellanos, G. Hu, V. Etienne, Géoazur (GEOAZUR 6526), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (... - 2019) (UNS), Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Géophysique Interne et Tectonophysique (LGIT), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Laboratoire Central des Ponts et Chaussées (LCPC)-Institut des Sciences de la Terre (ISTerre), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut national des sciences de l'Univers (INSU - CNRS)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS)-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR), BP Norge, BP NORGE, SEISCOPE, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Central des Ponts et Chaussées (LCPC)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), and Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Laboratoire Central des Ponts et Chaussées (LCPC)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Engineering, 010504 meteorology & atmospheric sciences, Discretization, business.industry, Model selection, Data interpretation, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Inversion (meteorology), Time transformation, 010502 geochemistry & geophysics, 01 natural sciences, Broadband, Imaging technology, 14. Life underwater, business, Algorithm, Full waveform, 0105 earth and related environmental sciences
Abstract: International audience; We present an application of 2D acoustic frequency-domain Full Waveform Inversion (FWI) to the hydrophone component of 4-C ocean bottom cable (OBC) data recorded from the Valhall field in North sea. The starting model for FWI was built by reflection traveltime tomography (RTT). Although this starting model leads to flat common-image gathers (CIGs), it does not allow us to match first-arrival traveltimes of diving waves from above the gas layers. This mismatch between vertical and horizontal velocities is likely the footprint of anisotropy. We updated the RTT model by first-arrival traveltime tomography (FATT) to build a new starting model for FWI. The velocities above the gas layers of the updated model are significantly higher than velocities from in-well seismic (VSP) data. FWI models were computed from the two starting models just mentioned. More stable results were obtained with the starting model updated by FATT. The resulting FWI model shows a reasonable agreement with a former model developed by 3D FWI. A reasonable match of both short-aperture and wide- aperture components of the data was obtained by isotropic FWI. This might indicate that layer-induced anisotropy was created by FWI in the gas layers to balance the increase of the shallow velocities created by the inversion of the wide-aperture data components. ©2010 Society of Exploration Geophysicists
Published: 2010

118. Efficient 3D frequency-domain full-waveform inversion of ocean-bottom cable data with sparse block low-rank direct solver: a real data case study from the North Sea

Author: Amestoy, P., primary, Brossier, R., additional, Buttari, A., additional, L'Excellent, J.-Y., additional, Mary, T., additional, Métivier, L., additional, Miniussi, A., additional, Operto, S., additional, Ribodetti, A., additional, Virieux, J., additional, and Weisbecker, C., additional
Published: 2015
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119. Efficient 3-D frequency-domain mono-parameter full-waveform inversion of ocean-bottom cable data: application to Valhall in the visco-acoustic vertical transverse isotropic approximation

Author: Operto, S., primary, Miniussi, A., additional, Brossier, R., additional, Combe, L., additional, Métivier, L., additional, Monteiller, V., additional, Ribodetti, A., additional, and Virieux, J., additional
Published: 2015
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120. Efficient 3D Frequency-domain Full-waveform Inversion of Ocean-bottom Cable Data - Application to Valhall in the Visco-ac

Author: Operto, S., primary, Miniussi, A., additional, Brossier, R., additional, Combe, L., additional, Haller, N., additional, Kjos, E., additional, Métivier, L., additional, Milne, R., additional, Ribodetti, A., additional, Song, Z., additional, Virieux, J., additional, and Zheng, Y., additional
Published: 2015
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121. Imaging of VTI media from wide-aperture data by frequency-domain full-waveform inversion

Author: S. Operto, A. Ribodetti, Romain Brossier, J. Virieux, Y. Gholami, Géoazur (GEOAZUR 6526), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (... - 2019) (UNS), Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Géophysique Interne et Tectonophysique (LGIT), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Laboratoire Central des Ponts et Chaussées (LCPC)-Institut des Sciences de la Terre (ISTerre), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut national des sciences de l'Univers (INSU - CNRS)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS)-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Laboratoire Central des Ponts et Chaussées (LCPC)-Centre National de la Recherche Scientifique (CNRS), Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Central des Ponts et Chaussées (LCPC)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), and Géoazur, Publications
Subjects: Regional geology, medicine.medical_specialty, 010504 meteorology & atmospheric sciences, Acoustics, Inversion (meteorology), 010502 geochemistry & geophysics, 01 natural sciences, Metamorphic petrology, Telmatology, Frequency domain, medicine, Geomorphology, ComputingMilieux_MISCELLANEOUS, Full waveform, Geology, 0105 earth and related environmental sciences
Abstract: International audience
Published: 2010

122. An overview of the SEISCOPE project on frequency-domain Full Waveform Inversion Multiparameter inversion and efficient 3D full-waveform inversion

Author: Jean Virieux, Y. Jia, Y. Gholami, V. Etienne, Romain Brossier, Stéphane Operto, H. Ben Hadj Ali, Alessandra Ribodetti, G. Hu, D. Pageot, and V. Prieux
Subjects: Frequency domain, Outlier, Geophone, Inversion (meteorology), Minification, White noise, Solver, Acoustic approximation, Algorithm, Geology, Seismology
Abstract: We present an overview of the SEISCOPE project on frequency-domain full waveform inversion (FWI). The two main objectives are the reconstruction of multiple classes of parameters and the 3D acoustic and elastic FWI. The optimization relies on a preconditioned L-BFGS algorithm which provided scaled gradients of the misfit function for each classes of parameter. For onshore applications where body waves and surface waves are jointly inverted, P- and S-wave velocities (VP and VS) must be reconstructed simultaneously using a hierarchical inversion algorithm with two nested levels of data preconditioning with respect to frequency and arrival time. Simultaneous inversion of multiple frequencies rather than successive inversions of single frequencies significantly increases the S/N ratio of the models. For offshore applications where VS can have a minor footprint in the data, a hierarchical approach which first reconstructsVP in the acoustic approximation from the hydrophone component followed by the joint reconstruction of VP and VS from the geophone components can be the approach of choice. Among all the possible minimization criteria, we found that the L1 norm provides the most robust and easy-to-tune criterion as expected for this norm. In particular, it allowed us to successfully reconstruct VP and VS on a realistic synthetic offshore case study, when white noise with outliers has been added to the data. The feasibility of 3D FWI is highly dependent on the efficiency of the seismic modelling. Frequency-domain modelling based on direct solver allows one to tackle small-scale problems involving few millions of unknowns at low frequencies. If the seismic modelling engine embeds expensive source-dependent tasks, source encoding can be used to mitigate the computational burden of multiple-source modelling. However, we have shown the sensitivity of the source encoding to noise in the framework of efficient frequency-domain FWI where a limited number of frequencies is inverted sequentially. Simultaneous inversion of multiple frequencies is required to achieve an acceptable S/N ratio with a reasonable number of FWI iterations. Therefore, time-domain modelling for the estimation of harmonic components of the solution can be the approach of choice for 3D frequency-domain FWI because it allows one to extract an arbitrary number of frequencies at a minimum extra cost.
Published: 2010

123. An overview of the SEISCOPE project on frequency-domain Full Waveform Inversion Multiparameter inversion and efficient 3D full-waveform inversion

Author: Virieux, J., Operto, S., Ben, Hadj, Ali, H., Brossier, R., Etienne, V., Gholami, Y., Hu, G., Jia, Y., Pageot, D., Prieux, V., Ribodetti, A., Géoazur (GEOAZUR 6526), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (1965 - 2019) (UNS), and COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)
Subjects: ComputingMilieux_MISCELLANEOUS
Abstract: International audience
Published: 2010

124. Imaging of VTI media by elastic frequency-domain full-waveform inversion of global offset data

Author: Gholami, Y., Brossier, R., Ribodetti, A., Operto, S., Virieux, J., Géoazur, Publications, Géoazur (GEOAZUR 6526), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Géophysique Interne et Tectonophysique (LGIT), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Laboratoire Central des Ponts et Chaussées (LCPC)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (... - 2019) (UNS), Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Laboratoire Central des Ponts et Chaussées (LCPC)-Institut des Sciences de la Terre (ISTerre), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut national des sciences de l'Univers (INSU - CNRS)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS)-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR), Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Central des Ponts et Chaussées (LCPC)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), and Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: ComputingMilieux_MISCELLANEOUS
Abstract: International audience
Published: 2010

125. Sensitivity Analysis of Full Waveform Inversion in VTI Media

Author: J. Virieux, S. Operto, Romain Brossier, Y. Gholami, A. Ribodetti, Géoazur (GEOAZUR 6526), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Géophysique Interne et Tectonophysique (LGIT), Laboratoire Central des Ponts et Chaussées (LCPC)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Laboratoire Central des Ponts et Chaussées (LCPC)-Institut des Sciences de la Terre (ISTerre), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut national des sciences de l'Univers (INSU - CNRS)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS)-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR), Géoazur, Publications, Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), and Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Laboratoire Central des Ponts et Chaussées (LCPC)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 010504 meteorology & atmospheric sciences, Scattering, Attenuation, Mathematical analysis, Parameterized complexity, Inverse transform sampling, 010502 geochemistry & geophysics, 01 natural sciences, Finite element method, Discontinuous Galerkin method, Polygon mesh, Anisotropy, Geology, Seismology, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract: We present a 2D frequency-domain Full-Waveform Inversion method for imaging VTI media. The medium is parameterized by the P and S wavespeeds on the symmetry axis (VP0 and VS0), the density, the attenuation factors and the Thomsen's parameters delta and epsilon. The forward modeling is based on a finite element discontinuous Galerkin method on unstructured triangular meshes which allows for accurate modeling in presence of complex topographies. The optimization relies on a precontioned L-BFGS quasi-Newton algorithm which directly provides the scaled gradients of the misfit function associated with different parameter classes of different unit. The radiation pattern of the anisotropic parameters for the P-P scattering mode are first developed to assess the coupling between the different parameter classes. Second, application of FWI for imaging an anisotropic inclusion from an ideal circular acquisition suggests that VP0, VS0 and the Thomsen's parameters cannot be reconstructed simultaneously because of the coupling between VP0 and epsilon. Hierarchic inversions for VP0 followed by the joint reconstruction of VS0 and the Thomsen's parameters provide more stable results.
Published: 2010

126. Evolution of the Levant margin and western arabia platform since the mesozoic

Author: Alessandra Ribodetti, Laurent Camera, Jean Mascle, Homberg, C. (ed.), and Bachmann, M. (ed.)
Subjects: 010504 meteorology & atmospheric sciences, Seismic stratigraphy, Geology, Ocean Engineering, PROFIL SISMIQUE, STRATIGRAPHIE, 010502 geochemistry & geophysics, 01 natural sciences, MARGE CONTINENTALE PASSIVE, Continental margin, GEODYNAMIQUE, SISMIQUE A REFLEXION, DISCONTINUITE, Seismology, STRUCTURE SEDIMENTAIRE, 0105 earth and related environmental sciences, Water Science and Technology, TECTONIQUE
Published: 2010

127. Deep structure and seismic stratigraphy of the Egyptian Margin from Multichannel seismic data

Author: Camera, L., Ribodetti, A., Mascle, J., Géoazur (GEOAZUR 6526), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (1965 - 2019) (UNS), and COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)
Abstract: International audience; Regional multichannel seismic reflection (MCS) profiles across the Egyptian continental slope, offshore the Nile delta, were recorded during the MEDISIS survey (conducted in 2002 on board the R/V Nadir). The results of this survey allow an interpretation of the overall structure and evolution of this passive continental margin. The MCS data were processed using an amplitude preserving pre-stack depth migration technique, which has the advantage of providing a quantitative, and geometrically correct, image of seismic horizons. Well-defined reflecting events allow the identification of three main seismic units. The upper unit (a 7 km thick) is interpreted as the post-rift sedimentary cover of the margin; it includes an undisturbed Middle Cretaceous to Upper Miocene sedimentary pile, covered by thick Messinian (latest Miocene) salt-rich layers and by Pliocene to Quaternary sediments, locally intensively deformed by gravity tectonics. The underlying intermediate acoustic unit (6 km thick on average) is interpreted as the Mesozoic syn-rift sedimentary cover of the margin; the end of the last rifting event is marked by a strong angular unconformity, tentatively of Aptian age. The lower unit may correspond to the thinned continental crust of Africa (12 km thick on average in the study area) and its pre-rift cover. Its base is identified by strong, discontinuous reflector packages about 23–25 km below sea floor, interpreted as indicative of the Moho.
Published: 2010

128. Imaging of VTI media by elastic frequency‐domain full‐waveform inversion of global offset data

Author: Stéphane Operto, Alessandra Ribodetti, Y. Gholami, Jean Virieux, and Romain Brossier
Subjects: Offset (computer science), Geophysical imaging, Discontinuous Galerkin method, Acoustics, Frequency domain, S-wave, Polygon mesh, Inversion (meteorology), Anisotropy, Geology, Physics::Geophysics
Abstract: It is well acknowledged that accounting for anisotropy in seismic imaging improves focusing and depth positioning of reflectors. Indeed, at present day, seismic imaging of anisotropic media still remains one of the most challenging problem in exploration geophysics because of the possible coupling between the different anisotropic parameters. In this study, we develop a frequency-domain full-waveform inversion (FWI) method for imaging 2D visco-elastic VTI media from wideaperture data. Frequency-domain seismic modeling is performed in VTI media with a hp-adaptive finite-element discontinuous Galerkin (DG) method implemented on unstructured triangular meshes that allows for accurate seismic modeling in complex media with reflectors of arbitrary shape. The inversion relies on a quasi-Newton algorithm which allows for proper scaling of misfit-function gradients associated with different parameter classes. The model parameters are either the P and S wave speeds on the symmetry axis and the Thomsen’s parameters δ and e , or the stiffness coefficients c11, c33, c13 and c44.
Published: 2010

129. Geophysical evidence for a transform margin offshore Western Algeria: a witness of a subduction-transform edge propagator?

Author: Badji, Rabia, primary, Charvis, Philippe, additional, Bracene, Rabah, additional, Galve, Audrey, additional, Badsi, Madjid, additional, Ribodetti, Alessandra, additional, Benaissa, Zahia, additional, Klingelhoefer, Frauke, additional, Medaouri, Mourad, additional, and Beslier, Marie-Odile, additional
Published: 2014
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130. Continental breakup history of poor magmatic margins from seismic reflection and analogue modeling (oriental Gulf of Aden)

Author: Autin, J., Leroy, Sylvie, d'Acremont, Elia, Beslier, M.-O., Bellahsen, N., Husson, L., Ribodetti, A., Razin, P., Robin, C., K. Al, Toubi, Géoazur (GEOAZUR 6526), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Géosciences Rennes (GR), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre Armoricain de Recherches en Environnement-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), and Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre Armoricain de Recherches en Environnement-Centre National de la Recherche Scientifique (CNRS)
Subjects: [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, ComputingMilieux_MISCELLANEOUS
Abstract: International audience
Published: 2009

131. Estimating in Situ Rock Properties by Multiparameter Full Waveform Inversion. A Case Study

Author: Michal Malinowski, Stéphane Operto, Alessandra Ribodetti, Géoazur (GEOAZUR 6526), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (... - 2019) (UNS), and Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Regional geology, Hydrogeology, 010504 meteorology & atmospheric sciences, Attenuation, Engineering geology, Mineralogy, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Inversion (meteorology), 010502 geochemistry & geophysics, 01 natural sciences, Economic geology, Petrology, Igneous petrology, Geology, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Environmental geology
Abstract: This study deals with the extension of the frequency-domain full-waveform inversion/modelling (FWI) from the acoustic to the viscoacoustic case in application to the wide-aperture seismic data recorded in the Polish Basin. Attenuation was accounted for by introduction of complex velocities. Two inversion strategies were tested: (i) coupled inversion in which Qp and Vp were simultanously inverted and (ii) decoupled inversion in which Vp model was taken from the acoustic inversion and remain fixed during the inversion for Qp. The latter approach produced preferred attenuation model. Together with some a priori information from well-log data and laboratory measurements we interpret recovered high attenuation anomalies in terms of fluid saturation and rock permeabilities.
Published: 2009

132. Finite-difference frequency-domain modeling of viscoacoustic wave propagation in 2D tilted transversely isotropic (TTI) media

Author: Jean Virieux, Alessandra Ribodetti, Stéphane Operto, John E. Anderson, Géoazur (GEOAZUR 6526), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (... - 2019) (UNS), Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Géophysique Interne et Tectonophysique (LGIT), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Laboratoire Central des Ponts et Chaussées (LCPC)-Institut des Sciences de la Terre (ISTerre), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut national des sciences de l'Univers (INSU - CNRS)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS)-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR), Exxon, Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Nice Sophia Antipolis (... - 2019) (UNS), Université Côte d'Azur (UCA)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Central des Ponts et Chaussées (LCPC)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), and Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Laboratoire Central des Ponts et Chaussées (LCPC)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 010504 meteorology & atmospheric sciences, Discretization, Wave propagation, Finite difference, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Geometry, 010502 geochemistry & geophysics, Wave equation, System of linear equations, 01 natural sciences, Geophysics, Geochemistry and Petrology, Transverse isotropy, Boundary value problem, Dispersion (water waves), 0105 earth and related environmental sciences, Mathematics
Abstract: A 2D finite-difference, frequency-domain method was developed for modeling viscoacoustic seismic waves in transversely isotropic media with a tilted symmetry axis. The medium is parameterized by the P-wave velocity on the symmetry axis, the density, the attenuation factor, Thomsen’s anisotropic parameters [Formula: see text] and [Formula: see text], and the tilt angle. The finite-difference discretization relies on a parsimonious mixed-grid approach that designs accurate yet spatially compact stencils. The system of linear equations resulting from discretizing the time-harmonic wave equation is solved with a parallel direct solver that computes monochromatic wavefields efficiently for many sources. Dispersion analysis shows that four grid points per P-wavelength provide sufficiently accurate solutions in homogeneous media. The absorbing boundary conditions are perfectly matched layers (PMLs). The kinematic and dynamic accuracy of the method wasassessed with several synthetic examples which illustrate the propagation of S-waves excited at the source or at seismic discontinuities when [Formula: see text]. In frequency-domain modeling with absorbing boundary conditions, the unstable S-wave mode is not excited when [Formula: see text], allowing stable simulations of the P-wave mode for such anisotropic media. Some S-wave instabilities are seen in the PMLs when the symmetry axis is tilted and [Formula: see text]. These instabilities are consistent with previous theoretical analyses of PMLs in anisotropic media; they are removed if the grid interval is matched to the P-wavelength that leads to dispersive S-waves. Comparisons between seismograms computed with the frequency-domain acoustic TTI method and a finite-difference, time-domain method for the vertical transversely isotropic elastic equation show good agreement for weak to moderate anisotropy. This suggests the method can be used as a forward problem for viscoacoustic anisotropic full-waveform inversion.
Published: 2009

133. Continental break-up history of conjugate poor magmatic margins from seismic reflection (oriental Gulf of Aden)

Author: Autin, J., Leroy, Sylvie, d'Acremont, Elia, Beslier, M.-O., Ribodetti, A., Bellahsen, N., Razin, Ph., Robin, C., Géoazur (GEOAZUR 6526), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (1965 - 2019) (UNS), and COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)
Subjects: [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, ComputingMilieux_MISCELLANEOUS
Abstract: International audience
Published: 2009

134. Geologia y geofisica marina y terrestre del Ecuador : desde la costa continental hasta las Islas Galápagos

Author: Marcaillou, B., Spence, G., Collot, J.-Y., Wang, K., Ribodetti, A., Collot, Jean-Yves (ed.), Sallares, V. (ed.), Pazmino, N. (ed.), Institute for Research on Earth Evolution [Yokosuka] (IFREE), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Géoazur (GEOAZUR 6526), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Collot J-Y, V. Sallares, and A. Pazmiño, Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (1965 - 2019) (UNS), and COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)
Subjects: SISMICITE, ANALYSE THERMIQUE, SUBDUCTION, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, MARGE CONTINENTALE, SEDIMENTATION EN MER PROFONDE, TECTONIQUE
Published: 2009

135. Joint inversion of multichannel seismic reflection and wide-angle seismic data: Improved imaging and refined velocity model of the crustal structure of the north Ecuador–south Colombia convergent margin

Author: William Agudelo, Jean-Yves Collot, Alessandra Ribodetti, Stéphane Operto, Géoazur (GEOAZUR 6526), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (... - 2019) (UNS), and Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Atmospheric Science, 010504 meteorology & atmospheric sciences, Inversion (geology), Soil Science, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Oceanic plateau, Aquatic Science, Fault (geology), 010502 geochemistry & geophysics, Oceanography, 01 natural sciences, Geochemistry and Petrology, Oceanic crust, Earth and Planetary Sciences (miscellaneous), 14. Life underwater, 0105 earth and related environmental sciences, Earth-Surface Processes, Water Science and Technology, geography, geography.geographical_feature_category, Ecology, Subduction, Paleontology, Forestry, Crust, Tectonics, Geophysics, Basement (geology), 13. Climate action, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Seismology, Geology
Abstract: International audience; Improving seismic imaging of the crust is essential for understanding the structural factors controlling subduction zones processes. We developed a processing work flow based on the combined analysis of multichannel seismic reflection (MCS) and wide angle (WA) reflection/refraction data to derive both shallow and deep velocities suitable for prestack depth migration and to construct a blocky velocity model integrating all identifiable seismic phases contained in MCS and WA data. We apply this strategy to the study of the north Ecuador–SW Colombia subduction margin to improve the imaging and geostructural interpretation of a splay fault and surrounding outer and inner margin wedges. Results show improvements over tomographic inversion of WA data only, such as (1) sediment velocity variation across the trench and margin slope that correlates with lateral lithologic changes, tectonic compaction and effect of mass wasting processes; (2) a two-layer velocity structure of the inner wedge basement that is consistent with the crust of an oceanic plateau; (3) a complex velocity structure of the outer wedge basement that consists of a deep, high-velocity (5.0–5.5 km s−1) core and a low-velocity zone (3.8–5.0 km s−1) associated with the major splay fault; (4) a ∼1.3-km-thick, low-velocity (3.5–4.0 km s−1) subduction channel that extends beneath the margin outer wedge. Both the splay fault and subduction channel are expected to direct fluid flows; and (5) downdip velocity increase (5–6 km s−1) in the subducting oceanic crust associated with a low (7.8 km s−1) upper mantle velocity, possibly reflecting changes in rock nature or properties.
Published: 2009

136. Origin of a crustal splay fault and its relation to the seismogenic zone and underplating at the erosional north Ecuador–south Colombia oceanic margin

Author: Boris Marcaillou, William Agudelo, Alessandra Ribodetti, Jean-Yves Collot, Géoazur (GEOAZUR 6526), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Institute for Research on Earth Evolution [Yokosuka] (IFREE), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (... - 2019) (UNS), and Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Atmospheric Science, 010504 meteorology & atmospheric sciences, Inversion (geology), Soil Science, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Aquatic Science, 010502 geochemistry & geophysics, Oceanography, 01 natural sciences, Geochemistry and Petrology, Earth and Planetary Sciences (miscellaneous), Petrology, 0105 earth and related environmental sciences, Earth-Surface Processes, Water Science and Technology, Terrane, Underplating, Décollement, Ecology, Subduction, Paleontology, Forestry, Tectonics, Geophysics, Basement (geology), Space and Planetary Science, Rift zone, Seismology, Geology
Abstract: International audience; Splay faults within accretionary complexes are commonly associated with the updip limit of the seismogenic zone. Prestack depth migration of a multichannel seismic line across the north Ecuador–south Colombia oceanic margin images a crustal splay fault that correlates with the seaward limit of the rupture zone of the 1958 (Mw 7.7) tsunamogenic subduction earthquake. The splay fault separates 5–6.6 km/s velocity, inner wedge basement rocks, which belong to the accreted Gorgona oceanic terrane, from 4 to 5 km/s velocity outer wedge rocks. The outer wedge is dominated by basal tectonic erosion. Despite a 3-km-thick trench fill, subduction of 2-km-high seamount prevented tectonic accretion and promotes basal tectonic erosion. The low-velocity and poorly reflective subduction channel that underlies the outer wedge is associated with the aseismic, décollement thrust. Subduction channel fluids are expected to migrate upward along splay faults and alter outer wedge rocks. Conversely, duplexes are interpreted to form from and above subducting sediment, at ∼14- to 15-km depths between the overlapping seismogenic part of the splay fault and the underlying aseismic décollement. Coeval basal erosion of the outer wedge and underplating beneath the apex of inner wedge control the margin mass budget, which comes out negative. Intraoceanic basement fossil listric normal faults and a rift zone inverted in a flower structure reflect the evolution of the Gorgona terrane from Cretaceous extension to likely Eocene oblique compression. The splay faults could have resulted from tectonic inversion of listric normal faults, thus showing how inherited structures may promote fluid flow across margin basement and control seismogenesis.
Published: 2008

137. Coeval subduction erosion and underplating associated with a crustal splay fault at the Ecuador-Colombia convergent margin

Author: Collot, J.-Y., Ribodetti, A., Marcaillou, B., Agudelo, W., Géoazur (GEOAZUR 6526), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Institute for Research on Earth Evolution [Yokosuka] (IFREE), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (... - 2019) (UNS), and Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)
Subjects: [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, ComputingMilieux_MISCELLANEOUS
Abstract: International audience
Published: 2008

138. Influence of trench sedimentation rate on heat flow and location of the thermally-defined seismogenic zone in the North Ecuador – South Colombia margin

Author: Marcaillou, B., Spence, G., Wang, K., Collot, J.-Y., Ribodetti, A., Institute for Research on Earth Evolution [Yokosuka] (IFREE), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Géoazur (GEOAZUR 6526), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (1965 - 2019) (UNS), and COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)
Subjects: [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, ComputingMilieux_MISCELLANEOUS
Abstract: International audience
Published: 2008

139. Accuracy of qP Wave Modeling in Anisotropic Acoustic Media by a Finite-difference Frequency-domain Method

Author: Stéphane Operto, A. Ribodetti, Jean Virieux, Géoazur, Publications, Géoazur (GEOAZUR 6526), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Géophysique Interne et Tectonophysique (LGIT), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Laboratoire Central des Ponts et Chaussées (LCPC)-Centre National de la Recherche Scientifique (CNRS), SEISCOPE, Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (... - 2019) (UNS), Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Laboratoire Central des Ponts et Chaussées (LCPC)-Institut des Sciences de la Terre (ISTerre), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut national des sciences de l'Univers (INSU - CNRS)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS)-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR), Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Central des Ponts et Chaussées (LCPC)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), and Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Wavelength, Hydrogeology, Amplitude, Finite-difference frequency-domain method, Isotropy, Mathematical analysis, [SDU.STU] Sciences of the Universe [physics]/Earth Sciences, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Wave equation, Anisotropy, Seismogram, Geomorphology, Geology
Abstract: International audience; We assess the kinematic and dynamic accuracies of a finite-difference frequency-domain method for qP wave modelling in transversally isotropic acoustic media with tilted symmetry axis. This method was developed as a tool for frequency-domain full-waveform inversion which requires accurate traveltime and amplitude modelling. The modelling method is based on the parsimonious mixed-grid method which requires 5 grid points per wavelength in homogeneous media to mitigate numerical dispersion. We compare seismograms computed with the acoustic frequency-domain method with that provided by the complete solution of the transversally isotropic elastic wave equation. As expected we observed strong traveltime and amplitude mismatches in the case of strongly anisotropic materials such as zinc crystals. For weak anisotropy, we obtain a reasonable agreement although slight delay of the acoustic wide-angle reflections was observed in the case of a two-layer medium. The footprint of these inaccuracies in full-waveform inversion will need to be assessed before considering application to real data.
Published: 2008

140. Thermal segmentation along the N. Ecuador-S. Colombia margin (1-4 degrees N): prominent influence of sedimentation rate in the trench

Author: George D. Spence, Jean-Yves Collot, Alessandra Ribodetti, Boris Marcaillou, Kelin Wang, Géoazur (GEOAZUR 7329), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud]), School of Earth and Ocean Sciences, University of Victoria, Victoria BC, Canada, Geological Survey of Canada [Sidney - Vancouver] (GSC Pacific), Geological Survey of Canada - Office (GSC), Natural Resources Canada (NRCan)-Natural Resources Canada (NRCan), Géoazur (GEOAZUR 6526), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud]), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (1965 - 2019) (UNS), and COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Heat-flow, 010504 meteorology & atmospheric sciences, Mantle wedge, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], Plate, Flow (psychology), [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Colombia, 010502 geochemistry & geophysics, Megathrust earthquake, 01 natural sciences, Middle america trench, Seismogenic zone, Great subduction earthquakes, Japan, Convergent margin, Geochemistry and Petrology, Oceanic crust, Earth and Planetary Sciences (miscellaneous), Southwest colombia, Petrology, 0105 earth and related environmental sciences, [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, Depth, Sediment, Sedimentation, Geophysics, Updip limit, Space and Planetary Science, Thermal modelling, Trench, Reflection (physics), Seismotectonic, Ecuador, Rupture zone, Seismology, Geology, Seismic reflection
Abstract: Along the deformation front of the North Ecuador-South Colombia (NESC) margin, both surface heat flow and trench sediment thickness show prominent along-strike variations, indicating significant spatial variations in sedimentation rate. Investigating these variations helps us address the important question of how trench sedimentation influences the temperature distribution along the interplate contact and the extent of the megathrust seismogenic zone. We examine this issue by analysing 1/ a new dense reflection data set, 21 pre-stack depth migration of selected multichannel seismic reflection lines, 3/ numerous newly-identified bottom-simulating reflectors and 4/ the first heat probe measurements in the region. We develop thermal models that include sediment deposition and compaction on the cooling oceanic plate as well as Viscous corner flow in the mantle wedge. We estimate that the temperature from 60-150 degrees C to 350-450 degrees C, commonly associated with the updip and downdip limits of the seismogenic zone, extends along the plate interface over a downclip distance of 160 to 190 20 km. We conclude that the updip limit of the seismogenic zone for the great megathrust earthquake of 1979 is associated with low-temperature (60-70 degrees C) processes. Our models also suggest that 60-70% of the two-fold decrease in measured heat flow from 3 degrees N to 2.8 degrees N is related to an abrupt Southward increase in sedimentation rate in the trench. Such a change may potentially induce a landward shift of the 60-150 degrees C isotherms, and thus the updip limit of the seismogenic zone, by 10 to 20 km.
Published: 2008

141. Mixed-grid finite-difference frequency-domain viscoacoustic modeling in 2D TTI anisotropic media

Author: Alessandra Ribodetti, Jean Virieux, Mehdi Grini, Stéphane Operto, Géoazur (GEOAZUR 6526), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), SEISCOPE, Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (... - 2019) (UNS), and Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 010504 meteorology & atmospheric sciences, Discretization, Wave propagation, Numerical analysis, Mathematical analysis, Coordinate system, Finite difference, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, 010502 geochemistry & geophysics, 01 natural sciences, Stencil, law.invention, law, Frequency domain, Cartesian coordinate system, 0105 earth and related environmental sciences, Mathematics
Abstract: International audience; We present a 2D finite-difference frequency-domain method for modeling viscoacoustic wave propagation in TTI media. The numerical method relies on a parsimonious staggered-grid method implemented in the frequency domain. Differential operators are discretized along different rotated coordinate systems (the classic Cartesian one and a 45° rotated one) with second-order accurate staggered-grid stencils. The resulting discrete operators are combined linearly to mitigate numerical anisotropy. An anti-lumped mass strategy is applied to mitigate numerical dispersion. A dispersion analysis for infinite homogeneous media suggests a discretization rule of 5 grid points per wavelength. Numerical tests confirm the accuracy of the stencil.
Published: 2007

142. Multiparameter Full-Waveform Inversion for Velocity and Attenuation – Refining the Imaging of a Sedimentary Basin

Author: S. Operto, A. Ribodetti, M. Malinowski, Géoazur (GEOAZUR 6526), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), SEISCOPE, Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (... - 2019) (UNS), and Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Regional geology, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Attenuation, Engineering geology, Inversion (geology), [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Sedimentary basin, 010502 geochemistry & geophysics, 01 natural sciences, Glaciology, Economic geology, Geomorphology, Palaeogeography, Seismology, Geology, 0105 earth and related environmental sciences
Abstract: International audience; P276 Multiparameter Full-Waveform Inversion for Velocity and Attenuation – Refining the Imaging of a Sedimentary Basin M. Malinowski* (Institute of Geophysics PAS) A. Ribodetti (Geosciences Azur CNRS UMR) & S. Operto (Geosciences Azur CNRS UMR) SUMMARY This study deals with the extension of the frequency-domain full-waveform inversion/modelling (FWI) from the acoustic to the viscoacoustic case in application to the wide-aperture seismic data recorded in the Polish Basin. Attenuation was accounted for by introduction of complex velocities. Multiparameter inversion involving P-wave velocity and Q factor produces more focused and clearer images than obtained by the acoustic FWI however only the absorption ...
Published: 2007

143. Viscoacoustic Frequency-Domain Full-Waveform Inversion – Application to Numerical VSP Data

Author: Jean Virieux, René-Édouard Plessix, A. Ribodetti, Stéphane Operto, Géoazur (GEOAZUR 6526), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (... - 2019) (UNS), Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Géophysique Interne et Tectonophysique (LGIT), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Laboratoire Central des Ponts et Chaussées (LCPC)-Institut des Sciences de la Terre (ISTerre), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut national des sciences de l'Univers (INSU - CNRS)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS)-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR), SEISCOPE, Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Laboratoire Central des Ponts et Chaussées (LCPC)-Centre National de la Recherche Scientifique (CNRS), Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Central des Ponts et Chaussées (LCPC)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), and Géoazur, Publications
Subjects: medicine.medical_specialty, 010504 meteorology & atmospheric sciences, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Inversion (meteorology), 010502 geochemistry & geophysics, 01 natural sciences, Metamorphic petrology, Telmatology, Frequency domain, medicine, [SDU.STU] Sciences of the Universe [physics]/Earth Sciences, Numerical tests, Geomorphology, Full waveform, Seismology, Geology, 0105 earth and related environmental sciences
Abstract: International audience; C029 Viscoacoustic Frequency-Domain Full-Waveform Inversion – Application to Numerical VSP Data A. Ribodetti* (Geosciences Azur) R.E. Plessix (Shell) S. Operto (Geosciences Azur - CNRS) & J.M. Virieux (Geosciences Azur) SUMMARY This work presents numerical tests to show that viscoacoustic frequency-domain full waveform tomographic inversion can be a useful tool for velocity and attenuation Q factor estimates from Vertical Seismic Profiles data. EAGE 69 th Conference & Exhibition — London UK 11 - 14 June 2007 EAGE 69 th Conference & Exhibition — London UK 11 - 14 June 2007 EAGE 69 th Conference & Exhibition — London UK 11 - ...
Published: 2007

144. Asymptotic theory for imaging the attenuation factors Q P and Q S

Author: Jean Virieux and Alessandra Ribodetti
Subjects: Amplitude, Frequency domain, Attenuation, Inverse scattering problem, Mathematical analysis, Perturbation (astronomy), Integral element, Inversion (meteorology), Born approximation, Mathematics
Abstract: Linearized inverse scattering problem in anelasticity is solved for perturbations in different parameters treating P-to-P, P-to-S,S-to-P and S-to-S data. Three steps are required for finding the material parameters of the medium, i.e. the density and the complex relaxation functions. In a given smooth reference medium, an high-frequency Green function is expressed as a function of traveltime, amplitude and attenuation factors. For a slightly different medium, the perturbation of the asymptotic Green function is expressed as a linear integral over the diffracting region containing the model perturbations using the first-order Born approximation. The inversion scheme is developed in the frequency domain where we were enable to set up an analytical kernel for the Born approximation of asymptotic anelastic solutions used for the forward problem and an approximate analytical kernel for the linearized inversion. Radiation patterns are analysed to show that the simultaneous multiparameter inversion is possible when one takes into account the parameters related to attenuation. The iterative asymptotic inversion might resolve the difference between the elastic parameters and the attenuation factors.
Published: 2007

145. Seismic imaging for topographic site effect modeling at the Low Noise Underground Laboratory (LSBB), Rustrel, France

Author: Maufroy, E., Ribodetti, A., Sénéchal, G., Zeyen, H., Dietrich, M., Operto, S., Stéphane GAFFET, Géoazur (GEOAZUR 6526), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Modélisation et Imagerie en Géosciences - Pau (MIGP), Institut national des sciences de l'Univers (INSU - CNRS)-TotalFinaElf-Université de Pau et des Pays de l'Adour (UPPA)-Centre National de la Recherche Scientifique (CNRS), Interactions et dynamique des environnements de surface (IDES), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Géophysique Interne et Tectonophysique (LGIT), Laboratoire Central des Ponts et Chaussées (LCPC)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Laboratoire Central des Ponts et Chaussées (LCPC)-Institut des Sciences de la Terre (ISTerre), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut national des sciences de l'Univers (INSU - CNRS)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS)-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR), Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Nice Sophia Antipolis (... - 2019) (UNS), Université Côte d'Azur (UCA)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université de Pau et des Pays de l'Adour (UPPA)-TotalFinaElf-Institut national des sciences de l'Univers (INSU - CNRS), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Modélisation et d'Imagerie en Géosciences de Pau (MIGP), and Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Laboratoire Central des Ponts et Chaussées (LCPC)-Centre National de la Recherche Scientifique (CNRS)
Subjects: [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, ComputingMilieux_MISCELLANEOUS
Abstract: International audience
Published: 2007

146. Finite-Difference Frequency-Domain Modeling of Acoustic Wave Propagation in 2D TTI Anisotropic Media

Author: A. Ribodetti, Stéphane Operto, Jean Virieux, M. Grini, Géoazur, Publications, Géoazur (GEOAZUR 6526), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (... - 2019) (UNS), Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Géophysique Interne et Tectonophysique (LGIT), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Laboratoire Central des Ponts et Chaussées (LCPC)-Institut des Sciences de la Terre (ISTerre), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut national des sciences de l'Univers (INSU - CNRS)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS)-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR), SEISCOPE, Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Laboratoire Central des Ponts et Chaussées (LCPC)-Centre National de la Recherche Scientifique (CNRS), Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Central des Ponts et Chaussées (LCPC)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), and Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Hydrogeology, 010504 meteorology & atmospheric sciences, Discretization, Numerical analysis, Acoustics, Finite difference, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, 010502 geochemistry & geophysics, 01 natural sciences, Stencil, Frequency domain, [SDU.STU] Sciences of the Universe [physics]/Earth Sciences, Acoustic wave equation, Anisotropy, Geomorphology, Computer Science::Distributed, Parallel, and Cluster Computing, Geology, 0105 earth and related environmental sciences
Abstract: International audience; P323 Finite-Difference Frequency-Domain Modeling of Acoustic Wave Propagation in 2D TTI Anisotropic Media M. Grini* (Géosciences Azur - CNRS) A. Ribodetti (Géosciences Azur - IRD) J. Virieux (Géosciences Azur - UNSA) & S. Operto (Geosciences Azur - CNRS) SUMMARY We present a 2D finite-difference frequency-domain method for modeling acoustic wave propagation in TTI media. The numerical method relies on a parsimonious staggered-grid method implemented in the frequency domain. Discretization of the differential operators is performed along 45° rotated directions. We applied this discretization strategy to the anisotropic acoustic wave equation for TTI media derived by Zhou (2006). The finite-difference stencil ...
Published: 2007

147. Structural control on the megathrust slip: the example of the Ecuador-Colombia active margin

Author: Collot, J.-Y., Marcaillou, B., Agudelo, W., Sage, F., Ribodetti, A., Géoazur (GEOAZUR 6526), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (... - 2019) (UNS), and Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)
Subjects: ComputingMilieux_MISCELLANEOUS
Abstract: International audience
Published: 2007

148. Subduction Erosion Processes along the Northwestern Margin of South America

Author: Collot, J.-Y., Sage, F., Calahorrano, A., Agudelo, W., Ribodetti, A., Géoazur (GEOAZUR 6526), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (... - 2019) (UNS), and Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)
Subjects: ComputingMilieux_MISCELLANEOUS
Abstract: International audience
Published: 2007

149. Gas hydrate bottom-simulating reflector analysis on the Colombia-Ecuador convergent margin from multichannel seismic reflection data by viscoacoustic asymptotic waveform inversion

Author: Ribodetti, A., Operto, S., Virieux, J., Collot, J.-Y., Géoazur (GEOAZUR 6526), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), SEISCOPE, Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (... - 2019) (UNS), and Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)
Subjects: [SDU.STU]Sciences of the Universe [physics]/Earth Sciences
Abstract: Many studies have been performed to analyse the presence of gas hydrate through the observation of bottom- simulating reflectors (BSR). Much of the available information has come from seismic reflection data calibrated by limited in situ (drilling, borehole) data. Numerous studies involving forward modeling and inversion of multichannel seismic reflection and OBS refraction data have been carried out to constrain seismic velocity enhancement due to hydrate above the BSR and the presence of low velocity associated with free gas in the sediment beneath it. However, few studies involving forward modeling and inversion of multichannel seismic reflection data have been carried out to constrain seismic velocity and attenuation Q factor along the gas hydrate bottom-simulating reflector (BSR) and to analyse presence of free gas in the sediment beneath it. In particular, the volume of gas stored in the gas hydrate reservoir is currently poorly known. To analyse the physical properties (velocity and attenuation Q factor) along the bottom-simulating reflector we present an application of the conventional preserved amplitude prestack depth migration/inversion (PSDM) coupled with a specific post-processing of the tomographic model. The specific post-processing sequence allows us to: (1) mitigate effects of limited source bandwith and source-receiver aperture range from the tomographic images; (2) obtain the absolute values of the seismic attributes; (3) obtain the correct geometry of seismic reflectors reaching the theoretical seismic resolution of the source wavelet. During the post- processing sequence the model space exploration is made automatically via a random search of velocity and Q models, and optimal models are determined using the very fast simulated annealing algorithm. We present an application to multichannel seismic reflection data to obtain 2-dimensional viscoacoustic quantitative imaging of the BSR on a seismic profile (SIST-40) cutting across the Colombia-Ecuador subduction zone. Preliminary results suggest that the BSR corresponds to a 30 meters-thick layer. The BSR presents a dominant reverse polarity. Along the BSR we can observe regions with velocity between 1650-1200 m/s and with Q factor between 500-300, indicating the presence of hydrates. Locally, we can observe velocities around 1000 m/s and Q less than 90, indicating the presence of gassy sediments.
Published: 2006

150. 2D fine-scale imaging of the subduction channel in Gulf of Guayaquil by integrated iterative PSDM and simulated annealing optimization

Author: William Agudelo, Alessandra Ribodetti, Jean-Yves Collot, Jean Virieux, Ste´phane Operto, Géoazur (GEOAZUR 6526), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), SEISCOPE, Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (1965 - 2019) (UNS), and COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Décollement, 010504 meteorology & atmospheric sciences, Subduction, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Inversion (meteorology), Prestack, 010502 geochemistry & geophysics, 01 natural sciences, Amplitude, Simulated annealing, Negative velocity, Seismology, Geology, 0105 earth and related environmental sciences, Fluid pressure
Abstract: International audience; To analyze the physical properties of seismic reflectors as possible indicators of the presence of fluids, we apply a processing sequence based on preserved amplitude prestack depth migration/inversion (PSDM) coupled with a post-processing of the depth migrated image. Aim of the post-processing is to remove the effects of the limited source bandwidth, that is, to build a structural velocity model and an impulsional migrated section from the limited-bandwidth migrated image and to estimate the uncertainties of velocities and layer thicknesses.We present here an application of this depth-domain processing sequence to a 2D multichannel seismic reflection dataset for the study of the décollement reflector in the Gulf of Guayaquil (Ecuadorian margin). Preliminary results show that the décollement mainly corresponds to a layer of 80–100 meters in thickness with a mean and maximum negative velocity contrasts of −50 m/s and −150m/s respectively on top of it. Along the décollement, these negative velocity contrasts result from the contrast in the physical properties between the subducted sediments and the overriding plate materials above the décollement. Very likely, this velocity decrease is also associated with changes in fluid pressure.
Published: 2006

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