Building starting models for full waveform inversion from wide‐aperture data by stereotomography

Prieux, V.; Lambaré, Gilles; Operto, S.; Virieux, Jean

doi:10.1111/j.1365-2478.2012.01099.x

Cited by 51 publications

(27 citation statements)

References 62 publications

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“…This issue has been addressed in many studies by selecting appropriate initial models and making suitable measurements to avoid getting stuck in a local minimum (e.g. Pratt & Shipp 1999;Brossier et al 2009;Prieux et al 2013;Yuan & Simons 2014;Yuan et al 2015). Alternatively, taking advantage of broad-band seismic signals in earthquake seismology, nonlinearities may be avoided by starting with smooth models and long-period signals, and gradually increasing the frequency content in successive iterations (e.g.…”

Section: Starting Modelmentioning

confidence: 99%

Global adjoint tomography: first-generation model

Bozdag¹,

et al. 2016

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We present the first-generation global tomographic model constructed based on adjoint tomography, an iterative full-waveform inversion technique. Synthetic seismograms were calculated using GPU-accelerated spectral-element simulations of global seismic wave propagation, accommodating effects due to 3-D anelastic crust & mantle structure, topography & bathymetry, the ocean load, ellipticity, rotation, and self-gravitation. Fréchet derivatives were calculated in 3-D anelastic models based on an adjoint-state method. The simulations were performed on the Cray XK7 named 'Titan', a computer with 18 688 GPU accelerators housed at Oak Ridge National Laboratory. The transversely isotropic global model is the result of 15 tomographic iterations, which systematically reduced differences between observed and simulated three-component seismograms. Our starting model combined 3-D mantle model S362ANI with 3-D crustal model Crust2.0. We simultaneously inverted for structure in the crust and mantle, thereby eliminating the need for widely used 'crustal corrections'. We used data from 253 earthquakes in the magnitude range 5.8 ≤ M w ≤ 7.0. We started inversions by combining ∼30 s body-wave data with ∼60 s surface-wave data. The shortest period of the surface waves was gradually decreased, and in the last three iterations we combined ∼17 s body waves with ∼45 s surface waves. We started using 180 min long seismograms after the 12th iteration and assimilated minor-and major-arc body and surface waves. The 15th iteration model features enhancements of well-known slabs, an enhanced image of the Samoa/Tahiti plume, as well as various other plumes and hotspots, such as Caroline, Galapagos, Yellowstone and Erebus. Furthermore, we see clear improvements in slab resolution along the Hellenic and Japan Arcs, as well as subduction along the East of Scotia Plate, which does not exist in the starting model. Point-spread function tests demonstrate that we are approaching the resolution of continentalscale studies in some areas, for example, underneath Yellowstone. This is a consequence of our multiscale smoothing strategy in which we define our smoothing operator as a function of the approximate Hessian kernel, thereby smoothing gradients less wherever we have good ray coverage, such as underneath North America.

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Section: Starting Modelmentioning

confidence: 99%

Global adjoint tomography: first-generation model

Bozdag¹,

et al. 2016

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“…Many methods have been proposed to mitigate the dependency of FWI on the initial velocity model. One of these approaches is finding a better initial velocity model using methods such as traveltime tomography (Prieux et al, ; Taillandier et al, ) and wave equation migration velocity analysis that decomposes the velocity model into a smooth background model and a high wavenumber reflectivity model (Almomin & Biondi, ; de Hoop et al, ; Shen & Symes, ; Symes, ). Traveltime tomography requires that the velocity does not change drastically, while the migration velocity analysis requires a proper migration velocity model that relies on an initial model as well.…”

Section: Introductionmentioning

confidence: 99%

Multiscale Direct Envelope Inversion: Algorithm and Methodology for Application to the Salt Structure Inversion

Chen

2019

Earth and Space Science

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For the full‐waveform inversion, obtaining a globally optimal solution is difficult when the seismic data do not contain sufficient low‐frequency information and the inversion object is a salt structure with a large‐scale salt dome. The large salt dome presents difficulty for the inversion of the salt structure; however, it also confers a convenience that can be utilized: A large salt dome makes the events in the seismic record sparse and isolated. We use the envelope to obtain the arrival time of the events in the seismic data and apply multiscale strategies to extract the low‐frequency information of the seismic data that relates to the long‐wavelength components of the subsurface. In calculating the gradient, the envelope Fréchet derivative is used to take advantage of the multiscale envelope for the characteristics of the salt structure. Therefore, the multiscale direct envelope inversion using the window‐averaged envelope and the direct envelope Fréchet derivative is proposed. To further improve the computational efficiency and inversion quality of the multiscale direct envelope inversion, several auxiliary strategies are proposed: A joint misfit function is designed to make the inversion method more adaptable, and an offset weighting factor is introduced to implement the multioffset inversion method to improve the inversion quality of subsalt. We analyze the antinoise performance of the multiscale direct envelope inversion. The SEG/EAGE salt model is used to test the application effect of the multiscale direct envelope inversion. The antinoise ability and insensitivity to low‐frequency data of the method are verified in the numerical experiments.

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“…The undershooting technique is also used when short-offset sources or receivers cannot be lain down due to the presence of drilling platforms in exploration seismology or other obstacles in shallowseismic surveys (Howdeshell, 1986;Duncan et al, 1989;Stucchi and Mazzotti, 2009). Beside these applications, wide-angle reflections are used in AVO analysis to improve the accuracy of parameters' estimation (Drufuca and Mazzotti, 1995;Roberts, 2000;Downton and Ursenbach, 2006), and for creating starting models for full-waveform inversion (Prieux et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Nonstretch normal moveout through iterative partial correction and deconvolution

2014

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Source to receiver distances used in seismic data acquisition have been steadily increasing and it is now common to work with data acquired with more than 10 km of offset. Subbasalt exploration and seismic undershooting are just two applications in which long-offset reflections are sought. However, such reflections are often subjected to muting to suppress normal moveout (NMO) stretch artifacts, thus causing a loss of valuable information. To retrieve these portions of the recorded wavefield, we developed a nonstretch NMO correction based on wavelet estimation and on an iterative procedure of partial NMO correction and deconvolution. We evaluated this methodology using fourth-order traveltime curve approximations to increase the offset of usable reflections, but it can be adapted to traveltime curves of any order. Time- and space-variant wavelets, estimated by means of singular value decomposition along the sought traveltimes, were used to build the desired output for the deconvolution that aims at retrieving the original shape of the partially stretched wavelets. We tested our method on a synthetic gather presenting time and offset varying wavelets, on a real-marine line simulating an undershooting pattern and on true undershooting land-marine data. These examples demonstrated that our new algorithm effectively limits the stretching associated with the NMO correction and enables the recovery of those portions of the stacked sections that are typically lost from muting in the standard NMO correction

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Building starting models for full waveform inversion from wide‐aperture data by stereotomography

Cited by 51 publications

References 62 publications

Global adjoint tomography: first-generation model

Global adjoint tomography: first-generation model

Multiscale Direct Envelope Inversion: Algorithm and Methodology for Application to the Salt Structure Inversion

Nonstretch normal moveout through iterative partial correction and deconvolution

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