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Sirgue, Laurent, 2003. Inversion de la forme d'onde dans le ...

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LIST OF FIGURES<br />

xvii<br />

4.22 Standard waveform inversion at 7 Hz in the 1-D Marmousi mo<strong>de</strong>l. . . . . . . . 126<br />

4.23 1-D waveform inversion at 7 Hz with preconditioning of the data residuals and<br />

gradient vector. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127<br />

4.24 2D exten<strong>de</strong>d Marmousi mo<strong>de</strong>l. . . . . . . . . . . . . . . . . . . . . . . . . . . 128<br />

4.25 Standard waveform inversion at 7 Hz. . . . . . . . . . . . . . . . . . . . . . . 129<br />

4.26 Preconditioned <strong>Inversion</strong> at 7 Hz starting from the exten<strong>de</strong>d “FAST” mo<strong>de</strong>l. . . 130<br />

4.27 Velocity profi<strong>le</strong>s at 3 locations in the mo<strong>de</strong>l. . . . . . . . . . . . . . . . . . . . 131<br />

4.28 Shot gathers at 3 locations in the true mo<strong>de</strong>l. . . . . . . . . . . . . . . . . . . . 132<br />

4.29 <strong>Inversion</strong> at 7 Hz starting from an improved macro mo<strong>de</strong>l. . . . . . . . . . . . 133<br />

5.1 Converted waves in sub-basalt imaging. . . . . . . . . . . . . . . . . . . . . . 137<br />

5.2 The sub-basalt synthetic data. . . . . . . . . . . . . . . . . . . . . . . . . . . . 140<br />

5.3 <strong>Inversion</strong> starting from an accurate macro-mo<strong>de</strong>l. . . . . . . . . . . . . . . . . 142<br />

5.4 Evolution of the misfit function as the entire mo<strong>de</strong>l is <strong>de</strong>creasingly smoothed. . 143<br />

5.5 Evolution of the misfit function as the sediment and top basalt interface are<br />

<strong>de</strong>creasingly smoothed. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144<br />

5.6 Illustration of the i<strong>de</strong>alised <strong>la</strong>yer stripping strategy . . . . . . . . . . . . . . . . 145<br />

5.7 Evolution of the misfit function as the sediment <strong>la</strong>yer is <strong>de</strong>creasingly smoothed. 146<br />

5.8 Evolution of the misfit function as the basalt <strong>la</strong>yer is <strong>de</strong>creasingly smoothed. . 147<br />

5.9 Evolution of the misfit function as the sub-basalt <strong>la</strong>yer is <strong>de</strong>creasingly smoothed. 147<br />

5.10 A<strong>de</strong>quate velocity mo<strong>de</strong>ls. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148<br />

5.11 Waveform inversion at 7 Hz when for a wrong and a<strong>de</strong>quate starting mo<strong>de</strong>ls. . . 150<br />

5.12 Wavefield in the sediments in time in the true mo<strong>de</strong>l and inversion results with<br />

the bad starting mo<strong>de</strong>l. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152

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