Preconditioned Conjugate Gradient Algorithm-Based 2D Waveform Inversion for Shallow-Surface Site Characterization

Figure 3

Normalized seismograms and evaluation curves for the checkerboard model test. (a) The normalized seismograms of shot 11 from the true model. “L” and “S” indicate the first break Love wave and scattered wave events, respectively. (b) Comparison between the observed (red) and forward (blue) waveforms of shot 1 for the true and initial model. (c-d) The S-wave velocity vertical profiles of the true model, initial model, and inversion results of the PCG and CG at distance = 5 m and distance = 25 m, respectively. (e) Normalized misfits of PCG and CG versus iteration number. (f) The RMSE for the inversion results and the true value of the PCG and CG versus the iteration number. (g) Comparison between the observed (red) and forward (blue) waveforms of shot 1 of the CG inversion results. (h) Comparison between the observed (red) and forward (blue) waveforms of shot 1 of the PCG inversion results.

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