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

Figure 2

Noise-free data test for the checkerboard model. (a) The true model. The white arrows and the solid yellow circles represent the positions of the shots and the receivers. (b) The initial model. (c-d) The normalized descent directions of the CG and the PCG in the first iteration. (e-f) The inversion results of CG and the PCG. The black dotted lines represent the boundary where the S-wave velocity changes in the true model.

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