An initial model for Eurasia has been developed using PAVA and NACT and a global dataset of surface waveforms (Figure 13.47). This dataset includes waveforms both from our existing database (Li and Romanowicz, 1996; Mégnin and Romanowicz, 2000; Gung et al., 2003; Panning and Romanowicz, 2004), as well as new data, and includes 38826 3-component waveforms from 476 events recorded at 169 stations. While this model is smooth, it will serve as a starting point for the models developed using increasingly accurate theoretical approaches.

The next step is to invert the surface wave dataset using the 3D implementation of Born scattering. Using this approach, we can calculate 3D sensitivity kernels with show significant sensitivity to off-path structure. We have performed verification tests that show that this approach can produce much more accurate seismograms for particular source-receiver paths (Figure 13.48).

Future work will include CSEM calculation of synthetics used in the inversion, which will include both 3D effects as well as the non-linear dependence of the waveforms to velocity structure.

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