Simultaneous Source Elastic Inversion of Surface Waves

We show 2D and 3D field data examples of applying simultaneous-source elastic inversion to recover near-surface shear-wave velocity information from surface waves. The starting model is obtained from 3D dispersion analysis of surface waves. First, this starting model is used to perform conventional sequential-source iterative 2D elastic inversion of surface waves for shear-wave velocity updates. Data simulated using the updated model exhibit a close waveform match to field data. In addition, when the updated shear-wave model is used to remove phase dispersion on field shot records, the gathers are flattened more effectively. Next, we repeat the 2D inversion using the simultaneous source method and achieve equivalent results at a lower cost. Finally, we perform 3D simultaneous-source inversion of approximately 700 shot records over the same area and demonstrate that it is equally successful.