Field testing of the developed 3D FWI method using a mobile shaker at Newberry, FL

We have successfully developed an advanced 3D FWI method using surface-based seismic wavefields for geotechnical site characterization. The method is based on the solution of 3D elastic wave equations, and Gauss-Newton inversion approach. The capabilities of the developed 3D FWI method has been tested on both synthetic and several field experimental datasets. The analyzed results from synthetic datasets show great capabilities of the 3D FWI method in characterizing laterally variable low- and high-velocity layers, and in detecting buried voids at various depths. Comparing the conventional FWI analyses based on the classic cross-adjoint inversion, our method based on the Gauss-Newton inversion provides more accurate and higher resolution inverted results. Accurate results are also obtained from field experiments at four different test sites in Florida. Known cavity (culvert), unknown buried voids (pre-collapsed sinkholes) at both shallow depths of 5 m to 10 m and larger depths up to 40 m, and variable soil/rock layers are well characterized and confirmed by the ground truth.