FREQUENCY DOMAIN ELASTIC WAVEFORM INVERSION USING THE GAUSS-NEWTON METHOD

Chung, W., Shin, J., Bae, H.S., Yang, D. and Shin, CS., 2012. Frequency domain elastic waveform inversion using the Gauss-Newton method. Journal of Seismic Exploration, 21: 29-48. In spite of several advantages of using the Gauss-Newton method for waveform inversion, calculating a Hessian-matrix is problematic in the current computing environment. Consequently, many researchers have suggested a Conjugate Gradient Least Square (CGLS) algorithm to circumvent the Hessian matrix problem in the Gauss-Newton method. There has been no attempt, however, at using the CGLS method to perform elastic media waveform inversion. It is necessary to consider the characteristics of elastic media because the acoustic wave equation does not accurately simulate waveforms propagated through elastic media. Our objective is to develop a frequency domain waveform inversion algorithm using the CGLS method for elastic media. Numerical experiments with the Marmousi-2 model and the SEG/EAGE salt model verify enhancement of the inversion results. We confirm that a greatly improved waveform inversion can be carried out over a complicated layer structure with the Marmousi-2 model. We also verify that structures containing a high velocity salt can be reproduced correctly through an inversion experiment using the SEG/EAGE salt model. However, the improved inversion result of the SEG/EAGE salt model is limited to use with the long wavelength initial velocity, necessitating a method for obtaining the long wavelength velocity model.