NONLINEAR INVERSION OF THE SH WAVE-EQUATION IN A HALF-SPACE FOR DENSITY AND SHEAR MODULUS DETERMINATION

This paper deals with the problem of multi-parameter nonlinear inversi on of the SH wave equation in an elastic half-space. A numerical appro ach combining Born iteration and a regulatizing technique is presented for simultaneously reconstructing 2-D distributions of density and sh ear modulus in a scatterer embedded in a half-space. The well-to-well source-receiver scheme commonly used in geophysical exploration is con sidered in the model in which two incident frequencies are used to unc ouple the parameters in frequency domain. The weighted residual method , along with bilinear interpolating functions, are used in the discret ization procedure. Computer simulations have been conducted on several examples with different density and shear modulus configurations. The numerical results show that-the approach proposed has a uniformly con vergence for the given objects and has a feature of treating the limit ed-source well-to-well scheme that causes a more ill-conditioned equat ion in the inversion procedure, (C) 1998 Acoustical Society of America . [S0001-4966(98)05102-9].