Abstract: Thls paper presents a new conjugate gradient type algorithm to solve the damped, weighted least-squares problem for seismic tonlography. Combining the natural weight and a priori constralnt, the numerical tests with Gaussian noisy data are performed. The results show that the method is superior to the conventional least squares method. Finally, the method has been applied to Tongzhilin (Sichuan, China) Hydro-electric Power cross-well data, and the reconstructed velocity image agrees well with the geological conclusion.

Key words: Damped and weighted leastsquares solution, Seismic tomography, Conjugate gradient