3D Nonlinear First-arrival Traveltime Tomography and its Application

As one of the geophysical inversion problems, first-arrival traveltime tomography is actually a nonlinear inversion problem. In this paper, multiple linear iterations are used to simulate the process of nonlinear inversion and the simultaneous iterative reconstruction technique (SIRT) is used in each iteration to directly solve the basic equations of tomographic inversion. Compared with the conventional linear tomography, this algorithm has the characteristics of stable inversion, good convergence, high precision of model inversion, small amount of calculation and high adaptability for large data and large model. The theoretical model has verified the validity of the algorithm and the applications of real data have also shown good results.