Seismic traveltime tomography:: a simulated annealing approach

Seismic traveltime tomography involves finding a velocity model that minimizes the error energy between the measured and the theoretical traveltimes. When solving this nonlinear inverse problem, a local optimization technique can easily produce a solution for which the gradient of the error energy function vanishes, but the energy function itself does not take its global minimum. Other methods such as simulated annealing can be applied to such global optimization problems. The simulated annealing approach to seismic traveltime tomography described in this paper has been tested on synthetic as well as real seismic data. It is shown that unlike local methods, the convergence of the simulated annealing algorithm is independent of the initial model: even in cases of virtually no prior information, it is capable of producing reliable results. The method can provide a number of acceptable solutions. When prior information is sparse, the solution of the global optimization can be used as an input to a local optimization procedure, such as, e.g., simultaneous iterative reconstruction technique (SIRT), producing an even more accurate result. (C) 2000 Elsevier Science B.V. All rights reserved.