The application of evolution program to Rayleigh wave inversion

摘要

A goal of geophysical inversion is to find all earth models which, when operated upon by some forward method, produce synthetic data that gives an acceptable agreement with observed data. Unfortunately, most inverse problems in geophysics are non-linear and poorly constrained. Conventional procedures of Rayleigh wave inversion have many shortcomings such as only roughly defining the initial model with poor inversion reliability, strong inversion subjectivity and unsatisfactory inversion results. Hunaidi (1998) proposed the method of genetic algorithm based on evolution law. His method has not overcome the restriction of inversion layer number, but provides us an idea on how to solve the problem: finding genetic algorithm adapting to the Rayleigh waves inversion. In this paper, the application of optimized genetic algorithm-evolution program, to fundamental Rayleigh waves inversion is introduced. The new method of uniform thickness layered inversion of dispersion function and optimized objective function and population of genetic algorithm is proposed. The results of theoretical models and field data show that, in contrast to traditional linear inversion methods and genetic algorithm, evolution program to Rayleigh waves inversion effectively overcomes the limitation of inversion parameter number and improves the stability of the solutions.