Genetic algorithm-finite element inversion of stress field of Brazil

Based on the data of stresses orientation observed in Brazil, genetic algor ithms-finite element method (GA-FEM) is applied to inverse the plate bounda ry displacement and nodal forces within the plate. The inversion confirms t hat plate boundary actions are main factors controlling the regional stress field, and spreading forces of mountains and seashores are another importa nt factor. The inversion further shows that vertical loading on plate can p roduce significant affects on horizontal stresses. in addition to the well- known East-west compression, it is found that a north south compression als o exists in western Brazil, in agreement with recent GPS observations. The results show that GA-FEM is an effective way to solve inverse problems of p artial differential equations.