Abstract:

Due to the limited calculation space in the magnetotelluric numerical simulation with finite element method(FEM), mesh boundary is generrally truncated. The existence of truncated boundary may make boundary conditions unsatified and thus affect calculated results and precision to some degree. We calculated the responce of one-dimensional and two-dimensional geoelectric models with two-dimension FEM forward program in which the boundaries of researching area are taken as one-dimensional situation with different truncated boundary. There is no effects on calculated results when simulating one-dimension models, because boundary conditions is satisfied naturelly. But to two-dimensional models, the truncated boundary may make boundary conditions unsatisfied and affect the results and precision. With skin depth as measurement of mesh boundary,we calculated and compared the results of some models with different mesh boundary, and at last got the referenced truncated boundary in MT FEM simulation.

Key words: magnetotellurics（MT）, finite element method（FEM）, forward, boundary conditions, truncated boundary