We investigated how density and quality of mesh around interest domain affect electromagnetic （EM） responses of 3D Earth layered media using finite element method （FEM）. Effect of different mesh shapes was also investigated using a method of mixing structured and unstructured mesh. As a case study, we estimated the effects of meshing on selectivity phenomenon of seismic electric signal （SES）. Our results suggest that the relative errors resulting from mesh effects may not be negligible, which may lead to some unconvincing explanation of the SES selectivity based on the numerical modeling results.
Chen＇s technique of computing synthetic seismograms, which decomposes every vector with a set of basis of orthogonality and completeness before applying the Luco-Apsel-Chen （LAC） generalized reflection and transmission coefficients method, is confirmed to be efficient in dealing with elastic waves in multi-layered media and accurate in any frequency range. In this article, we extend Chen＇s technique to the computation of coupled seismic and electromagnetic （EM） waves in layered porous media. Expanding the involved mechanical and electromagnetic fields by a set of scalar and vector wave-function basis, we obtain the fundamental equations which are subsequently solved by using a recently developed version of the LAC generalized reflection and transmission coefficients method. Our approach and corresponding program is validated by reciprocity tests. We also show a numerical example of a two-layer model with an explosion source. The P-to-EM conversion waves radiated from the interface may have potential application.
