摘要
3D surface conductivity can cause the distortion of regional magnetotelluric response.Traditional researches for such distortion are based on the assumption that geological structures near earth surface are 3D,and regional structures are 1D or 2D.For more general 3D/3D formation,this paper realized 3D integral equation numerical modeling of magnetotelluric phase tensor and studied the phase tensor responses in the context of different geological models,in order to analyze and remove the distortion,and reflect true 3D subsurface regional formation.The results indicate that,phase tensor not only can reflect common 3D structures,but also can reflect 3D structures covered by complicated 3D surface conductivity distribution without supposing that regional formations are 1D or 2D.For accelerating forward modeling,meanwhile keeping some precision,the forward modeling makes use of integral equation multi-grid method.