Forward Method for Gravity, Gravity Gradient and Magnetic Anomalies of Complex Body

Based on the improved analytical expression for computing the gravity anomalies due to a homogeneous polyhedral body composed of polygonal facets, and by applying the forward theory with the coordinate transformation of vector and tensor, we deduced the analytical expressions for both gravity gradient tensor and magnetic anomalies due to a polygon, and obtained new analytical expressions for computing vertical gradient of gravity anomalies and vertical component of magnetic anomalies due to a polyhedral body. And we also explicitly developed the complete and unified expressions for calculating gravity anomalies, gravity gradient and magnetic anomalies due to the homogeneous polyhedra. Furthermore, we deduced new analytical expressions for computing the vertical gradient of gravity anomalies due to a finite rectangular prism by applying the new obtained expressions for gravity gradient tensor due to a polyhedral target body. Comparison with forward calculation of models testified the correctness of these new expressions. It will reduce forward time of gravimagnetic anomaly and improve computational efficiency by applying our unified expressions for joint forward of gravimagnetic anomalies due to homogeneous polyhedral bodies.