Two methods for computer interpretation of magnetic anomalies of dikes

Abstract

Abstract Two computer-oriented methods are presented in this paper for interpreting the magnetic anomalies of a dipping dike. In the first method, horizontal derivatives of the observed magnetic anomalies are calculated which define a single linear equation of the type X 4 G + C 1 X 3 G + C 2 X 2 G + C 3 XG + C 4 G + C 5 X 2 + C 6 X + C 7 = 0, where G is the horizontal gradient of the anomaly, and X is the distance of the gradient measured from any convenient point in the profile. Seven normal equations are derived and the coefficients C 1 to C 7 are solved from which the various parameters (Fignre 1) of the body are obtained asEquationandEquationIn the second method, the method of iteration, the magnitudes and positions of the maximum and minimum anomaly points are located in the profile, and the approximate parameters of the dike are computed from these shape characteristics. The resulting anomalies are then calculated and compared with the observed data. The errors at each point of observation are solved for the changes to be given to the initial values. The process is repeated until the sum of the squares of the errors is less than a specified allowable error.Important features of the methods developed here are that all the observed data are utilized in the course of interpretation, and no input to the computer is required except the anomalies and their distances measured from a convenient point of observation in the profile.