A least-squares approach to depth determination from self-potential anomalies caused by horizontal cylinders and spheres

We have developed a least-squares approach to depth determination from self-potential anomalies caused by horizontal cylinders and spheres. By defining the zero-anomaly distance and the anomaly value at the origin on the profile, the problem of depth determination from self-potential data has been transformed into finding a solution to a nonlinear equation. Procedures are also formulated to estimate the electric dipole moment and the polarization angle. The error in the depth parameter estimation introduced by data errors was also studied through imposing 1 to 10% errors in the zero-anomaly distance and the anomaly value at the origin in one synthetic profile caused by a sphere. When the zero-anomaly distance and the anomaly value at the origin possess errors of equal magnitude and of the same signs, the results will not differ much from the true values. When errors have opposite signs, the maximum error in depth is 10%. Finally, the validity of the method is tested on a field example from Ergani Copper district, Turkey.