A RAPID METHOD OF DEPTH DETERMINATION FROM SELF–POTENTIAL ANOMALIES

The self- potential (SP) anomaly expression produced by most geologic structures can be represented by a continuous function in depth and angle of polarisation with an amplitude coefficient known as the electrical dipole moment. In the present paper, we have developed a rapid and simple method to determine the depth of a buried structure from residual self-potential anomalies. The problem of depth determination has been transformed into the problem of finding the zero anomaly distance (x0) and the nearest minimum anomaly distance (xm) from the origin on the anomaly profile. Formulae have been derived for vertical and horizontal cylinders and spheres. Procedures are also formulated to estimate the polarisation angle and the electrical dipole moment. Errors in model parameters due to errors in the characteristic points and distances were studied through imposing ± 1% to ± 10% errors on these parameters on one synthetic profile due to a horizontal cylinder. The method can be automated if desired. Finally, the validity of the method is tested on a field example from Turkey