Maximum Depth Rules for Total Magnetic Field Anomalies at Low Latitude

Monday A. Isogun, Adekunle A. Adepelumi

Abstract: The maximum depth rules have benn derived for total magnetic field anomalies at low latitude using homogeneous sphere as model. Three different rules were derived for both N-S and E-W profiles over the centre point of magnetic sphere. For the E-W traverse, the rules are: Inflexion Point Rule (IPR); Half-Width Rule (HWR); and Amplitude-Slope Rule (ASR) and for N-S traverse, the rules are: IPR, ASR and Amplitude-Distance Rule (ADR). The reliability of these rules was tested using a set of synthetic total magnetic field data generated over 10 linear spherical magnetic source bodies of 3 ? 10 m depth range. The rules give very close values to the true depth of the magnetic source bodies with maximum variation of ?1 m. On E-W profile, the correlation coefficients between computed and the real depths are 0.95, 0.96 and 0.97 respectively for IPR, HWR and ASR. Also, on N-S profile, the correlation coeffecient between computed and the real depths are 0.96, 0.97 and 0.96 respectively for IPR, ADR and ASR. The maximum depth rules are adjudged reliable on the basis of their results.

Keywords: maximum depth, inflexion point, half-width, amplitude, slope, sphere, magnetic anomaly