Numerical second horizontal derivative self‐potential (SP) anomalies obtained from SP data using filters of successive window lengths (graticule spacings) can be used to determine the shape and depth of a buried structure. For a fixed window length, the depth is determined using a simple formula for each shape factor. The computed depths are plotted against the shape factors on a graph. All points for a fixed window length are connected by a continuous curve (window curve). The solution for the shape and depth of the buried structure is read at the common intersection of the window curves. The method is applied to theoretical data with and without random noise and tested on a field example from Turkey.

We have developed a least-squares minimization approach to determine the shape (shape-factor) of a buried polarized body from a residual self-potential anomaly profile. By defining the zero anomaly distance and the anomaly value at the origin on the profile, the problem of the shape-factor determination is transformed into the problem of finding a solution of a nonlinear equation of the form f(q)= 0. Procedures are also formulated to estimate the depth of polarization angle, and the electric dipole moment. The method is applied to synthetic data with and without random noise. The obtained shape-factor agrees very well with the model shape-factor when using synthetic data. After adding 92 percent random error in the synthetic data, the shape factor obtained is within 94 percent. Finally the validity of the method is tested on a field example from the Ergani copper district, Turkey.

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We have developed a simple method to simultaneously determine the shape (shape factor) and the depth of a buried structure from magnetic data. The method is similar to Euler deconvolution, but it solves for shape and depth independently. The method involves using a relationship between the shape factor, the depth to the source, and a combination of observations at symmetric points with respect to the coordinate of the source center with a free parameter (graticule spacing). The relationship represents a parametric family of curves. For a fixed free parameter, the depth is determined for each shape factor. The computed depths are plotted against the shape factors representing a continuous monotonically increasing curve. The solution for the shape and depth of the buried structure is read at the common intersection of the parametric curves. The parametric curves method is applied to two theoretical magnetic anomaly profiles due to a thin dike and a horizontal cylinder. The method is also tested on a field example from Brazil. In all cases, the shape and depth solutions obtained are in good agreement with the actual ones.

ABSTRACT. The Helma-Madrakah area lies in the northern part of the Makkah quadrangle located in the southern part of the Hijaz region, western Saudi Arabia. The area is bounded by longitudes 39º30′N and 39º54′E and latitudes 21º45′N and 22º00′N; i.e., north of Makkah AlMukarramah and north-east of Jeddah.The present study deals with the interpretation of aeromagnetic data, which conducted by Aero-Service Corporation in the period 1965-1966 to depict subsurface regional and residual subsurface structural features. The Filon Fourier spectral analysis technique is used to determine average depths to the causative bodies (6.0, 1.2 and 0.7 km) of regional and residual anomalies. Special windows are designed and used to calculate the regional and residual components at each point along several profiles. Accordingly, the regional and residual magnetic maps of the area under study were produced.The regional magnetic contour map indicates the rocks in the eastern part of the area to be more acidic than these in the western part.The residual magnetic contour maps, on the other hand, show a number of higher frequency dipole magnetic anomalies. This reveals that the near surface rocks contain a certain amount of magnetic minerals. Therefore, the locations of these anomalies are considered very important for mineral exploration.