A rapid graphical method for the interpretation of the self‐potential anomaly over a two‐dimensional inclined sheet of finite depth extent

Geophysics ◽  
1988 ◽  
Vol 53 (8) ◽  
pp. 1126-1128 ◽  
Author(s):  
H. V. Ram Babu ◽  
D. Atchuta Rao
Keyword(s):  
Graphical Method ◽  
Amplitude Ratio ◽  
Finite Depth ◽  
Ore Deposits ◽  
Characteristic Features ◽  
Zero Potential ◽  
Depth Extent ◽  
Self Potential ◽  
Sp Anomaly ◽  
Inclined Sheet

The inclined sheet is an important model for interpreting self‐potential (SP) anomalies over elongated ore deposits. Many techniques (Roy and Chowdhurry, 1959; Meiser, 1962; Paul, 1965; Atchuta Rao et al., 1982; Atchuta Rao and Ram Babu, 1983; Murty and Haricharan, 1985) have been proposed for interpreting SP anomalies over this model. We propose a simple graphical procedure for locating the upper and lower edges of an inclined sheet of infinite strike extent from its SP anomaly V(x) using a few characteristics points including [Formula: see text] [Formula: see text], and [Formula: see text] The amplitude ratio [Formula: see text], is shown to vary with θ, the dip of the sheet, making it possible to estimate θ. The two edges of the sheet are equidistant from the abscissa of [Formula: see text] the zero potential point. The sheet, when extrapolated onto the line of observation, meets the x‐axis at a point where [Formula: see text] From these characteristic features of V(x), the sheet can be located easily using the simple geometrical construction presented below.

On: “A rapid graphical method for the interpretation of the self‐potential anomaly over a two‐dimensional inclined sheet of finite depth extent” by H. V. Ram Babu and D. Atchuta Rao (GEOPHYSICS, 53, 1126–1128, August 1988).

Geophysics ◽  
1989 ◽  
Vol 54 (9) ◽  
pp. 1215-1216 ◽  
Author(s):  
L. Eskola ◽  
H. Hongisto
Keyword(s):  
Graphical Method ◽  
Theoretical Models ◽  
Finite Depth ◽  
The Self ◽  
Inversion Method ◽  
Two Dimensional ◽  
Depth Extent ◽  
Self Potential ◽  
Graphical Algorithm ◽  
Inclined Sheet

Ram Babu and Atchuta Rao (1988a, b) presented a graphical algorithm for the interpretation of a self‐potential anomaly over a sheet. Ram Babu and Atchuta Rao (1988b) also presented an inversion method based on iterative optimization for the self‐potential anomalies caused by spherical, cylindrical, and sheetlike bodies. The theoretical models on which the algorithms are based are very simple: for the sphere, an electrostatic dipole; for the cylinder, a line dipole; and for the sheet two line poles, the negative one along the upper edge of the sheet and the positive one along its lower edge.

Quantitative interpretation of self‐potential anomalies due to two‐dimensional sheet‐like bodies

Geophysics ◽  
1983 ◽  
Vol 48 (12) ◽  
pp. 1659-1664 ◽  
Author(s):  
D. Atchuta Rao ◽  
H. V. Ram Babu
Keyword(s):  
Finite Depth ◽  
Horizontal Gradient ◽  
Quantitative Interpretation ◽  
Two Dimensional ◽  
Analytical Relations ◽  
Depth Extent ◽  
Self Potential ◽  
Maximum Minimum ◽  
Inclined Sheet

A method for quantitative interpretation of self‐potential anomalies due to a two‐dimensional sheet of finite depth extent is proposed. In the case of an inclined sheet, positions and amplitudes of the maximum, minimum, and zero‐anomaly points are picked and then the origin is located on the horizontal gradient curve using the template of Rao et al (1965). The parameters of the sheet may be evaluated either geometrically or by using some analytical relations among the characteristic distances. When the sheet is vertical, the parameters may be evaluated using the positions of half and three‐quarter peak amplitudes.

An analytical method to interpret self‐potential anomalies caused by 2-D inclined sheets

Geophysics ◽  
1998 ◽  
Vol 63 (5) ◽  
pp. 1551-1555 ◽  
Author(s):  
N. Sundararajan ◽  
P. Srinivasa Rao ◽  
V. Sunitha
Keyword(s):  
Surrounding Medium ◽  
Mathematical Expression ◽  
Constant Term ◽  
Hilbert Transforms ◽  
The Hilbert Transform ◽  
Point Of Intersection ◽  
Self Potential ◽  
Derivatives Of ◽  
Sp Anomaly ◽  
Inclined Sheet

The first‐order horizontal and vertical derivatives of the self‐potential (SP) anomalies caused by a 2-D inclined sheet of infinite horizontal extent are analysed to obtain the depth h, the half width a, the inclination α and the constant term containing the resistivity ρ and the current density I of the surrounding medium. The vertical derivative of the SP anomaly is obtained from the horizontal derivative via the Hilbert transform, which is also redefined to yield a modified version, a 270° phase shift of the original function. The point of intersection of these two Hilbert transforms corresponds to the origin. The amplitudes constitute a similar case. The practicability of the method is tested on a theoretical example as well as on field data from the Surda area of Rakha mines, Singhbhum belt, Bihar, India. The results agree well with those of other methods in use. Since the procedure is based on a simple mathematical expression involving the real roots of the derivatives, it can easily be automated.

scholarly journals A study of the self-potential field produced by a polarised inclined sheet in an electrically homogeneous and transversely anisotropic ground

2001 ◽  
Vol 34 (4) ◽  
pp. 1343
Author(s):  
Γ. Α. ΣΚΙΑΝΗΣ ◽  
Τ. Δ. ΠΑΠΑΔΟΠΟΥΛΟΣ ◽  
Δ. Α. ΒΑΪΟΠΟΥΛΟΣ
Keyword(s):  
Potential Field ◽  
The Self ◽  
Quantitative Interpretation ◽  
Potential Field Data ◽  
Synthetic Model ◽  
Transversely Anisotropic ◽  
Self Potential ◽  
Sp Anomaly ◽  
Interpretation Method ◽  
Inclined Sheet

In the present paper, the self-potential (sp) field is studied, which is produced by an inclined sheet (thin dyke) in an electrically homogeneous and transversely anisotropic ground. At first, the mathematical expression for the sp anomaly is deduced, by integration of the formula for the self-potential field produced by a point pole in a transversely anisotropic medium (Skianis & Herntmdez 1999). Then, the behavior of the sp curve is studied, for various angles of schistosity. The whole anomaly may be displaced along the horizontal axis and deformed in terms of amplitude and shape. Particular emphasis is given on the enhancement and suppression of the positive center of the self-potential, which depends on the values and orientations of the schistosity angle of the ground and the dip angle of the inclined sheet. These deformations of the sp anomaly, may introduce significant errors in the calculation of the parameters of the polarized body, if ground anisotropy is not taken into account. Therefore, new methodologies have to be developed, for a reliable quantitative interpretation of self-potential field data. In this paper, a direct interpretation method is proposed, which consists of two steps: In step one, the parameters of the inclined sheet are determined, assuming a homogeneous and isotropic ground. In this stage, any quantitative interpretation method, referred in the international bibliography, may be used. Secondly, the true parameters of the dyke are estimated, by a set of transformations in which the anisotropy coefficient and the schistosity angle are introduced. In order to apply this method, a priori information about ground anisotropy should be available, by dc geoelectrical and geological investigations. The efficiency of the method was tested on a synthetic model. In the first stage, the quantitative interpretation method of Murty & Haricharan 1985 was employed. In the second stage, the calculated parameters of the first step, served as input values of the transformations, and the real parameters of the inclined sheet were estimated. There was a good agreement between the parameter values of the synthetic model and the ones found by the proposed method. The results and conclusions of this paper, may be useful in detecting sulfide mineralization deposits or graphite.

scholarly journals Modeling of Self Potential (SP) Anomalies over a Polarized Rod with Finite Depth Extents

2019 ◽  
pp. 51-56
Author(s):  
T. S. Fagbemigun ◽  
M. O. Olorunfemi ◽  
S. A. Wahab
Keyword(s):  
Potential Distribution ◽  
Synthetic Data ◽  
Field Measurements ◽  
Finite Depth ◽  
Distribution Data ◽  
Geophysical Field ◽  
Dip Angle ◽  
Self Potential ◽  
Depth Of Burial ◽  
Sp Anomaly

Modeling is a powerful tool used by Geoscientists to provide pre-knowledge about the expectations of any geophysical field measurements. This study generates Self Potential (SP) anomalies over a typical dike-like structure to observe the influence of depth of burial and dip on SP anomalies. A computer program was developed from the potential distribution equation of an inclined polarized rod with a limited depth extent using Visual Basic (VB) programming language to produce synthetic data for potential distribution. The potential distribution data were used to generate theoretical SP anomaly curves for a polarized rod for varying depth of burial and dip. Twenty SP anomaly curves were generated with different dip values and depth of burial and from these curves, superimposed curves were also generated. The anomalies were analyzed for the effect of depth of burial and attitude or dip. The SP anomaly curves generated show that an increase in depth of burial causes a reduction in the peak negative amplitude of SP anomaly curves. For inclined polarized rod at relatively shallow depth (<2.0 m), the peak negative amplitude remains virtually the same with a positive shoulder over the down dip side of the target. Also as the dip angle decreases from 90o for a fixed depth of burial, the anomaly curves become asymmetrical. At 0o, the distance between the peak negative and peak positive amplitude of the anomaly curve is equal to the linear extent of the rod. Therefore, this study shows that the depth of burial inversely influences the amplitude of self-potential (SP) anomalies while the dip angle affects the form or symmetry of anomaly curves.

scholarly journals Implications of Self-Potential Distribution for Groundwater Flow System in a Nonvolcanic Mountain Slope

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Tada-nori Goto ◽  
Kazuya Kondo ◽  
Rina Ito ◽  
Keisuke Esaki ◽  
Yasuo Oouchi ◽  
...  
Keyword(s):  
Groundwater Flow ◽  
General Trend ◽  
Flow System ◽  
Ground Surface ◽  
Mountain Slope ◽  
Infiltration Process ◽  
Groundwater Flow System ◽  
Self Potential ◽  
Sp Anomaly ◽  
Fft Analysis

Self-potential (SP) measurements were conducted at Mt. Tsukuba, Japan, which is a nonvolcanic mountain, to infer groundwater flow system in the mountain. Survey routes were set around the northern slope, and the reliability of observed SP anomaly was checked by using SP values along parallel survey routes; the error was almost within 10 mV. The FFT analysis of the spatial SP distribution allows us a separation of raw data into two components with shorter and longer wavelength. In the shorter (altitudinal) wavelength than ∼200 meters, several positive SP peaks of more than 100 mV in magnitude are present, which indicate shallow perched water discharges along the slope. In the regional SP pattern of longer wavelength, there are two major perturbations from the general trend reflecting the topographic effect. By comparing the SP and hydrological data, the perturbation around the foothill is interpreted to be caused by heterogeneous infiltration at the ground surface. The perturbation around the summit is also interpreted to be caused by heterogeneous infiltration process, based on a simplified numerical modeling of SP. As a result, the SP pattern is well explained by groundwater flow and infiltration processes. Thus, SP data is thought to be very useful for understanding of groundwater flow system on a mountain scale.

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