摘要:

AbstractThe acceptance of articles in Geophysical Prospecting is strictly based on the originality and relevance of the contents. In order to be published a paper has to satisfy additional requirements on its external form and on its style and language: it should be written preferably in English though articles in French and German are permitted. A paper should consist of (i) a title page, (ii) an abstract, (iii) the text, (iv) list of references, (v) captions to illustrations, if any, (vi) tables, if any, and (vii) illustrations, if any. These seven parts should be mailed together but be physically separable and should be prepared according to rules which are either based on printing necessities or on the editorial style of the Journal.Failure to comply with these rules may result in delay in further processing of the article. Since Geophysical Prospecting is edited with a minimal budget correspondence with authors is kept to a minimum.

ISSN:0016-8025    

DOI:10.1111/j.1365-2478.1974.tb00079.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractDepths of investigation for normal (bipolar) and focusing (unipolar) linear electrode arrays have been computed following the method given earlier (Roy and Apparao 1971) both in homogeneous and layered earth. The focusing arrangement is found to be superior to normal arrangement both in regard to depth of investigation and zone of uniform depth of investigation. This analysis holds good in layered media too. Further, the depth of investigation increases with the increase in the length (2M) of the electrode and reaches a limit, 0.29Lfor normal and 0.50Lfor focusing, when the electrode attains an optimum length to satisfy the infinite condition. This optimum length of the electrode is six times the distanceLof the observation point from the electrode for normal and about ten times for focusing. A contour diagram for contributions of individual ground elements to the total signal measured at the centre of focused system is also discussed.

ISSN:0016-8025    

DOI:10.1111/j.1365-2478.1974.tb00080.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractThis paper describes the procedure for interpreting the apparent resistivity data measured with the two‐electrode array directly with the help of kernel function. The calculation of kernel function from the observed resistivity curve is done by the method of decomposition. In the method of decomposition the resistivity curve is approximated by a sum of certain functions, whose choice is only restricted by the requirement that the contribution to the kernel function corresponding to them should be easily computable. A few such functions are classified. These, and the standard curves for corresponding kernel functions obtained by utilising an integral expression for two‐electrode array expressing the kernel explicitly in terms of the apparent resistivity functions, are plotted on log‐log scale. The determination of layer parameters, that is, the layer resistivities and thicknesses from the kernel function can be carried out by a method proposed by Pekeris (

ISSN:0016-8025    

DOI:10.1111/j.1365-2478.1974.tb00081.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractIn a transversely electrically anisotropic rock mass of arbitrary dip, the potential distribution about an electrode at arbitrary depth is the sum of the whole‐space potential about that electrode, plus the whole‐space potential about a postulated image electrode displaced up‐dip from the source position. Equipotential lines on the rock‐air surface are ellipses, elongated parallel to strike, and with centers displaced up‐dip from the surface projection of the electrode position. In metamorphosed rocks frequently encountered in mining geophysics, anisotropy is such that elongation is most marked in steeply dipping rocks, with displacement most evident in low to moderate dip.Graphs relating the anisotropy coefficient to displacement and elongation assist in separation of the anisotropy‐related effects from those of a significant subsurface conductive body, particularly if surface resistivity sounding establishes the coefficient of

ISSN:0016-8025    

DOI:10.1111/j.1365-2478.1974.tb00082.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractThe authors generalize a method expounded in a previous paper (1971, Geoph. Prosp. 18, 786‐799) to the case of a local conductivity σ(M) of the infinite medium satisfying the relationwhere theRi'sare the distances from the pointMtonfixed pointsSi(i= 1,.n),kis a positive real constant andCi,Ciiare constants ensuring the condition α>O.The sub‐surface conductivity distributions (half‐spaces) complying with (1) provide a wide variety of conducting structures, which can fit quite successfully the rather complicated distributions of conductivity occurring in natural ore bodies.An exact algebraic calculation of the apparent resistivity for these grounds, valid for any dc electrical prospecting devices (Wenner, Schlumberger, dipole, etc.) leads to a set of simultaneous linear equations, with a matrix which is invariant with respect to the position of the quadrupole being used. This greatly simplifies the numerical computation.We also present some examples of cross sections for the real and apparent resistivity obtained by this

ISSN:0016-8025    

DOI:10.1111/j.1365-2478.1974.tb00083.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractBasic requirements for a seismic reflection system using a moderate‐power controlled source are discussed. General considerations and computer modelling show promise for geophysical prospecting, especially at low penetration and very high noise level. For many applications, ranging from mineral and water prospecting, to civil and military engineering, and even archeology, a relatively cheap, small and portable device of this kind might be more convenient than conventional explosive sources or sophisticated controlled sources of the vibroseis type. The use of a simple, low frequency periodic signal facilitates rapid data processing procedures and suggests that the mechanical generator will be very simple and chea

ISSN:0016-8025    

DOI:10.1111/j.1365-2478.1974.tb00084.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractA six‐channel wide‐band digital system for magnetotelluric measurements is described The system is designed to operate in the frequency band 10‐.0001 Hz. The recording is made on a 7 track tape in an IBM compatible 12 bit format. The amplitude and phase responses of the system and sample records are pres

ISSN:0016-8025    

DOI:10.1111/j.1365-2478.1974.tb00085.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractAn earth model with a transition layer (anisotropic inhomogeneous) is considered. The inhomogeneity in σv(vertical conductivity) of the transition layer is represented by a power law variation. Expressions for potential distribution in the upper layer, transition layer and bottom layer are obtained by solving appropriate differential equation for each layer. By utilizing the boundary conditions, expressions of apparent resistivity for Wenner and Schlumberger configurations are derived. Numerical analysis is performed for linear and quadratic variation of σv. The results are presented in the form of theoretical apparent resistivity curves for both configurations. Negative apparent resistivities are the interesting feature of this analysi

ISSN:0016-8025    

DOI:10.1111/j.1365-2478.1974.tb00086.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractSection migration after stack has been widely accepted by the industry. From a theoretical point of view, section migration before stack should provide superior results, the improvement warranting the drastically increased cost is not realized in most cases.There are a number of reasons that explain the discrepancy between actual and theoretically expected quality: Long period statics, refraction of rays, two‐dimensional treatment of an actually three‐dimensional problem.The section migration package subject to this paper allows(i) to take refraction into account,(ii) to discriminate against noise with a variety of statistical and geometrical criteria,(iii) to adapt processing time to problem complexity by a special process called SEMI‐STACK.A number of examples will demonstrate the effects of section migr

ISSN:0016-8025    

DOI:10.1111/j.1365-2478.1974.tb00087.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractA method is described to transform a dipole sounding curve, obtained with any one of the common dipole arrays over a horizontally layered earth, to the form of a Schlumberger sounding curve. Starting from the general expression which relates the dipole apparent resistivity to the Schlumberger apparent resistivity and its derivative with respect to the spacing, it is possible with some approximations to derive an easy numerical computation procedure in order to perform the transformation. The applicability of the method is discussed briefly.

ISSN:0016-8025    

DOI:10.1111/j.1365-2478.1974.tb00088.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY