COMBINED ANALYSIS OF GRAVITY AND MAGNETIC ANOMALIES

Geophysics ◽  
1951 ◽  
Vol 16 (1) ◽  
pp. 51-62 ◽  
Author(s):  
G. D. Garland
Keyword(s):  
Magnetic Anomalies ◽  
The Body ◽  
Rock Material ◽  
Combined Analysis ◽  
Gravity And Magnetic ◽  
Anomalous Density ◽  
The Relationship

The relationship betwen gravity and magnetic anomalies is investigated. It is shown that the ratio of the anomalous susceptibility to the anomalous density of an unknown body may be determined from gravimeter and vertical magnetometer observations, independent of assumptions as to the depth or form of the body. The use of this ratio in identifying the rock material of the body is discussed, and illustrated by applying the method to a well‐known case.

A DIRECT COMPUTATION OF GRAVITY AND MAGNETIC ANOMALIES CAUSED BY 2- AND 3-DIMENSIONAL BODIES OF ARBITRARY SHAPE AND ARBITRARY MAGNETIC POLARIZATION BY EQUIVALENT‐POINT METHOD AND A SIMPLIFIED CUBIC SPLINE

Geophysics ◽  
1977 ◽  
Vol 42 (3) ◽  
pp. 610-622 ◽  
Author(s):  
Chao C. Ku
Keyword(s):  
Arbitrary Shape ◽  
Gaussian Quadrature ◽  
Magnetic Anomalies ◽  
Cubic Spline ◽  
The Body ◽  
Point Method ◽  
Magnetic Polarization ◽  
3 Dimensional ◽  
Equivalent Point ◽  
Gravity And Magnetic

A computational method, which combines the Gaussian quadrature formula for numerical integration and a cubic spline for interpolation in evaluating the limits of integration, is employed to compute directly the gravity and magnetic anomalies caused by 2-dimensional and 3-dimensional bodies of arbitrary shape and arbitrary magnetic polarization. The mathematics involved in this method is indeed old and well known. Furthermore, the physical concept of the Gaussian quadrature integration leads us back to the old concept of equivalent point masses or equivalent magnetic point dipoles: namely, the gravity or magnetic anomaly due to a body can be evaluated simply by a number of equivalent points which are distributed in the “Gaussian way” within the body. As an illustration, explicit formulas are given for dikes and prisms using 2 × 2 and 2 × 2 × 2 point Gaussian quadrature formulas. The basic limitation in the equivalent‐point method is that the distance between the point of observation and the equivalent points must be larger than the distance between the equivalent points within the body. By using a reasonable number of equivalent points or dividing the body into a number of smaller subbodies, the method might provide a useful alternative for computing in gravity and magnetic methods. The use of a simplified cubic spline enables us to compute the gravity and magnetic anomalies due to bodies of arbitrary shape and arbitrary magnetic polarization with ease and a certain degree of accuracy. This method also appears to be quite attractive for terrain corrections in gravity and possibly in magnetic surveys.

THE DETERMINATION OF AN INFINITE INCLINED DIKE FROM THE RESULTS OF GRAVITY AND MAGNETIC SURVEYS

Geophysics ◽  
1948 ◽  
Vol 13 (3) ◽  
pp. 437-442 ◽  
Author(s):  
Laszlo Egyed
Keyword(s):  
Magnetic Susceptibility ◽  
Magnetic Anomaly ◽  
The Body ◽  
Gravitational Gradient ◽  
Ore Bodies ◽  
Gravity And Magnetic ◽  
Anomalous Density

The equations are given for the gravitational gradient and curvature, and for the horizontal and vertical components of the magnetic anomaly for ore bodies of the Kursk type. It is then shown how from these equations the depth, width of crest, angle of dip, anomalous density and magnetic susceptibility of the body may be determined.

REMANENT MAGNETIZATION FROM COMPARISON OF GRAVITY AND MAGNETIC ANOMALIES

Geophysics ◽  
1976 ◽  
Vol 41 (1) ◽  
pp. 56-61 ◽  
Author(s):  
D. H. Shurbet ◽  
G. R. Keller ◽  
J. P. Friess
Keyword(s):  
Remanent Magnetization ◽  
Spatial Relationship ◽  
Gravity Anomalies ◽  
Magnetic Anomalies ◽  
The Body ◽  
Gravity And Magnetic

Gravity and magnetic anomalies caused by deeply buried rock bodies in northwest Texas are compared. Interpretation of the gravity anomalies by modeling is used to locate and define the geometry of the body in a way analogous to the use of bathymetry in studies concerned with magnetization of seamounts. The direction of magnetization is then determined from the spatial relationship between the gravity and magnetic anomalies. This procedure amounts to an in‐situ determination of direction of magnetization of the body. In one example direction of magnetization indicates the time of intrusion and in another it indicates regional heating since intrusion.

COMPUTATION OF GRAVITY AND MAGNETIC ANOMALIES DUE TO INHOMOGENEOUS DISTRIBUTION OF MAGNETIZATION AND DENSITY IN A LOCALIZED REGION

Geophysics ◽  
1977 ◽  
Vol 42 (3) ◽  
pp. 602-609 ◽  
Author(s):  
B. K. Bhattacharyya ◽  
K. C. Chan
Keyword(s):  
Rock Mass ◽  
Physical Property ◽  
Magnetic Anomalies ◽  
The Body ◽  
Inhomogeneous Distribution ◽  
Uniform Magnetization ◽  
Gravity And Magnetic ◽  
First Vertical Derivative ◽  
Analytical Expressions ◽  
Distribution Of Magnetization

Analytical expressions in the form of a convolution of two functions have been derived for the gravity and magnetic anomalies due to inhomogeneous distribution of magnetization and density in a localized region. These expressions show explicitly that the anomalies are completely determined by the divergence of magnetization and the first vertical derivative of density. It is thus analytically established that when a body with uniform magnetization or density is considered, the impulsive change in the physical property of the rock mass at the boundary of the body is responsible for generating an anomalous magnetic or gravity field. These properties are utilized to derive efficient algorithms for computing gravity and magnetic anomalies. An example is given to demonstrate the usefulness of the derived algorithm in computing the anomaly due to magnetization of an irregularly shaped topography.

A simple method for the analysis of magnetic anomalies over dike‐like bodies

Geophysics ◽  
1986 ◽  
Vol 51 (5) ◽  
pp. 1119-1126 ◽  
Author(s):  
H. V. Ram Babu ◽  
V. Vijayakumar ◽  
D. Atchuta Rao
Keyword(s):  
Maximum Amplitude ◽  
Magnetic Anomalies ◽  
The Body ◽  
Total Amplitude ◽  
Magnetization Direction ◽  
Simple Method ◽  
Aeromagnetic Anomalies ◽  
Susceptibility Contrast ◽  
Minimum Amplitude ◽  
The Relationship

Magnetic anomalies may be simply analyzed using a dike model. In this model, the depth to the source is approximately 1.25 S, where S is the straight‐slope distance measured on the steepest flank. The dip of the body may be evaluated from θ, the combined magnetic angle found from the ratio of the maximum amplitude to the minimum amplitude. In the presence of remanence, the body dip δ may be found from θ only when the direction of resultant magnetization is either known or assumed, and magnetization direction may be found only if the dip is known. The minimum susceptibility contrast k of the source may be calculated from the total amplitude A and intensity T of the inducing field using the relationship k = 0.3 A/T. A large number of aeromagnetic anomalies have been interpreted using this method. A few such anomalies are presented here to illustrate the applicability of the method.

SPECTRAL ANALYSIS OF GRAVITY AND MAGNETIC ANOMALIES DUE TO RECTANGULAR PRISMATIC BODIES

Geophysics ◽  
1977 ◽  
Vol 42 (1) ◽  
pp. 41-50 ◽  
Author(s):  
B. K. Bhattacharyya ◽  
Lei‐Kuang Leu
Keyword(s):  
Spectral Analysis ◽  
Approximation Method ◽  
Magnetic Anomalies ◽  
The Body ◽  
Exponential Approximation ◽  
Prismatic Body ◽  
First Order ◽  
Gravity And Magnetic ◽  
Sums Of Exponentials ◽  
Prismatic Bodies

The spectra of gravity and magnetic anomalies due to a prismatic body can be expressed as sums of exponentials. The complex exponents of these exponentials are functions of frequency and locations of the corners of the body. An exponential approximation method is used for the analysis of the radial spectra of an anomaly and its first order moments for obtaining accurate estimates of the depths to the top and bottom of the body. A method has also been developed for determining approximately the location of the centroid of the body. When the location of the centroid and the depths to the top and bottom are known for the causative body, it is possible to calculate the horizontal dimensions with the help of the spectrum of the anomaly.

The use of Body Surface Index as a Better Clinical Health indicators Compare to Body Mass Index and Body Surface Area for Clinical Application

2018 ◽  
pp. 131-136
Author(s):  
Shirazu I. ◽  
Theophilus. A. Sackey ◽  
Elvis K. Tiburu ◽  
Mensah Y. B. ◽  
Forson A.
Keyword(s):  
Surface Area ◽  
Body Surface Area ◽  
Clinical Application ◽  
Body Surface ◽  
Body Height ◽  
Health Indicators ◽  
The Body ◽  
Body Parameters ◽  
The Relationship ◽  
Individual Body

The relationship between body height and body weight has been described by using various terms. Notable among them is the body mass index, body surface area, body shape index and body surface index. In clinical setting the first descriptive parameter is the BMI scale, which provides information about whether an individual body weight is proportionate to the body height. Since the development of BMI, two other body parameters have been developed in an attempt to determine the relationship between body height and weight. These are the body surface area (BSA) and body surface index (BSI). Generally, these body parameters are described as clinical health indicators that described how healthy an individual body response to the other internal organs. The aim of the study is to discuss the use of BSI as a better clinical health indicator for preclinical assessment of body-organ/tissue relationship. Hence organ health condition as against other body composition. In addition the study is `also to determine the best body parameter the best predict other parameters for clinical application. The model parameters are presented as; modeled height and weight; modelled BSI and BSA, BSI and BMI and modeled BSA and BMI. The models are presented as clinical application software for comfortable working process and designed as GUI and CAD for use in clinical application.

CONCEPTUALISING RISK CULTURE ON ERM IMPLEMENTATION IN CONSTRUCTION COMPANIES

2020 ◽  
Vol 17 (1) ◽  
pp. 59
Author(s):  
Ching Ching Wong
Keyword(s):  
Risk Management ◽  
Risk Identification ◽  
The Body ◽  
Risk Indicators ◽  
Construction Companies ◽  
Risk Appetite ◽  
Risk Culture ◽  
Risk Treatment ◽  
Managing Risk ◽  
The Relationship

Enterprise Risk Management (ERM) is an effective technique in managing risk within an organization strategically and holistically. Risk culture relates to the general awareness, attitudes and behaviours towards risk management in an organisation. This paper presents a conceptual model that shows the relationship between risk culture and ERM implementation. The dependent variable is ERM implementation, which is measured by the four processes namely risk identification and risk assessment; risk treatment; monitor and consult; communicate and consult. The independent variables under risk culture are risk policy and risk appetite; key risk indicators; accountability; incentives; risk language and internal relationships. This study aims to empirically test the relationship between risk culture and ERM implementation among Malaysian construction public listed companies. Risk culture is expected to have direct effects and significantly influence ERM. This study contributes to enhance the body of knowledge in ERM especially in understanding significant of risk culture that influence its’ implementation from Malaysian perspective.

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