TECHNIQUE FOR IMPROVED CONVERGENCE IN ITERATIVE ANALYSIS OF GRAVITY ANOMALY PROFILES

Geophysics ◽  
1973 ◽  
Vol 38 (3) ◽  
pp. 500-506 ◽  
Author(s):  
K. P. Fournier ◽  
S. F. Krupicka
Keyword(s):  
Bouguer Anomaly ◽  
Gravity Anomalies ◽  
Computer Time ◽  
Two Dimensional ◽  
Profile Data ◽  
Plate Method ◽  
Modeling Process ◽  
Iterative Analysis ◽  
Dimensional Gravity ◽  
Number Of Iterations

Narrow two‐dimensional gravity anomalies are difficult to interpret iteratively by the relatively simple flat‐plate method suggested by Bott (1960) and employed by others. In this report Bott’s formula is modified empirically after a number of iterations have proceeded. The process is repeated until satisfactory convergence is obtained. The results can be applied to other profiles across the anomaly of interest and thus save substantial computer time by requiring fewer iterations. The technique is applied to two Bouguer anomaly profiles. Analysis of adjoining anomaly profile data with similar amplitudes and widths can be used to speed the convergence in the iterative modeling process.

A LEAST‐SQUARES PROCEDURE FOR GRAVITY INTERPRETATION

Geophysics ◽  
1965 ◽  
Vol 30 (2) ◽  
pp. 228-233 ◽  
Author(s):  
Charles E. Corbató
Keyword(s):  
Least Squares ◽  
High Speed ◽  
Gravity Anomalies ◽  
The Body ◽  
Two Dimensional ◽  
Partial Derivatives ◽  
Dimensional Gravity ◽  
Gravity Interpretation ◽  
Relationship Of ◽  
Derivatives Of

A procedure suitable for use on high‐speed digital computers is presented for interpreting two‐dimensional gravity anomalies. In order to determine the shape of a disturbing mass with known density contrast, an initial model is assumed and gravity anomalies are calculated and compared with observed values at n points, where n is greater than the number of unknown variables (e.g. depths) of the model. Adjustments are then made to the model by a least‐squares approximation which uses the partial derivatives of the anomalies so that the residuals are reduced to a minimum. In comparison with other iterative techniques, convergence is very rapid. A convenient method to use for both the calculation of the anomalies and the adjustments is the two‐dimensional method of Talwani, Worzel, and Landisman, (1959) in which the outline of the body is polygonized and the anomalies and the partial derivatives of the anomaly with respect to the depth of a vertex on the body can be expressed as functions of the coordinates of the vertex. Not only depths but under certain circumstances regional gravity values may be evaluated; however, the relationship of the disturbing body to the gravity information may impose certain limitations on the application of the procedure.

scholarly journals Análise e interpretação de dados gravimétricos nas porções terrestre e marítima do Brasil Meridional

1997 ◽  
Vol 20 ◽  
pp. 201-214
Author(s):  
Paula Lúcia Ferrucio da Rocha ◽  
Luiz Fernando Santana Braga
Keyword(s):  
Bouguer Anomaly ◽  
Two Dimensional ◽  
Gravity Modelling ◽  
Bouguer Anomalies ◽  
Dimensional Gravity ◽  
Marine Data ◽  
Anomaly Map ◽  
Bouguer Anomaly Map ◽  
Geological Constraints ◽  
South Brazil

We have interpreted the Bouguer anomaly map from South Brazil and its adjoining oceanic areas, using the land data from the SAGP Project (1990), and the marine data derived from GEOSAT. With the aid of the vertical derivatives and the maximum horizontal gradientes of the Bouguer anomalies we have mapped the boundaries between the major lithospheric compartments, here characterized by their gravity signatures. Two dimensional gravity modelling with available geological constraints have also been performed aiming to estimate the crustal thicknesses within each individual compartment. We show that the gravity responses of the continental, transitional and oceanic lithospheres are well distinguished.

On: “Gravity Interpretation using the Fourier Integral” by J. W. Berg, Jr., and M. E. Odegard (GEOPHYSICS, vol. 30, no. 3, p. 424–438, June 1965)

Geophysics ◽  
1970 ◽  
Vol 35 (2) ◽  
pp. 358-358 ◽  
Author(s):  
H. A. Meinardus
Keyword(s):  
Fourier Transform ◽  
Gravity Anomalies ◽  
Fourier Integral ◽  
Hankel Transform ◽  
Cylindrical Symmetry ◽  
Two Dimensional ◽  
One Dimensional ◽  
Dimensional Gravity ◽  
The One ◽  
Gravity Interpretation

The authors do not state explicitly that equations (1) and (12) express gravity anomalies of the two‐dimensional cylinder and fault respectively. These structures have an infinite extension along the strike, and all the gravity profiles perpendicular to the strike are identical. For this reason it is admissible to apply the one‐dimensional Fourier transform to obtain the one‐dimensional amplitude spectra shown in Figures (1) and (5). The situation, however, is different for the sphere, which does not have a one‐dimensional gravity profile in the above sense, but rather a two‐dimensional field with cylindrical symmetry. Instead of using the one‐dimensional Fourier transform as given by (6) along a straight line, we must apply the two‐dimensional Fourier transform over the whole area. Because of the circular symmetry, one radial variable will suffice in place of the two Cartesian coordinates x and y, and the two‐dimensional Fourier transform can be expressed as Hankel transform, so that equation (6) becomes [Formula: see text]

scholarly journals Interpretation of two-dimensional magnetotelluric profile data with three-dimensional inversion: synthetic examples

2005 ◽  
Vol 160 (3) ◽  
pp. 804-814 ◽  
Author(s):  
Weerachai Siripunvaraporn ◽  
Gary Egbert ◽  
Makoto Uyeshima
Keyword(s):  
Three Dimensional ◽  
Two Dimensional ◽  
Profile Data

scholarly journals New exact relations for steady irrotational two-dimensional gravity and capillary surface waves

2017 ◽  
Vol 376 (2111) ◽  
pp. 20170220 ◽  
Author(s):  
Didier Clamond
Keyword(s):  
Free Surface ◽  
Gravity Waves ◽  
Water Waves ◽  
Two Dimensional ◽  
Physical Plane ◽  
Theme Issue ◽  
Nonlinear Water Waves ◽  
Dimensional Gravity ◽  
Irrotational Motion ◽  
Exact Relations

Steady two-dimensional surface capillary–gravity waves in irrotational motion are considered on constant depth. By exploiting the holomorphic properties in the physical plane and introducing some transformations of the boundary conditions at the free surface, new exact relations and equations for the free surface only are derived. In particular, a physical plane counterpart of the Babenko equation is obtained. This article is part of the theme issue ‘Nonlinear water waves’.

TOPOLOGICAL CONFORMAL ALGEBRA IN POLYAKOV’S LIGHT-CONE GAUGE GRAVITY

1992 ◽  
Vol 07 (35) ◽  
pp. 3291-3302 ◽  
Author(s):  
KIYONORI YAMADA
Keyword(s):  
Light Cone ◽  
Matter Field ◽  
Conformal Algebra ◽  
Two Dimensional ◽  
Topological Algebras ◽  
Light Cone Gauge ◽  
Brst Cohomology ◽  
Dimensional Gravity ◽  
Conformal Gauge ◽  
Gauge Gravity

We show that the two-dimensional gravity coupled to c=−2 matter field in Polyakov’s light-cone gauge has a twisted N=2 superconformal algebra. We also show that the BRST cohomology in the light-cone gauge actually coincides with that in the conformal gauge. Based on this observation the relations between the topological algebras are discussed.

EQUIVALENCE OF TWO-DIMENSIONAL GRAVITIES

1990 ◽  
Vol 05 (16) ◽  
pp. 1251-1258 ◽  
Author(s):  
NOUREDDINE MOHAMMEDI
Keyword(s):  
Gauge Theory ◽  
Explicit Solution ◽  
Light Cone ◽  
Equations Of Motion ◽  
Two Dimensional ◽  
Induced Gravity ◽  
Light Cone Gauge ◽  
Dimensional Gravity ◽  
The Relationship ◽  
Chern Simons

We find the relationship between the Jackiw-Teitelboim model of two-dimensional gravity and the SL (2, R) induced gravity. These are shown to be related to a two-dimensional gauge theory obtained by dimensionally reducing the Chern-Simons action of the 2+1 dimensional gravity. We present an explicit solution to the equations of motion of the auxiliary field of the Jackiw-Teitelboim model in the light-cone gauge. A renormalization of the cosmological constant is also given.

A COMPACT BOSON COUPLED TO TWO-DIMENSIONAL GRAVITY

1991 ◽  
Vol 06 (15) ◽  
pp. 2743-2754 ◽  
Author(s):  
NORISUKE SAKAI ◽  
YOSHIAKI TANII
Keyword(s):  
Field Theory ◽  
Partition Function ◽  
Quantum Gravity ◽  
Matrix Models ◽  
Riemann Surfaces ◽  
Partition Functions ◽  
Two Dimensional ◽  
Dimensional Gravity ◽  
The Continuum ◽  
Continuum Field

The radius dependence of partition functions is explicitly evaluated in the continuum field theory of a compactified boson, interacting with two-dimensional quantum gravity (noncritical string) on Riemann surfaces for the first few genera. The partition function for the torus is found to be a sum of terms proportional to R and 1/R. This is in agreement with the result of a discretized version (matrix models), but is quite different from the critical string. The supersymmetric case is also explicitly evaluated.

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