Empirical mode decomposition (EMD) of potential field data: airborne gravity data as an example

With the continuing growth in influence of near surface geophysics, the research of the subsurface structure is of great significance. Geophysical imaging is one of the efficient computer tools that can be applied. This paper utilize the inversion of potential field data to do the subsurface imaging. Here, gravity data and magnetic data are inverted together with structural coupled inversion algorithm. The subspace (model space) is divided into a set of rectangular cells by an orthogonal 2D mesh and assume a constant property (density and magnetic susceptibility) value within each cell. The inversion matrix equation is solved as an unconstrained optimization problem with conjugate gradient method (CG). This imaging method is applied to synthetic data for typical models of gravity and magnetic anomalies and is tested on field data.

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Three-dimensional depth-to-basement modelling based on seismic and potential field data – basement configuration in the westernmost Polish Outer Carpathians

10.5194/egusphere-egu2020-7882 ◽

2020 ◽

Author(s):

Mateusz Mikołajczak ◽

Jan Barmuta ◽

Małgorzata Ponikowska ◽

Stanislaw Mazur ◽

Krzysztof Starzec

Keyword(s):

Qualitative Analysis ◽

Cross Sections ◽

Potential Field ◽

Field Data ◽

Gravity Data ◽

Three Dimensional ◽

Magnetic Data ◽

Gravity Inversion ◽

Potential Field Data ◽

Outer Carpathians

The Silesian Nappe in the westernmost part of the Polish Outer Carpathians Fold and Thrust Belt exhibits simple, almost homoclinal character. Based on the field observations, a total stratigraphic thickness of this sequence equals to at least 5400 m. On the other hand, the published maps of the sub-Carpathian basement show its top at depths no greater than 3000 m b.s.l. or even 2000 m b.s.l. in the southern part of the Silesian Nappe. Assuming no drastic thickness variations within the sedimentary sequence of the Silesian Nappe, such estimates of the basement depth are inconsistent with the known thickness of the Silesian sedimentary succession. The rationale behind our work was to resolve this inconsistency and verify the actual depth and structure of the sub-Carpathian crystalline basement along two regional cross-sections. In order to achieve this goal, a joint 2D quantitative interpretation of gravity and magnetic data was performed along these regional cross-sections. The interpretation was supported by the qualitative analysis of magnetic and gravity maps and their derivatives to recognize structural features in the sub-Carpathian basement. The study was concluded with the 3D residual gravity inversion for the top of basement. The cross-sections along with the borehole data available from the area were applied to calibrate the inversion.In the westernmost part of the Polish Outer Carpathians, the sub-Carpathian basement comprises part of the Brunovistulian Terrane. Because of great depths, the basement structure was investigated mainly by geophysical, usually non-seismic, methods. However, some deep boreholes managed to penetrate the basement that is composed of Neoproterozoic metamorphic and igneous rocks. The study area is located within the Upper Silesian block along the border between Poland and Czechia. There is a basement uplift as known mainly from boreholes, but the boundaries and architecture of this uplift are poorly recognized. Farther to the south, the top of the Neoproterozoic is buried under a thick cover of lower Palaeozoic sediments and Carpathian nappes.Our integrative study allowed to construct a three-dimensional map for the top of basement the depth of which increases from about 1000 m to over 7000 m b.s.l. in the north and south of the study area, respectively. Qualitative analysis of magnetic and gravity data revealed the presence of some &#160;basement-rooted faults delimiting the extent of the uplifted basement. The interpreted faults are oriented mainly towards NW-SE and NE-SW. Potential field data also document the correlation between the main basement steps and important thrust faults.&#160;This work has been funded by the Polish National Science Centre grant no UMO-2017/25/B/ST10/01348

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A method for inversion of 1D vertical soundings of gravity anomalies

Geophysics ◽

10.1190/geo2017-0186.1 ◽

2018 ◽

Vol 83 (2) ◽

pp. G15-G23

Author(s):

Andrea Vitale ◽

Domenico Di Massa ◽

Maurizio Fedi ◽

Giovanni Florio

Keyword(s):

Potential Field ◽

Field Data ◽

Gravity Data ◽

Finite Size ◽

Gravity Anomalies ◽

Real Data ◽

Gravity Inversion ◽

Chain Process ◽

Potential Field Data ◽

Gamma Density

We have developed a method to interpret potential fields, which obtains 1D models by inverting vertical soundings of potential field data. The vertical soundings are built through upward continuation of potential field data, measured on either a profile or a surface. The method assumes a forward problem consisting of a volume partitioned in layers, each of them homogeneous and horizontally finite, but with the density changing versus depth. The continuation errors, increasing with the altitude, are automatically handled by determining the coefficients of a third-order polynomial function of the altitude. Due to the finite size of the source volume, we need a priori information about the total horizontal extent of the volume, which is estimated by boundary analysis and optimized by a Markov chain process. For each sounding, a 1D inverse problem is independently solved by a nonnegative least-squares algorithm. Merging of the several inverted models finally yields approximate 2D or 3D models that are, however, shown to generate a good fit to the measured data. The method is applied to synthetic models, producing good results for either perfect or continued data. Even for real data, i.e., the gravity data of a sedimentary basin in Nevada, the results are interesting, and they are consistent with previous interpretation, based on 3D gravity inversion constrained by two gamma-gamma density logs.

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Edge enhancement of potential-field data using normalized statistics

Geophysics ◽

10.1190/1.2837309 ◽

2008 ◽

Vol 73 (3) ◽

pp. H1-H4 ◽

Cited By ~ 111

Author(s):

Gordon R. J. Cooper ◽

Duncan R. Cowan

Keyword(s):

Standard Deviation ◽

Potential Field ◽

Field Data ◽

Gravity Data ◽

Edge Enhancement ◽

Potential Field Data ◽

Geologic Interpretation ◽

Derivatives Of ◽

High Pass ◽

Detection Filter

Edge enhancement in potential-field data helps geologic interpretation. There are many methods for enhancing edges, most of which are high-pass filters based on the horizontal or vertical derivatives of the field. Normalized standard deviation (NSTD), a new edge-detection filter, is based on ratios of the windowed standard deviation of derivatives of the field. NSTD is demonstrated using aeromagnetic data from Australia and gravity data from South Africa. Compared with other filters, the NSTD filter produces more detailed results.

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Potential field data interpolation by Taylor series expansion

Geophysics ◽

10.1190/geo2021-0032.1 ◽

2021 ◽

pp. 1-46

Author(s):

Tao Chen ◽

Dikun Yang

Keyword(s):

Series Expansion ◽

Taylor Series ◽

Potential Field ◽

Field Data ◽

Taylor Series Expansion ◽

Critical Parameters ◽

Airborne Gravity ◽

Query Point ◽

Data Interpolation ◽

Potential Field Data

Data interpolation is critical in the analysis of geophysical data when some data is missing or inaccessible. We propose to interpolate irregular or missing potential field data using the relation between adjacent data points inspired by the Taylor series expansion (TSE). The TSE method first finds the derivatives of a given point near the query point using data from neighboring points, and then uses the Taylor series to obtain the value at the query point. The TSE method works by extracting local features represented as derivatives from the original data for interpolation in the area of data vacancy. Compared with other interpolation methods, the TSE provides a complete description of potential field data. Specifically, the remainder in TSE can measure local fitting errors and help obtain accurate results. Implementation of the TSE method involves two critical parameters the order of the Taylor series and the number of neighbors used in the calculation of derivatives. We have found that the first parameter must be carefully chosen to balance between the accuracy and numerical stability when data contains noise. The second parameter can help us build an over-determined system for improved robustness against noise. Methods of selecting neighbors around the given point using an azimuthally uniform distribution or the nearest-distance principle are also presented. The proposed approach is first illustrated by a synthetic gravity dataset from a single survey line, then is generalized to the case over a survey grid. In both numerical experiments, the TSE method has demonstrated an improved interpolation accuracy in comparison with the minimum curvature method. Finally we apply the TSE method to a ground gravity dataset from the Abitibi Greenstone Belt, Canada, and an airborne gravity dataset from the Vinton Dome, Louisiana, USA.

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Multi-Scale Edge Detection Method for Potential Field Data Based on Two-Dimensional Variation Mode Decomposition and Mathematical Morphology

IEEE Access ◽

10.1109/access.2020.3021287 ◽

2020 ◽

Vol 8 ◽

pp. 161138-161156

Author(s):

Yao Pei ◽

Changyin Liu ◽

Renxing Lou

Keyword(s):

Edge Detection ◽

Potential Field ◽

Field Data ◽

Detection Method ◽

Two Dimensional ◽

Potential Field Data ◽

Multi Scale ◽

Mode Decomposition ◽

Dimensional Variation ◽

Edge Detection Method

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Correction of topographic distortions in potential‐field data: A fast and accurate approach

Geophysics ◽

10.1190/1.1443434 ◽

1993 ◽

Vol 58 (4) ◽

pp. 515-523 ◽

Cited By ~ 28

Author(s):

Jianghai Xia ◽

Donald R. Sprowl ◽

Dana Adkins‐Heljeson

Keyword(s):

Potential Field ◽

Field Data ◽

Gravity Data ◽

Source Distribution ◽

Potential Field Data ◽

Equivalent Source ◽

Horizontal Shift ◽

Maximum Elevation ◽

Rms Error ◽

Forward Calculation

The equivalent source concept is used in the wavenumber domain to correct distortions in potential‐field data caused by topographic relief. The equivalent source distribution on a horizontal surface is determined iteratively through forward calculation of the anomaly on the topographic surface. Convergence of the solution is stable and rapid. The accuracy of the Fourier‐based approach is demonstrated by two synthetic examples. For the gravity example, the rms error between the corrected anomaly and the desired anomaly is 0.01 mGal, which is less than 0.5 percent of the maximum synthetic anomaly. For the magnetic example, the rms error is 0.7 nT, which is less than 1 percent of the maximum synthetic anomaly. The efficiency of the approach is shown by application to the gravity and aeromagnetic grids for Kansas. For gravity data, with a maximum elevation change of 500 m reducing to a horizontal datum results in a maximum correction in gravity anomaly amplitude of up to 2.6 mGal. For aeromagnetic data, the method results in a maximum horizontal shift of anomalies of 470 m with a maximum correction in aeromagnetic anomaly amplitudes up to 270 nT.

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Preliminary Study on Fusion Scheme of Multi-dimensional and Multi-scale Potential Field Data

10.5194/egusphere-egu2020-6651 ◽

2020 ◽

Author(s):

Xiaolin Ji ◽

Wanyin Wang ◽

Fuxiang Liu ◽

Min Yang ◽

Shengqing Xiong ◽

...

Keyword(s):

Potential Field ◽

Field Data ◽

Gravity Data ◽

Magnetic Data ◽

Potential Field Data ◽

Multi Scale ◽

Gravity And Magnetic ◽

Different Dimensions ◽

Fusion Scheme ◽

Gravity And Magnetic Data

Gravity and magnetic surveys are widely used in geology exploration because of its advantages, such as efficient and economy, green and environment-friendly, widely coverage and strong horizontal resolution. In order to well study in the geology exploration, it is required to comprehensively combine the different scales (different scales data) and different dimensions (satellite data, aeronautical data, ground data, ocean data, well data, etc.) of gravity and magnetic data that were observed in different periods, however, the comprehensive application of the multi-dimensional and multi-scale gravity and magnetic data still stays in the initial stage. In this paper, we do research on the key point of the fusion of potential field data (gravity and magnetic data): the way to fuse the different scales and different dimensions of potential field data into a benchmark and the same surface. Based on this research, we propose a scheme to fuse the multi-dimensional and multi-scale gravity and magnetic data. The synthetic models show that this fusion scheme is able to fuse the multi-dimensional and multi-scale gravity and magnetic data with great fusion results and small errors, in addition, the most important is that the fusion data conform to the characteristics of the potential field data and can meet the needs of data processing in the following steps. One of case studies in China has been accomplished to fuse aeronautical and ground gravity data that are different scales by using this fusion scheme. The fusion scheme we proposed in this study can be used in the fusion of the multi-dimensional (aeronautical, ground and ocean) and multi-scale gravity and magnetic data, which is good for interpretation and popularization.

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