Terracing gravity and magnetic data using edge-preserving smoothing filters

Geophysics ◽  
2016 ◽  
Vol 81 (2) ◽  
pp. G41-G47 ◽  
Author(s):  
Xiong Li
Keyword(s):  
Nearest Neighbor ◽  
Magnetic Data ◽  
Major Purpose ◽  
Edge Preserving ◽  
Gravity And Magnetic ◽  
Domain Boundaries ◽  
Variance Filter ◽  
Geologic Map ◽  
Homogeneous Domains ◽  
Gravity And Magnetic Data

One major purpose of gravity and magnetic transformations is to produce a result that can be related to geology. The terracing operator achieves this purpose by converting gravity and magnetic data into a geologic map-like field wherein homogeneous domains with sharp domain boundaries are defined. Edge-preserving smoothing filters developed in image processing have the same capability. I have applied the Kuwahara, mean of least variance, and symmetric nearest neighbor filters to gravity and magnetic data. Synthetic and field data examples suggest that these edge-preserving smoothing filters produce terraced effects cleaner than the terracing operator, and the mean of least variance filter often produces the cleanest and sharpest result.

An improved terracing algorithm for potential-field data

Geophysics ◽  
2020 ◽  
Vol 85 (5) ◽  
pp. G109-G113
Author(s):  
G. R. J. Cooper
Keyword(s):  
Potential Field ◽  
Field Data ◽  
Shape Index ◽  
Magnetic Data ◽  
Threshold Parameter ◽  
Potential Field Data ◽  
Gravity And Magnetic ◽  
Realistic Result ◽  
Geologic Map ◽  
Gravity And Magnetic Data

Although the boundaries between geologic units with different physical properties are usually quite distinct, the potential-field anomalies associated with them are relatively smooth, particularly for deeper bodies. The terracing filter has been introduced to sharpen anomaly edges and to produce regions of constant amplitude between them, mimicking geologic units on a geologic map. The boundaries between the pseudogeologic units are defined by the zero contour of the Laplacian function. Unfortunately, this can result in the domains of terraced anomalies extending far from the original location of the causative body, producing an image that poorly represents the geology. I have determined that the use of the mathematical shape index of the anomalies, rather than their Laplacian, produces a much more geologically realistic result. The effect can be controlled as desired using a threshold parameter. I evaluate the benefits of the method on gravity and magnetic data from southern Africa.

Automatic 3-D interpretation of potential field data using analytic signal derivatives

Geophysics ◽  
1997 ◽  
Vol 62 (1) ◽  
pp. 87-96 ◽  
Author(s):  
Nicole Debeglia ◽  
Jacques Corpel
Keyword(s):  
Signal Amplitude ◽  
Vertical Gradient ◽  
Analytic Signal ◽  
Magnetic Data ◽  
Practical Implementation ◽  
Potential Field Data ◽  
Gravity And Magnetic ◽  
Second Derivatives ◽  
Gravity And Magnetic Data ◽  
Derivatives Of

A new method has been developed for the automatic and general interpretation of gravity and magnetic data. This technique, based on the analysis of 3-D analytic signal derivatives, involves as few assumptions as possible on the magnetization or density properties and on the geometry of the structures. It is therefore particularly well suited to preliminary interpretation and model initialization. Processing the derivatives of the analytic signal amplitude, instead of the original analytic signal amplitude, gives a more efficient separation of anomalies caused by close structures. Moreover, gravity and magnetic data can be taken into account by the same procedure merely through using the gravity vertical gradient. The main advantage of derivatives, however, is that any source geometry can be considered as the sum of only two types of model: contact and thin‐dike models. In a first step, depths are estimated using a double interpretation of the analytic signal amplitude function for these two basic models. Second, the most suitable solution is defined at each estimation location through analysis of the vertical and horizontal gradients. Practical implementation of the method involves accurate frequency‐domain algorithms for computing derivatives with an automatic control of noise effects by appropriate filtering and upward continuation operations. Tests on theoretical magnetic fields give good depth evaluations for derivative orders ranging from 0 to 3. For actual magnetic data with borehole controls, the first and second derivatives seem to provide the most satisfactory depth estimations.

3D inversion modeling of joint gravity and magnetic data based on a sinusoidal correlation constraint

2019 ◽  
Vol 16 (4) ◽  
pp. 519-529
Author(s):  
Xiu-He Gao ◽  
Sheng-Qing Xiong ◽  
Zhao-Fa Zeng ◽  
Chang-Chun Yu ◽  
Gui-Bin Zhang ◽  
...  
Keyword(s):  
Magnetic Data ◽  
3D Inversion ◽  
Gravity And Magnetic ◽  
Gravity And Magnetic Data
Sign in / Sign up

Export Citation Format

Share Document