Directional spectral analysis and filtering of geophysical maps

Thorarinsson, Freyr; Magnusson, Stefan G.; Björnsson, Axel

doi:10.1190/1.1442440

Cited by 14 publications

(8 citation statements)

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“…In contrast to other types of directional filtering (e.g. Thorarinsson, Magnusson and Bjornsson 1988), these filters are physically comprehensjble. Jacobsen (1987) argued for the use of upward continuation as a standard separation filter.…”

Section: Discussion a N D Conclusionmentioning

confidence: 94%

CONSTRUCTION OF COMPONENT MAPS FROM AEROMAGNETIC TOTAL FIELD ANOMALY MAPS¹

Pedersen

Rasmussen

Dyrelius

1990

Geophysical Prospecting

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PEDERSEN, L.B., RASMUSSEN, T.M. and DYRELIUS, D. 1990. Construction of component maps from aeromagnetic total field anomaly maps. Geophysical Prospecting 38,795-804.Total field anomalies as defined from normal aeromagnetic surveys give good approximations of the anomalous components along the direction of the main geomagnetic field, which is generally much larger than the anomalous field. Using the relations between vertical and horizontal components of the field, the total field anomaly is related to any vertical or horizontal component and the corresponding horizontal and vertical derivatives. An example from the Siljan impact structure indicates that such directional filters may be applied to extract useful information from magnetic maps.

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Section: Discussion a N D Conclusionmentioning

confidence: 94%

CONSTRUCTION OF COMPONENT MAPS FROM AEROMAGNETIC TOTAL FIELD ANOMALY MAPS¹

Pedersen

Rasmussen

Dyrelius

1990

Geophysical Prospecting

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“…These filters have been employed extensively in the past for easier detection of linear anomalies (Thorarinsson, Magnusson and Bjornsson 1988 and references therein). These filters have been employed extensively in the past for easier detection of linear anomalies (Thorarinsson, Magnusson and Bjornsson 1988 and references therein).…”

Section: Methods 2: 2d Fft Filtersmentioning

confidence: 99%

“…Another strategy of microlevelling is to use 2D directional filters in the frequency domain for the first steps of the process (the sampling and further filtering is conceptually unchanged). These filters have been employed extensively in the past for easier detection of linear anomalies (Thorarinsson, Magnusson and Bjornsson 1988 and references therein). Preprocessing is necessary before applying the forward FFT; it basically involves trend removal (order 1), expansion to square dimensions and filling of dummy values within the grid.…”

Section: Methods 2: 2d Fft Filtersmentioning

confidence: 99%

Microlevelling procedures applied to regional aeromagnetic data: an example from the Transantarctic Mountains (Antarctica)

Ferraccioli

Gambetta

Bozzo

1998

Geophysical Prospecting

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The extensive application of digital enhancement and filtering as a powerful tool for aeromagnetic interpretation, not only of high resolution but also of regional data, requires an improved levelling. Two microlevelling techniques were thus compared in order to find an effective but relatively simple procedure to remove, or at least to reduce, residual magnetic errors remaining after standard levelling processes. This study was carried out on regional aeromagnetic data recently acquired at high magnetic latitudes along the Transantarctic Mountains in Antarctica, where it is particularly critical to remove time‐dependent magnetic variations. Two‐dimensional FFT filters applied to the gridded data, namely the Butterworth and a directional cosine filter, proved to be more effective than previously proposed one‐dimensional space‐domain filters in the reduction of the ‘residual corrugation’ not removed by statistical levelling. Tectonic interpretation of trends detected in the total field magnetic anomaly map and in the 3D analytic signal improved after application of frequency‐domain microlevelling. However, we also show that when interpreting microlevelled data, two factors must be considered: (i) the possible presence of real geological trends aligned along the flight lines; (ii) modifications in the results yielded by depth estimates of magnetic sources due to the FFT filters applied during the microlevelling procedure. Such changes were seen both in the well‐established 2D FFT method, based on the slope of the energy spectrum, and in the more recent 3D Euler deconvolution technique. Overall our results indicate that microlevelling could profitably be applied to older gridded aeromagnetic data sets in Antarctica, thus improving the accuracy and geological significance of future regional magnetic compilations, as already seen in other continents.

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“…SYKES and DAS (2000) have applied steerable filtering for linear feature enhancement of geophysical maps. Some new studies are focused on directional filtering, radial and angular spectrum as in THORARINSSON et al (1988) and OZMEN et al (2002). FEDI and FLORIA (2001) have introduced a highresolution border detection approach, Enhanced Horizontal Derivative (EHD).…”

Section: Introductionmentioning

confidence: 99%

Modelling Potential Field Sources in the Gelibolu Peninsula (Western Turkey) Using a Markov Random Field Approach

Albora

Uçan

Aydoğan

2007

Pure appl. geophys.

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In this study, a Markov Random Field (MRF) approach is used to locate source boundary positions which are difficult to identify from Bouguer gravity and magnetic maps. As a generalized form of Markov Chains, the MRF approach is an unsupervised statistical model based algorithm and is applied to the analysis of images, particularly in the detection of visual patterns or textures. Here, we present a dynamic programming based on the MRF approach for boundary detection of noisy and super-positioned potential anomalies, which are produced by various geological structures. In the MRF method, gravity and magnetic maps are considered as two-dimensional (2-D) images with a matrix composed of N 1 · N 2 pixels. Each pixel value of the matrix is optimized in real time with no a priori processing by using two parameter sets; average steering vector (h) and quantization level (M). They carry information about the correlation of neighboring pixels and the locality of their connections. We have chosen MRF as a processing approach for geophysical data since it is an unsupervised, efficient model for image enhancement, border detection and separation of 2-D potential anomalies. The main benefit of MRF is that an average steering vector and a quantization level are enough in evaluation of the potential anomaly maps.We have compared the MRF method to noise implemented synthetic potential field anomalies. After satisfactory results were found, the method has been applied to gravity and magnetic anomaly maps of Gelibolu Peninsula in Western Turkey. Here, we have observed Anafartalar thrust fault and another parallel fault northwest of Anafartalar thrust fault. We have modeled a geological structure including a lateral fault, which results in a higher susceptibility and anomaly amplitude increment. We have shown that the MRF method is effective to detect the broad-scale geological structures in the Gelibolu Peninsula, and thus to delineate the complex tectonic structure of Gelibolu Peninsula.

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Directional spectral analysis and filtering of geophysical maps

Cited by 14 publications

References 0 publications

CONSTRUCTION OF COMPONENT MAPS FROM AEROMAGNETIC TOTAL FIELD ANOMALY MAPS¹

CONSTRUCTION OF COMPONENT MAPS FROM AEROMAGNETIC TOTAL FIELD ANOMALY MAPS¹

Microlevelling procedures applied to regional aeromagnetic data: an example from the Transantarctic Mountains (Antarctica)

Modelling Potential Field Sources in the Gelibolu Peninsula (Western Turkey) Using a Markov Random Field Approach

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Directional spectral analysis and filtering of geophysical maps

Cited by 14 publications

References 0 publications

CONSTRUCTION OF COMPONENT MAPS FROM AEROMAGNETIC TOTAL FIELD ANOMALY MAPS1

CONSTRUCTION OF COMPONENT MAPS FROM AEROMAGNETIC TOTAL FIELD ANOMALY MAPS1

Microlevelling procedures applied to regional aeromagnetic data: an example from the Transantarctic Mountains (Antarctica)

Modelling Potential Field Sources in the Gelibolu Peninsula (Western Turkey) Using a Markov Random Field Approach

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CONSTRUCTION OF COMPONENT MAPS FROM AEROMAGNETIC TOTAL FIELD ANOMALY MAPS¹

CONSTRUCTION OF COMPONENT MAPS FROM AEROMAGNETIC TOTAL FIELD ANOMALY MAPS¹