A combined analytic signal and Euler method (AN‐EUL) for automatic interpretation of magnetic data

Geophysics ◽  
2003 ◽  
Vol 68 (6) ◽  
pp. 1952-1961 ◽  
Author(s):  
Ahmed Salem ◽  
Dhananjay Ravat
Keyword(s):  
Source Parameters ◽  
Euler Method ◽  
Analytic Signal ◽  
Magnetic Data ◽  
Euler Deconvolution ◽  
Automatic Interpretation ◽  
Different Depths ◽  
Ground Magnetic ◽  
Theoretical Simulations ◽  
Airborne Magnetic

We present a new automatic method of interpretation of magnetic data, called AN‐EUL (pronounced “an oil”). The derivation is based on a combination of the analytic signal and the Euler deconvolution methods. With AN‐EUL, both the location and the approximate geometry of a magnetic source can be deduced. The method is tested using theoretical simulations with different magnetic models placed at different depths with respect to the observation height. In all cases, the method estimated the locations and the approximate geometries of the sources. The method is tested further using ground magnetic data acquired above a shallow geological dike whose source parameters are known from drill logs, and also from airborne magnetic data measured over a known ferrometallic object. In both these cases, the method correctly estimated the locations and the nature of these sources.

scholarly journals Performance of Two Different Flight Configurations for Drone-Borne Magnetic Data

Sensors ◽  
2021 ◽  
Vol 21 (17) ◽  
pp. 5736
Author(s):  
Filippo Accomando ◽  
Andrea Vitale ◽  
Antonello Bonfante ◽  
Maurizio Buonanno ◽  
Giovanni Florio
Keyword(s):  
Electromagnetic Interference ◽  
Source Parameters ◽  
Spectral Characteristics ◽  
Magnetic Data ◽  
Prototype System ◽  
Control Dataset ◽  
Periodic Data ◽  
Ground Magnetic ◽  
The Stability ◽  
Careful Processing

The compensation of magnetic and electromagnetic interference generated by drones is one of the main problems related to drone-borne magnetometry. The simplest solution is to suspend the magnetometer at a certain distance from the drone. However, this choice may compromise the flight stability or introduce periodic data variations generated by the oscillations of the magnetometer. We studied this problem by conducting two drone-borne magnetic surveys using a prototype system based on a cesium-vapor magnetometer with a 1000 Hz sampling frequency. First, the magnetometer was fixed to the drone landing-sled (at 0.5 m from the rotors), and then it was suspended 3 m below the drone. These two configurations illustrate endmembers of the possible solutions, favoring the stability of the system during flight or the minimization of the mobile platform noise. Drone-generated noise was filtered according to a CWT analysis, and both the spectral characteristics and the modelled source parameters resulted analogously to that of a ground magnetic dataset in the same area, which were here taken as a control dataset. This study demonstrates that careful processing can return high quality drone-borne data using both flight configurations. The optimal flight solution can be chosen depending on the survey target and flight conditions.

Imaging depth, structure, and susceptibility from magnetic data: The advanced source-parameter imaging method

Geophysics ◽  
2005 ◽  
Vol 70 (4) ◽  
pp. L31-L38 ◽  
Author(s):  
Richard S. Smith ◽  
Ahmed Salem
Keyword(s):  
Source Parameters ◽  
Thin Sheet ◽  
Signal Amplitude ◽  
Horizontal Cylinder ◽  
Analytic Signal ◽  
Magnetic Data ◽  
Imaging Method ◽  
Structural Index ◽  
Synthetic Test ◽  
Vertical Contact

An important problem in the interpretation of magnetic data is quantifying the source parameters that describe the anomalous structure. We present a new method that uses various combinations of the local wavenumbers for estimating the depth and shape (structural index) of the structure. Because the estimates are derived from third derivatives of the magnetic data, they are noisy. However, there are multiple ways of calculating the depth and index, and these solutions can be averaged to give a stable estimate. Even so, a synthetic test shows that the results are erratic away from the locations where the analytic-signal amplitude is large. Hence, when we generate images of the depth and structural index, we make the results most visible where the analytic-signal amplitude is large and less visible where the signal is small. The advantage of the method is that estimates can be obtained at all locations on a profile and used to generate continuous profiles or images of the source parameters. This can be used to help identify the locations where interference might be corrupting the results. The structural index image can be used to determine the most appropriate type of model for an area. Assuming this model, it is possible to calculate the depth that would be consistent with the model and the data. Knowing both the depth and model, the analytic-signal amplitude can be converted to apparent susceptibility. If a vertical-contact model is assumed, the susceptibility contrast across the contact can be imaged. For the thin-sheet and horizontal-cylinder models, we can image the susceptibility-thickness and susceptibility-area products, respectively.

Automatic interpretation of magnetic dike parameters using the analytical signal technique

Geophysics ◽  
2001 ◽  
Vol 66 (2) ◽  
pp. 551-561 ◽  
Author(s):  
Mehrdad Bastani ◽  
Laust B. Pedersen
Keyword(s):  
Source Parameters ◽  
Synthetic Data ◽  
Analytical Signal ◽  
Magnetic Data ◽  
Impact Structure ◽  
Horizontal Position ◽  
Coherent Signals ◽  
Automatic Interpretation ◽  
Horizontal Curvature ◽  
The Magnetic Field

The analytical signal of the magnetic field is used to automatically determine the source parameters of dikelike structures. The method is particularly useful for interpreting large amounts of data collected during airborne surveys because it makes full use of the high density of data along the flight lines while simultaneously checking for two‐dimensionality and strike directions by searching for coherent signals in neighboring profiles. The maximum horizontal curvature of the amplitude of the analytical signal is used to locate the dikes along a given profile. Tests with synthetic data show that the dike’s horizontal position is resolved accurately. Magnetic data from the Siljan impact structure in Sweden show that the estimated strikes are reliable and that dip, depth, and width estimates are coherent, especially for well‐isolated dikelike structures.

scholarly journals Automatic Interpretation of Magnetic Data Using Euler Deconvolution with Nonlinear Background

2007 ◽  
Vol 164 (11) ◽  
pp. 2359-2372 ◽  
Author(s):  
Pawan Dewangan ◽  
T. Ramprasad ◽  
M. V. Ramana ◽  
M. Desa ◽  
B. Shailaja
Keyword(s):  
Magnetic Data ◽  
Euler Deconvolution ◽  
Automatic Interpretation

scholarly journals Analytic Signal and Euler Depth Interpretation of Magnetic Anomalies: Applicability to the Beatrice Greenstone Belt

2015 ◽  
Vol 7 (4) ◽  
pp. 108
Author(s):  
Thabisani Ndlovu. ◽  
Mashingaidze R. T. ◽  
Mpofu P.
Keyword(s):  
Regional Scale ◽  
Data Interpretation ◽  
Analytic Signal ◽  
Magnetic Data ◽  
Body Location ◽  
Geological Map ◽  
Ground Magnetic ◽  
Depth Relationship ◽  
Two Parameters ◽  
Good Agreement

We apply the Analytic Signal and Euler depth filtering techniques on magnetic data to identify a magnetic causative body location-depth relationship, two parameters of importance in both geophysical exploration and ore body modelling. We identify a dipping magnetic contact from the interpreted Euler depth anomalies, showing a good agreement with both the Total Field Magnetic (TFM) map and the Analytic Signal (AS) map. The Euler depth anomalies correlate well with the locations and edges of shallow causative bodies. The deeper Euler interpreted sources explain the magnetic high on the regional aeromagnetic map which is coincident with neither geological contacts nor the more recent dolerite intrusions. This suggests that the magnetic highs on the regional aeromagnetic map are due to deep seated sources, otherwise invisible on the regional geological map. The results show the usefulness and relevancy of these two filters not only in interpreting routine TFM data from the study area, but up to a regional scale. While the aeromagnetic data shows that the magnetisation pattern is predominantly divorced from the geological map, the ground magnetic data interpretation points to a more recent magnetisation of the belt, enabling conclusions to be drawn about the geological history and structural geology otherwise not evident on the geological map.

scholarly journals New approach of solving Euler deconvolution relation for the automatic interpretation of magnetic data

2018 ◽  
Vol 29 (3) ◽  
pp. 243-259 ◽  
Author(s):  
Nuraddeen Usman ◽  
Khiruddin Abdullah ◽  
Mohd Nawawi ◽  
Amin Esmail Khalil
Keyword(s):  
Magnetic Data ◽  
Euler Deconvolution ◽  
New Approach ◽  
Automatic Interpretation

scholarly journals Interpretation of high resolution airborne magnetic data (HRAMD) of Ilesha and its environs, Southwest Nigeria, using Euler deconvolution method

2017 ◽  
Vol 64 (4) ◽  
pp. 227-241
Author(s):  
Oluwaseun Tolutope Olurin
Keyword(s):  
High Resolution ◽  
High Amplitude ◽  
Sharp Contrast ◽  
Magnetic Data ◽  
Magnetic Intensity ◽  
Euler Deconvolution ◽  
Southwestern Nigeria ◽  
Near Surface ◽  
Low Amplitude ◽  
Airborne Magnetic

AbstractInterpretation of high resolution aeromagnetic data of Ilesha and its environs within the basement complex of the geological setting of Southwestern Nigeria was carried out in the study. The study area is delimited by geographic latitudes 7°30′–8°00′N and longitudes 4°30′–5°00′E. This investigation was carried out using Euler deconvolution on filtered digitised total magnetic data (Sheet Number 243) to delineate geological structures within the area under consideration. The digitised airborne magnetic data acquired in 2009 were obtained from the archives of the Nigeria Geological Survey Agency (NGSA). The airborne magnetic data were filtered, processed and enhanced; the resultant data were subjected to qualitative and quantitative magnetic interpretation, geometry and depth weighting analyses across the study area using Euler deconvolution filter control file in Oasis Montag software. Total magnetic intensity distribution in the field ranged from –77.7 to 139.7 nT. Total magnetic field intensities reveal high-magnitude magnetic intensity values (high-amplitude anomaly) and magnetic low intensities (low-amplitude magnetic anomaly) in the area under consideration. The study area is characterised with high intensity correlated with lithological variation in the basement. The sharp contrast is enhanced due to the sharp contrast in magnetic intensity between the magnetic susceptibilities of the crystalline and sedimentary rocks. The reduced-to-equator (RTE) map is characterised by high frequencies, short wavelengths, small size, weak intensity, sharp low amplitude and nearly irregular shaped anomalies, which may due to near-surface sources, such as shallow geologic units and cultural features. Euler deconvolution solution indicates a generally undulating basement, with a depth ranging from −500 to 1000 m. The Euler deconvolution results show that the basement relief is generally gentle and flat, lying within the basement terrain.

On the application of Euler deconvolution to the analytic signal

Geophysics ◽  
2006 ◽  
Vol 71 (6) ◽  
pp. L87-L93 ◽  
Author(s):  
G. Florio ◽  
M. Fedi ◽  
R. Pasteka
Keyword(s):  
Potential Field ◽  
Harmonic Functions ◽  
Horizontal Plane ◽  
Homogeneous Function ◽  
Source Parameters ◽  
Analytic Signal ◽  
Euler Deconvolution ◽  
Structural Index ◽  
Vertical Derivative ◽  
First Vertical Derivative

Standard Euler deconvolution is applied to potential-field functions that are homogeneous and harmonic. Homogeneity is necessary to satisfy the Euler deconvolution equation itself, whereas harmonicity is required to compute the vertical derivative from data collected on a horizontal plane, according to potential-field theory. The analytic signal modulus of a potential field is a homogeneous function but is not a harmonic function. Hence, the vertical derivative of the analytic signal is incorrect when computed by the usual techniques for harmonic functions and so also is the consequent Euler deconvolution. We show that the resulting errors primarily affect the structural index and that the estimated values are always notably lower than the correct ones. The consequences of this error in the structural index are equally important whether the structural index is given as input (as in standard Euler deconvolution) or represents an unknown to be solved for. The analysis of a case history confirms serious errors in the estimation of structural index if the vertical derivative of the analytic signal is computed as for harmonic functions. We suggest computing the first vertical derivative of the analytic signal modulus, taking into account its nonharmonicity, by using a simple finite-difference algorithm. When the vertical derivative of the analytic signal is computed by finite differences, the depth to source and the structural index consistent with known source parameters are, in fact, obtained.

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