Magnetic Field Anomalies Research Articles

The Identification of Faults using Magnetic Method in Kulonprogo, Yogyakarta, Indonesia

The aims of this study to identify faults and identify subsurface lithology using magnetic anomaly data in the Kulonprogo. In the acquisition was carried out using a Proton Procession Magnetometer (PPM) Geotron G5 with 62 measurement points and a distance of ±1 km between point. Measurements were made on Kebobutak (Tmok), Aluvium (Qa), Andesit (a), and Sentolo (Tmps) formations. The total magnetic field data processing is done with several correction, namely diurnal correction, IGRF, reduce to equator, upward continuation at an altitude of 2000 m, and reduce to pole, and 2D modelling using the forward modelling method. The result of the analysis obtained magnetic field anomaly values in the range of values -400 to 950 nT. The 2D modelling shows that the research area is composed of 4 dominating rock types, namely andesite rock with a susceptibility value of 94 x 10-3, andesite breccia rock with a susceptibility value of 29 x 10-3, clay rock with a susceptibility value of 0,013 x 10-3, and sandstone with a susceptibility value of 5 x 10-3. The identification result show the existence of faults line on Mount Watuaglik, Mount Kamal, and Mount Bodag.

Estimation of Subsurface Structure Using Euler Deconvolution Method of Magnetic Data at the Geothermal Area of Sonai Village and its Surroundings, Konawe Regency

It has been carried out research with the aim of determining the subsurface structure at the geothermal area of Sonai Village and its surroundings, Konawe Regency. The data used are magnetic data obtained through field measurements at 126 points in the N180oS direction. After the data were subjected to diurnal and IGRF corrections, a residual (local) magnetic field anomaly of around -150 nT to 90 nT was obtained. On the residual magnetic anomaly map which has been reduced to the Pole (RTP), the Euler Deconvolution (ED) method is applied to the Index Structure N=0 to estimate the subsurface structure in the form of the presence of minor faults, and it is known that there are 5 minor faults at a depth of around 9 to 38 meters. Information on the existence of these faults is then used in 2D modeling. Modeling results show that these minor faults cut through two rock layers, which are the layers composed of conglomerate rocks from the Alangga Formation and peridotites as bedrock from the Ultramafic Complex. One of the minor faults closest to the manifestation area (hot spring) is at coordinates around 4o1’12.412” S and 122o7’24.263” E to 4o1’15.532” S and 122o7’19.561” E with a distance of ±15 meters. The existence of these minor faults is thought to be the migration routes for heat flow or conduction to the surface at the geothermal area of Sonai Village and its surroundings.

Development of three-dimensional forward modeling method for the magnetometric resistivity (MMR) method

We have developed a 3-D forward modeling method for the magnetometric resistivity (MMR) technique, specially focusing on the marine MMR method, which utilizes a vertical bipole source and seafloor receivers to measure magnetic field variations. The bipole source generates an artificial electric current between two electrodes: one on the sea surface and another on the seafloor. When computing the electric potential using the relaxation method, while conserving electric current, singularities arise at the electrode locations. To address this issue, we introduce two electrical resistivity structures to mitigate the effects of these singularities and to obtain magnetic field anomalies caused by arbitrary 3-D electrical resistivity anomalies beneath the seafloor. By determining the sign of the magnetic field anomaly, we can infer whether the electrical resistivity of the anomalous body is more conductive or more resistive compared to the surrounding oceanic crust. Furthermore, we demonstrate that increasing the number of bipole sources is more effective in exploring anomalous bodies than increasing the number of receivers.Graphical abstract

Estimating Bedrock Depth Based on Total Magnetic Field Anomaly Data in Medan City Area in the Northern Sumatra Basin Using the Peter Half Slope Method

Estimating Bedrock Depth Based on Total Magnetic Field Anomaly Data in Medan City Area in the Northern Sumatra Basin Using the Peter Half Slope Method

A Passive Approach to Mine Detection and Classification Utilizing Magnetic Fields and Convolutional Neural Networks

Active detectors are widely used today for mine detection, providing high accuracy. However, their operating principle can pose a danger, as it has the potential to trigger the detonation of hidden mines. This study introduces an innovative method for detecting and classifying mines composed of different materials (metallic, semi-metallic, plastic) through the use of a convolutional neural network. The network analyzes anomalies derived from a uniquely designed feature matrix, achieving notable accuracy in classification. The classification process is based on a feature input vector that includes: voltage readings from the FLC-100 magnetic field sensor, which detects magnetic field anomalies near mines with sensitivities ranging from 10⁻¹⁰ to 10⁻⁴ Tesla; data from six soil types, considering their moisture content; and the sensor's height above the mine. Since mines made from different materials exhibit distinct magnetic properties, utilizing magnetic field anomaly data allows for effective material-based mine classification. The classification accuracy was evaluated using various metrics, such as F1, Precision, Accuracy, FPR, FNR, Recall, and TNR.

Robust Heading and Attitude Estimation of MEMS IMU in Magnetic Anomaly Field Using a Partially Adaptive Decoupled Extended Kalman Filter and LSTM Algorithm

Robust Heading and Attitude Estimation of MEMS IMU in Magnetic Anomaly Field Using a Partially Adaptive Decoupled Extended Kalman Filter and LSTM Algorithm

ВПЛИВ МІГРАЦІЇ ФЛЮЇДІВ НА МАГНІТНУ МІНЕРАЛОГІЮ ҐРУНТІВ

Background. The war in Ukraine arises the urgent need to intensify hydrocarbon production on its own territory in order to maintain and develop the country's energy independence. The effectiveness, low cost and relevance of the involvement are demonstrated by magnetic methods of studies of the near surface geological section and the soil for the oil and gas prospecting. Methods. The methodology of magnetic studies for the hydrocarbon prospecting is based on the methods of studying the environmental magnetism and soil, precision magnetic survey of natural systems and authigenic models of changes in magnetic mineralogy under the influence of hydrocarbon fluid migration. Results. The crucial aim is to distinguish the sources of the formation of the magnetic minerals. In most cases, soils contain minerals of natural pedogenic origin, authigenic secondary magnetic minerals, and sometimes detrital fine-coarse magnetic phases. For Ukraine, magnetite, maghemite, hematite, and goethite are the most common magnetic minerals of soils of the pedogenic origin. At the same time, the experience of conducting magnetic mineralogical analyzes of soils in the territories of oil and gas deposits indicates the presence of iron sulfides. First of all, monoclinic pyrrhotite is identified. The soils also contain accompanying hexagonal pyrrhotite, pyrite, and greigite. The results of thermomagnetic analyzes and hysteresis loops of soil samples collected at the territories of hydrocarbon deposits are presented and their mineral composition is analyzed. Conclusions. The results of the study of the impact of hydrocarbon fluid migration (microseepage) on the change in the mineral composition of soils indicate significant informativeness and the perspective of introducing the method into the complex of geological exploration works at various stages. Authigenic changes of magnetic minerals in the near surface geological section and soil, as well as natural and anthropogenic accumulation of hydrocarbon products in soils, cause changes in magnetic properties and form magnetic field anomalies.

УДОСКОНАЛЕНА МЕТОДИКА ДЕТАЛЬНОЇ МАГНІТНОЇ ЗЙОМКИ ДЛЯ ВИРІШЕННЯ ЗАВДАНЬ НАФТОГАЗОВОЇ ГЕОЛОГІЇ

Background. Nowadays, interest in studying the local anomalous magnetic field to solve the problems of oil and gas geology is growing, and the capabilities of the equipment can significantly increase the speed, accuracy and detail of work. Accordingly, the development and testing of an improved method of detailed magnetic recording in motion becomes relevant. Methods. For areas with low gradient magnetic field, we assessed the accuracy of the survey by comparing the maps obtained from repeated surveys of the site. Results. The survey of the magnetic field was conducted in the movement. The total surveyed area was about 20 square kilometers in the Zinkovsky district of the Poltava region. The inter-profile distance was about 50 meters, the distance between the points of observation on the profile was about 1 meter. This grid of observations allows us to get maps that differ significantly from the maps obtained by the usual density of observations. This technique also allows identifying local anomalies, and drawing conclusions about the fine structure of the magnetic field. The main objects that form anomalies and their geological characteristics are identified. On this basis, interpreted magnetic field anomalies in oil and gas regions were catalogued. Conclusions. We have proposed explanation of tectonic and geochemical factors, which form local anomalies of the magnetic field of the studied areas. Three types of anomalies associated with ravines are distinguished. Positive anomalies over ravines and step-type anomalies, in our opinion, are associated with tectonic movements, and negative anomalies are due to slope wash processes. Alternating magnetic fields in the studied areas may be due to ferruginized deposits.

Preface Special Issue: Developments in Earthquake Precursors Studies

This Special Issue of Annals of Geophysics is dedicated to present recent developments in the field of earthquake (EQ) precursors. Due to their potentially catastrophic nature, EQs have early attracted the attention of humans. During the last decades, a considerable amount of scientific effort has been devoted to the study of EQ precursors, aiming at EQ forecast. Prediction of large EQs, especially in the short-term, is of outmost importance for our society, since it could prevent, or at least restrict, their disastrous consequences, both in terms of infrastructure / material damages and in terms of casualties. It is clear that EQ preparation processes are complex and multifaceted, which call for a multidisciplinary approach. Many possible precursors have been reported and studied during the last decades, which include (just to mention some): foreshock activity, pre-slip effect, surface deformation, seismic electric signals (SES), ultra-low frequency (ULF) magnetic field anomalies, fracture-induced electromagnetic emissions (FEME) (fracture-induced electromagnetic radiation, FEMR), ULF/ELF (extremely low frequency) atmospheric electromagnetic radiation, atmospheric anomalies (such as SLHF, OLR etc.) and ionospheric (lower and upper regions) anomalies, lithosphere-atmosphere-ionosphere (LAI) coupling, even abnormal animal behavior.

Structural and tectonic features of the Transcarpathian trough according to gravity and magnetic data

Based on the analysis and interpretation of gravity and magnetic field anomalies, we studiedthe peculiarities of fault tectonics, structural-tectonic structure (including salt dome tectonics) of the Transcarpathian trough. We identified signs of the manifestation of deep faults and other large structural-tectonic elements in anomalies of gravity and magnetic fields. We then traced these structural-tectonic units by comparing the morphology, intensity, dimensions, and directions of the typical anomalous zones in the gravitational and magnetic fields with the tectonic structure of the region.
 We used digital maps of gravitational and magnetic fields; averaging transforms and relief-shadow images, we mapped local gravimagnetic anomalies. Analysis of the spatial structure of the original gravimagnetic fields and their transforms and structural-tectonic maps yielded a reflection of large tectonic elements of fault tectonics, anticlinal and salt dome structures in the gravimagnetic fields. Based on gravimagnetic data, the tectonic structure of the Transcarpathian trough was clarified, and the boundaries of tectonic zones and microplates were traced. The zone of the Transcarpathian deep fault is identified as a tectonic zone traced by a band of intense local positive anomalies of the gravity field along the Flysch Carpathians to the border of the Marmarosh massif. It is limited by high gradients from the southwest and northeast and is a reflection of the Pieniny and Marmarosh rock zones. The zone of the Transcarpathian deep fault is considered a suture zone of the Inner and Flysch Carpathians. In the structure of the anomalous gravity field of the Transcarpathian trough, a number of local anomalies associated with salt stocks, as well as individual anomalies, expected to be connected to salt-bearing deposits, werefound.
 We confirmed the effectiveness of gravimagnetic methods in the geological conditions of the Transcarpathian trough to detect anticlinal structures, basement protrusions, which create favorable conditions for oil and gas traps in sedimentary strata. Interpreting anomalous gravimagnetic fields in combination with geological and tectonic materials is an important condition for the integral process of studying the geological and tectonic structure of the Earth’s crust in the Transcarpathian region.

New geophysical and zircon data support an impact hypothesis for the Velingara structure (Senegal)

On Earth, impact structures are rare in intertropical zones. Here we evaluate the 35–40 km diameter Velingara depression in Senegal as a candidate impact structure. The depression has a topographic relief of only 50 m and is essentially buried under modern sediments. For the first time, potential-field ground observations and a microstructural survey of detrital zircons for shock features were conducted at Velingara. A 15 mGal gravity low in a 10 km diameter central anomaly was found, while significant (100 nT) amplitude magnetic field anomalies were observed in the depression. Forward modeling was used to explain the crustal sources of the anomalies, arguing in favor of the presence of a buried impact structure. An electron backscatter diffraction survey of circa 5,000 detrital zircons from a sample of modern alluvium identified a single granular zircon; orientation data for the grain does not record the former presence of reidite, but does closely resemble grains with highly dispersed neoblast orientations that have only been reported from impact settings. Age determination by LA-ICP-MS indicates the unusual granular zircon recorded an age of ca. 550 Ma. Results of the geophysical data and zircon microstructural survey reported here are consistent with, but do not yet prove, an impact origin hypothesis for the Velingara structure. The difference in amplitude between the diameter of the depression, and that of the gravity anomaly remains puzzling. Several impact scenarios are considered, which include the subsequent evolution via surface processes of a 10-km crater into a larger depression, or a large-scale (d = 40 km) complex impact crater with a peculiar geophysical anomaly limited to its central region.

Magnetic field map of the Wilhelm Archipelago shelf zone, West Antarctica

The Antarctic Digital Magnetic Anomaly Project is an international research effort to construct a magnetic map of the continent based on ground, satellite, marine, and aeromagnetic surveys. This paper reports the magnetic mapping of the shelf zone in the SE part of the Wilhelm Archipelago, West Antarctica, based on magnetic surveys conducted with Zodiac boats. A spectacular feature of this area is the strong magnetic anomaly of the Antarctic Peninsula (AP) batholith, which was the product of subduction-related Mesozoic–Cenozoic arc magmatism on the former margin of Western Gondwana. We constructed and analyzed a detailed magnetic map of magnetic field anomalies using field observations of rock exposures on the islands and magnetic properties of rocks from laboratory data. The oldest volcanic rocks of Jurassic to Lower Cretaceous age relate to N-NE trending bands of negative magnetic field. The largest feature in the study area is an Upper Cretaceous/Paleogene granodiorite complex that produces a positive magnetic anomaly. Many smaller anomalies are also present over gabbroid bodies of Cretaceous age. Two-dimensional magnetic modeling shows that heterogeneities in the upper crust may have magnetic susceptibilities in the range of 0.005–0.13 SI. Magnetic field anomalies also delineate an orthogonal system of tectonic faults, including the main NE fault along the Penola Strait (sub-parallel to the AP coastline) and four intersecting faults. These fault systems may be associated with different stages of continental margin evolution along the Antarctic Peninsula.

Interpretasi Struktur Bawah Permukaan Menggunakan Data Anomali Medan Magnet Daerah Manifestasi Panas Bumi Sampuraga Kabupaten Mandailing Natal

This research was conducted to identify the distribution of magnetic field anomalies to determine the subsurface structure of the area around Sampuraga hot springs. Magnetic field data was measured using a magnetometer in an area with dimensions of 1400 m x 1100 m with 154 points. The measurement data is a total magnetic field, and to obtain magnetic field anomaly values, corrections are made for diurnal variation and IGRF correction. Magnetic field anomaly values range from 353,1 nT to 7622,0 nT. Magnetic field anomaly data were processed using the Oasis Montaj software by reducing to the poles, upward continuation, and 2D modeling. The 2D modeling results show three layers of soil in the study area. The upper part (first and second layers) is interpreted as a caprock. This layer consists of sedimentary rock types of sandstone and clay and igneous rock in the form of granite at a depth of up to 1700 m. The lower part (third layer) is interpreted as a reservoir. This layer consists of metasedimentary volcanic rock, clay alteration, andesitic lava, and dacitic lava with a depth of up to 2030 m from the ground surface. The results of this model also interpret the fault zone as an outflow zone so that it forms manifestations on the surface. These three geothermal system components show that the Sampuraga area can be further developed and explored.

Seismic regime and features of geophysical fields in the epicentral area of the Andrey-Tas earthquake (seismotectonic zone of the Chersky Randge, northeast Yakutia)

This paper describes the strong Andrey-Tass earthquake (Mѡ=6.1), which occurred in 2008 on the northeastern flank of the seismotectonic zone of the Chersky Randge in the region of the interaction of the Eurasian and North American lithospheric plates. Geophysical fields were using to elucidate structural and tectonic features of the study area and their relationship with seismicity. Using data from digital maps of magnetic and gravity field anomalies, it was possible to clarify the kinematic parameters of the western end of the Ilin-Tas fault, where the epicenter of the Andrey-Tas earthquake occurred. This fault separates the Indigiro-Zyrian Trough from the Momskii Randge and Andrei Tas Locke elevations and is traced by gradient zones of transition from negative to positive ΔTa and Δg values. The main seismic shock is confining to thickening of Δg isoanomalies, which form a gravitational step, within which gravity values decrease from south to north. The entire epicentral field with aftershocks covers the western slope of the Andrei Tas Locke. The development of the seismic process during three stages was analyzed: 1963-2007 (before the event), 2008 (the event with aftershocks), 2009-2020 (after the event). We plotted the recurrence of the aftershocks of the Andrei Tas earthquake. Information obtained because of study of Andrei Tas earthquake aftershocks enables us to detail manifestations of local seismic activity.

An enhanced view on the Mediterranean Sea crust from potential fields data

The Earth’s crust is exceptionally important to understand the geological evolution of our planet and to access natural resources as minerals, critical raw materials, geothermal energy, water, hydrocarbons, etc.. However, in many regions of the world it is still poorly modelled and understood. Here we present the latest advance on three-dimensional modelling of the Mediterranean Sea crust based on freely available global gravity and magnetic field models. The proposed model, based on the inversion of gravity and magnetic field anomalies constrained by available a-priori information (such as interpreted seismic profiles, previous studies, etc.), provides, with an unprecedented spatial resolution of 15 km, the depths of the main modelled geological horizons (Plio-Quaternary, Messinian and Pre-Messinian sediments, crystalline crust and upper mantle), coherent with the known available constraints, together with the three-dimensional distribution of density and magnetic susceptibility. The inversion is carried out by means of a Bayesian algorithm, which allows to modify at the same time the geometries and the three dimensional distributions of density and magnetic susceptibility, always respecting the constraints introduced by the initial information. In addition to unveil the structure of the crust beneath the Mediterranean Sea, the present study also shows the informative content of freely available global gravity and magnetic models, thus putting the base for the development of future high resolution models of the Earth crust at global level.

Local magnetic anomalies of the Ukrainian Shield as indicators of the manifestation of different-age stages of focal-channel magmatism

A special class of local small sizes of subisometric magnetic field anomalies (AMF) of the Ukrainian Shield (USh) is considered here. Such AMF are united by the volcanogenic-intrusive-tubular origin of the sources associated with the assumed source-channel manifestations of pulsed plutonic-degassing processes of the Earth. The geological study of such anomalies indicates the enrichment of their sources with mineralization of dark, noble, non-ferrous and rare metals. Some of these AMF (Zhdanivska group, Rivnenska) in general contours coincide with local gravitational minima due to decompaction and grinding of the rocks that cause them, despite the basic-ultrabasic composition. Other anomalies, on the contrary, fully correspond to the maxima of gravity due to the enrichment of rocks with magnetite (Pischansk AMF) or ilmenite (Stremigorodsk AMF) on an industrial scale. In the section, all the studied sources of anomalies have a funnel-shaped (sometimes fungal-shaped) or stock-like shape, which indicates the focal-channel type of their genesis.
 A characteristic feature of some of the studied AMF are peculiarities of the magnetization vector of their sources, which has variable directions in the section and is often subhorizontal (Kalyniv group of anomalies, Rivne and Stremigorod AMF), which is unusual for the USh latitudes. This indicates a multiphase and separation in time formation of the sources of these anomalies from the Archean-Proterozoic time of formation of the surrounding USh rocks. This time may be either Proterozoic (Stremigorod AMF), or Phanerozoic (Rivnenska AMP — early Paleozoic). A number of similar in size and concentrically-zonal shape of Cenozoic AMF has been established, for example, within the TransCarpathian fault zone.
 The obtained results show that within the Ukrshield there is a certain number of small-sized structures associated with different-age focal-channel manifestations of pulsed intrusive and plutonic-degassing processes of the Earth, which are much more widespread than it has been supposed. This does not only extend the prospecting possibilities for new types of minerals associated with the processes of magmatism and degassing of the Earth, but also contains a new additional information in the context of the universal history of the Ukrshield formation and its ore potential

Mapping structural lineaments using the edge filters of the potential field: a case study of the Rizhao–Lianyungang area, East China

Background: Edge enhancement plays an important role in potential field data processing and interpretation, which facilitate regional tectonic studies, mineral and energy exploration. This is because edges on potential field often indicate linear geological structures such as fractures, edges of geological bodies and so on. With the development of meticulous edge enhancement on potential field, the phenomenon of false edges caused by the associated anomalies when detect ing edges from magnetic field cannot be ignored.Methods: Aiming at this problem, we proposes a modified magnetic edge detection method (SP Mag) based on the second order spectral moment. This method has been tested on both synthetic and field data. The synthetic test show that SP Mag cannot only balanced edges no matter from strong or weak anomalies, but also eliminates those false edges caused by the associated anomalies in magnetic field, which provide more effective information for subsequent interpretation.Results: We apply this new method to the RTP aero magnetic field and gravity field of Rizhao Lianyungang area. The lineaments recognized by the SP Mag method correspond well with geologic structures through comparing with geological maps.Discussion: The results illustrate the usefulness of the method for potential field interpretation. Furthermore, more geological and geophysical data should be still combined for comprehensive interpretation in the actual interpretation, though the SP Mag method can recognize lineaments effectively.

Coherence of Bangui Magnetic Anomaly with Topographic and Gravity Contrasts across Central African Republic

The interactions between the geophysical processes and geodynamics of the lithosphere play a crucial role in the geologic structure of the Earth’s crust. The Bangui magnetic anomaly is a notable feature in the lithospheric structure of the Central African Republic (CAR) resulting from a complex tectonic evolution. This study reports on the coherence in the geophysical data and magnetic anomaly field analysed from a series of maps. The data used here include raster grids on free-air altimetric gravity, magnetic EMAG2 maps, geoid EGM2008 model and topographic SRTM/ETOPO1 relief. The data were processed to analyse the correspondence between the geophysical and geologic setting in the CAR region. Histogram equalization of the topographic grids was implemented by partition of the raster grids into equal-area patches of data ranged by the segments with relative highs and lows of the relief. The original data were compared with the equalized, normalized and quadratic models. The scripts used for cartographic data processing are presented and commented. The consistency and equalization of topography, gravity and geoid data were based using GMT modules ‘grdfft’ and ‘grdhisteq’ modules. Using GMT scripts for mapping the geophysical and gravity data over CAR shows an advanced approach to multi-source data visualization to reveal the relationships in the geophysical and topographic processes in central Africa. The results highlighted the correlation between the distribution of rocks with high magnetism in the central part of the Bangui anomaly, and distribution of granites, greenstone belts, and metamorphosed basalts as rock exposure. The correspondence between the negative Bouguer anomaly (<−80 mGal), low geoid values (<−12 m) and the extent of the magnetic anomaly with extreme negative values ranging from −1000 to −200 nT is identified. The integration of the multi-source data provides new insights into the analysis of crustal thicknesses and the average density of the Earth in CAR, as well as the magnitude of the magnetic fields with notable deviations caused by the magnetic flux density in the Bangui area related to the distribution of mineral resources in CAR.

Mapping the structural and tectonic objects of the Upper-Kama potassium salt deposit in the magnetic field

Introduction. Petrophysical properties of rocks and strata reflect the long history of the Upper Kama potassium salt deposit (VKMKS) formation and development (about 300 million years) as well as its various endogenous and exogenous geological and geochemical processes. VKMKS geological structure as well as past and present processes at the field are effectively studied by geophysical methods. Experience has shown that, considering the gigantic area of the salt strata development and multi-layer potassium-magnesium salt deposits, high-precision and detailed geophysical studies performed on most of the VKMKS territory are most effective from a geological viewpoint, namely, gravity survey at a scale of 1 : 25,000 and aeromagnetic survey at a scale of 1 : 10,000 together with other geological and geophysical data. VKMKS structural-tectonic objects occurrence conditions and magnetic properties of their rocks and strata, especially magnetic susceptibility, form the petrophysical basis for the aeromagnetic survey applied to map the objects. The task of mapping structural-tectonic objects on the VKMKS territory in a magnetic field is a specific task of using aeromagnetic survey to map structural-tectonic objects in a weakly magnetic sedimentary cover of the entire Perm Cis-Urals. Methods of research includes studying and analyzing the research data of the Perm Cis-Urals sedimentary cover rock magnetic properties (magnetic susceptibility). The morphology of structural-tectonic objects magnetic field anomalies in the Perm Cis-Urals sedimentary cover and the morphology of VKMKS structural-tectonic objects magnetic field anomalies are studied and analyzed. Research results. The analysis of sedimentary cover rocks magnetic susceptibility and aeromagnetic survey data interpretation showed that the structural-tectonic objects of the cover create anomalies in the magnetic field. The anomalies exceed the intensity of three times the root-mean-square measurement error, and therefore are mapped with confidence. Conclusions. It is reasonable to use the data of areal high-precision aeromagnetic survey at a scale of 1 : 10,000 together with other geological and geophysical methods to improve the reliability of mapping such important structural and tectonic objects as tectonic faults of various ranks, from deep faults to fracture zones, at VKMKS.

Fast and Noise-Resilient Magnetic Field Mapping on a Low-Cost UAV Using Gaussian Process Regression.

This study presents a comprehensive approach to mapping local magnetic field anomalies with robustness to magnetic noise from an unmanned aerial vehicle (UAV). The UAV collects magnetic field measurements, which are used to generate a local magnetic field map through Gaussian process regression (GPR). The research identifies two categories of magnetic noise originating from the UAV's electronics, adversely affecting map precision. First, this paper delineates a zero-mean noise arising from high-frequency motor commands issued by the UAV's flight controller. To mitigate this noise, the study proposes adjusting a specific gain in the vehicle's PID controller. Next, our research reveals that the UAV generates a time-varying magnetic bias that fluctuates throughout experimental trials. To address this issue, a novel compromise mapping technique is introduced, enabling the map to learn these time-varying biases with data collected from multiple flights. The compromise map circumvents excessive computational demands without sacrificing mapping accuracy by constraining the number of prediction points used for regression. A comparative analysis of the magnetic field maps' accuracy and the spatial density of observations employed in map construction is then conducted. This examination serves as a guideline for best practices when designing trajectories for local magnetic field mapping. Furthermore, the study presents a novel consistency metric intended to determine whether predictions from a GPR magnetic field map should be retained or discarded during state estimation. Empirical evidence from over 120 flight tests substantiates the efficacy of the proposed methodologies. The data are made publicly accessible to facilitate future research endeavors.