scholarly journals Application of magnetic method to characterize Abaya campus building site, Southern Ethiopia

2022 ◽  
Author(s):  
Abraham Mulualem
Keyword(s):  
Analytical Signal ◽  
Magnetic Data ◽  
Magnetic Method ◽  
Southern Ethiopia ◽  
Geological Structures ◽  
Engineering Structures ◽  
Building Site ◽  
Corrected Data ◽  
Anomaly Map ◽  
East West

Abstract A geophysical survey involving magnetic method is conducted using ENVI-MAG proton precision magnetometer. The study is carried out with the aim of identifying the possible geological structures which may responsible for the failure of engineering structures. Three traverses having east –west orientation with a ten meters profile spacing and a readings station spacing and one traverse across the three traverses and randomly collected magnetic data were used. At each station three readings were taken and averaged out in order to increase the accuracy of data and diurnal and geomagnetic corrections were made. With the corrected data different anomalous maps were produced like total magnetic field anomaly map, residual magnetic anomaly map and analytical signal map using Oasis montaji6.4 software for further interpretation. The result of this research has shown that the area is affected by different geological structures which may be the cause for the crack and the failure of the building in the area.

scholarly journals Tectonic blocks and suture zones of eastern Thailand: evidence from enhanced airborne geophysical analysis

2013 ◽  
Vol 56 (1) ◽  
Author(s):  
Arak Sangsomphong ◽  
Dhiti Tulyatid ◽  
Thanop Thitimakorn ◽  
Punya Charusiri
Keyword(s):  
Analytical Signal ◽  
Magnetic Data ◽  
Visual Interpretation ◽  
Tectonic Plates ◽  
Magnetic Signature ◽  
Magnetic Signatures ◽  
Reduction To The Pole ◽  
Airborne Geophysical Data ◽  
Cenozoic Sediments ◽  
East West

<p>Airborne geophysical data were used to analyze the complex structures of eastern Thailand. For visual interpretation, the magnetic data were enhanced by the analytical signal, and we used reduction to the pole (RTP) and vertical derivative (VD) grid methods, while the radiometric data were enhanced by false-colored composites and rectification. The main regional structure of this area trends roughly in northwest-southeast direction, with sinistral faulting movements. These are the result of compression tectonics (sigma<span style="font-size: 8px;">_1</span> in an east-west direction) that generated strike-slip movement during the pre Indian-Asian collision. These faults are cross-cut by the northeast-southwest-running sinistral fault and the northwest-southeast dextral fault, which occurred following the Indian-Asian collision, from the transpession sinistral shear in the northwest-southeast direction. Three distinct geophysical domains are discernible; the Northern, Central and Southern Domains. These three domains correspond very well with the established geotectonic units, as the Northern Domain with the Indochina block, the Central Domain with the Nakhonthai block, the Upper Southern Sub-domain with the Lampang-Chaing Rai block, and the Lower Southern Sub-domain with the Shan Thai block. The Indochina block is a single unit with moderate radiometric intensities and a high magnetic signature. The direction of the east-west lineament pattern is underlain by Mesozoic non-marine sedimentary rock, with mafic igneous bodies beneath this. The Nakhonthai block has a strong magnetic signature and a very weak radiometric intensity, with Late Paleozoic-Early Mesozoic volcanic rock and mélange zones that are largely covered by Cenozoic sediments. The boundaries of this block are the southern extension of the Mae Ping Faults and are oriented in the northwest-southeast direction. The Lampang-Chaing Rai and Shan Thai blocks, with very weak to moderate magnetic signatures and moderate to very strong radiometric intensities are dominated by marine clastic and igneous rocks or a northwest-southeast trending deformation zone of inferred Precambrian complexes, respectively. It is suggested that these tectonic plates collided against one another in a west-east direction.</p>

scholarly journals Geophysical perspective on the structural interference zone along the Neoproterozoic Brasília and Ribeira fold belts in West Gondwana

2017 ◽  
Vol 47 (1) ◽  
pp. 3-19
Author(s):  
João Gabriel Motta ◽  
Norberto Morales ◽  
Walter Malagutti Filho
Keyword(s):  
Bouguer Anomaly ◽  
Shear Zones ◽  
Magnetic Data ◽  
Gravity Modeling ◽  
West Gondwana ◽  
Fold And Thrust Belt ◽  
Fold Belts ◽  
Thrust Sheets ◽  
Anomaly Map ◽  
Bouguer Anomaly Map

ABSTRACT: The Brasília and Ribeira fold belts have been established in south-southwestern São Francisco Craton during the Brasiliano-Pan African orogeny (0.9-0.5 Ga - Tonian to Cambrian), and played an important role in West Gondwana continent assembly. The region is given by a complex regional fold and thrust belt superposed by shearing during the orogeny late times, with superposing stress fields forming a structural interference zone. These thrust sheets encompasses assemblies from lower- to upper-crust from different major tectonic blocks (Paranapanema, São Francisco), and newly created metamorphic rocks. Re-evaluation of ground gravity datasets in a geologically constrained approach including seismology (CRUST1 model) and magnetic data (EMAG2 model) unveiled details on the deep- crust settings, and the overall geometry of the structural interference zone. The Simple Bouguer Anomaly map shows heterogeneous density distribution in the area, highlighting the presence of high-density, high metamorphic grade rocks along the Alterosa suture zone in the Socorro-Guaxupé Nappe, lying amid a series of metasedimentary thrust scales in a regional nappe system with important verticalization along regional shear zones. Forward gravity modeling favors interpretations of structural interference up North into Guaxupé Nappe. Comparison to geotectonic models shows similarities with modern accretionary belts, renewing the discussion.

scholarly journals PEMODELAN BAWAH PERMUKAAN MANIFESTASI MINERAL DENGAN METODE GEOMAGNETIK DAERAH PACITAN JAWA TIMUR

KURVATEK ◽  
2019 ◽  
Vol 4 (1) ◽  
pp. 25-33
Author(s):  
Fatimah Fatimah
Keyword(s):  
Image Data ◽  
Geological Structure ◽  
Magnetic Data ◽  
Magnetic Intensity ◽  
Magmatic Arc ◽  
The North ◽  
Ore Minerals ◽  
Ore Mineralization ◽  
Extensional Structure ◽  
Anomaly Map

Tulakan Subdistrict, Pacitan Regency, East Java Province. This area is part of the Southern Mountain Zone of East Java, which is the Sunda-Banda magmatic arc of Oligo-Miocene age, where there are alterations and indications of valuable ore minerals. Field magnetic data is taken in an area of 1 x 1 km, with the looping method on the grid trajectory within 200 x 100 m. Then, magnetic data correction and data processing were carried out with Oasis Montaj. From the magnetic anomaly map, the value of high magnetic intensity in the southern part is fresh (intrusive) andesit-dasitic rock as host rock which causes alteration, in the middle has a low magnetic intensity value which is in the direction of the relatively NE-SW river direction, whereas in the north with high intensity is fresh andesite lava. From the image data, it can be seen that the straightness pattern of the geological structure which is dominated by the extensional structure with the direction of NE-SW and E-W is the main trap of epithermal veins carrying ore mineralization mainly Cu, Pb in the study area.

scholarly journals PEMETAAN SEBARAN BATUAN PENYUSUN PAGAR CANDI DI SITUS CANDI LOSARI DUSUN LOSARI, DESA SALAM, KECAMATAN SALAM, KABUPATEN MAGELANG BERDASARKAN METODE MAGNETIK

2013 ◽  
Vol 33 (1) ◽  
pp. 121-131
Author(s):  
Novi Dwi Ariani ◽  
Thaqibul Fikri Niyartama ◽  
Nugroho Budi Wibowo
Keyword(s):  
Magnetic Field ◽  
Field Data ◽  
Daily Variation ◽  
Local Magnetic Field ◽  
Magnetic Data ◽  
Reference Field ◽  
Magnetic Pole ◽  
Local Anomaly ◽  
Anomaly Pattern ◽  
Anomaly Map

Mapping geophysics research was conducted by geomagnetic method to know anomaly pattern of magnetic pole and to know distribution location and depth of temple gate composing stone in Losari Temple Site by using magnetic data. Data collection used Proton Precessions Magnetometer (PPM) G-856AX by area width of 88 km x 40 km and measurement space of 3 meter used looping method. Field data was corrected by daily variation and IGRF (International Geomagnetics Reference Field) correction and then reduction to pole. The slice modeling was conducted on local anomaly map on height of 6 meter. The result of the local magnetic field anomalies incision then interpolated to get an idea of the spread and depth of rocks making up the fence Losari temple. Local anomaly map shows that anomaly position lies in southwest, southeast, and northeast from main temple. Based from interpolated distribution of magnetic pole anomaly is dominated in depth of 2 meter to 4 meter. 

scholarly journals Inner structure of the Puy de Dôme volcano: cross-comparison of geophysical models (ERT, gravimetry, muon imaging)

2013 ◽  
Vol 2 (1) ◽  
pp. 47-54 ◽  
Author(s):  
A. Portal ◽  
P. Labazuy ◽  
J.-F. Lénat ◽  
S. Béné ◽  
P. Boivin ◽  
...  
Keyword(s):  
Electrical Resistivity Tomography ◽  
Bouguer Anomaly ◽  
Geophysical Methods ◽  
Geological Structures ◽  
Resistivity Tomography ◽  
Density Distributions ◽  
Stage Of Development ◽  
The World ◽  
Joint Interpretation ◽  
East West

Abstract. Muon imaging of volcanoes and of geological structures in general is actively being developed by several groups in the world. It has the potential to provide 3-D density distributions with an accuracy of a few percent. At this stage of development, comparisons with established geophysical methods are useful to validate the method. An experiment has been carried out in 2011 and 2012 on a large trachytic dome, the Puy de Dôme volcano, to perform such a comparison of muon imaging with gravimetric tomography and 2-D electrical resistivity tomography. Here, we present the preliminary results for the last two methods. North–south and east–west resistivity profiles allow us to model the resistivity distribution down to the base of the dome. The modelling of the Bouguer anomaly provides models for the density distribution within the dome that are directly comparable with the results from the muon imaging. Our ultimate goal is to derive a model of the dome using the joint interpretation of all sets of data.

APPLICATION OF SEMI-AUTOMATED AND INTERACTIVE MAGNETIC INTERPRETATION TECHNIQUES IN PETROLEUM EXPLORATION

1977 ◽  
Vol 17 (1) ◽  
pp. 85
Author(s):  
Robert J. Whiteley ◽  
Barry F. Long ◽  
David A. Pratt
Keyword(s):  
Sedimentary Basin ◽  
Sedimentary Basins ◽  
Magnetic Anomalies ◽  
Petroleum Exploration ◽  
Magnetic Data ◽  
Magnetic Method ◽  
Magnetic Interpretation ◽  
Geological Information ◽  
Detailed Interpretation ◽  
Insight Into

The magnetic method is used at many stages of a modern petroleum exploration program. Effective interpretation techniques are required to extract maximum geological information from magnetic data. Those techniques which provide the greatest flexibility and make full use of the talents of experienced interpreters are generally of a semi-automated and interactive nature.There are several practical methods for semi-automated quantitative magnetic interpretation in sedimentary basins. Initial interpretation can be achieved by automatic calculation of characteristic anomaly parameters continuously along original or processed magnetic data profiles. Detailed interpretation of more subtle magnetic features can then follow by theoretical anomaly comparison with field anomalies using interactive portfolio modelling or by direct computation.Examples of the use of these semi-automated techniques in the interpretation of basement and intra-sedimentary magnetic anomalies show that combined magnetic and seismic interpretations can provide considerable insight into the structural processes which have operated in a sedimentary basin.

RESPONSE OF MU-MESON DETECTORS DEEP IN THE ATMOSPHERE TO PRIMARY COSMIC-RAY PARTICLES OF MAGNETIC RIGIDITY BETWEEN 10 AND 25 GV

1967 ◽  
Vol 45 (5) ◽  
pp. 1643-1653 ◽  
Author(s):  
T. Mathews ◽  
G. G. Sivjee
Keyword(s):  
Sea Level ◽  
Scintillation Counter ◽  
Cosmic Ray ◽  
Decay Rates ◽  
Atmospheric Effects ◽  
Ionization Chambers ◽  
Corrected Data ◽  
Counter Telescope ◽  
East West ◽  
Different Altitudes

The cosmic-ray mu-meson intensities at three different altitudes at the equator were measured as a function of zenith and azimuth angles by means of a portable scintillation counter telescope of semi-opening angles 23°. The data were analyzed to assess the effects of differences in pi- and mu-meson decay rates on the intensity of the penetrating ionizing component at different zenith angles. It was found that the changes of intensity as a function of zenith angles could be attributed almost entirely to differences in atmospheric absorption, provided that at all zenith angles the threshold rigidities were the same. Hence the intensities measured at different zenith angles in the east–west plane at the equator could be corrected to remove the atmospheric effects and the corrected data used for determining the response of meson detectors at sea level to particles of rigidity up to 25 GV. The response curve thus obtained is presented and compared with that obtained from sea-level latitude surveys by means of ionization chambers.

Interpretation of airborne magnetic survey of Gabel Um Tineidba area, south eastern desert, Egypt

2015 ◽  
Vol 12 (6) ◽  
pp. 563-576
Author(s):  
Tharwat H. Abdel Hafeez
Keyword(s):  
Analytical Signal ◽  
Eastern Desert ◽  
Structural Features ◽  
Geological Mapping ◽  
Magnetic Data ◽  
Magnetic Survey ◽  
Aeromagnetic Survey ◽  
Reasonable Proportion ◽  
The Cost ◽  
Airborne Magnetic

The study area is regionally covered by rock exposures ranging in age from the Precambrian to Quaternary. The aeromagnetic survey is a useful tool that help in geological mapping, providing information at a reasonable proportion of the cost of ground mapping. The reduced to the northern magnetic pole (RTP) map was separated into regional and residual magnetic component maps by the computed power spectrum of the magnetic data. The estimated mean depths of both regional and residual magnetic sources were found to be 2510 m and 383 m respectively. Also, two advanced techniques were used to analyze the depth magnetic data. These methods are analytical signal (AS) and source parameter imaging (SPI). The results of average depth estimates both methods (–950 m). These depth values were helped -to great extent- for define the direction of throw for the interpreted faults in the basement tectonic map. The statistical analysis shows that, most of the welldeveloped structural features are oriented mostly in the N-S, NNE-SSW, NW-SE and NNWSSE trending faults are considered the main trends affecting the distribution of the radioactive minerals.

The Mid-Atlantic Ridge Near 45°N. XXIII. Analysis of Bathymetric and Magnetic Data

1975 ◽  
Vol 12 (3) ◽  
pp. 337-346 ◽  
Author(s):  
P. J. Bhattacharyya ◽  
R. D. Hyndman ◽  
M. J. Keen
Keyword(s):  
Cross Correlation ◽  
General Trend ◽  
Magnetic Data ◽  
Spreading Center ◽  
Transform Fault ◽  
Contour Maps ◽  
Regional Trends ◽  
Mid Atlantic Ridge ◽  
Lateral Displacements ◽  
East West

Bathymetric and magnetic data obtained from the Mid-Atlantic Ridge near 45°N have been analyzed numerically to determine trends, offsets and local structure. The estimates of regional trends in the data reveal that the average structural trend in this area is 17°E of north, made up of nearly north–south segments periodically offset by small right lateral displacements. The east–west offsets, not always visually manifest in contour maps of the data have been located by a cross-correlation scheme. Frequent small offsets may be the way a ridge crest accommodates to a spreading direction not perpendicular to the general trend of the crest. There is evidence for an old, now dead spreading center to the west of the median valley. This old center with an orientation of about 15°W, terminating in a right lateral transform fault has been abandoned in favor of frequent small offsets which provide smaller resistance to spreading.

A new look at Belgian aeromagnetic and gravity data through image-based display and integrated modelling techniques

1993 ◽  
Vol 130 (5) ◽  
pp. 583-591 ◽  
Author(s):  
B. C. Chacksfield ◽  
W. De Vos ◽  
L. D'Hooge ◽  
M. Dusar ◽  
M. K. Lee ◽  
...  
Keyword(s):  
Large Scale ◽  
Gravity Data ◽  
Bouguer Anomaly ◽  
Digital Processing ◽  
Integrated Modelling ◽  
Magnetic Data ◽  
Gravity Gradient ◽  
The North ◽  
Anomaly Map ◽  
Shaded Relief

AbstractDigital processing and image-based display techniques have been used to generate contour and shaded-relief maps of Belgian aeromagnetic data at a scale of 1:300000 for the whole of Belgium. These highlight the important anomalies and structural trends, particularly over the Brabant Massif. North and vertically illuminated shaded-relief plots, enhanced structural belts trending west–east to northwest–southeast in the Brabant Massif and west–east to southwest–northeast in the core of the Ardennes. The principal magnetic lineaments have been identified from the shaded-relief plots and tentatively correlated to basement structures. Most short lineaments are correlated with individual folds while the more extensive lineaments are correlated with large scale fault structures. Magnetic highs within the Brabant Massif are attributed to folded sediments of the Tubize Group. The magnetic basement in the east of Belgium is sinistrally displaced to the north by an inferred deep NNW–SSE crustal fracture. The Bouguer anomaly map of Belgium identifies the Ardennes as a negative area, and the Brabant Massif as a positive area, with the exception of a WNW–trending gravity low in its western part. The southern margin of the Brabant Massif is defined by a steep gravity gradient coincident with the Faille Bordiere (Border Fault). Trial modelling of the gravity and magnetic data, carried out along profiles across the Brabant and Stavelot massifs, has identified probable acid igneous intrusions in the western part of the Brabant Massif, and a deep magnetic lower density body underlying the whole Ardennes region, which is thought to be a distinctive Precambrian crustal block.

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