scholarly journals Magnetic field of the Western Carpathians (Slovakia): reflections on the structure of the crust

2010 ◽  
Vol 61 (5) ◽  
pp. 437-447 ◽  
Author(s):  
Peter Kubeš ◽  
Vladimír Bezák ◽  
Ľudovít Kucharič ◽  
Miroslav Filo ◽  
Jozef Vozár ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Anomalies ◽  
Geological Structure ◽  
Variable Magnetic Field ◽  
Present Knowledge ◽  
Western Carpathians ◽  
The West ◽  
Anomalous Field ◽  
Sizable Number

Magnetic field of the Western Carpathians (Slovakia): reflections on the structure of the crustA new digital magnetic map of Slovakia on the scale of 1: 200,000 and 1: 500,000 was compiled at the end of 2008 as the output of database magnetic objects from the whole territory of Slovakia at a scale of 1: 50,000. The variable geological structure of the West Carpathian crust is depicted in the equally variable magnetic field of this region. A sizable number of magnetic anomalies with manifold character have been recognized. The basic anomalies distribution was divided into two groups: anomalies connected with rocks of the pre-Neogene basement and anomalies which originate in Neogene and Quaternary volcanic products. Most of the significant anomalies in the pre-Neogene basement were interpreted, modelled and consequently its geological and tectonic classification was worked out. On the basis of the anomalous field features, the following sources of anomalies have been distinguished: a) known, located on the surface, or at shallow depths verified by boreholes, mainly expressed by simple morphology, b) deep-seated and expressed by complicated morphology, reinterpreted or newly interpreted and also problematic. According to our present knowledge the interpretations are insufficient and remain open for further investigation. The above mentioned sources of magnetic anomalies are classified in terms of tectonic provenience to the main tectonic units.

A generalized multibody model for inversion of magnetic anomalies

Geophysics ◽  
1980 ◽  
Vol 45 (2) ◽  
pp. 255-270 ◽  
Author(s):  
B. K. Bhattacharyya
Keyword(s):  
Magnetic Field ◽  
Three Dimensional ◽  
Magnetization Vector ◽  
Critical Dimension ◽  
Magnetic Anomalies ◽  
Field Vector ◽  
Magnetic Survey ◽  
Multibody Model ◽  
Anomalous Field ◽  
Rectangular Block

The height of the observation surface above a magnetized region primarily determines the critical dimension of the smallest inhomogeneity in magnetization that can be resolved from magnetic survey data. When a rectangular block is smaller in size than this critical dimension, it appears homogeneously magnetized in the observed magnetic field. This consideration leads to the selection of a unit rectangular block of suitable dimensions with homogeneous magnetization. The magnetized region creating the anomalous field values in the area of observation can, therefore, be broken up into several blocks having different magnetizations, each block being equal in size and uniformly magnetized. The iterative method described here assumes initially that the anomalous field values are caused by a three‐dimensional (3-D) distribution of magnetized rectangular blocks. The optimum orientation of these blocks with respect to geographic north is then determined. This orientation is particularly insensitive to adjustments in the dimensions of the blocks. The top and bottom surfaces of each of the blocks in one or more layers are adjusted in a least‐squares sense to minimize the difference between observed and calculated field values. A method is also described for constraining the magnetization vector of each block to lie within a specified angle of the normal or reversed direction of the geomagnetic field vector. The procedure for analysis of data can also be extended to the case of anomalies over a draped surface. At the conclusion of the iterations, a 3-D distribution of magnetization is generated to delineate the magnetized region responsible for the observed anomalous magnetic field. Examples including model and aeromagnetic data are provided to demonstrate the usefulness of a generalized multibody model for inversion of magnetic anomalies.

scholarly journals GEODYNAMICS

GEODYNAMICS ◽  
2011 ◽  
Vol 1(10)2011 (1(10)) ◽  
pp. 127-133 ◽  
Author(s):  
V. H. Kuznietsova ◽  
◽  
V. Yu. Maksymchuk ◽  
Keyword(s):  
Magnetic Field ◽  
East European Platform ◽  
Magnetic Anomalies ◽  
Geological Structure ◽  
East European ◽  
Anomalous Magnetic Field

Peculiarities of anomalous magnetic field in Ukrainian Carpathians territory were considered. It was stated that on the base of magnetic anomalies characters in can be divided in 4 zones that generally matches with main tectonic elements of the region (in SW – NE direction): Transcarpathian trough, Folded Carpathians, Precarpathian trough, SE edge of East-European platform. It was concluded that the peculiarities of geological structure and tectonics of Carpathians are reflected in anomalous magnetic field of the region.

scholarly journals Volcanomagnetic anomalies: a review and the computation of the piezomagnetic field expected at Vulcano (Aeolian Islands, Italy)

1994 ◽  
Vol 37 (5 Sup.) ◽  
Author(s):  
C. Del Negro ◽  
G. Budetta ◽  
F. Ferricci
Keyword(s):  
Magnetic Field ◽  
Pressure Pulse ◽  
Surrounding Medium ◽  
Magnetic Anomalies ◽  
Source Zone ◽  
Volcanic Area ◽  
High Susceptibility ◽  
Anomalous Field ◽  
Drill Holes ◽  
The Magnetic Field

he volcanic area of Vulcano experienced major unrest, which brought the fumarolic field temperatures from slightly less than 300 °C to ca. 700 °C between 1988-1993. The structure underlying the crater, investigated by drillings and by different geophysical techniques, is relatively well-known. This led us to attempt modelling the magnetic anomaly which could be generated by sudden pressure variations in the magma chamber at shallow depth. The rocks embedding the intrusive rock penetrated by drill-holes to a depth of ca. 2000 m are characterized by high susceptibility, which points to the possibility of obtaining significant magnetic anomalies with acceptably weak pressure pulses. The model for straightforward computing of the anomalous field was drawn accounting for (1) the inferred geometry of the Curie isotherrn, (2) presence of a spherical magma reservoir, 2 km wide and centred at a depth of 3.5 km, overlain by (3) a 0.5 km wide and 1.5 km high cylinder simulating the intrusion first revealed by drillings. The model elements (2) and (3) behave as a single source zone and are assumed to lie beyond the Curie point, the contribution to the piezomagnetic effect being provided by the surrounding medium. Under such conditions, a 10 MPa pressure pulse applied within the sourcezone provides a 4 nT piezomagnetic anomaly, compatible with the amplitude of the anomalies observed at those volcanoes of the world where magnetic surveillance is routinely carried out. The analytical method used for computation of the magnetic field generated by mechanical stress is extensively discussed, and the contribution of piezomagnetism to rapid variations of the magnetic field is compared to other types of magnetic anomalies likely to occur at active volcanoes.

scholarly journals Night-time Sferic Propagation at Frequencies Below 10 KHz

1967 ◽  
Vol 20 (1) ◽  
pp. 101 ◽  
Author(s):  
KJW Lynn ◽  
J Crouchley
Keyword(s):  
Magnetic Field ◽  
Geographic Distribution ◽  
Angle Of Incidence ◽  
European Studies ◽  
Earth’S Magnetic Field ◽  
Night Time ◽  
The West ◽  
Earth's Magnetic Field ◽  
Effective Angle

Results of a study at Brisbane of individual night-time sferics of known origin are described. A propagation attenuation minimum was observed in the 3-6 kHz range. The geographic distribution of sferic types was also examined. Apparent propagation asynunetries were observed, since sferics were detected at greater ranges to the west than to the east at 10 kHz, whilst the number of tweek-sferics arising from the east was about four times that arising from the west. Comparison with European studies suggest that these asymmetries are general. These results are then " interpreted in terms of an ionospheric reflection cgefficient which is a function of the effective angle of incidence of the wave on the ionosphere and of orientation with respect to the Earth's magnetic field within the ionosphere.

scholarly journals New approach to describe two coupled spins in a variable magnetic field

2021 ◽  
Author(s):  
Yury Belousov ◽  
Roberto Grimaudo ◽  
Antonino Messina ◽  
Agostino Migliore ◽  
Alessandro Sergi
Keyword(s):  
Magnetic Field ◽  
Variable Magnetic Field ◽  
New Approach

scholarly journals Magnetic Fields in the Lower Corona Associated with the Expanding Limb Burst On March 30th 1969 Inferred from the Microwave High-Resolution Observations

1971 ◽  
Vol 43 ◽  
pp. 413-416 ◽  
Author(s):  
Shinzo Énomé ◽  
Haruo Tanaka
Keyword(s):  
Magnetic Field ◽  
High Resolution ◽  
Magnetic Fields ◽  
The West ◽  
Lower Corona ◽  
Energetic Electrons ◽  
West Limb ◽  
Flare Region ◽  
Solar Microwave ◽  
Solar Microwave Burst

An expansion of the source of a great solar microwave burst was observed a little beyond the west limb on March 30, 1969. This expansion is interpreted in terms of diffusion of energetic electrons in a turbulent magnetic field in the flare region. The height of the source is estimated to have been 104 km.

Large scale magnetic anomalies over western Canada and the Arctic: a discussion

1976 ◽  
Vol 13 (6) ◽  
pp. 790-802 ◽  
Author(s):  
R. L. Coles ◽  
G. V. Haines ◽  
W. Hannaford
Keyword(s):  
Magnetic Field ◽  
Large Scale ◽  
Elevated Temperatures ◽  
Magnetic Anomalies ◽  
The Arctic ◽  
Evolutionary Development ◽  
Magnetic Feature ◽  
Western Canada ◽  
Arctic Regions ◽  
The Magnetic Field

A contoured map of vertical magnetic field residuals (relative to the IGRF) over western Canada and adjacent Arctic regions has been produced by amalgamating new data with those from previous surveys. The measurements were made at altitudes between 3.5 and 5.5 km above sea level. The map shows the form of the magnetic field within the waveband 30 to 5000 km. A magnetic feature of several thousand kilometres wavelength dominates the map, and is probably due in major part to sources in the earth's core. Superimposed on this are several groups of anomalies which contain wavelengths of the order of a thousand kilometres. The patterns of the short wavelength anomalies provide a broad view of major structures and indicate several regimes of distinctive evolutionary development. Enhancement of viscous magnetization at elevated temperatures may account for the concentration of intense anomalies observed near the western edge of the craton.

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