Secular variations of the geomagnetic field at the African plate
Journal Title: Геофизический журнал - Year 2017, Vol 39, Issue 2
Abstract
Geomagnetic secular variations at the African plate consist of shortperiod and longperiod components. Shortperiod SV depends on solar activity. To separate longperiod SV for the Athens magnetic observatories with confidence is impossible so, as rows of mean year values at most observatories are short. We used the data of fifteen observatories, but only MLT, TAN and PLS made observations from the twentieth century beginning. On the data of these observatories and fragment data another ones, the 80-year period of SV may be discovered. These variations have quasisinusoidal form and their extremums coinside to the solar activity maximuma. SV are generated by internal and external sources. The internal sources manifest itself at vertical component and external ones in horizontal component of the geomagnetic field. SV (observed variation) may be devided on the quasiconstant (SV1) and variable quantities. We have chosen as SV1 variations at 1979 year. At this year the sign of SV changes at all observatories. There was supposed that SV1 reflects the sources connected to the changes of region tectonic. The differences between SV and SV1 reflects the external sources component, and it is confirmed by its connection to solar activity change.On the coast and islands observatories the values of shortperiod and longperiod variations were increased. On the tectonic most active east part of African plate SV were more active. Distinctive peculiarity of the SV on the African plate is decreasing of the SV absolute values. It begins at the end of 70-th year of twentieth century. It means the sources of the geomagnetic field relaxe.
Authors and Affiliations
Yu. P. Sumaruk, T. P. Sumaruk
Keywords
Related Articles
- EP ID EP198054
- DOI 10.24028/gzh.0203-3100.v39i2.2017.97375
- Views 75
- Downloads 0
The experiment of integrated mobile technologies used for deep hydrocarbon accumulation prospecting and geophysical mapping at the West Antarctic bottom structures
The data obtained confirm earlier assumption about possible existence of large accumulations of oil and gas hydrates in this part of the West Antarctica. Their formation in the structures of passive continental margin of...
Pareto-optimal solutions of the inverse problem of gravimetry with indeterminate a priori information
The paper discusses theoretical aspects of solving the nonlinear inverse problem of gravimetry with uncertainty of a priori information. The a priori information is described by fuzzy sets. Special-purpose geophysical pr...
Magnetic field and dike belts of eastern Azov block of the Ukrainian shield
The article analyzes the pattern of displaying of the geological structure of multiphase intrusive arrays of the Eastern Azov region introduction in a magnetic field. Features of deep structure are discussed including da...
Earth’s crust composition of the Ingul megablock of the Ukrainian Shield (types of crust) and patterns of location of ore mineral resources
Within the Ingul Megablock of the Ukrainian Shield, according to the data of three-dimensional density modeling, at the scale of 1 : 200 000, the thickness of conditionally allocated “granite”, “diorite”, “basalt” layers...
Nonlinear dynamics, seismic activity and aerospace sounding systems
Processes and phenomena are under consideration, which can be realized from the viewpoint of nonlinear dynamics and are typical for geosystems. Attention is focused on the main features and new possibilities given by the...