scholarly journals Reconstruction of seismotectonic deformations of Asia in different layers of the Earth’s crust

2022 ◽  
pp. 4-12
Author(s):  
O. A. Kuchay
Keyword(s):  
Central Asia ◽  
Strain Tensor ◽  
Earth’S Crust ◽  
North Eastern ◽  
Earth's Crust ◽  
North Western ◽  
Gps Observations

The calculation of seismotectonic deformations for different depth levels 1–15, 16–35, 36–70 km was performed according to the data of 1819 mechanisms of earthquake foci that occurred in Central Asia (φ = 25° – 60° N, λ=60° – 115° E) for the period from 1976 to the end of July 2020 with M>4.7. The orientation of the main axes of the strain tensor reconstructed from the mechanisms of earthquake foci with M>4.7 coincide at different depth levels with mainly submeridional and north-eastern shortening and varying elongation from sublatitude to north-western and near-vertical. The consistency of the orientation of the main axes of shortening and elongation reconstructed from seismological materials and from the published results of calculating GPS observations, is traced.

scholarly journals COMPARATIVE ANALYSIS OF GEODYNAMIC PARAMETERS OBTAINED FROM ASTRONOMIC AND GPS OBSERVATIONS IN POLTAVA

2021 ◽  
pp. 11-16
Author(s):  
L. Halyavina ◽  
N. Zalivadnyj
Keyword(s):  
Deep Structure ◽  
Theoretical Explanation ◽  
Earth’S Crust ◽  
Plumb Line ◽  
Gps Data ◽  
The South ◽  
The North ◽  
Earth's Crust ◽  
Gps Station ◽  
Gps Observations

The functioning of the GPS station and regular astrometric observations with a prismatic astrolabe in Poltava provides series of local displacements of the earth's crust and plumb line in time, characterizing the changes in the gravitational field. The analysis of the N-component of the earth's crust movement and the displacement of the meridional projection of the plumb line was carried out on the basis of GPS data and from observations on the astrolabe, respectively, for the period 2002-2020. Comparison of the trends of these series showed that their shifts occur in opposite directions. It is noted that the movement of the point occurs in the northern direction at a speed of +0.3mm/yr, and the displacement of the plumb line - to the south, at a speed of -2.6mas/year. Similarly, an abrupt displacement of the N-component to the north by + 2mm at the turn of 2014 was accompanied by a displacement of the plumb line to the south by approximately -50 mas. These facts can be explained within the framework of the hypothesis of the existence of a deep structure in the vicinity of Poltava, in which a significant change in mass occurs. The spectra of both series show the presence of cyclicities with close periods: about 3.2, 2.8, 1.0, 0.5, and 0.3 yr. It is known that harmonics with those periods are present in many astrometric series. The geodynamic interpretation of the presented facts requires additional confirmation in observations of neighboring GPS stations, as well as a theoretical explanation and justification.

scholarly journals Stress-strain state of the earth’s crust of the Central Asian mountain belt: distant effect of the tectonic impact of the Indo-Eurasian collision

2021 ◽  
Vol 929 (1) ◽  
pp. 012003
Author(s):  
M M Buslov
Keyword(s):  
Central Asia ◽  
Sedimentary Basins ◽  
Tien Shan ◽  
Earth’S Crust ◽  
High Mountain ◽  
Mountain Ranges ◽  
Central Asian ◽  
Sayan Region ◽  
Earth's Crust ◽  
Cenozoic Sediments

Abstract In recent decades, extensive geological, geophysical and geochronological data have been obtained that characterize in detail the results of the distant tectonic impact of the Indo-Eurasian collision on the lithosphere of Central Asia, which led to the formation of the mountain systems of the Pamirs, Tien Shan, Altai-Sayan region and Transbaikalia from the Late Paleogene (about 25 million years ago). It has been established that the formation of the structure of Central Asia occurred as a result of the transmission of deformations from the Indo-Eurasian collision over long distances according to the “domino principle” through the rigid structures of Precambrian microcontinents located among the Paleozoic-Mesozoic folded belts. The study of peneplain surfaces deformed into simple folds on high-mountain plateaus surrounded by rugged mountain ranges made it possible to reveal the parameters of the deformations of the earth’s crust, the interrelationship of the formation of relief and sedimentary basins. Apatite track dating data, structural and stratigraphic analyses of Late Cenozoic sediments in the basins prove a period of intense tectonic activation the entire lithosphere of Central Asia from the Indian continent to the Siberian platform starting from the Pliocene (about 3.5 million years). As a result of reactivation of the heterogeneous basement of Central Asia, high seismicity was manifested, which is concentrated mainly along the border of the microcontinents (Central Tianshan, Junggar and Tuva-Mongolian) and the Siberian craton, as well as in the zones of articulation of regional faults.

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