Seismic instruments: article

ANALYSIS OF THE TIME STRUCTURE OF DEFORMATION PROCESSES IN THE ZONE OF THE ASHGABAT FAULT (NORTHERN KOPET DAGH)
KUZMIN YURI OLEGOVICH
FATTAKHOV EVGENY ALBERTOVICH
Schmidt Institute of Physics of the Earth of the Russian Academy of Sciences, Russia, 123242, Moscow, Bolshaya Gruzinskaya str. 10, building 1
Journal: Seismic instruments
Tome: 57
Number: 4
Year: 2021
Pages: 33-50
UDK: 551.24, 551.243, 550.342
DOI: 10.21455/si2021.4-3
Keywords: ASHGABAT FAULT, GEODYNAMIC MONITORING, LIGHT-DIMENSIONAL OBSERVATIONS, VERTICAL DISPLACEMENTS, LOCAL DEFORMATIONS, LEVELING OBSERVATIONS, PARAMETRIC EXCITATION, POROELASTIC INCLUSION, HETEROGENEITY OF ELASTIC PROPERTIES, PROCESSING OF GEOPHYSICAL DATA, COLLISION ZONE, PLATE KINEMATICS, PERIODOGRAM
Аnnotation: The results of long-term (55 years) ground-based geodetic observations with increased spatial and temporal detail (the distance between the reference points is 0.3-0.5 km, the intervals between measurements are 1-2 months) in the zone of the Ashgabat fault (Northern Kopet Dagh) are presented and local (width - 0.5 km) anomalous deformations of the Earth's surface with the rates of average annual deformations (1-3)×10-5/year are detected. The results of comparing the velocities of vertical and horizontal displacements of the Earth's surface in the zone of the Ashgabat fault with the data on the modern kinematics of the interaction of the Turan and Iranian plates, obtained on the basis of GNSS measurements according to the Iranian Geodetic Network, are discussed and it is shown that the rate of reduction of the Kopet Dagh by ground geodetic measurements is almost 100 times less than by GPS observations. This proves that local anomalies of vertical displacements occur under conditions of a quasi-static regional stress field. The spectral analysis of long-term series of leveling observations was carried out and the prevailing periods of anomalies of vertical displacements of the Earth's surface were revealed. It is shown that the annual harmonic dominates in the block parts of the leveling profiles. The maximum periods in the fault zone do not correspond to the annual component and have a shorter duration. It is established that the annual harmonic is associated with seasonal thermoelastic deformations, and local changes in the fault zone are caused by periodic changes in the pore pressure associated with the precipitation regime. A mechanism of parametric excitation of local vertical displacements of the Earth's surface is proposed, when changes in the internal parameters of the medium (volume modulus of elasticity) occur under stationary regional loading.