IDENTIFICATION OF WAVE DEFORMATION PROCESSES OF LANDSLIDES IN THE NORTHWESTERN BLACK SEA USING THE INSTRUMENTAL OBSERVATION DATA

Abstract

Problem Statement and Purpose. At present, considering the conditions of slopes equilibrium, only the stresses caused by gravity, hydrodynamic and seismic effects are most often taken into account. As for tectonic stresses, their effect on landslide slopes has hardly been studied. At the same time, landslides and deformations ofslopes in a wide spatio-temporal range (with the frequency from several months to several dozens of years and the levels of massifs tectonic discreteness from first tensof meters to first kilometres) is also recorded in fact. Empirical data indicate that wave mechanism caused by rotational regime of the Earth can be one of the possible mechanisms explaining the high-frequency quasi-cyclic spatio-temporal variability of the rock mass stress-strain state. Purpose of the work has been to identify wave deformation processes in the Earth’s upper crust according to the data of instrumentalobservation of landslide slopes and relatively long line facilities deformation regime. In this work, we also intend to substantiate the thesis that wave exotectogenesis isone of the factors reducing the overall stability of landslide slopes. Data&Methods. The data of instrumental observations of structural components deformation in the underground drainage facilities of the landslide prevention works on Odesa coast that have accumulated during 50 years of operation, as well as the results of geodetic monitoring of landslide slope and the crest of plateau on the right bank of the Malyi Adzhalyk Liman within the territory of the Port Plant (ammonium plant) in 2000–2019 have been used to study the dynamics of deformation wave processes in the Earth’s upper crust. Statistical and cartographic analyses of the data sets mentioned above were carried out according to traditional methods using the Statistica, Matlab and Surfer software packages. Results. It has been found that modern dynamics of landslide slopes is significantly influenced by the periodic change of the stress-strainstate of rocks in space and time. The authors interpret the empirically revealed alternating in space zones of compression and extension, which cause the dynamics of vertical and horizontal reference benchmarks displacements in the inter-annual regime of marks displacement on the right bank of the Malyi Adzhalyk Liman and in the tunnels of Odesa coast as thereflection of wave geodynamics with periodic change of the stress-strainstate of rocks in space and time. Hierarchical layering of the tectonosphere in depth (the presence of layers with different elastic properties), tectonic discreteness and blockiness of rock massifs determine the spatial framework of the dynamically complex structure of the deformation field. Multiple cycles of compression-extensionof rocks lead to decrease in the rocks strength, accumulation of plastic deformations and activation of landslide displacements even on the coastal areas where anti-landslide measures have been implemented. To prepare design models correctly, it is important to take into account both the landslide formation mechanism and the factors that reduce the overall stability of the slope. The latter include the quasiperiodic variability of the rock mass stress-strain state controlled by rotational dynamics via wave mechanism.