Abstract
The paper presents the results of comparative neogeodynamic analysis of the Baltic syneclise and northern Voronezh anteclise based on structural-geomorphological interpretation, digital elevation model (DEM) processing procedure using LESSA program [Zlatopolsky, 2011], seismic analysis, and computer geodynamic modeling. Both regions are seismically active areas of the East European Platform. The automated DEM analysis showed that they are dominated by NW-striking lineaments oriented across the strike of the neoextension axis. Computational neogeodynamic models imply that the areas under consideration develop in shear environment, with the compression axis oriented northwest. Another important result of modeling is numerical correlation between earthquake energy, interpolated over the Baltic syneclise, and the probability of occurrence of ruptures: the Pearson correlation coefficient is 0.58 for the sedimentary cover and 0.42 for the basement. For the northern Voronezh anteclise, a correlation was found between the epicentral density of earthquakes and "Fracture regions" parameter, with reference to which there were distinguished the areas with the probable occurrence of new short-extension ruptures (the Pearson correlation coefficient is 0.41). This parameter is informative for contouring seismically active parts since the areas with probable occurrence of new ruptures, occupying 39 % of the northern Voronezh anteclise, account for 71 % of earthquake epicenters. Structuralgeomorphological interpretation yielded a high degree of correlation between relief and active faults identified as "weak" zones to which the earthquake epicenters are largely confined. Therefore, both regions considered are characterized by high sedimentary-cover seismic activity, develop in shear stress field, with the stress axis oriented northwest, and have similar orientations of linear elements of relief and "weak" zones. The analysis of the earthquake recurrence curves shows considerable differences between seismic regimes of the northern Voronezh anteclise and the Baltic syneclise, and those between the sedimentary-cover and basement seismicity of the latter. These differences may be due the fact that the stressed state of the Voronezh anteclise is affected by active structures of the Urals and Caucasus, and that the upwarping Fennoscandian shield is largely responsible for neodeformations of the Baltic syneclise. Practical significance of the study is concerned with the identification of earthquake source zones.
Highlights
The analysis of the earthquake recurrence curves shows considerable differences between seismic regimes of the northern Voronezh anteclise and the Baltic syneclise, and those between the sedimentary-cover and basement seismicity of the latter. These differences may be due the fact that the stressed state of the Voronezh anteclise is affected by active structures of the Urals and Caucasus, and that the upwarping Fennoscandian shield is largely responsible for neodefor mations of the Baltic syneclise
Structural-Kinematic Model of Neotectonic Deformations in the South of the East European Platform
Summary
Принима ется ряд допущений о геометрии активных разломов (они не должны пересекаться), величинах напряжений, считающихся достаточными для возникновения но вых разрывов малой протяженности. Под воздействи ем внешней нагрузки в связи с влиянием активных разломов, рассматриваемых как вертикальные неодно родности, происходит перераспределение напряжений, в результате чего на некоторых площадках достига ется сочетание нормального и касательного напряже ния, приводящее, согласно теории Мора, к нарушению прочности и возникновению новых разломов. Выделение зоны ВОЗ проведено по максимумам плотности эпицентров землетрясений с учетом распо ложения областей возможного формирования новых разрывов малой протяженности: все зоны ВОЗ распо ложены в пределах этих областей и отличаются высо кими значения плотности эпицентров сейсмических событий. Более подробно основные черты новейшей тектоники Балтийской синеклизы описаны в монографии [Garets ky, Nesmeyanov, 2009]. Что за инструменталь ный период наблюдений на территории Балтийской синеклизы произошло 85 землетрясений, гипоцентры 24 из них локализованы в пределах кристаллического фундамента. Отдельное рассмотрение сейсмичности в осадочном чехле и фундаменте связано с различиями физических свойств слагающих их пород и разным ха рактером сейсмотектонических процессов: 1) большин ство эпицентров землетрясений расположено на малых
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