Abstract
The current state of crustal stresses in the Caucasus and adjacent territories has been reconstructed. Stress inversion was performed by the cataclastic analysis of earthquake focal mechanisms considered as seismological strain indicators. The data were taken from the unified catalogue of focal mechanisms of the Northern Eurasia, which was consolidated by the Laboratory of Tectonophysics of IPE RAS in the early 1990s. It contains the information from many seismological data sources of various authors who worked both in the USSR and abroad. Seismological data for the last years after the collapse of the USSR were taken from Global CMT catalogue. The study area has been quite densely covered by reconstructions of the principal stress axes. At the same time, the area of stress averaging has been considerably reduced by the iterative use of a window for stress averaging, which was gradually expanded for zones with reduced densities of earthquake epicenters. The revealed regularities of the current stress field based on the unified catalogue of focal mechanisms collected by different authors correlate with the reconstructions performed according to the Global CMT catalogue. The cataclastic analysis of displacements along fractures allowed estimating the stress magnitudes, and the crust of the study area was zoned with respect to the intensity of normalized values of the lowest and highest stresses of horizontal compression, as well as to the normalized values of shear stresses acting on the crustal basement. In all cases, the values were normalized to the rock strength. The stress parameters are presented in “Tectonic Stresses of Eurasia”. This new Internet resource created by the Laboratory of Tectonophysics on the IPE RAS website shows the stress data in different scales and levels of details.
Highlights
Stress inversion was performed by the cataclastic analysis of earthquake focal mechanisms considered as seismological strain indicators
The data were taken from the unified catalogue of focal mechanisms of the Northern Eurasia, which was consolidated by the Laboratory of Tectonophysics of IPE RAS in the early 1990s
Seismological data for the last years after the collapse of the USSR were taken from Global CMT catalogue
Summary
Южная граница Восточно-Европейской платформы является наиболее сейсмичной ее частью. Горный Кав каз представляет собой ядро этого региона, к которому с целью полноты исследования сейсмического режима следует также отнести сопредельные с ним террито рии: с запада – Крым и восточную часть Черноморского бассейна, с юга – Восточный Понт, часть Анатолии, горный Эльбурс, с востока – центральную часть Кас пийского бассейна, западную часть Копетдага (рис. 1). В частности, для территории бывше го СССР общий каталог механизмов очагов землетрясе ний РК, составленный сотрудник ами лаборатории тек тонофизики ИФЗ РАН Начали появляться статьи из стран бывшего СССР, в которых были представлены каталоги не только землетрясений, но и механизмов их очагов [Yetirmishli, Kazimova, 2017, 2018]. За прошедшие годы сейсмологами так и не был создан единый каталог механизмов очагов землетрясений России и бывшего СССР. Хотя многие российские сейсмологи относятся к задаче определения механизмов очагов землетрясе ний как к некой побочной, вторичной проблеме (глав ное внимание уделяется определению места, време ни и силы событий), следует отметить, что этот тип данных всегда был востребован при решении проб лем геодинамики, так как позволял по ориентации осей главных сброшенных напряжений дать первич ную информацию о геодинамическом режиме терри тории [Zoback, 1992]. Таким образом, актуальность каталогов механизмов очагов землетрясений во всем мире с конца ХХ в. толь ко возрастает
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