STRESS STATE MODELING AND GEODYNAMIC ZONING IN SEISMICALLY ACTIVE REGIONS

Stress state of epicentral area before and after earthquake (after formation of major fracture) is modeled. The employed software system allows 2D (plain-strain deformation) modeling of stress state of heterogeneous geological medium with a system of tectonic faults. The faults were modeled as extended zones of loosened geomaterial with elastic modulus essentially lower than the elastic modulus of the host medium. The modeling was carried out using the structure and tectonics layout of the Erzincan earthquake area, including geology and geophysics of tectonics and seismicity in this region. The strong Erzincan Earthquake (Ms 6.8) occurred on March 13, 1992 in Turkey, in the zone of the North-Anatolian Fault with the hypocenter at the depth of 10 km. Two days after that, a strong Ms 5.8 aftershock took place. All in all, more than 300 aftershocks were recorded in the epicentral area. High-density concentration of aftershocks is observed in the zone of the North-Anatolian Fault intersection with adjacent tectonic faults. The results of modeling stress state in the zone 60×60 km before and after the earthquake are analyzed. It is shown that zones of high intensity and peak values of shear stresses conform with the zone of highdensity concentration of aftershocks. The strongest aftershocks with M > 3.7 localize in the zone of maximally relaxed intensity of stresses after formation of the fault. Stress relaxation after the fault formation promotes relief of “secular” accumulated tectonic stresses during subsequent series of aftershocks. These results are useful in deterministic approach to assessment of seismic hazard and in geophysical studies aimed at prediction of strong continental crust earthquakes.

This study was supported by the Geophysical Center of the Russian Academy of Sciences within the framework of the state contract on topic No. 0145-2016-004.

Keywords

Modeling, stress state, earthquake, earthquake foci, faults, tectonics.

Issue number: 8
Year: 2018
ISBN:
UDK: 550.34.06; 550.34.01
DOI: 10.25018/0236-1493-2018-8-0-123-132
Authors: Morozov V. N., Manevitch A. I., Tatarinov V. N.

About authors: Morozov V.N., Doctor of Technical Sciences, Professor, Chief Researcher, e-mail: morozov@gcras.ru, Manevitch A.I., Junior Researcher, e-mail: ai.manevich@yandex.ru, Tatarinov V.N., Doctor of Technical Sciences, Head of Laboratory, e-mail: v.tatarinov@gcras.ru, Geophysical Center of Russian Academy of Sciences, 119296, Moscow, Russia.

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STRESS STATE MODELING AND GEODYNAMIC ZONING IN SEISMICALLY ACTIVE REGIONS

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