GEOPHYSICAL RESEARCH, 2018, vol. 19, no. 1, pp. 17-29. https://doi.org/10.21455/gr2018.1-2
UDC 550.34.06; 550.34.01
Abstract References Full text (in Russian)
MODELING STRESS-STRAIN STATE IN THE EPICENTRAL ZONE OF THE EARTHQUAKE 13.03.1992, MS=6.8 (TURKEY)
V.N. Morozov, A.I. Manevich
Geophysical Center RAS, Moscow, Russia
Abstract. The strong Erzincan earthquake (Ms = 6.8, hypocentral depth of ~10 km) occured in Turkey on March 13, 1992 in the area of the North Anatolian fault and was followed by the strong aftershock (Ms=5.8) two days after. In total, more than 3000 aftershocks were recorded in the epicentral region. Aftershock area is densely concentrated within the joint area of segments of the North Anatolian and adjoining tectonic faults.
The stress-strain state (SSS) of the epicentral zone is modeled before and after the earthquake. The software utilized allows SSS modeling of the block heterogeneous geological medium disrupted by a system of tectonic faults in 2-D formulation (plane stress condition). Faults are modeled as extended zones of dispersed geological material whose elastic modulus is significantly lower than the elastic modulus of surrounding medium. The structural-tectonic scheme of the Erzincan earthquake area is used together with geological and geophysical data on the tectonics and seismicity of the area.
The results of SSS modeling of 60×60 km area before and after the earthquake are analyzed. It is shown that zones of high stress intensity and the maximum shear stress values correspond to the area of high density of following aftershocks. The strongest aftershocks with M>3.7 are located in the area of the maximum stress drop after the rupture formation. Stress drop after the rupture formation stimulates the discharge of accumulated “secular” tectonic stresses in the subsequent aftershocks.
The results obtained may be useful in the deterministic approach to seismic hazard assessment and formulation of geophysical observations focused on the forecast of strong crustal earthquakes in continental areas.
Keywords: modeling, stress-strain state, strong tectonic earthquakes, earthquake, aftershocks, forecast of earthquakes, Erzincan Earthquake.
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