RUSSIAN JOURNAL OF EARTH SCIENCES, VOL. 20, ES5006, doi:10.2205/2020ES000705, 2020


Regional characteristics of radiation and propagation of seismic waves in the North-Eastern Caucasus

Olga V. Pavlenko

Abstract

Regional characteristics of radiation and propagation of seismic waves in the north-eastern Caucasus are estimated based on $\sim 40$ records of local earthquakes obtained by seismic station "Makhachkala" (MAK) (magnitudes $m_b \sim 3.0-5.7$, epicentral distances $r \sim 30-190$ km). Strong earthquakes with magnitudes $Mw \sim 7.5$ are probable there, and knowledge of characteristics of radiation and propagation of seismic waves is necessary for correct assessments of seismic hazard in the region. Previously, the quality function of the earth's crust and the upper mantle was estimated by the envelope method and by coda normalization method. Empirical methods and stochastic simulations were applied to estimate other parameters, such as, the stress drop ($\Delta \sigma \sim 50$ bars), the geometrical spreading (as a three-segment function $1/r$ for $r \sim 1-50$ km, 1/50 for $r \sim 50-150$ km and $1/\sqrt{r}$ for $r >150$ km), the duration of seismic motion depending on the hypocentral distance, kappa value ($\kappa \sim 0.08$ s), the amplification of seismic waves in the upper parts of the Earth's crust $A(f)$, and some others. The estimated characteristics of radiation and propagation of seismic waves show a good agreement between the simulations and observations and can be used for forecasting parameters of strong ground motion in future strong earthquakes in the region. Generally, the obtained characteristics of radiation and propagation of seismic waves are close to similar characteristics of the north-western Caucasus (Sochi and Anapa areas) and of central Japan.

Received 4 February 2020; accepted 10 March 2020; published 17 September 2020.


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Citation: Pavlenko Olga V. (2020), Regional characteristics of radiation and propagation of seismic waves in the North-Eastern Caucasus, Russ. J. Earth Sci., 20, ES5006, doi:10.2205/2020ES000705.


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