Coda Q in the geophysical medium of the Northeast Caucasus

Abstract

For the eastern zone of the North Caucasus, including the Tersko-Caspian trough, the Dagestan wedge and adjacent structures, with the maximum coverage of the data from the Federal network of seismological observations of the Geophysical Survey of the Russian Academy of Sciences (GS RAS), the regional frequency-dependent relations for estimating the seismic Q-factor of the Earth’s crust and upper mantle are determined by the coda-wave envelope method. In total, waveforms of 394 crustal earthquakes with source depths from 1 to 42 km and magnitudes from 2.2 to 5.5 are analyzed using the Coda Q module of the SEISAN software package (Havskov et al., 2020). The seismic-Q estimation technique using the single-scattering model is described in detail. Recommendations are given how to practically use the obtained estimates characterizing the wave properties of different-scale volumes of the fault-block geological environment to make attenuation corrections when calculating the source spectral parameters in the eastern zone of the North Caucasus. The results of the study will help to improve the information content of earthquake catalogs, in particular, to fill them with data on the energy characteristics of seismic events (universal values of moment magnitudes, Mw) in the most seismically active regions of the Russian Federation.