Coda Wave Attenuation for Three Regions of Georgia (Sakartvelo) Using Local Earthquakes

Seventy-two local earthquakes were analyzed and the quality factor (Q(c)) was calculated for three regions of Georgia using the single-scattering model in the frequency range of 1-32 Hz. Standard International Association of Seismology and Physics of the Earth's Interior (IASPEI) routines for the coda Q(c) determination have been used. The coda window varied from 35 to 45 s and the lapse time was up to 63 s. The epicenter distances and the focal depths of the earthquakes were up to 50 km and 20 km, respectively. Local magnitudes ranged from 1.7 to 4.1. These earthquakes were recorded by three digital seismic stations equipped with broadband Guralp CMG40T seismometers. The Q(c) values show strong frequency dependence for three regions. The value of Q(c) at frequency 1 Hz varies from 35.1 +/- 5.3 to 83 +/- 8.2, and the frequency parameter, n, increases from 0.890 +/- 0.062 to 1.095 +/- 0.056 depending on the model of the coda generation and the considered region. Observed Q(c) values reflect the average attenuation property of the whole crust beneath each region and are correlated with the seismicity pattern and geology in the studied regions.