SEISMIC QUALITY FACTOR OF THE LITHOSPHERE OF THE SOUTHWESTERN FLANK OF THE BAIKAL RIFT SYSTEM
A.A. Dobryninaa, V.V. Chechel'nitskiib, and V.A. San'kova
a Institute of the Earth's Crust, Siberian Branch of the Russian Academy of Sciences, ul. Lermontova 128, Irkutsk, 664033, Russia
b Baikal Regional Seismological Center of Geophysical Survey, Siberian Branch of the Russian Academy of Sciences, ul. Lermontova 128, Irkutsk, 664033, Russia
Keywords: Baikal rift system, quality factor, coda wave, attenuation
Pages: 555-564
Abstract
The seismic quality factor ( Qс), the frequency parameter ( n ), and the attenuation coefficient (δ) of seismic waves in the lithosphere of the southwestern flank of the Baikal rift system are obtained from records of S coda waves from regional earthquakes. There is a strong dependence of the quality factor on the frequency and coda window length: for central frequencies of 0.3 and 12.0 Hz and a coda window length W = 20 s, Qс varies from 47 ± 51 to 1036 ± 190, and for the same frequencies and W = 60 s, it varies from 83 ± 46 to 1596 ± 573. The values of the quality factor and the attenuation coefficient are calculated for the whole southwestern flank of the Baikal rift system and for individual tectonic blocks: the stable Siberian Platform, Khamar-Daban and East Sayan uplifts, and South Baikal and Tunka basins. A comparison of the obtained values of Qс with data on the age, tectonics, and seismic activity level of the structures shows that the quality factor depends on the recent tectonic activity of the structures, and to a lesser extent, on the age of the crust.
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