Tomographic regionalization of crustal Lg Q in eastern Eurasia

Abstract

We measure Q of crustal Lg waves in eastern Eurasia using the reliable two‐station methods. More than 5,000 spectral ratios are collected over 594 interstation paths, and are used to determine values of Lg Q 0 and η (Q at 1 Hz and its frequency dependence) over these paths. These values are used to derive tomographic models of laterally varying Q 0 and η with resolutions between 4 and 10°. The Q 0 model contains values that vary between 100 and 900. Q 0 are the lowest in the Tibetan plateau, increase to moderate levels towards the east and north, and reach maxima in the Siberian and eastern Europe Cratons. Q 0 values correlate well with regional tectonics. Most η values are between −0.14 and 0.50, with a mean of 0.18. These values are lower than those obtained previously using either an Lg coda Q method, or a method of simultaneous inversion of source spectra and Q.