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 Q0 and η (Q at 1 Hz and its frequency dependence) over these paths. These values are used to derive tomographic models of laterally varying Q0 and η with resolutions between 4 and 10°. The Q0 model contains values that vary between 100 and 900. Q0 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. Q0 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. Copyright 2006 by the American Geophysical Union.