Crust and upper mantle structure of the Eurasian continent from the phase velocity and Q of surface waves

A review of studies using surface waves to determine crust and upper mantle structures of the Eurasian continent is presented. The results of these studies have assisted in the analysis of a new set of propagation data for lateral variation of phase velocity and Q on the continent. A Rayleigh wave phase velocity regionalization based on crustal conditions and topography is proposed involving five continental provinces: Indian Shield, Northern Platforms and Shields, Forelands and Coastal Plains, Tectonic, and Plateau. Phase velocities in the Indian Shield are 20% higher than velocities in the Plateau province at 26‐s period and 5% higher at 90‐s period. Stable platforms of northern Asia have significantly higher phase velocities than those of tectonic provinces out to 150‐s period. Shear velocity structures that incorporate published crustal structures and satisfy the regionalized dispersion curves and reported S n velocities are presented. Surface wave amplitudes are shown to be strongly affected by horizontal refraction, causing focusing of ray paths, defocusing, and multipathing. Three very different average Rayleigh wave Q curves over periods of 25–60 s are obtained for stable northern platforms and tectonic provinces east and west of Central Asia. Interpretations of the observations are given in terms of intrinsic Q of the medium. The Q models as well as shear velocity models are discussed in the light of Eurasia's tectonic history.