Peculiarities of mantle waves from long-range profiles

Abstract

Long-range seismic experiments carried out in different regions of the USSR show strong variations of the mantle wave velocities and attenuation.Relatively high mantle velocities, more than 8.2-8.3 km/s, are observed in the old platform areas.To exclude the crustal influence on the mantle waves and to separate the vertical and horizontal inhomogeneity effect the relations between the overlapping travel-time curves are analyzed.As a result, a mantle stratification with positive average velocity gradient in the strata is revealed up to depths of 200 km.Local inclusions with very high (more than 8.5 km/s) and relatively low (less 8.0 km/s) velocities are typical of the mantle.