Velocity of seismic waves in the Earth's mantle

Abstract

On the basis of our present knowledge the Earth's mantle may be divided into four sections: (a) from the Mohorovicic discontinuity to a depth of about 200 km, with small changes in the wave velocities which have minima in this section; (b) from 200 to 950± km with relatively rapid, fairly regular increase in velocity; (c) from 950 to 2700± km with smaller and less regular increase in velocity; almost straight line portions of the travel-time curves and relatively small wave amplitudes at certain ranges of distance indicate at least two portions of (c) where the wave velocity increases relatively little with depth; (d) from 2700 km depth to the core boundary with little change in velocity and probably maxima roughly 100 km above the core boundary.

Files

Additional details