USE OF RAYLEIGH-WAVE GROUP VELOCITIES FOR THE ANALYSIS OF CONTINENTAL MARGINS

Rayleigh wave group velocities provide a low-cost means for a quick assessment of averaged local properties of the Earth's crust in continental margin regions of the Atlantic type. Sufficiently accurate measurements (with a standard error of 0.3 km/s or less) of group velocities in continental shelf areas at periods between 5 and 30 seconds provide important information about structural parameters. They may resolve the Moho depth to within 4 or 5 km, depending on crustal thickness and give useful estimates of the average velocities in the upper part of the crust. The group velocities of Rayleigh waves in this period range are influenced most by the shear velocity at all depths and the compressional velocity and the density near the surface. For continental rise regions, the dominating influence of the water layer limits the effectiveness of the method. © 1979.