FIGURE 5.10 Effect of crustal structure on ground motion attenuation. Synthetic seismograms (bottom) calculated for a crustal waveguide (top left). The contributions of direct and reflected rays (top right) to the attenuation relation are shown in the top right panel. SOURCE: R.W. Burger, P.G. Somerville, J.S. Barker, R.B. Herrmann, and D.V. Helmberger, The effect of crustal structure on strong ground motion attenuation relations in eastern North America, Bull. Seis. Soc. Am., 77, 420-439, 1987. Copyright Seismological Society of America.