Determining Generic Velocity and Density Models for Crustal Amplification Calculations, with an Update of the Boore and Joyner (1997) Generic Site Amplification for (V)over-barS(Z)=760 m/s

This short note contains two contributions related to deriving depth-dependent velocity and density models for use in computing generic crustal amplifications. The first contribution is a method for interpolating two velocity profiles to obtain a third profile with a time-averaged velocity (V) over bar (Z) to depth Z that is equal to a specified value (e.g., for shear-wave velocity V-S, (V) over bar (S)(Z) = 760 m/s for Z = 30 m, in which the subscript S has been added to indicate that the average is for shear-wave velocities). The second contribution is a procedure for obtaining densities from V-S. The first contribution is used to extend and revise the Boore and Joyner (1997) generic rock V-S model, for which (V) over bar (S)(30 m) = 618 m/s, to a model with the more common (V) over bar (S)(30 m) = 760 m/s. This new model is then used with the densities from the second contribution to compute crustal amplifications for a generic site with (V) over bar (S)(30 m) = 760 m/s.