TORO ET AL. (1993) MOTIONS

The ground motions for Toro et al. (1993) are for a hard-rock site, with kappa = 0.006. Modification factors to convert their values to a firm-rock site were developed by first computing motions using the stochastic model discussed above, but with hard-rock site amplifications and kappa = 0.006, and then forming the ratio of these motions with those from the firm-rock model discussed above at each magnitude, distance, and oscillator period. (The input parameters for the hard-rock calculations are given in Table A7; the shallow shear-wave velocity profile is shown in Figure A1). For a given oscillator period these ratios are generally independent of magnitude and distance, and we have applied magnitude- and distance-independent factors to the Toro et al hard-rock values (see main text)