Nomogram for the rock GMPE of Ambraseys et al. (1996)
figureposted on 26.09.2018, 16:17 by John Douglas
A nomogram to evaluate the ground motion prediction equation of Ambraseys et al. (1996) for the peak ground acceleration (PGA) and response spectral acceleration (SA) at 1s on rock. Connect any two variables with a straight line (e.g. magnitude and distance) to find the third (e.g. PGA or SA). Blue values give the 16% percentile PGA or SA (-1 sigma/standard deviation), red values give the median PGA or SA and black values give the 84% percentile PGA or SA (+1 sigma/standard deviation).
The use of this nomogram is illustrated for a magnitude (Ms) 6.5 earthquake at a Joyner-Boore distance of 20km by the dashed black line.
Because of slight differences in the pseudo-depth coefficient for the equations for PGA and SA(1s) the SA estimates for very short distances (<5km) are slightly incorrect.
Not that the GMPE of Ambraseys et al. (1996) is used for illustration purposes only and because it can be shown on a simple nomogram. There are many more modern GMPEs that could be preferred for actual seismic hazard assessments.