It has now been fifty years since the first model for the prediction of earthquake ground motions accounting for both magnitude and distance dependence was derived directly from strong-motion data (Esteva and Rosenblueth, 1964). Such models are now called: ground-motion models or ground-motion prediction equations (GMPEs), but originally were referred to as (strong-motion) attenuation relation(ship)s. Models are currently published at the rate of more than one a month and at the last count the total number of equations for the prediction of peak ground acceleration (PGA) was roughly 300 (Douglas, 2011). They are one of the key components of seismic hazard assessment since they predict the median ground motion at a site and its variability given the occurrence of a particular earthquake at a certain distance. The purpose of this study is to summarise the current state of the art in the field of GMPEs...
