An Adaptive Ground Motion Prediction Equation for Use in Low-to-Moderate Seismicity Regions

In regions of low-to-moderate seismicity where representative strong motion data is lacking, the modelling of seismic hazard relies on the use of seismological models. This paper presents a set of expressions that can be used as ground motion prediction equations that have been transformed from seismological models which resolve the generation of seismic waves into several components. The feature of this presented set of expressions is that it can be adapted to represent earthquake ground motion behaviour that is defined by a diversity of seismological models. The motivation behind the development of the presented adaptive predictive relationship which is known as the Component Attenuation Model (CAM) was to fast track, and make transparent, the transformation from seismological models to predictions of response spectral values for engineering applications. Thus, CAM can be used to waive away the need of executing any software for undertaking stochastic simulations nor time-history analyses for calculation of the response spectral ordinates. An important and original, the feature of CAM is incorporating the shear wave velocity profile of the bedrock and the associated upper-crustal modification into the model. This article presenting CAM is essentially a contribution to engineering as opposed to seismology. The potential benefits derived from the fast-tracking can be considerable given that the transformation is seldom a one-off process and would need to be repeated for any given targeted area, in view of uncertainties surrounding seismological conditions of the earth crust around the globe.