Model Validation of Recent Ground Motion Prediction Relations for Shallow Crustal Earthquakes in Active Tectonic Regions

Recent earthquake ground motion prediction relations, such as those developed from the Next Generation Attenuation of Ground Motions (NGA) project in 2008, have established a new baseline for the estimation of ground motion parameters such as peak ground acceleration (PGA), peak ground velocity (PGV), and spectral acceleration (Sa). When these models were published, very little was written about model validation or prediction accuracy. We perform statistical goodness-of-fit analyses to quantitatively compare the predictive abilities of these recent models. The prediction accuracy of the models is compared using several testing subsets of the master database used to develop the NGA models. In addition, we perform a blind comparison of the new models with previous simpler models, using ground motion records from the two most recent earthquakes of magnitude 6.0 or greater to strike mainland California: (1) the 2004 M 6.0 Parkfield earthquake, and (2) the 2003 M 6.5 San Simeon earthquake. By comparing the predictor variables and performance of different models, we discuss the sources of uncertainty in the estimates of ground motion parameters and offer recommendations for model development. This paper presents a model validation framework for assessing the prediction accuracy of ground motion prediction relations and aiding in their future development