Ground-Motion Prediction Equation for the Chilean Subduction Zone

A ground-motion prediction equation for the horizontal component of the response spectral values from the Chilean subduction zone is developed. The dataset contains 3774 recordings from 473 earthquakes, including the latest megathrust events that occurred in the country (i.e., 2010 Mw 8.8 Maule, 2014 M-w 8.1 Iquique, and 2015 Mw 8.3 Illapel). The functional form for the median model follows the proposal by Abrahamson et al. (2016). Site effects are estimated based on VS30. An additional model is built using only ground motions associated with measured values of VS30 and reliable Mw estimates (termed the high-quality [HQ] model). The standard deviation of the HQ model is much lower than the main model, particularly the component of the standard deviation that corresponds to site-to-site variability, indicating that better site characterization can significantly reduce the overall uncertainty in ground-motion estimation.