Systematic Ground Motion Observations in the Canterbury Earthquakes and Region‐Specific Non‐Ergodic Empirical Ground Motion Modeling

This paper presents an examination of ground motion observations from 20 near‐source strong motion stations during the most significant ten events in the 2010–2011 Canterbury earthquake sequence to examine region‐specific systematic effects based on relaxing the conventional ergodic assumption. On the basis of similar site‐to‐site residuals, surfical geology, and geographical proximity, 15 of the 20 stations are grouped into four sub‐regions: the Central Business District; and Western, Eastern, and Northern suburbs. Mean site‐to‐site residuals for these sub‐regions then allows for the possibility of non‐ergodic ground motion prediction over these sub‐regions of Canterbury, rather than only at strong motion station locations. The ratio of the total non‐ergodic vs. ergodic standard deviation is found to be, on average, consistent with previous studies, however it is emphasized that on a site‐by‐site basis the non‐ergodic standard deviation can easily vary by ±20%.