ABSTRACT
The Christchurch earthquake series from September 4 2010 to 13 June 2011 comprised six damaging earthquakes. Detailed analyses of the comprehensive set of strong motion data recorded shows that the 4 September event was approximately 0.7 times the Ultimate Limit State (ULS) design level specified by the New Zealand seismic loading standard over the period range of 0.5 to 4 seconds, the 22 February event was 1.5 to 2 times the ULS and the largest 13 June earthquake 0.9 times ULS. While the duration of strong shaking of each earthquake was short (around 10 to 15 seconds) the cumulative duration of strong shaking was over 60 seconds.
