A summary of strong ground motions observed in the Canterbury earthquake sequence

This paper provides a summary of the ground motions observed in the recent Canterbury, New Zealand earthquake sequence. The sequence occurred in a region of relatively moderate seismicity, 130km to the east of the Alpine Fault, the major plate-boundary in the region. From an engineering perspective, the sequence has been primarily comprised of the initial 04/09/2010 Darfield earthquake (Mw7.1) followed by the 22/02/2011 Christchurch earthquake (Mw6.3), and two aftershocks on 13/06/ 2011 (Mw5.3 and 6.0, respectively). The dense spacing of strong motions in the region, and their close proximity to the respective causative faults, has resulted in strong ground motions far exceeding the previous catalogue of strong motion observed in New Zealand. The observed ground motions have exhibited clear evidence of: (i) near-source directivity; (ii) sedimentary basin focusing, amplification and basin effect refraction; (iii) non-linear site response; (iv) cyclic mobility postliquefaction; and (v) extreme vertical ground motions exceeding 2g, among others

Performance-Based Issues from the 22 February 2011 Christchurch Earthquake

At 12:51 pm local time on 22 February 2011, a Mw 6.2 aftershock of the September 4, 2010, Darfield Earthquake shook the city of Christchurch, New Zealand. The aftershock occurred on an unmapped fault less than 8 km from the city center resulting in the collapse of two reinforced concrete office buildings and one concrete parking garage, and severe damage to numerous others. The region has continued to suffer from aftershocks and further damage to building structures throughout the year following the February earthquake. This paper summarizes the observed damage to buildings in the Central Business District (CBD), with a specific focus on identifying future research to support the development of performance-based design procedures. © Springer Science+Business Media Dordrecht 2014