Lessons from the February 2011 M6.3 Christchurch Earthquake

A magnitude 6.3 earthquake struck Christchurch, New Zealand at 12:55 pm on 22nd February 2011 resulting in liquefaction, rockfall and shaking induced building damage. The peak horizontal ground acceleration of 1.68 g was much higher than the design level of 0.22 g and it is much greater than that recorded in most other earthquakes around the world. The severity of shaking was due to the fault proximity to Christchurch, the fault rupture mode and local site effects/conditions. The death toll was 185 mainly due to building collapse. Backgrounds to a number of post-earthquake decisions are described. These relate to: the level of shaking to be considered in future Christchurch building designs; earthquake-prone buildings; University of Canterbury reactions; governmental response; engineering community activities; insurance company issues; and decisions by citizens affected by earthquake damage. Major lessons learnt relate to the effects of severe earthquake shaking, ground deformation and aftershocks on loss and recovery, the need to develop better assessment and repair methodologies, and the need to develop buildings which will sustain much less damage in future earthquake events.