At 12.51 p.m. on 22 February 2011, the Canterbury region was struck by a magnitude 6.3 earthquake. At the time it was still recovering from the effects of a 7.1-magnitude earthquake on 4 September 2010.Though smaller than the first quake, and technically part of its aftershock sequence, the February earthquake was more destructive.
https://nzhistory.govt.nz/culture/february-2011-christchurch-earthquake

