On 22 February 2011, a 6.3 magnitude earthquake struck Christchurch shortly before 12:50pm at a shallow depth of four kilometres. Several aftershocks were reported, some registering at a 5.6 magnitude. This was the second major earthquake to hit the city; the previous quake occurred on 4 September 2010 and registered at a 7.1 magnitude. Civil defence declared a category 3 emergency, the highest possible for a regional disaster.
The Christchurch earthquake caused extensive damage to infrastructure and buildings. Multiple buildings collapsed, and the city was impacted by burst water mains, flooding, liquefaction and power outages. The port was damaged, and many roads cracked. More than 4,500 vehicles were stranded in the city centre during the recovery period. Schools were closed; the Christchurch airport remained open only for emergencies.
As a result of both the September 2010 and February 2011 earthquakes, 10,000 homes needed to be rebuilt and 3,500 demolished.
There were 185 deaths as a result of the earthquake, and 6,659 major injuries (in the first 24 hours).
According to the Australian Department of Foreign Affairs, 8,000 Australians were registered as being in the Canterbury region during this period. Of these, 350 were registered as being in Christchurch. One Australian was among the confirmed 185 fatalities.
During the rescue effort, 600 Australian emergency services workers assisted with the recovery efforts, including, police, search and rescue, medical and forensic experts.