December 2011 Christchurch earthquakes

On December 23, 2011, at 1:58 pm, a magnitude 5.8 earthquake struck east of Christchurch, followed by three more quakes within the next two hours, measuring 5.0, 5.4, and 5.9. These earthquakes were offshore, east of the city, on faults under Pegasus Bay, at depths ranging from 7 to 10 kilometers.

The city had already experienced significant seismic activity, including the 2010 Darfield earthquake, which caused the biggest ground shaking recorded in New Zealand at the time, and the devastating February 2011 earthquake that resulted in 185 deaths. A 6.0 earthquake in June 2011 had also caused further damage.

These December quakes caused liquefaction and flooding, particularly in eastern suburbs like Avondale, Bexley, Burwood, New Brighton, and Parklands. Parklands also lost its sewerage and water supply, and the liquefaction led to road closures. The 1:58 pm quake left 26,000 properties without electricity, though most had power restored by the next day. The telecommunications network was strained, and people were encouraged to use text messages. Gridlocked roads were also a problem as people tried to get home.

A magnitude 4.3 earthquake the following day broke a water pipe, leading to homes in Redcliffs and Sumner losing their mains water supply until it was restored that afternoon. Hospitals like Christchurch and Princess Margaret used boiled water as a precaution, and Burwood Hospital had to use backup power and temporarily move its birthing unit.

There was also rock fall from the Port Hills, affecting Sumner and Redcliffs, though the worst of it hit shipping containers used for protection. Cliffs near Boulder Bay on Banks Peninsula collapsed, and an uninjured family was rescued from there.

St John, the ambulance service, received around 140 emergency calls and treated about 60 patients for issues including falls and anxiety. One person died after tripping on uneven ground. An unoccupied house and a partially demolished building collapsed. The rose window of Christ Church Cathedral, already damaged, collapsed, and its western wall sustained more damage. The Hornby Clocktower building was badly damaged and later demolished, and two apartment buildings at The Terrace on the Park were demolished in February 2012 due to major damage.

By September 2012, the Earthquake Commission had received over 48,000 damage claims and paid out $15.4 million. A state of emergency was declared in Canterbury, and the City Council set up an Emergency Operations Centre. Christchurch Airport was evacuated and closed for inspections but reopened for flights at 6 pm after no runway damage was found. All city shopping centers were temporarily closed as a precaution.